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Transcendent 2000 Powertran PCB diagram

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Re: Transcendent 2000 Powertran PCB diagram

Postby midierror » Sat Jan 31, 2015 4:49 pm

Thanks very much guys, it`s been a real eye-opener how much you`ve helped. The keyboard is aligned now, but waveforms will require an oscilloscope of some kind - maybe a software one? :S

Also, do you think its worth replacing the LM311 now its on the way? It sounds like its fully working, so is there any reason to keep an eye on voltages etc??

You`ve all be made honorary members of my Transcendent 2000 investment fund.
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Re: Transcendent 2000 Powertran PCB diagram

Postby Wonks » Sat Jan 31, 2015 11:07 pm

I promise I will try and start work on mine over the next day or so. Been too busy either guitar fettling or feeling ill up to now. At least I have a lot of the groundwork already done by you wonderful chaps.

Midi, do all your keyboard notes trigger properly? When I first received it and before it went strange, most of the notes were fine but some seemed intermittent. I had a look at the keyboard contact springs and they all seemed to be OK.
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Re: Transcendent 2000 Powertran PCB diagram

Postby midierror » Mon Feb 02, 2015 9:15 am

I had the same issue Wonks, 4 or 5 keys didn`t work. Having done the calibration some of them began working...?!

For the more persistent offenders, I turned the unit over and had a tinker with the contacts. All working now :lol:
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Re: Transcendent 2000 Powertran PCB diagram

Postby Folderol » Mon Feb 02, 2015 11:06 am

midierror wrote:I had the same issue Wonks, 4 or 5 keys didn`t work. Having done the calibration some of them began working...?!
That's probably because simply using them wiped off a small amount of dirt/oxide that had accumulated on the contacts :)


For the more persistent offenders, I turned the unit over and had a tinker with the contacts. All working now :lol:
I would guess that you didn't need much more than a little bit of contact cleaner.

Incidentally, there are a few programs out there that can use a half decent soundcard to turn your 'pooter into a basic oscilloscope, although I've never used them myself.
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Re: Transcendent 2000 Powertran PCB diagram

Postby Wonks » Mon Feb 02, 2015 12:09 pm

I have secured the loan of a decent scope from a friend at Siemens when it gets to the fine tuning.
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Re: Transcendent 2000 Powertran PCB diagram

Postby midierror » Tue Feb 03, 2015 10:03 pm

Thats a good call, the software one I used ran at about 1 frame per decade
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Re: Transcendent 2000 Powertran PCB diagram

Postby BJG145 » Tue Feb 03, 2015 11:02 pm

Nice work fellas!
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Re: Transcendent 2000 Powertran PCB diagram

Postby Wonks » Tue Feb 03, 2015 11:53 pm

I now have the top and bottom off the Transcendent. Tomorrow I will battle my way through 2mm of snow to the garage where my multimeter must be as I couldn't find it in the house.

I may be some time.
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Re: Transcendent 2000 Powertran PCB diagram

Postby Folderol » Wed Feb 04, 2015 5:12 pm

Wonks wrote:I now have the top and bottom off the Transcendent. Tomorrow I will battle my way through 2mm of snow to the garage where my multimeter must be as I couldn't find it in the house.

I may be some time.

Never mind the snow (bad though it may be) Did you survive entering the garage?
Did you need assistance to get out again?
Where do we send the flowers? ;)

P.S.
Email the electrons to me and I'll count them for you :D
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Re: Transcendent 2000 Powertran PCB diagram

Postby Wonks » Wed Feb 04, 2015 8:11 pm

Could I find my Multimeter? Could I £%&"! I now have two multimeters, only one of which I know the location of. However, I bet the the first thing I see tomorrow when I get up will be the missing multimeter in a very obvious place.

My power supply board is fine, with a nice +12.03v and -12.00v, both when loaded and unloaded.

But sound produces had degraded even more since I last powered it up. I can get the filter to self-oscillate, but that's about the only noise it's making now apart from some slight background noise when a key is pressed. The VCA ADSR is doing the right things to the noise, so the main problem would seem to be the oscillator, or lack thereof.

I'm going to need to do a lot of loose cable rewiring, as it's been done very badly with lots of exposed wire ends and no heatshrink - especially the mains switch and fuseholder. Also going to fit an IEC mains socket to it rather than the captive mains lead it's currently got.

