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Envelope/Gating Circuit peak test
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Envelope/Gating Circuit peak test

by Biggs7 on Sun Nov 05, 2017 2:57 am

Hello all, I'm building a WillZYX kit and I ran into a problem testing the gating circuit. I have no problems with the 12VDC at D35, but I cannot get 12V peak from the R3 trigger. I have visually inspected the pcb for poor solder joints and orientation of the Q's. I will try to start testing some components in circuit if possible. Any suggestions please?
Thank you!
Sincerely,
BIGGS7

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Re: Envelope/Gating Circuit peak test

by antto on Sun Nov 05, 2017 5:12 am

Biggs7 wrote:Hello all, I'm building a WillZYX kit and I ran into a problem testing the gating circuit. I have no problems with the 12VDC at D35, but I cannot get 12V peak from the R3 trigger.

R3 trigger? R3 is on the IO board, part of the circuit that makes the 5.333V voltage

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Re: Envelope/Gating Circuit peak test

by Biggs7 on Sun Nov 05, 2017 1:40 pm

Hello. Sorry for the confusion. Yes. R3 on the I/O board (5v) is the reference point that is used in the build manual on pages 56 and 57 to pulse 12vdc to D36, using a jumper wire from R3 to R146(gate I believe) and touching R3 momentarily to send 12vdc. I do not see this pulse ever.... I do have good 12vdc on D35 when a jumper is connected from R3 to R146. And I also have no voltage when the jumper is disconnected as normal...
Thanks again.
Biggs

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Re: Envelope/Gating Circuit peak test

by Biggs7 on Mon Nov 06, 2017 6:27 pm

Antto, any suggestions?
Thank you.
BIGGS

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Re: Envelope/Gating Circuit peak test

by antto on Tue Nov 07, 2017 1:16 pm

the signal at D36 should be a very short spike (probably about 1ms, don't quote me on that)
if you're measuring with a multimeter chances are very high that you won't "see" it
if you're measuring with a scope, make sure you've configured it to trigger properly so that it pauses when it catches the spike

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Re: Envelope/Gating Circuit peak test

by Biggs7 on Tue Nov 07, 2017 9:51 pm

Antto, thanks. I was using a dmm and I did see a bit of a jump, but never see 12vdc. I also tried to turn on the hold feature on my dmm, but i never see it or hear an audible beep. l do also have a scope which I just purchased. It's an older tek 453.... Still getting the hang of it.... I didn't think too much of this problem I'm having originally and I just noted it in the manual and kept on building. I've finished the vca now and when I try and do the test on pg. 61, I don't hear a note being played. I need to double check my headphone wires again, as there are 3 conductors. They are cheap earbuds... I do hear some noise when I rub the headphone wire around the rightmost pin hole of vr8 for the volume pot.... you have to use r146 again in this test, so I figured something was not right with the envelope gate section.... I'll try to see the pulse on the scope with it setup appropriately and let you know what I see...

Biggs7
 
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Re: Envelope/Gating Circuit peak test

by Biggs7 on Wed May 30, 2018 9:07 pm

Hello Antto, all,
I finally took my WillZYX kit over to a friend of mine who is a good engineer and it seems my problem might be in the amp section? We were able to see the 12V pulse on the scope ok for the gate, but my friend seems to think the transistors in the amp section are acting backwards? We are seeing the collector of Q3 go down when it's gated. Pin 4 goes down also, but stays down(no pulse.) My friend would like to know the following if possible..... How does the gain of the 6110 pin #6 respond to control voltage @ pin #4? Also, what is quiescent voltage at pin 4? And how does it change when the VCA is gated? Thanks in advance!
BIGGS

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Re: Envelope/Gating Circuit peak test

by Biggs7 on Sun Jun 03, 2018 4:27 pm

Hello all, can someone here in the forum please give me some information for the questions I asked? I'd really like to resolve this problem, so I can continue on....
-Biggs

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