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Korg DW-8000 with battery leak damage and repair.
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Korg DW-8000 with battery leak damage and repair.
YashN
Got this :



It has several issues:
1. The battery leaked and was removed. There's nothing where the battery used to be right now.
2. There appears to be some acid damage to the circuit just below the battery location (see pic below)
3. Some keys don't trigger notes
4. All notes are the same note (strange thing, first time I come across this)

How would I test the circuit for damage and then repair it?

YashN
Look what happened today after I spent some time last night opening it up and cleaning the circuit up, and also pushing in the connectors:

[s]http://soundcloud.com/yashn/dw-8000-strings[/s]

Only internal DW-8000 effects (delay with lots of feedback, giving it a reverb feel) with Nebula (AlexB TFT console and CDSoundMaster R2R Revox Tape), played from the Kurzweil.

sound fantastic here: 8 stunning analog Korg NJM2069 filters.

Bliss. Guinness ftw!
Matos
Yeah! Glad you got it sorted out. Looks like an interesting sound generator. Never heard much about these before.
YashN
Matos, it's the filters my friend. The same one as on the Poly-800, except that as its name doesn't indicate at all, the Poly-800 is actually paraphonic: 8 voices but with a single analog Korg NJM2069 filter (but DCO, i.e. digitally controlled VCOs).

The DW-8000 has 8 of these (but Digital Oscs).

That filter is strong, brash, smooth, creamy, aggressive, lush, superb.

It's in the DSS-1 as well. And some people say it's up there with the best CEMs and SSMs and that it's the best filter Korg ever put in an analog synth.

This, together with the $100 Micron is probably the best value purchase I've ever made.

I'm so happy right now as I nearly thought of putting the NJMs up for sale...
Matos
Ahhhh , the filters. I'm going to have to get my google on and read more.
dougt
Usually lithium batts don't leak like that unless someone installed it backwards or something. Are you sure it's from the battery and not something that spilled into it?

Interesting that you have the all keys playing the same note problem - my EX8000 has the same problem. I thought it might be some invalid patch data but a full reset hasn't solved it.
YashN
Hi Doug,

They are less prone to leakage than the other coin batteries and other non-coin ones, but this one still did. I actually also took the battery from the seller as a souvenir and the greenish residue does come from its edge.

The sounds on the DW-8000 are awesome: lots of superb strings, pads, brasses and clangorous tones too.

Did you try removing the connectors, cleaning them up and putting them back?

Also, try a power on while maintaining 5 and 8 and re-send the patches by SysEx.

Apart from cleaning and brushing the board myself last night and pushing the connector back in, I am not too sure what else I could have done to make it work.

However, the following is something I tried yesterday with all the filters while the Arpeggiator was on, and hence I knew that I would be able to make it work at one point: connect the penultimate pin down on the left to the third pin from the top on the right.

This should be pin 10 to pin 20.

When I did this, I heard the notes arpeggiating correctly, so I deduced that the synth is working correctly up to the voice + filter board and that perhaps the issue was the next board, i.e. the one holding the battery.

I guess the cleaning and brushing gave it the final kick and maybe pushing those connectors too.

I am really, really tempted to try and do an External Audio into VCF mod on this synth. First, I need to get a new battery holder and battery there, and maybe fix some of those non-triggering keys.

An aside:
Thanks to the other DougT's inspiration about salvaging parts this summer, I practised and managed to repair the broken encoder on an Alesis Micron. Desoldering it was a lengthy process, but I had perfected the craft somewhat. smile Thanks. we're not worthy
YashN
That pin 10 to pin 20 connection actually takes the VCA out and feeds it back into the filter input signal Mix #2.

Since I could hear different pitches then, it possibly meant that the voice boards were actually working correctly. The issue must therefore have been elsewhere is what I thought.

Also on my synth, that keybed is the same technology as my resurrected and used JX-8P. I remember botching some key contacts while repairing the aftertouch, and that would make several notes not work.

I wonder if the keybed also had a role on the DW-8000. Most probably it was interfering somewhere. Maybe the residues were short-circuiting something too.

A good brushing with acetone was necessary.
dougt
OK yeah I'm sure the problem is on the CPU board not the voice boards. Do you know at what point did you get the correct key pitches back? Was it after you send the sysex dump?
YashN
Sometime between last night and tonight and the synth was off the whole day, so it can't have kept any patches.

So I'd say that probably the issue was already gone last night but then I was off to sleep without noticing it or else the issue was gone today when I put it on and had to transfer patches again.

Hard to say precisely, but for sure, transferring patches can help since if there's any memory corruption or erasure, some parameters like 84 will be set to gibberish values.

Keep me posted.
dougt
Well I've sent it sysex dumps, cassette dumps, and done resets but no luck.
LektroiD
I'm thinking of selling mine, it's been in my storage room for months, has a great sound but don't have the space for it in my main setup.

I do love the filters, I wonder if anyone has cloned the filter section?

I've seen a few Korg filter clones on modulars, but never a DW8000 clone.

If anyone does a run of these, let me know! hyper
YashN
We could 'dive in' together and see where we get and discuss notes, and it will sure be good along the way to get your thoughts about any mods to it e.g. External Audio into the VCF as I did to my Korg Poly-800 except this time, there are 8 filters...

I do need to dive in again since there are non-triggering or stuck keys, so I'll probably have to remove the keybed and work on it completely. I am fortunate that the single note issue seems solved: the synth engine is working perfectly.

dougt wrote:
Well I've sent it sysex dumps, cassette dumps, and done resets but no luck.
YashN
Wonderful filters indeed. I've never ever come across a clone. There is at least one instance where somebody took the chip and built a modular filter unit with it, but not a clone. Korg was very secretive on the internals of their filters.

