I have ensured that the psu is outputting +15v and -15v to the main board though I think after that point something is screwed that i have done. When testing tp4, it comes in is just a perpetual decline in mv, when testing u12 for bass drum at the indicated points its exhibiting the same declining mv. Where should i start with identifying the issue? thanks
Edit- Removed vr4 replaced with the correct 500k pot, i didnt check the pots before putting them in only to realize it was a 20k pot.
Bass Drum Decay Issue SOLVED
-
Last edited by Virtualcrimes on Nov 28th, '17, 14:45, edited 5 times in total.
I'm certainly not an expert here but I can tell you what I would do in your shoes.
Since the noise section feeds into the bass drum I would troubleshoot the noise section. You can trace through the schematic (page 6) and focus on the components before TP4. I would check the input into the noise section and then check orientation and solder joints of each component in the section. Then you can test component by components. To further isolate you could pull the e-caps that feed power to the bass drum (c44/46) to ensure that circuit is not feeding back into your noise section.
I don't have much experience in working on synths. Most of my electronic troubleshooting experience is in vintage audio repair and this is how I approach repairs in that space.
Since the noise section feeds into the bass drum I would troubleshoot the noise section. You can trace through the schematic (page 6) and focus on the components before TP4. I would check the input into the noise section and then check orientation and solder joints of each component in the section. Then you can test component by components. To further isolate you could pull the e-caps that feed power to the bass drum (c44/46) to ensure that circuit is not feeding back into your noise section.
I don't have much experience in working on synths. Most of my electronic troubleshooting experience is in vintage audio repair and this is how I approach repairs in that space.
Thanks for your help,
Yeh so im an idiot and didnt do the power bus, now am seeing tp4 fluctuating between 160-140 going up and down, i got +/- 15 from the two pins of the ic at u24 for the noise. I have my noise and my bass drum done and do not hear anything coming out of the main out when for testing purposes, is this generally how you test the voice? just plug into the main out?
Yeh so im an idiot and didnt do the power bus, now am seeing tp4 fluctuating between 160-140 going up and down, i got +/- 15 from the two pins of the ic at u24 for the noise. I have my noise and my bass drum done and do not hear anything coming out of the main out when for testing purposes, is this generally how you test the voice? just plug into the main out?
You need to be sure you have the boards cabled together correctly. Wiring up J1 -> J11 will get you sound out of the individual out. Wiring up J6 -> J14 will also get you sound out of the master. Also ensure that your power cable (big 4 pin) and sequencer cable (8 pin) are connected (these ensure you have analog and digital power).
To test sound I get have a pair of cheap self-powered computer speakers plugged into the individual out. I think if you leave the master not hooked that all voices come out of all individual outs.
My recommendation is to print out the individual voice parts list and just start on page 1 and go in sequential order all the way through. This way you never miss a part. This is a huge build and it can be easy to get confused.
To test sound I get have a pair of cheap self-powered computer speakers plugged into the individual out. I think if you leave the master not hooked that all voices come out of all individual outs.
My recommendation is to print out the individual voice parts list and just start on page 1 and go in sequential order all the way through. This way you never miss a part. This is a huge build and it can be easy to get confused.
Acetate thank you for the suggestions. I think I was following the assembly guide too literally and not using common sense. I have the individual outs working and tested the noise on the op amp and getting noise for sure. I got bass drum on the individual output however no decay, vr6 has no effect, the level and tone are working though. Does decay not work in voice test mode? I was going to build it from right to left after I finished the power bus, so noise, kick, snare etc, should I build the sequencer before doing that? As per your suggestion you said start from beginning and work my way down, I believe the sequencer is the first thing on individual parts list, without the sequencer should the bass drum still decay or just output the length of the trig? Thanks!