Search found 138 matches

by wadesey
Thu Jan 14, 2021 8:16 pm
Forum: Music Tech DIY
Topic: Arp Omni Troubleshooting
Replies: 28
Views: 1217

Re: Arp Omni Troubleshooting

Just replacing the caps fixed the phaser and most of the dead notes. There are still some problems with the synth section and a few other various glitches that are probably from a dead op amp or logic chip here and there, but it seems manageable. I'm wondering what people do about replacing, or refu...
by wadesey
Mon Jan 04, 2021 1:56 am
Forum: Music Tech DIY
Topic: Arp Omni Troubleshooting
Replies: 28
Views: 1217

Re: Arp Omni Troubleshooting

Thanks a bunch for looking at that.

That's what I gathered that section was, but as a guy who doesn't know too much, it's good to ask.

It was a real head scratcher seeing those caps purposefully cut out, and the neighboring cap replaced with a 10uf 35v tantalum about 3xs the size of the original.
by wadesey
Sun Jan 03, 2021 3:27 pm
Forum: Music Tech DIY
Topic: Arp Omni Troubleshooting
Replies: 28
Views: 1217

Re: Arp Omni Troubleshooting

It is MN3002, unfortunately.
by wadesey
Sun Jan 03, 2021 1:58 pm
Forum: Music Tech DIY
Topic: Arp Omni Troubleshooting
Replies: 28
Views: 1217

Re: Arp Omni Troubleshooting

I'm slowly replacing all the tantalum capacitors and noticed something weird on the phaser board. C102 (plus the equivalents on the other delay lines, 202 and 302) was cut out of the circuit and C101 had been replaced. The replacement was also a 10uf tantalum cap so it wasn't a situation where they ...
by wadesey
Wed Dec 23, 2020 12:00 am
Forum: Music Tech DIY
Topic: Arp Omni Troubleshooting
Replies: 28
Views: 1217

Re: Arp Omni Troubleshooting

Cool, thanks. The first thing I was going to do was replace all of the tantalum caps anyway. So that confirms that as the place to start. I noticed the other two times this thing was repaired was 1980 and 1982, when a few tantalum caps and A series logic chips failed. One of the replacement electrol...
by wadesey
Tue Dec 22, 2020 7:59 pm
Forum: Music Tech DIY
Topic: Arp Omni Troubleshooting
Replies: 28
Views: 1217

Re: Arp Omni Troubleshooting

Apologies for exhuming this post, but I'm embarking on an Omni 1 restoration and was hoping to catch some people in the know with a question... This Omni was a "you can just have it" acquisition from a friend since it had never really worked since he bought it and had sat pretty much unused for at l...
by wadesey
Thu Dec 03, 2020 10:43 pm
Forum: General Gear
Topic: Silent brass users?
Replies: 7
Views: 655

Re: Silent brass users?

@wadesey did you use the last generation mute ? SB7X ? Did you plus the mute straight into the DI for real ? Without the "personnal studio" ? The cable is stereo and I have read online the mute requires some sort of phantom power (a weird 3V DC). Or is this voltage just to identify the mute in some...
by wadesey
Mon Oct 12, 2020 10:37 pm
Forum: Music Software
Topic: Any simple VST bus for real time plugins?
Replies: 18
Views: 711

Re: Any simple VST bus for real time plugins?

Would Mainstage 3 work? You can use it as an effects rack, but I'm pretty sure it'll be AU only unless you use something like Blue Cat Patchwork to load VSTs, and actually you can also chain effects together inside Patchwork. The upside is since it's an Apple product it always works with the newest ...
by wadesey
Thu Aug 20, 2020 11:45 am
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

Woah great news. Congratulations and thanks everyone for sharing the process. I'm trying to fix my midiverb II as well and this has been a source for inspiration. Where on earth did you acquire the DSP? From an untested midiverb on sale? It's the only part in mine that's left to try/change. I've dr...
by wadesey
Thu Aug 13, 2020 1:56 pm
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

I am pleased to report that I replaced the DSP chip and the thing works!! So the end score is that both the DSP and that 157 logic chip had failed. I took a risk with the $22 untested DSP IC vs. the $150 or whatever it was "tested and guaranteed" one and it worked out. Big thanks to guest and EATyou...
by wadesey
Wed Aug 12, 2020 8:32 pm
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

guest is basically trying to get at how much thermal inertia this bad part has. how fast does it get hot and how fast does it get cold. it would be great if you knew what the TDP of each IC is for a working unit. the one IC that is hotter than normal would stick out. some parts run hot normally so ...
by wadesey
Wed Aug 12, 2020 8:11 pm
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