LektroiD wrote:
I do love the filters, I wonder if anyone has cloned the filter section?

I've seen a few Korg filter clones on modulars, but never a DW8000 clone.

If anyone does a run of these, let me know! hyper
YashN
Doug, here are a few things I would have checked:

1. Battery installed and functioning properly
2. Perform the whole of the adjustment procedure in the service manual
3. If this still does not do it, recap the power supply and repeat steps 1 & 2
4. If this still does not do it, recap the whole boards and repeat steps 1 & 2

It's pushing 25 years, and based on what I've read these past two days, I'd better recap it some day as well.
YashN
The areas between IC47, IC48, IC49, IC50 and the two capacitors above is the area I cleaned thoroughly.

The case is sturdy, mostly metal on the lower case, and mostly plastic on the upper case. On opening, the two sections aren't hinged like the JX-8P, so you are in an awkward position if you want to both dabble with the synth settings and test inside the synth for mods or anything else. I will need to find a way to elevate it sufficiently so that there's enough space for the audio, MIDI and power cables to still be connected without being bent or pressured and be able to put the two parts at right angles or so.

On the docket:
1. Installing a new battery (already purchased, no battery holder for now, so I'll probably do one myself)

2. Inspecting, cleaning and repairing the key-bed (non-triggering, badly triggering notes)

3. Cleaning the switches as they are not acting solidly (bought some cleaning spray with a very small tube)





fonik
yes, the filters! i have a DSS-1, and he filters make it sound special. the DCO's are common 12bit, so it is obvious to me.
i even thought of buying another DSS-1 just to salvage these ICs - alas, this might break my heart, since i love the DSS-1...

oh, YashN: awesome job you do!
YashN
Here you are again, after I just replied to you on the other forum wink Great minds, great minds.

I love this filter, Fonik, love it, love it.

Quote:
oh, YashN: awesome job you do!


Barely, barely, but thanks. I was quite close to envisioning extracting the filter chips and selling them separately. Heaven made it so that after some cleaning and connector-pushing, it's aliiiive!

I want to fix it as much as possible and then plan some enhancements to it, with the help of Doug and other knowledgeable brothers-in-synth-diy-arms.

Last night I cleaned up the upper plastic casing and rubbed hydrogen peroxide on the keys. You wouldn't imagine the amount of greasy dirt on that casing and the grime on the keys. Or, since you may have bought some second-hand equipment yourself, you would imagine exactly how it is!

I think I have become something of a nostalgic old man, because seeing poly analog synths mistreated like this makes me sad. People don't know the value of these instruments.

And yes I know the DW-8000 uses digital oscs, but it's a polyphonic analog/hybrid with real analog filters, and those filters... wait till I manage a realtime Cutoff Frequency and Resonance mod on it, it will scream. There's a reason the original mod on the Poly-800 is called the Moog Slayer. While some would argue it wouldn't slay any Moog, I would argue it would be better called a 'Speaker Slayer' or an 'Amp Slayer'. This filter, with the mods, wants to kill other equipment.

So, to recap (no pun intended razz ) it's a bit sad how people dismiss these instruments (yes they are machines, but also instruments, to make music, with beautiful, beautiful sounds), but it's also a newly welcome blessing in my life, as I discover and re-discover the joys of analog (or hybrid) electronic synths and manage to obtain them at bargain prices.

Here is also the moment to thank the other DougT again for his inspiration about salvaging parts and building one's own synth - I came across his blog this summer while thinking about building my own modular synth and learned to salvage parts and desolder parts. This helped build confidence and was knowledge and practical experience which came in handy when repairing my broken Micron bought used.

So, with this thread, I am hoping to perfect my own knowledge of synth DIY and repair, as well as help others including Doug if possible since his issue was one of mine of the DW-8000, and perhaps plan some mods to the DW-8000. Wouldn't that be awesome and beautiful to have been inspired and helped on this journey and to be able to inspire and help others in return?

Here are some pics of it after partly cleaning the plastic upper cover with glass cleaner and wiping the white keys with Hydrogen Peroxide. The black keys still need to be cleaned. You can see the cleaning spray with the tiny precision tube as well as the replacement Maxell CR2032 3V coin battery.







Tonight, I'll tackle the keybed and switches if possible.

fonik wrote:
yes, the filters! i have a DSS-1, and he filters make it sound special. the DCO's are common 12bit, so it is obvious to me.
i even thought of buying another DSS-1 just to salvage these ICs - alas, this might break my heart, since i love the DSS-1...
YashN


That should clear any doubt about the capacity of this battery to leak and damage the board. I am not sure it's the original battery but it could be: a Sanyo Li-Mn.
YashN
I used a canister of Nexxtech "Contact and Head Cleaner". Relatively expensive as everything at The Source. Should have bought the canister at the small shop a few streets away.

Composition:

    Isopropanol
    Isobutane
    Butane




Spray between the switches and around them while the synth is on, and click the switches in turn until they work well.

Note: do not spray this on the faders. You'd need a cleaner with lubricant for these.



Note the white residue left on the upper panel. This suggests that this mixture is actually not that good of a cleaner, since if the same residue accumulates between contacts, it can decrease their efficiency when dry.
YashN
Now, this synth is unhinged, unlike the interior of the Roland JX-8P as previously mentioned. So, there's no way to hinge it properly when open and keep it powered while accessing the upper panel.

Things are totally different when the keybed is removed as you will see. Then the parts can be set up in all sorts of easy configurations.



