Search found 1269 matches

by Don T
Thu Sep 24, 2020 10:42 pm
Forum: Music Tech DIY
Topic: Has this M083 T.O.S. gone bad?
Replies: 4
Views: 84

Re: Has this M083 T.O.S. gone bad?

Looks like something isn't grounded that should be. What, I'm not sure.
by Don T
Thu Sep 24, 2020 9:40 am
Forum: Music Tech DIY
Topic: Roland JX-3P noisy voice VCA and the BA662B
Replies: 41
Views: 413

Re: Roland JX-3P - Max input to the VCF

Is there a max threshold to take care of when inputting a signal to the Core of the VCF so as not to damage it? Due to almost a total lack of a real data sheet, I'd suggest running the filter with no resonance, the cutoff CV all the way up, then feeding it a signal while monitoring the output with ...
by Don T
Thu Sep 24, 2020 6:34 am
Forum: Music Tech DIY
Topic: Roland JX-3P noisy voice VCA and the BA662B
Replies: 41
Views: 413

Re: Roland JX-3P noise level w Res PB Zipper noise

Hi Don! Happy to help! That’s weird! I wonder if it’s a regular thing with the Kiwi mod? Good luck with it!! Ps: other than that, how do you like the Kiwi mod? It‘s a fairly intriguing! It adds a few cool features I like very much, but the main thing is just how much it makes it easier to program!!!
by Don T
Wed Sep 23, 2020 9:40 pm
Forum: Music Tech DIY
Topic: Roland JX-3P noisy voice VCA and the BA662B
Replies: 41
Views: 413

Re: Roland JX-3P noise level w Res PB Zipper noise

One quick, possibly related, possibly not, question: In the JX-3P, has anyone noticed a difference in noise level when a patch uses resonance vs. a patch that does not? Hey Don, let me test and get back to you. Is there a specific patch where this is heard better or a custom patch design that allow...
by Don T
Wed Sep 23, 2020 3:57 am
Forum: Music Tech DIY
Topic: Roland JX-3P noisy voice VCA and the BA662B
Replies: 41
Views: 413

Re: Roland JX-3P noisy voice VCA and the BA662B

One quick, possibly related, possibly not, question: In the JX-3P, has anyone noticed a difference in noise level when a patch uses resonance vs. a patch that does not?
by Don T
Tue Sep 22, 2020 12:31 am
Forum: Music Tech DIY
Topic: Moog MG-1 Power supply issue
Replies: 68
Views: 431

Re: Moog MG-1 Power supply issue

MoyaMoya wrote:
Mon Sep 21, 2020 9:27 am
I see the NJM is meant for a much lower supply voltage..
well I feel like an idiot..
:doh: :doh: :doh:
If that's the worst mistake you've ever made, you're doing REALLY well!
by Don T
Sun Sep 20, 2020 10:26 pm
Forum: Music Tech DIY
Topic: Moog MG-1 Power supply issue
Replies: 68
Views: 431

Re: Moog MG-1 Power supply issue

According to the service manual, the emitter of the TIP30 should be -11V, so I powered up my MG-1 and probed. My readings are near identical to MoyaMoya's, and I know mine is working fine, so carry on! :)

If more voltage/resistance readings are needed for comparison purposes, feel free to ask!
by Don T
Sun Sep 20, 2020 3:34 pm
Forum: Music Tech DIY
Topic: Moog MG-1 Power supply issue
Replies: 68
Views: 431

Re: Moog MG-1 Power supply issue

guest wrote:
Sun Sep 20, 2020 1:44 pm
replace U11 and see if that fixes those voltages.
:popcorn:
by Don T
Sat Sep 19, 2020 9:24 pm
Forum: Music Tech DIY
Topic: Moog MG-1 Power supply issue
Replies: 68
Views: 431

Re: Moog MG-1 Power supply issue

guest wrote:
Sat Sep 19, 2020 7:43 pm
the LM386 might be blown.
Yes, I was thinking taking this out would be the next step if the power supply was ok. It may be worth it to go ahead and pull it and test before the power supply is sorted.
by Don T
Sat Sep 19, 2020 9:20 pm
Forum: Music Tech DIY
Topic: Moog MG-1 Power supply issue
Replies: 68
Views: 431

Re: Moog MG-1 Power supply issue

Yes, at least in the US, the MG-1 only has one fuse, a slow-blow type on the high voltage side. F1 and F2 are just jumpers
by Don T
Sat Sep 19, 2020 3:59 am
Forum: Music Tech DIY
Topic: Moog MG-1 Power supply issue
Replies: 68
Views: 431

Re: Moog MG-1 Power supply issue

Since I happen to have one of these open (and in working condition) in front of me, I'll offer some help: 1. I'd replace all the power supply caps, double-checking polarity. 2. Remove both voltage regulators, U12 and U13, The LM741, U11, and the TIP30, Q3. 2a. While these parts are out, check across...
by Don T
Thu Sep 17, 2020 6:18 pm
Forum: Music Tech DIY
Topic: How much drift is a good thing?
Replies: 15
Views: 365

Re: How much drift is a good thing?

I wouldn't replace a styrene cap, I doubt there'd be much difference, if any at all, with a silver/mica cap.