3hands wrote:
Wed Aug 12, 2020 7:32 pm
This thread is hands down, the most exciting thing on the internet currently. I’m routing so hard for this Midiverb! And for you Wadesey!
Haha, this has definitely escalated to a full on white whale experience
by wadesey
Wed Aug 12, 2020 8:03 pm
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

guest wrote:
Wed Aug 12, 2020 7:23 pm
ok, thats seems to be working right now. do you have another one from when its not sounding good?
Ah, interesting. Here's after it's been on for ~10 minutes
by wadesey
Wed Aug 12, 2020 7:19 pm
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

i wonder if the dac data lines 2,3 are shorted together. can you measure the resistance between them? these would be the two bits next to the MSB, so it goes MSB,2,3. its line 3 that isnt changing when it should, but i also just noticed that its never different from line 2. Good eye... I just looke...
by wadesey
Wed Aug 12, 2020 5:26 pm
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

guest wrote:
Wed Aug 12, 2020 5:01 pm
yeah, thats still failing SAR, which is starting to make me think there are multiple things wrong.
Haha, yeah...

It should just be the DSP and/or DAC, hopefully? Since everything else involved in the SAR circuitry has been replaced?

I may as well try out this new DSP chip and see what happens.
by wadesey
Wed Aug 12, 2020 4:54 pm
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

Time from last shutoff does seem to affect it. First power on when cold takes roughly 3-4 minutes to go completely "bad", but after it's warmed it starts to sputter out in about a minute after power off/power on. But it is mostly normal even after quick power off/on. To be clear, it doesn't sound co...
by wadesey
Wed Aug 12, 2020 3:27 pm
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

does the time to failure vary? for example, if you use short delay settings, does it occur faster? if you shut the device off for 30s, and then turn it back on, does it fail immediately? also, when you said the analog switch lines were failing, does that mean they were no longer recieving signal? d...
by wadesey
Wed Aug 12, 2020 12:47 pm
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

yes. this is directly related to heat or build up of static charge through some leakage or some 10M resistance somewhere. could be flux on the board actually. the heat could be a very small junction heat inside a failed piece of silicon. or it could be more general concept of heat like the regulato...
by wadesey
Tue Aug 11, 2020 8:16 pm
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

I took a second to listen through this again, and found something interesting, maybe a clue? Right when it's powered on it almost functions normally. You can hear the effect of whatever program is loaded clearly, but there is some distortion/modulation. I snooped through the signal path again and wh...
by wadesey
Sat Aug 08, 2020 5:55 pm
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

did you go through all the 157 lines and compare them with the A/B select, to make sure the switches are working? you dont need to figure out the connection for this, just check in1,in2,out,switch and see if it selects the right thing. if thats all good, and all the data and address lines toggle, t...
by wadesey
Sat Aug 08, 2020 4:00 pm
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

the big question is if those transients are there and you are measuring them or if the measurement device is flipping high randomly in error. if you can't trust the measurement device then what is a measurement. Absolutely. I re-tested and everything looked correct. So I must've had a probe poorly ...
by wadesey
Sat Aug 08, 2020 12:40 pm
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

also, as far as i can tell, the DAC is still doing the wrong thing when in ADC mode. Thanks, I read over how the SAR works again, and it seems like the DSP chip might actually be the problem. Or this part of the problem... The only other thing could be the 22pf capacitor connected to the analog swi...
by wadesey
Sat Aug 08, 2020 1:33 am
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

It looks like the DAC might be working correctly now? The first 8 bits at least? I attached a txt of that. The logic and SRAM stuff is really hard to figure out without the schematic. I'm having a hard time matching up the outputs of the 157 to the SRAM, unless something really is wrong with either ...
by wadesey
Fri Aug 07, 2020 9:48 pm
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

This was before Alesis switched to the 4pin DIN power connector, so it was super easy to plug in some other DC power instead of 9vac. I don't know how much damage that can cause though. The only part that for sure failed is the 157 multiplexer, everything else was me semi-blindly replacing stuff tha...
by wadesey
Fri Aug 07, 2020 8:20 pm
Forum: Music Tech DIY
Topic: Broken Midiverb II: Troubleshooting Tips?
Replies: 181
Views: 3424

Re: Broken Midiverb II: Troubleshooting Tips?

I replaced the 157 that seemed broken -- and the overflow light is now off! But the thing is still broken! haha... Beneath all the digital noise you can sort of hear whatever program has been loaded. And sort of hear whatever signal is put through it. So that intense feedback/glitching sound is gone...

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