Labeling the keyboard cables and cutting them free (not cutting them...)



Check whether you labeled every cable. I had missed one.



The keybed is unscrewed and removed.



The synth is tested keyboard-less and still works.



This is just one way you can position the Keybed, connect it again with the synth open. To be able to do this, you need to unscrew the small keybed PCB:

YashN


Spraying between the middle and lower contact, I cleaned all of the keys.

To clean the other contact, press the key and then spray between the middle contact and the upper contact.

Here I reached another milestone as all keys started triggering when tested this time. Hurray!
YashN
Bought a Maxell 3V CR2032 and didn't manage to get hold of a coin battery holder.



I soldered two thin wires I extracted from an ethernet-type cable to the board, red for positive and black for negative.



These leads were cut long enough so that I could route them both through a single heat vent slit in the lower case and still have some length to spare outside.



Since I have nothing better for now, I taped the two wires to the new replacement battery and put the whole into the original plastic container of the Maxell CR2032.

This whole new contraption is then taped to the middle of the lower case which is slanted, in such a way as this ultra DIY 'solution' is not very visible, but is easily accessible if there is a need to replace the battery again.

Transferred Data over via SysEx, turned off the synth, turned it on again and all programs were still available.

Battery mod successful.
YashN
Found the DW-8000 service manual online and performed some of the easy adjustment procedures verification. I don't have an oscilloscope handy nor a digital voltmeter.



YashN
In Adjustment mode 2, the green LED screen will change every time a key is hit. This is useful to diagnose all keys, together with sound if possible.



During this final test, I mark the dodgy keys which sometimes get stuck or which sometimes have some trouble triggering or which trigger with a lower velocity using a removable marker:



I repeated the contacts spraying procedure until I was happy with:
1. All keys triggering
2. No keys get stuck on ON
3. All keys have velocity working properly
4. All keys triggering and effecting aftertouch properly.

Success!

In the following picture, you can see layers of grime and yellowing. I cleaned this with Hydrogen Peroxide.

YashN
Before doing all this, of course, I couldn't help tinkering with a wire inside connecting the NJM2069 pins for feedback and with the voice ICs. There were some fun effects. I also turned a few of the semi-fixed adjustment pots like resonance and VCA. In fact, I am tempted to turn these pots to their maximum to drive the filters, but for now have put them back in their original position.

I would like to perform these mods:
1. External Audio into VCF (pin 19)
2. Getting the 12dB output switchable from the 24dB
3. Realtime Cutoff Frequency Control pot
4. Realtime Resonance Control pot
5. Perhaps some AM or FM from the Oscs to the Oscs or to the VCF Cutoff Freq respectively.
YashN
To recap:

1. Single Note issue

Cleaning circuit board and re-inserting connectors: All notes now transposing. Status: Ok!

2. Malfunctioning switches

Cleaning switches with contact cleaner spray: All switches now working normally. Status: Ok!

3. Non-triggering notes and other keybed issues (stuck notes, low velocity)

Cleaning key contacts with contact cleaning spray: All keys trigger, no stuck notes, all keys with aftertouch, all keys with velocity. Status: Ok!

4. Battery missing - memory loss at each power cycle

Soldering battery leads extension and makeshift battery holder stuck to external portion of lower casing. On powering off then on, all patches are still in memory. Status: Ok!

5. Dirt, grime and yellowed keys

Cleaning up with glass cleaning fluid and treating the keys with Hydrogen Peroxide. Status: Ok!

It was a moderately easy restoration. And I am very happy about it.

Guinness ftw!
fonik
YashN wrote:
3. Non-triggering notes and other keybed issues (stuck notes, low velocity)

Cleaning key contacts with contact cleaning spray: All keys trigger, no stuck notes, all keys with aftertouch, all keys with velocity.

what's the actual mixture/agent of the contact cleaning spary you used? i still have to do this job on my DSS-1 (already replaced the floppy w00t ).
Paradigm X
its really good youve documented all this so well with photos, help anyone else out whos got issues. Very helpful.

/looks on ebay for a dw8000!

Cheers
YashN
fonik wrote:
what's the actual mixture/agent of the contact cleaning spary you used? i still have to do this job on my DSS-1 (already replaced the floppy w00t ).


See the post entitled 'Switch cleaning' in this thread with the first photo of the spray and the switches.

I came across a good mod for the DSS-1 to use a new USB or smart card interface instead of the floppy. I don't know if this is still available, but it would be worthwhile.
YashN
Paradigm X wrote:
its really good youve documented all this so well with photos, help anyone else out whos got issues. Very helpful.

/looks on ebay for a dw8000!

Cheers


Thanks Paradigm X thumbs up

Good luck on finding one and enjoy the sounds once you do.
fonik
YashN wrote:
I came across a good mod for the DSS-1 to use a new USB or smart card interface instead of the floppy. I don't know if this is still available, but it would be worthwhile.

i saw this. i found it being too expensive IIRC. YMMV though.
YashN
I think it's actually a great idea and not just for the DSS-1. If one could have a small device with SysEx transfer, instrument selection and an SDCard to use with all synths that would be rather awesome.

fonik wrote:
YashN wrote:
I came across a good mod for the DSS-1 to use a new USB or smart card interface instead of the floppy. I don't know if this is still available, but it would be worthwhile.

i saw this. i found it being too expensive IIRC. YMMV though.
YashN
Looks like I confused one Dougt with another Dougt hihi
YashN
Hunting high and low for DW-8000 mods, I found some stealth information from Sean Ellis on Analogue Heaven, posted a long time ago. I actually wrote to Sean, not sure whether he had the same email address still and asking for details. He replied that coincidentally, he was just looking at this very thread.