Apart from fix the wife's laptop power supply I haven't done anything more electronic-wise today (as I was feeling really rough yesterday and only just a bit better today). Hopefully some voltage measurements will be taken tomorrow.
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Re: Transcendent 2000 Powertran PCB diagram

Postby Wonks » Thu Feb 05, 2015 7:28 pm

Right. My VCO voltages all seem to stack-up against the working voltages for Q9, IC10 and IC11, so it doesn't look like it was the same problem as Midierror's.

One thing that may point to the problem area was that when I got it, it was initially slightly out of tune across the keyboard, so I set it up again and it was OK for a day or two. The next time I turned it on, the keyboards tracking was way out again - a long way out. I thought maybe something had been moved when re-assembling the boards. The next time I switched it on, it was basically only making one note, regardless of key press. And since then, just noise.
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Re: Transcendent 2000 Powertran PCB diagram

Postby Folderol » Thu Feb 05, 2015 9:42 pm

My first suspicion would be the keyboard resistor network around IC3 do you get a progressive voltage change at the junction of R13 and the key common line as you press keys? If these resistors are equal value it should be a linear progression. If one of them has gone high, or a joint at one end of the chain has corroded I think that would give the symptoms you describe.
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Re: Transcendent 2000 Powertran PCB diagram

Postby Wonks » Thu Feb 05, 2015 10:57 pm

Cheers. I will try that.
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Re: Transcendent 2000 Powertran PCB diagram

Postby Wonks » Sun Feb 08, 2015 2:38 pm

Well I found my lost multimeter. I seem to be getting a fairly linear response at R13 on most key, up to about 2.5v at the low end of the keyboard and reducing as I went higher, A couple of them seemed to produce an unsteady value jumping between say 1.8v and 4v but I'm not sure if that's down to some dodgy contacts (see other post) or a poor connection on one ladder resistor. But the majority of them seemed OK, so it doesn't look like that's the real problem.
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Re: Transcendent 2000 Powertran PCB diagram

Postby Folderol » Sun Feb 08, 2015 6:57 pm

OK.
Next check is for a step voltage on IC4 pin 2 when you press keys (actually it will be a very fast ramp), and if that's OK, check you have a solid step voltage on IC4 pin 6, just about rail to rail swing.

Also check around SW2 (in the right position?) and D4. This controls Q4 gate - Hmmm, gate of the gate! That should swing from -12 to 0V when any key is pressed - and once you've found the any key do let Microsoft know :)

Ultimately you should get a ramp on IC6 pin 6 depending on the position of the portamento control and the distance between the keys you press.
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Re: Transcendent 2000 Powertran PCB diagram

Postby midierror » Tue Feb 17, 2015 3:52 pm

hello again, nice to see wonks has his transcendent 2000 out of the garden shed!

Plugged mine in today and was sad to hear a very poor signal to noise ratio:
https://soundcloud.com/midi-error/tan/s-1KdDZ

Sounds like white noise, but doesn`t get affected by the filter in any way. Have turned everything up, down, on and off but still it remains. It definitely wasnt this loud before, I`ve referenced the first recordings. Its not affected by the white noise knob being totally turned off.

Any ideas?

[I had a new project on the way, maybe that was my mistake!]
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Re: Transcendent 2000 Powertran PCB diagram

Postby Wonks » Tue Feb 17, 2015 4:59 pm

I'm awaiting delivery of the new contacts, so my progress is on hold until they arrive.
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Re: Transcendent 2000 Powertran PCB diagram

Postby Wonks » Tue Feb 17, 2015 5:01 pm

Sounds like you may need to trace back through the audio path with a scope to see where the noise is coming from.
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Re: Transcendent 2000 Powertran PCB diagram

Postby Folderol » Tue Feb 17, 2015 7:10 pm

That noise signal is remarkably (almost suspiciously) smooth, so I think we can probably eliminate dry joints as the cause.

With the envelope switch in 'bypass' to eliminate any possible action from that, does switching the the filter shape switch make any difference? If not, it's around the final stage, the VCA.
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Re: Transcendent 2000 Powertran PCB diagram

Postby midierror » Tue Feb 17, 2015 9:49 pm

Yeah nothing affects it...I`m beginning to think its the fabled background noise - but it does seem quite loud. Where can I look on the VCA Folderol?

Would you recommend doing these small mods?
http://www.cykong.com/Synths/Transcendent2000/T2k-General-Mo...
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