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Post voltages for all transistors Q3 with the kill switch in both positions, put simply Q3 is working as a variable resistor controlled by the gate voltage when you adjust P2 it should vary the voltage coming from Q4 which then changes the resistance between Q3 drain and source as it says in the control section
Q4 collector should vary up to what you’re getting off D1 cathode
It is a case of a process of elimination starting at D1 as you have making sure Q4 is getting what it should and moving into Q3 etc
All transistor voltages may tell us something and lead us to the problem
Q1
G-4.40
S-4.73
D-9.26
Q2
E-.97
B-1.59
C-5.85
Q3 (on)
G-0
S-0
D-0
Q3 (off)
G-0
S-0
D-0
Q4
E-0
B-.60
C-6.06
Q3 seems to be your problem
You need a small voltage on the gate less than the forward voltage of the transistor so less than 0.6v for a a silicon transistor
Check all your components from Q4 collector to Q3 gate including your A and B switch connections
Also check if you get a voltage on Q3 socket with the transistor removed
As far as I know it’s an AC voltage that makes it work as as a variable resistor which is controlled by the small gate voltage
Q4 collector looks good so at least we know that’s ok
alright, no clue if I’ve done this correctly, I don’t seem to be getting anything from R10 and R11. C5 is getting 6.07 from the right pad and 0 from the left, and from SW2 im only getting a voltage from the F pad at 1.38 and the lug that F is wired to at 1.27
and there’s no voltage coming from the Q3 socket itself
For some reason it wouldn’t let me post I’m at work right enough on trains so WiFi is a bit sketchy
Anyway I’d check everything after Q4 collector to Q3 gate C5, R10, P2 all you’re doing is checking voltage black probe on a ground connection red to whatever you’re checking if you’ve done that your good
First check continuity to make sure there’s an electrical connection here’s a PDF
https://drive.google.com/file/d/176vVBWeRaSQ0QvZlnozjKHE6AeHsvxFP/view?usp=drivesdk
Everything up to Q4 collector seems good
R13 is getting 6.08 from the left and 0 from the right, C6 is only getting 6.08 when I touch the enclosure or pcb, nothing from C7, C8 will only get a reading if im touching the pcb and its 3.30 on the right pad and 5.50 on the left, R14 is getting .58 while touching the pcb, and R15 is 0.
seem to be getting continuity from both switches. I will have to check the continuity later today for the rest of the components, got a busy day today, since its new to me it’ll take some time to figure it out how all the components are connected on the pcb.
but since im only getting reading on the components in the LFO section when I touch the pcb, its safe to assume that there’s a grounding issue there?
It could be a number of possibilities poor connection or ground, faulty pot, something shorting on the bare metal enclosure etc
if you get a consistent voltage from Q4 collector I’d concentrate there to see why you get nothing on Q3 gate
Do you have a solder bridge between the two center lugs of the kill switch?I see it now (red wire).
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