As I say, there are no coincidences wink

Hi Sean, if you're reading this again thumbs up

Tonight I spent some time tinkering with his idea of a global Audio input into the VCF, and had a good measure of success.



Here you can see that I'm tapping onto the +ve leg of the Capacitor as indicated with a resistor in series (not shown), and this allows the external audio to be controlled by the filter cutoff frequency, the resonance and all the other internal parameters.

Results:

1. External Audio into the VCF for a whole track, Cutoff, Res and delay (which you hear as I close the filter) as well as some increase of the Arpeggio speed:

[s]http://soundcloud.com/yashn/dw-8000-external-audio-into[/s]

For this example, I've had to put the arpeggiator on, as the sound would get into the filter only when a note's VCA is 'on'.

2. External Audio into the VCF from the Kurzweil K2500 Oscs. It sounds really organic and sounds just as analog and sweet expected, despite the digital Oscs.

[s]http://soundcloud.com/yashn/dw-8000-kurzweil-oscs[/s]

Here, I wire the Kurzweil's MIDI Out into the MIDI In of the Korg, so every key pressed on the Kurzweil triggers the corresponding note on the Korg, so there was no need to have the arpeggiator on.
YashN
All right, I had fun with those digital oscs, and now it is time to test all analog oscs into the Korg's NJM2069 filters.

Ladies and gentlemen, I thereby present you the Korland JXD-8000P:

[s]http://soundcloud.com/yashn/jx-8p-oscs-through-dw-8000[/s]

Roland JX-8P oscillators in XMod mode into Korg DW-8000 Filters.
Poly->Poly,
Poly->Unison2,
Unison->Unison2,
Unison2->Unison2,
Solo->Unison2,
Solo2->Unison2

Recorded with Nebula AlexB TFT Console Emulation.

Excuse the sloppy playing and some distortion at times.
YashN
This week's experiment:

Controlling the DW-8000's global Resonance and Filter Cutoff Frequency with an Arduino UNO.

From the Arduino, I have programmed 3 different CV signals. These signals are sequenced in 8 steps with randomized CV levels and delays between each step. One such CV signal is sent to the Global Resonance. Another one is sent to the Global Cutoff frequency but the effect currently is mild as I still need to rewire things differently.

You can hear varying Resonance in this extract:
[s]http://soundcloud.com/yashn/dw-8000-and-arduino-cv[/s]








Extreme DIY: when you don't have a steady spare finger, use a piece of scotch tape.
drip.feed
I am LOVING this thread. It inspired me to open my DW8000 last night and replace its flat battery. Unfortunately it made no difference - my synth loses its presets when I power off. BOO! Maybe I screwed up the soldering job.
YashN
Glad you like the thread, Dripfeed.

Check the connections again. I am wondering if I should really solder to the other lead or it's there for physical stability.

Have you tried the external audio in?
drip.feed
YashN wrote:
Check the connections again. I am wondering if I should really solder to the other lead or it's there for physical stability.

Stability I think. I actually soldered a 2-legged battery holder into the location but wired it into the board with 3 wires. But, like an idiot, I didn't check that I was getting 3 volts across the tracks on the underside of the board. I assumed my soldering skills were good enough.


YashN wrote:
Have you tried the external audio in?

Do you mean reloading from tape? I actually have a standalone MEX memory bank for my DW8000. The synth plays fine if I reload it from that. It just doesn't remember anything when I turn it off confused
YashN
drip.feed wrote:
Do you mean reloading from tape? I actually have a standalone MEX memory bank for my DW8000. The synth plays fine if I reload it from that. It just doesn't remember anything when I turn it off confused


No, I meant the External Audio into VCF mod as I demonstrated above.
drip.feed
YashN wrote:

No, I meant the External Audio into VCF mod as I demonstrated above.

Oh, lol No, not yet. I'm too busy with my Dark Energy to devote much time to hacks like that. I will probably try it some day though, now that you have explained how to do it.
kjackman
This is awesome. I have a DW-8000 and a DSS-1 sitting idle. Be nice if I could mod them to work as CV-controlled filter banks, install jacks on the outsides of the cases, and just plug them into my rig and use them like "normal" modular analog filters. In a non-destructive way, I mean. So I could still use them as intended when they're not acting as modules.

That would probably take a LOT of modding.
YashN
drip.feed wrote:
lol No, not yet. I'm too busy with my Dark Energy to devote much time to hacks like that. I will probably try it some day though, now that you have explained how to do it.


But, but, the DW-8000 is also dark and has plenty of energy hihi
YashN
Thanks kjackman. It's not a lot of modding actually, a decent small project with lots of potential. It depends if you are looking for an 8-channel LP Filterbank or a single-channel LP filterbank with 8 peaks. Also, would you want to control each filter separately? If so, you would also need to wire pots for each. Then, for all this to be non-destructive, you would need switches too or perhaps those special jacks which have an internal switch inside. You would also need jacks for external CV inputs probably.

This is a good idea of what is involved in the simpler case as a guy did that with his Kawai K3m: Kawai K3m Filter Bank mod

The simple External Audio into VCF mod as described above allows you to pass a single channel into a global VCF input.

I read some obscure posts on the Yahoo group about tapping into the Capacitor which is higher than the one I used.

To make this mod correctly, I would still need to mount the ICs onto sockets and disconnect then rewire some of the pins correctly.

Resonance would be easier to tackle first as it has a single pin on the IC that is affected and a simple 0-3+V range whereas the Cutoff Frequency is linked to 2 pins on the relevant IC, and also, has a weird range of -3+V to 0 to +3V for its full values, so I would need a voltage divider here.

