208p build thread (papz's PCBs)

[papz]

Yes it's safe.

[papz]

Except for the SOT 2N4339 on card 8 all 2N43xx FETs can be replaced by a cheaper and easier to find J201 without other mod.
Check datasheets for the pinout.

[papz]

The metal can DG200A becomes rare and expensive and Chinese fakes is a risk.
I designed a small adapter PCB to use the DIP 14 THT or SMT version, which is still available from common suppliers for a few €/$ only.
https://www.mouser.be/Search/Refine?Keyword=dg200a
https://be.farnell.com/fr-BE/search?st=dg200a

It mounts to the PCB with components leads.
It will be included in the 208p PCB set.
If you already bought a 208p set and need one, please PM or email me and I'll send you it for free.

Installed on card 9 :

[captnapalm]

The metal can DG200A becomes rare and expensive and Chinese fakes is a risk.
I designed a small adapter PCB to use the DIP 14 THT or SMT version, which is still available from common suppliers for a few €/$ only.
https://www.mouser.be/Search/Refine?Keyword=dg200a
https://be.farnell.com/fr-BE/search?st=dg200a

It mounts to the PCB with components leads.
It will be included in the 208p PCB set.
If you already bought a 208p set and need one, please PM or email me and I'll send you it for free.

Very nice Papz!

[papz]

Cheers Luther !

[AshtrayWasp]

Made a excel total BOM for all the 208 boards together if anyone wants it, the only things missing are the actual PCB designations for the components, and the mouser number for the resistors as I wanted to use different ones from the recommended.

[papz]

Thanks !
I'll put a link on my website's 208p page ?

[AshtrayWasp]

Sure

[papz]

Thanks
Link added, I did 2 updates : it's better to use CD4016 on board 8 because a CD4066 there might upset the sine and I mentioned the DG200A-dapter.
http://www.portabellabz.be/images/208/P ... ayWasp.xls

[xahdrez]

Thanks Papz! Well, the plot thickens! Turns out that R14 isn't making any difference at any value between 10k and 300k so guess the issues must be elsewhere. Tried substituting the pa726 for 2 x 2N3904 as suggested above for another builder, and behaviour remained the same. As far as I can tell, their issue was resolved by swapping the ICs on card 7, so perhaps that's a good place to start looking? Sure I'm missing something obvious! As ever, any ideas very welcomed, I'll get there in the end!

Bit of a life delay, but finally got a chance to switch out IC2, IC3 and Q1 and seems like the situation is very much the same. Neither R14 or R44 values seem to change the CO tracking, and best I can get it to is around 1.4V per octave.

Been doing my best to trace through the schematic on card 7, and as far as I can tell everything is connected up okay. I've given the PCB another clean as a precaution, and double checked all the resistor values again in case I made a mistake on previous checks but still nothing I can spot.

I don't suppose anyone has any ideas of where else I could look? Am I right in assuming the issue must be located on card 7 (seems to handle all the CO control voltage at least?), or is that a dangerous assumption?! Maybe I could just try recalibrating at 2V per octave?! Any thoughts/ideas/wisdom very much appreciated as ever!

[xahdrez]

Scratch all this...turns out I just got myself into a right muddle between R14 and R44 with all the gaps between working on this

Now tracking beautifully over 5 Octaves with R44 at 150k and R14 increased slightly to 56k.

Time to do the final tweaks, put it back together and get back to playing

[papz]

A builder reported a small typo in AshtrayWasp's BOM.
The axial cap to replace the hard to find Sprague 390µF is 330µF, not 330pF.
This one is fixed http://www.portabellabz.be/images/208/P ... ayWasp.xls

[papz]

Wow. I found it. The Alps sliders have small metal tabs, which touch the traces for -15 and the trace to pin 21 of card 2.

With the slider removed, -15v is NOT present on the banana jack or pin 21 .

I’m surprised nobody has seen this problem before.

8D5FEF51-BB3E-4CB4-96E0-216BCEC71215.jpeg

Although it is the only related problem reported so far, it’s good to snip the protruding part of the 4 metal tabs on the Alps faders to prevent the risk of short with the motherboard traces located below.

I updated the build notes.


If the faders are already in place, it's easy to desolder the bottom lug (ground) and lift them to snip the tabs.

[sendepause]

Question:
I have build a 208 ( not Papz) and there is a lot of knowhow in this thread I put the question here.
So how noisy is your 208? I have a new card 12 installed and without any cards, except the 12, there is some serious noise on the output. Headphone out is a total no go.
I’m doing a open heart surgery atm and check everything on the motherboard and can’t find any weird things.
So: is your 208 noisy as well? How noisy? Headphone out noisy?

[papz]

This is not normal. A good working 208 is not noisy.

