Had the exact same issue, it's unlikely to be the chip. Get those orange dipped caps swapped out, they fail intermittently. I replaced all mine with Mylar 5% (the originals are 10% dipped ceramic). Recalibrated as per service manual, crackle gone. I also retrobrighted the slider caps and buttons, i...

Thanks for the suggestions, the synth has been working on an off over the years. Its currently in its defunct state, I'll revisit its health once I'm done building the TTSH v4 kits I'm currently working on

You gave me an idea, I measured the clock signal and reset signal at boot time to see if it was cycling at least 24 times before reset goes low. https://mikeder.net/wp-content/uploads/2016/12/bewFile3.bmp Yellow = Reset @ CPU Blue = 12mhz clock pin 19 https://mikeder.net/wp-content/uploads/2016/12/a...

You never specifically said, but I'm assuming that the CPU operation is stable once booted, right? If so, then you've got good clock, power, ground, etc. That leaves the RESET line for intermittent boot (which is the most obvious candidate, anyway). Yep, the synth is rock solid once booted. I did h...

I've scoped the start up numerous times, catching both a normal boot and non-boot. The only difference I could see was about 5ms difference on the non-boot but even still that wasn't super consistent. When the CPU is in non-boot fault mode all of the data pins are held high @ 5v (at least all the on...

Yea the resistors were the next thing I was looking at, some of them can be measured in circuit but at least one or two need to be pulled to verified. I figured before I started pulling more components I would try and check with the more experienced people here. I'd mainly like to confirm that what ...

Oberheim TVS

I'm chasing an intermittent no-boot on my Jupiter 6 but I'm not 100% sure the issue I think I have is what is causing my problem. If that makes sense. Could someone more knowledgeable than myself tell me if I'm on the right track or if I should be looking somewhere else? My Jupiter 6 won't boot some...

Hey neanalog, I have put a scope on the PSU lines as well as the RESET line from the PSU and at TP3 on the CPU board. As far as I can tell everything looks okay. Reset signal: http://mikeder.net/wp-content/uploads/2016/11/NewFile7.bmp -Yellow = TP3 on CPU board -Blue = RST on PSU board I'm not sure ...

Hi all, I've got a very sick Jupiter 6 that a previous owner installed the Europa mod in. I suspect something is wrong with the CPU and would like to turn the board to stock to rule out the mod as the fault. I have already ordered a couple 8031's from Jameco but I understand that I will also have to...

So I bought this Jupiter 6 w/ Europa mod on Ebay a while back and it has never been quite right. When I first got it one of the sliders was broken and all the others were scratchy so values would jump around a lot. I recently rebuilt all the sliders and replaced the one broken one. Now that they're ...

I was always under the impression that they used talk boxes for their vocal parts, hence the helmets to hide the tubes. I'm probably not correct, just what I thought.

Not sure if you had it shipped to you but that process can be brutal on synths no matter how well packed. Wouldn't surprise if there's a solder joint or connector plug that can easily come loose w/ vibrations and impacts during shipping. Im assuming this is my problem, I was playing the synth probl...

Thanks for the lengthy reply, I'll try some of those tonight and see what I come up with. The part that is kind of bothering me is the fact that this synth was supposedly gone over by a tech in NY before I bought it and they gave it a clean bill of health. So either that tech didn't know what they w...

Well the IR3109's aren't in sockets so I wont be able to easily swap them, c**p. Anyone know which voice is which on the PCB? There are 4 voices on one board and 2 on another, but they're both labeled the same. Also looking at these guts, I wonder if anyone has tried populating the rest of the empty...