I guess an order for parts is... in order...

kjackman wrote:
This is awesome. I have a DW-8000 and a DSS-1 sitting idle. Be nice if I could mod them to work as CV-controlled filter banks, install jacks on the outsides of the cases, and just plug them into my rig and use them like "normal" modular analog filters. In a non-destructive way, I mean. So I could still use them as intended when they're not acting as modules.

That would probably take a LOT of modding.
YashN
Just a heads-up for switching the filter to 12dB mode.

Thought this would be super easy with an 8PDT switch but this is a very rare component indeed. So right now, I am investigating with other people how to best implement this, for instance with a couple of 4PDT switches or analog switches.
cupwise
any updates on this?

btw, which value of capacitor would be best before going into the chip?
YashN
Try the connection as shown above and hear for yourself.

Not sure why you are asking for a capacitor value here. Resistors would be in order though.

cupwise wrote:
any updates on this?

btw, which value of capacitor would be best before going into the chip?
dslocum
I have a working DW8000 and a second for parts that's almost working. I just need the time... Well, you know. very frustrating

Anyway, I think I recall the keybed using silicone strip type contacts (or maybe not - can't recall exactly). I had a couple of funky keys when I got it, and ended up taking the entire keybed apart and LIGHTLY cleaned the pcb with rubbing alcohol and QTips, and contact strips with warm water with a tiny drop of dish detergent - letting them air dry.

One of your springy rubbery things may be stuck down, or there's something conductive on the pcb. ???? seriously, i just don't get it

Good luck.
YashN
dslocum wrote:
One of your springy rubbery things may be stuck down, or there's something conductive on the pcb. ???? seriously, i just don't get it
Good luck.


Could be, but cleaning the keybed contacts seems to have done the trick. Sometimes the keyboard still has some issues, but since I'm controlling it all with a Kurzweil K2500XS and an iPad for the parameters, it's fine for me.
Francesco64
Hi! I am the newest member of this Forum. I am a proud owner of a DW8000 and of an EX8000. I read that there's a problem about same note, whatever is the key pressed. Maybe the copper trails of the circuit close the battery leakage are under a short-circuit? Well, now to my problem: I read here that a guy tried to improve the resonance, output an so on, using a screwdriver on the white pots on the oscillators board. Interesting, and I myself tried to do this, with the only achievement of messing up totally the synth!!! d'oh! I have a Pdf of the service manual, but it's barely readable, and I am not so good with electronic testers. Is there anybody here who can help me? Sorry for my english, I am italian. Oh, by the way there's a guy on Youtube who shows this marvellous machine modded with the result of adding of LOTS OF WAVEFORMS to the original wavwtable! A dream! Unfortunately, he says on his webpage he doesn't want to loose time in order to show somebody else this modding. Well, I can understand, but I would pay for this , even if only for a DIY documentation.... What would You all think to write all together to him? His name should be Glenn Stegner, or something. Let me please know if it's interesting for Your ears.
All the best,
Francesco.
Francesco64
Sorry, everybody!! I had in mind a guy who is involved in a good Dss1 resource page and a Vsti maker! d'oh! The name of the modder is Chris Strellis

http://www.strellis.com/dw6000.shtml

http://www.youtube.com/watch?v=XyQyGtIZbSk .

Synthasy2000 wrote:

"Ulrich Schnauss DW8000 Waveform Expansion Mod by Chris Strellis

32 selectable banks of 16 waveforms. The banks can be changed at any time for PPG like sounds.

This is very much an early prototype with a lot of time consuming custom work required.

I'm not intending to offer this as an kit for self installation as the quality would not be professional enough.

Similarly I won't be offering an installation service as the cost would be too prohibitive because it is very time consuming and I have precious little of that at the moment."

Chris Strellis wrote:

"Forget about the presets and their "banks". This is strictly a waveform expansion. These new waves come in banks of 16. Bank 1 of the waveforms is the same as the originals. Banks 2 to 32 and completely new banks of 16 different waveforms making 256 less 16 totally new waveforms.

I hope this helps."


calyx93 :

"Very cool - is the mod very difficult?"

Synthasy2000 :

"Yes and no wink

The first realisation of the modification is the hardest with loads of software to write, logic to program and ROMs to extract without damage to the board or ROM.

After that it isn't too bad but you need to desolder the 4 ROM chips, drill a hole and cut out a section for the display and attach wires.".

Well, that's all folks. See You!
Francesco.
BrianD
Hi - This is a very informative thread, and I was hoping someone might help me with this problem:

I have 8 dead keys (from C to G). After cleaning the contacts (which didn't restore sound), I removed the key contact assembly and found that the dead C is right at the PC split on the contact board. The diodes in that section all seemed to be working so I replaced the assembly and reconnected everything. The 8 keys were still dead, but when I fiddled with the PC board (by pressing on it) the keys came back. I put the synth back together, hooked it up and it played beautifully. However, when I went back to it a few minutes later (hadn't turned it off) the 8 keys were dead again - all others played fine.

Anyone have an idea on a permanent fix?

Thanks,
Brian
YashN
cupwise wrote:
any updates on this?

btw, which value of capacitor would be best before going into the chip?


Ah, Cupwise, just re-visiting this thread after a bout of insomnia and thinking of hacking on the DW-8000 again, I totally misunderstood your question.

One capacitor which I know for sure works is the one shown in one of the pics above (C65), upper leg if you are looking down on the circuit with the keyboard placed normally. All the sound examples with Audio into the global VCF were recorded this way.