Just curious, what is your power supply like?
by Don T
Sat Sep 12, 2020 10:40 pm
Forum: Music Tech DIY
Topic: Roland Jupiter 8 VCO1 drift
Replies: 42
Views: 1203

Re: Roland Jupiter 8 VCO1 drift

On my JP-8, the saws on the odd numbered voices are slightly flat compared to the pulses, and this is both before and after auto-tune. The auto-tune seems to work fine for the pulse. Ah, this I did not know. I thought it was affecting only one voice, not all of them on a card. That means I had you ...
by Don T
Sat Sep 12, 2020 6:11 pm
Forum: Music Tech DIY
Topic: Roland Jupiter 8 VCO1 drift
Replies: 42
Views: 1203

Re: Roland Jupiter 8 VCO1 drift

If I remember correctly, a lot of Roland power supplies do not have a negative rail adjustment. I assume because the value isn't as critical.
by Don T
Thu Sep 10, 2020 11:47 pm
Forum: Buchla, EMS & Serge
Topic: Randomizing Sequencer on Buchla Easel Command
Replies: 5
Views: 326

Re: Randomizing Sequencer on Buchla Easel Command

Let me look over the schematics for the original 208. I cannot off the top of my head remember if 1., You have to access a point on Card 1, 2., If it can be done from a programming card, or 3., It would have to be done digitally. Edit: Ok, if I've heard correctly, the Easel Command does not have sep...
by Don T
Wed Sep 09, 2020 6:45 pm
Forum: Music Tech DIY
Topic: How much drift is a good thing?
Replies: 15
Views: 365

Re: How much drift is a good thing?

Place it inside an enclosure and test with a tuner over a period of 20 minutes. The lack of air movement around it should make it more stable. If testing this way does not yield satisfactory results, then explore other options, such as thermal paste or thermal epoxy
by Don T
Tue Sep 01, 2020 6:23 am
Forum: Buchla, EMS & Serge
Topic: MEMS and The University of Illinois Buchla 200
Replies: 41
Views: 1455

Re: MEMS and The University of Illinois Buchla 200

I am so insanely jealous! I would've given anything to be there for this! I can't wait to see all the info that comes out of this project, I would love to build a 1:1 217 and 284 for myself. I'd also REALLY love to see good photos of a 258. I have etched a 1:1 circuit board for it, and have it parti...
by Don T
Mon Aug 31, 2020 8:15 am
Forum: Music Tech DIY
Topic: Troubleshooting advice for borked Pro One
Replies: 7
Views: 116

Re: Troubleshooting advice for borked Pro One

If it's been fried that badly, there could be places that the circuit board itself has been so scorched and carbonized that it will conduct as well. I've done many a repair where I had to take a Dremel tool and remove the PCB substrate between traces. Thanks Don. This is the worst part and it doesn...
by Don T
Sun Aug 30, 2020 3:50 pm
Forum: Music Tech DIY
Topic: Troubleshooting advice for borked Pro One
Replies: 7
Views: 116

Re: Troubleshooting advice for borked Pro One

If it's been fried that badly, there could be places that the circuit board itself has been so scorched and carbonized that it will conduct as well. I've done many a repair where I had to take a Dremel tool and remove the PCB substrate between traces.
by Don T
Sun Aug 30, 2020 10:23 am
Forum: Music Tech DIY
Topic: Roland Jupiter 8 VCO1 drift
Replies: 42
Views: 1203

Re: Roland Jupiter 8 VCO1 drift

Ok, after looking over the schematics again, I've got nothing. Sorry
by Don T
Sat Aug 29, 2020 5:01 pm
Forum: Music Tech DIY
Topic: Roland Jupiter 8 VCO1 drift
Replies: 42
Views: 1203

Re: Roland Jupiter 8 VCO1 drift

Oh, you do have a copy of the service manual, yes?
by Don T
Sat Aug 29, 2020 4:53 pm
Forum: Music Tech DIY
Topic: Roland Jupiter 8 VCO1 drift
Replies: 42
Views: 1203

Re: Roland Jupiter 8 VCO1 drift

Probed the pins on the 3046, switching between saw and pulse on VCO1. The voltage did not change. I have attached a clip, each time rotating through the eight voices. First is VCO1 and pulse only. There seems to be a weird bleed on the odd numbered voices. There is no bleed if set to triangle, saw,...
by Don T
Fri Aug 28, 2020 11:18 am
Forum: Music Tech DIY
Topic: Roland Jupiter 8 VCO1 drift
Replies: 42
Views: 1203

Re: Roland Jupiter 8 VCO1 drift

Looked at the output of pin 6 on IC 3A, and switching between waveforms had no effect. Ok, scope or DMM, Probe pins 8, 9, and 11 of the 3046, and repeat same test for each pin, looking for any changes from saw to square. Also, not sure if you have seen this site, but it may be useful: https://jup8r...
by Don T
Wed Aug 26, 2020 3:45 am
Forum: Music Tech DIY
Topic: Roland Jupiter 8 VCO1 drift
Replies: 42
Views: 1203

Re: Roland Jupiter 8 VCO1 drift

Looked at the output of pin 6 on IC 3A, and switching between waveforms had no effect. Ok, scope or DMM, Probe pins 8, 9, and 11 of the 3046, and repeat same test for each pin, looking for any changes from saw to square. Also, not sure if you have seen this site, but it may be useful: https://jup8r...
by Don T
Tue Aug 25, 2020 2:02 am
Forum: Music Tech DIY
Topic: Roland Jupiter 8 VCO1 drift
Replies: 42
Views: 1203

Re: Roland Jupiter 8 VCO1 drift

Suggestion: Place the scope probe at the output of the VCO core, before the square wave shaper. Switch back and forth between saw and square to see if wavelength changes at all.

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