The noisy phones out is a known issue easy to fix with 4 resistors added to the socket. This fix is implemented on the 208p PCBs but not on the 208r.

I recently rescued a Boops built 208r with his new card 12 which caused various problems (noise, clipping, inverted waveforms, Q-N grounds connection lacking, weird reverb mix...) that were all fixed when I replaced it with a normal card 12.
Do you have the normal card 12 ? If so try and swap these.
Otherwise I could build one for you, or you're welcome to send your 208 over to me to have it fully checked and returned perfectly working, there are maybe/likely other issues. I'm located in Belgium and I've built or rescued over 50 ones. Feel free to drop me an email via http://www.portabellabz.be/papa.html

[Virusinstaller]

Howdy folks. I am in need of a little timbre card help.
My sliders are not working, my switch & pot however are working.

I have used a VTLC1, not sure if that will make any difference?
I have the 4016 installed & I have tried 3 or 4 different ICs.
I have replaced the LM3900 & the RC4136N still no luck.
I replaced the 4399 with a genuine one from Mouser.
I have slightly raised the timbre sliders off the motherboard to ensure no shorts... still no luck.

Any suggestions much appreciated!

[AshtrayWasp]

A builder reported a small typo in AshtrayWasp's BOM.
The axial cap to replace the hard to find Sprague 390µF is 330µF, not 330pF.
This one is fixed http://www.portabellabz.be/images/208/P ... ayWasp.xls

Thanks for the corrections! Good thing I haven't bought the parts yet.

[Virusinstaller]

Howdy folks. I am in need of a little timbre card help.
My sliders are not working, my switch & pot however are working.

I have used a VTLC1, not sure if that will make any difference?
I have the 4016 installed & I have tried 3 or 4 different ICs.
I have replaced the LM3900 & the RC4136N still no luck.
I replaced the 4399 with a genuine one from Mouser.
I have slightly raised the timbre sliders off the motherboard to ensure no shorts... still no luck.

Any suggestions much appreciated!

I put my card 8 in another easel and it worked fine. I put another card in my easel and still no go. So it's either the motherboard or card 7. At least thats my next options for problem solving.

[papz]

Timbre is managed on card 7.
Check VT1 is ok and not wired upside down.
Check IC1.
Of course, also check solder joints and values are ok.

[Virusinstaller]

Timbre is managed on card 7.
Check VT1 is ok and not wired upside down.
Check IC1.
Of course, also check solder joints and values are ok.

Hey Papz
We had dinner in Wollongong with Jono & then you played the Synthi at his house, finally got my 208 finished
Thanks for that, that helped and I got the timbre slider working, just need to work on the CV for timbre.
Thus the journey continues. I will keep checking!

[Don T]

Howdy folks. I am in need of a little timbre card help.
My sliders are not working, my switch & pot however are working.

I have used a VTLC1, not sure if that will make any difference?
I have the 4016 installed & I have tried 3 or 4 different ICs.
I have replaced the LM3900 & the RC4136N still no luck.
I replaced the 4399 with a genuine one from Mouser.
I have slightly raised the timbre sliders off the motherboard to ensure no shorts... still no luck.

Any suggestions much appreciated!

I put my card 8 in another easel and it worked fine. I put another card in my easel and still no go. So it's either the motherboard or card 7. At least thats my next options for problem solving.

Make sure that motherboard is supplying +5V to every card that needs it. I learned the hard way that the 208 80% works without +5V, and timbre doesn't work at all without it.

[EDIT] Just noticed the problem was solved. Will leave here for others in future that may have the same issue

[papz]

I remember this dinner and evening, was very nice, Jono's wine was excellent.

For the timbre CV, doublecheck solder joints on the MB and the banana socket wiring.

[friedemann]

Hey folks!
I am on finishing my 208p and learned a lot in that time.
I am on stuffing the first Cards to the motherboard now. I get 13,57V on pin 4/card3.
Card 3 and 4 alone are working (I get pulser and envelope)
When installing card 1 and card 2 nothing happened anymore, then IC 2 (a 4066) burned on pin 10.
With card 1/3/4 installed now also nothing working.
Something says me there is a problem on the motherboard which is already mounted on the frontpanel...
Do You have Ideas where to check.
Thanks a lot!!
Bye Friedemann

[papz]

Doublecheck the cards male/female headers alignment, IC orientation, solder bridges, short between the power rails...

[friedemann]

Thanks!
Random, Envelope and Pulser are working now. But I cant get the Sequencer starting and Sequence LEDs 2-5 are lighting doesnt matter witch switch positions there. I get CV out from sequencer but all Faders 2-5 do the same.
I have one card stuffed with decoupling caps and one without, I used 4066.
It is the same on two different motherboards and different Card 1s.
Any Ideas - changing some ICs? Traces and solder points are looking good...
Thanks Friedemann