Will need to find out about that other higher Cap if it helps.
YashN
Francesco64 wrote:
Hi! I am the newest member of this Forum. I am a proud owner of a DW8000 and of an EX8000. I read that there's a problem about same note, whatever is the key pressed. Maybe the copper trails of the circuit close the battery leakage are under a short-circuit? Well, now to my problem: I read here that a guy tried to improve the resonance, output an so on, using a screwdriver on the white pots on the oscillators board. Interesting, and I myself tried to do this, with the only achievement of messing up totally the synth!!! d'oh! I have a Pdf of the service manual, but it's barely readable
Francesco.


Come stai, Francesco?

Try this one, it looks very readable, you will want to try the test/adjustment procedures in the three last pages or so:

Korg DW-8000 Service Manual

The synth just needs to be adjusted a little, it's not totally messed up, but calibration has been undone.

As for Chris's mod, it is awesome, relies on FPGA and some wave hacking. I think he planned to market the mod at one point, but maybe he changed his mind. It's a very tough mod to build initially. Chris is very, very good indeed to have managed that.

Rather than try and do this (I think it would be way too difficult), I will use the External Audio input into VCF mod. That should be much, much simpler and allow plugging other hardware into the Korg DW-8000 to 'modularize' it a little.
YashN
Not too sure where the issue is, but if it's a connector or an IC, you could try just re-heating the solder joints to make sure the contacts are well made again as with time, solder joints can develop hairline cracks which are detrimental to proper conductivity and contact.

BrianD wrote:
Hi - This is a very informative thread, and I was hoping someone might help me with this problem:

I have 8 dead keys (from C to G). After cleaning the contacts (which didn't restore sound), I removed the key contact assembly and found that the dead C is right at the PC split on the contact board. The diodes in that section all seemed to be working so I replaced the assembly and reconnected everything. The 8 keys were still dead, but when I fiddled with the PC board (by pressing on it) the keys came back. I put the synth back together, hooked it up and it played beautifully. However, when I went back to it a few minutes later (hadn't turned it off) the 8 keys were dead again - all others played fine.

Anyone have an idea on a permanent fix?

Thanks,
Brian
YashN
An even better Service Manual Korg DW-8000 [PDF]
YashN
For Cupwise and for reference, the other capacitor I have seen mentioned with respect to the External Audio Input mod is C61 (using the + leg).

My own tests were performed with the + leg of C65.
YashN
Found and fixed a surplus Stereo Switching input Jack from my Addison supply, so I thought of taking this mod again.

But first, I took the battery holder from the Poly-800, removed the extension leads from the DW-8000 battery spot, then wired in the battery holder, so that I can have the DW-8000 keep the sounds in memory during experimentation. This helps because the leads had stop working, and I would have had to re-transfer sounds via SysEx each time.

Now, for the External Audio Input, I chose to experiment with C65 again, since on the schematics, what I believe is that if we go through C61 instead, we are not really bypassing the noise circuit, but rather integrating into it.

C65+, on the other hand, is where the total noise signal is injected through a resistor and IC14.

So the idea is to use the switching jack to allow bypassing the noise circuit without the use of a switch to mount on the front panel.

I pumped solder out from beneath the PCB board, and then lifted C65+.

I wired up leads from C65+ and the via to the jack. I wired the two inputs of the jack together.

The signal was very, very distorted, so I added a 27k resistor to the signal line (which goes to the via). Also experimented adding a small 10uF capacitor on the signal line, and another time from that point to the ground.

The sound is clearer, but I can hear TV or Radio stations as background noise.... I swear I heard ads for Mitsubishi and MasterCard.

I bet if I had attempted to build a circuit to do TV or Radio reception, it wouldn't have worked first time. help
YashN
The plan is to experiment some more with the connection to C65+ and its via, by changing resistor values, and if the radio signals still go through, I will probably insert a small RF filter arrangement near the jack.
YashN
I was wondering why the DW-8000 wouldn't power on today, figured I'd post the result of a 10-second investigation to MilfStraddler:



Back to soldering before tinkering
YashN
This was on Analogue Heaven a few years back by Sean Ellis. Tried it as is but without any switch nor pot for input: it works. It does seem my Kurz oscs output is quite low for feeding it properly so I've had to use the HiZ (DI) button on the mixer input where the DW-8000 output is plugged.

Quote:
The audio input is quite easy since all voices share a common input for the noise source.

The input goes at the junction of C65, R60 and IC14. You should go through a 10-33k resistor (for line signals) and 10uF electro. You'd want to install a
high value (1meg) pulldown resister across the jack too. I am installing an
audio taper pot and on/off switch just above the bender joystick because at
these values the input is a little hot (but overdriving sounds great).
zaphod betamax
Does the Dw8000 suffer from the low volume output as the DW6000 does?
It is only half as loud as my JX3P reference synth.
sammy123
It's pretty quiet. So is the DSS-1.
SonnyBoy
BrianD wrote:
Hi - This is a very informative thread, and I was hoping someone might help me with this problem:

I have 8 dead keys (from C to G). After cleaning the contacts (which didn't restore sound), I removed the key contact assembly and found that the dead C is right at the PC split on the contact board. The diodes in that section all seemed to be working so I replaced the assembly and reconnected everything. The 8 keys were still dead, but when I fiddled with the PC board (by pressing on it) the keys came back. I put the synth back together, hooked it up and it played beautifully. However, when I went back to it a few minutes later (hadn't turned it off) the 8 keys were dead again - all others played fine.

Anyone have an idea on a permanent fix?

Thanks,
Brian


I have a similar issue on my DW-8000 (one with an Angel City expansion board). No sound between C3 and G3.
Has anyone found a fix?

Cheers!
r0main
Dear all,
Just bought a used Korg DW-8000, cheap, with only half the voices working (press any keys, first 1-2-3-4 working, 5-6-7-8 are silent), then again 1-2-3-4 ok.
My guessing is that either IC4 or IC15 is not working (on board 662). What can I check to confirm this?

Best regards,
Romain
homesweethome
YashN

You seem to know a LOT about synths in general and especially about the Korg DW-8000, so I would like to ask your precious opinion on what my problem could be. Yesterday I got a beautiful-looking DW-8000, mint condition outside, although there is a couple of problems inside (it seems so). First of all, it messes the octaves and in the lower octaves it sounds like it's playing some notes from higher octaves.

https://www.gearslutz.com/board/attachments/electronic-music-instrumen ts-electronic-music-production/563288d1464795922-weird-korg-dw-8000-wa veform-oscillators-problem-there-solution-faultykorg.mp3

Also, the first four waveforms (the most useful ones) are sounding really dirty, there are artifacts and weird unwanted noise when played. This happens in both oscillators, but only in the first four waveforms of each one. Any possible solution? Should I try to find any new chips? Whatever help is deeply appreciated smile

https://www.gearslutz.com/board/attachments/electronic-music-instrumen ts-electronic-music-production/563292d1464797430-weird-korg-dw-8000-wa veform-oscillators-problem-there-solution-faultymecano.mp3

In the last audio clip I copied the exact settings from the patch used in the following video:

https://www.youtube.com/watch?v=8qwvTjpwRoY

As you can hear, there is no relation between the two. Well, there is some, but in my clip it sounds like it's coming out from a bad radio, really frustrated :(
YashN
homesweethome wrote:
Yesterday I got a beautiful-looking DW-8000, mint condition outside, although there is a couple of problems inside (it seems so). First of all, it messes the octaves and in the lower octaves it sounds like it's playing some notes from higher octaves.


Did you manage some fix? Well worth it.
u0421793
By the way, if anyone's interested, I mentioned the DW-8000 and 6000 and also Poly800 in my video on the Korg iM1 DWGS waves here https://youtu.be/6Mf6_yLhyMc
YashN
u0421793 wrote:
By the way, if anyone's interested, I mentioned the DW-8000 and 6000 and also Poly800 in my video on the Korg iM1 DWGS waves here https://youtu.be/6Mf6_yLhyMc


Cool video!
YashN
r0main wrote:
Dear all,
Just bought a used Korg DW-8000, cheap, with only half the voices working (press any keys, first 1-2-3-4 working, 5-6-7-8 are silent), then again 1-2-3-4 ok.
My guessing is that either IC4 or IC15 is not working (on board 662). What can I check to confirm this?


Got it working, Romain?
paperCUT
Another good mod is to tap the mixed audio off the voice cards before going through the delay board (there is a test point you can use). On my DW8000 the delay adds a lot of hiss, it's a very good analog delay but if you're using external effects you don't want extra noise.
YashN
paperCUT wrote:
Another good mod is to tap the mixed audio off the voice cards before going through the delay board (there is a test point you can use). On my DW8000 the delay adds a lot of hiss, it's a very good analog delay but if you're using external effects you don't want extra noise.


Definitely: I am going to do it too although I really like the DW-8000 effects section. I like what they did there.

Did you do it? If so, can you post the instructions?
paperCUT
YashN wrote:


Definitely: I am going to do it too although I really like the DW-8000 effects section. I like what they did there.

Did you do it? If so, can you post the instructions?


I did it and measured a huge drop in hiss and hum. My synth is in storage but if you get the service manual you should be able to figure this out.
There is a test point after the voices get mixed on the main voice board before they get sent to the effects board. If you add a 10-100k resistor to this you can then add a socket on the back for a 'clean' output. Here's the location from the service manual:

YashN
Indeed, papercut, that looks great, thanks a lot. thumbs up
YashN
So, getting an external analogue envelope to the Global Cutoff is easy. I was wondering if I could do the same with the VCA.

That is, making an External CV IN to the VCAs of the DW-8000 and then use an external analogue envelope to it.

Not sure if tapping into the points right after the 8-bit DAC going to 13-A/B - 2 is OK or not though...
robertlo
Hi all. I acquired a DW 8000 with a dead battery (I thought/hoped this was the only problem). I put in a battery holder, new battery, reloaded the sound banks, and everything was great. However, it started to occasionally flicker, with all of the LEDs going blank.

It quickly got worse and worse, to where the LEDs would scramble, to the point where now it's just dead. The only light that's on is the arp speed light. Nothing I press or move has any effect. Occasionally if I start it up with 5 & 8 held down, I get some nonsensical LED combinations, but still no buttons or sliders have any effect.

I've built a fair amount of DIY stuff, but I'm terrible at troubleshooting, and can't really read a schematic. Does anyone have any suggestions as to where I might start, what I could test, etc?

Many thanks!
paperCUT
You'd have to pull out the main board with the battery and carefully inspect for any signs of damage from a leaky battery. Then I would start measuring the power and see if anything is out.

It's pretty hard to tell what could cause the problem you describe without doing some investigating.
robertlo
Thanks for the reply. I did as you suggested and took everything apart from the main board so I can get a close look. Cleaned everything up really well, etc.

There was one tiny spot just under the old battery where there was a little touch of green corrosion and an exposed trace. But when I followed where both ends were going, I checked for continuity and it was perfect, so that doesn't seem to be an issue.

After all that, I plugged everything back in, and unfortunately it's still not working. Except now it's doing something slightly different: Upon powering up, only the arp speed lights up as before, but now after about 10 seconds I get some other LEDs and a strange display (but all controls still have no effect). Not sure what that might mean, or what to try next ....

paperCUT
Have you tried all the diagnostic modes in the service manual?
On power up:
Hold 5+8 to clear patch data
Hold 5+6 to check D/A at the test points
Hold 7+8 for calibration mode then use various program numbers to change the test routine.

I see you have the Angel City mod, nice! I believe there is a jumper wire needed for power but am not 100% certain on that. Have a look to see if there is a loose wire around the main CPU.
rithma
hey robertlo - sounds like you might be suffering some flailing caps in the power supply.... have you checked the voltages yet?

/E
rithma
This has been a super informative thread!!!

So, I have an EX-8000 that i found at a garage sale some time ago, it powers on and sees midi... but no sound.

Went through it with a volt meter and of the 3 5 volt regulators (7805) in the power supply, one outputs .5v, the other 1v... only one with a steady 5 volts.

Question - should I just replace the 7805s in question? Is it common for those to go bad?


Thanks!
/Etienne Rithma
paperCUT
I would isolate the whole power supply and check with no load, it's not normal for multiple regulators to go bad without a reason.
rithma
Okay! I isolated the power supply from the synth, and here's the voltages I am getting. For some reason, im getting about .7v from 2 of the 5v regulators. Is this a sign that I should replace the caps or has something else gone awry?
[/img]
rithma
Okay GOT IT !!!!!!!!!!

Changed out the big caps in the power supply to no avail;
The swapped out the 2 questionable 7805 regulators,
and BAM. all voltages good!
... tiny sirens at first ....
then followed the very satisfying data tape load procedure,
and now enjoying the swelling, warm, fattest sounding
bells and pads and strings from 1985.

its ...
so ...
lovely ...

all for under
wolfmoonx
awesome thread YashN, i just found this post after getting a dw-6000 that is kinda dead.

Do you think the dw-6000 is similar enough to dw-8000 in terms of doing repairs?

I inquire as I see online, there are many more discussions for repairing a dw-8000
wolfmoonx
roberlo, what happened to your dw-8000, any progress?
Maffez
Hey wigglers!

First post here but thought I'd share. Inspired by you and the folks on gearsl... I ventured into implementing a 12/24db filter mod. Wrote it up here, so I hope just the link is okay: https://www.gearslutz.com/board/showpost.php?p=13056084&postcount=40

Fairly easy even for an amateur like me (might be improved tho)

As to sound, check the soundloud demos: https://soundcloud.com/uibkmedan/dw8000-filtermod24-12db

peace & lemme know if/how you did similar mods
YashN
Maffez wrote:
Hey wigglers!

First post here but thought I'd share. Inspired by you and the folks on gearsl... I ventured into implementing a 12/24db filter mod. Wrote it up here, so I hope just the link is okay: https://www.gearslutz.com/board/showpost.php?p=13056084&postcount=40

Fairly easy even for an amateur like me (might be improved tho)

As to sound, check the soundloud demos: https://soundcloud.com/uibkmedan/dw8000-filtermod24-12db


Neat, Maffez! I wanted to do it but hadn't yet found a proper way to do it to switch the 8 filters at a time. Maybe one day with a uProc and analog switches or something like that.

Well done!
stickman393
Hi folks -

I recently pulled my EX-8000 out of storage to give it some TLC. Upon turning it on, I recognised that the memory is corrupted, of course.

After replacing the battery with a nice CR-2032 socket, I've verified that I can alter patch settings and they are retained between power-offs.

Pro Tip: Initially I could not get it to respond to MIDI notes, but after reading the manual I learned about parameters 87 and 88 to reset the key window range. The memory corruption had set these both to C1 or similar.

OK so my problem is that the tape interface does not appear to be allowing me to load the default patches in from .wav. When I play the clip into the FROM port, I see the "Lo Ad" LED flicker for about 6 seconds, three times (I think the clip contains the same information in three blocks) but I do not see the bank number change from 1-8 as the data is received. After the clip has played, I do not see "Good", it just stays at "LoAd". I hit cancel at this point.

I've tried a couple of ways of playing back the .wav, with both LOW and HIGH on the input switch.

Any advice gratefully received, thanks.
stickman393
>> my problem is that the tape interface does not appear to be allowing me
>> to load the default patches in from .wav. When I play the clip into the
>> FROM port, I see the "Lo Ad" LED flicker for about 6 seconds, three times
>> but I do not see the bank number change from 1-8 as the data is received.
>> After the clip has played, I do not see "Good", it just stays at "LoAd".
>> I hit cancel at this point.

Well, good news - I found a series of steps that work:
-- Emailed the .wav file to myself
-- opened the email on my iPhone
-- connected my iPhone headphone out to the FROM input
-- Set the HIGH-LOW switch to LOW
-- Set the iPhone headphone output to maximum
-- Pressed LOAD and hit play on the iPhone
-- Success! Patches loaded.

I hope that helps someone else.
paperCUT
That's great stickman nanners
Dr Gris
This thread got me thinking... I wonder if I should dig up my DW-6000.
It's been in storage for 30 years and my memory tells me I didn't like it back then...

//M
stickman393
Thanks to everyone who contributed to this thread. It helped me a lot.
I've got my EX-8000 working again, and I wrote about my experiences here:

http://www.prodigalsounds.com/blog/post/2019/02/16/They-dont-make-them -like-they-used-to

Includes:
installing a battery holder, replacing battery
restoring factory sounds
changing up the power supply from 240V to 120V and IEC power cord.
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