All things G1176 - the new "repost" thread.

[a2d]

should I remove R18 to take the fet out of circut?

 

[gswan]

Just disconnect the wire at the junction of the two pots (7).

 

[a2d]

ok I removed the connection from the pot and  I hhave 142mv with the pot in either direction

 

[gswan]

Is this measured at the pot (not the wire)? What is the voltage on either end of the Release pot (just to check where you have the Qbias pot set to)?

 

[a2d]

this was measured at point 7 on the main board ith it removed from the pot

 

[a2d]

on either side of the pot to grnd on the high side I have -1.16v and on the low side -1.19v( with wire disconnected going to pad 7

 

[gswan]

Now measure the junction of the attack & release pots (high side of release pot) with the pot at each extreme.

 

[a2d]

ok release pot CCW -0.820  CW -1.15v

 

[gswan]

Lift one end of each of the two FDH333 diodes and try again.

 

[a2d]

ok CCW-.798  and CW -1.14

 

[gswan]

Check point (19), it's sounding like a wiring error. There should be no change of the voltage at the junction of the attack and release pots with the diodes lifted and the wire to point (7) also disconnected.

 

[a2d]

release pot CCW -.670v  CW -.963 at point 19

 

[gswan]

Check the wiring between point 19 and the pots. Check the circuit board for shorts at point 19. There's a problem here by the look of it.

 

[a2d]

I'm looking into it, thanks so so much for your help!!! your a good man

 

[a2d]

ummmm the pot wiring is good, as the ratio board wiring ???

 

[mac]

Geoff is da guru  ;D  ;D

 

[a2d]

if I have -9.05 V on the low side of the release pot I should have a constant voltage output on the other end of the 5 meg pot regardless of the pots positin , is this correct
if it is it sounds like a bad pot, because the voltage changes then you turn the pot

 

[gswan]

ummmm the pot wiring is good, as the ratio board wiring ???

Check again. Current is leaking out somewhere. You have the Qbias voltage source feeding the Release pot and attack pots and nothing else. There is no path to ground so you must have a constant voltage (V18) at both these points (top of attack pot, which used to go to point 19, and junction of two pots which used to go to 7), irrespective of pot position.

 

[gswan]

if I have -9.05 V on the low side of the release pot I should have a constant voltage output on the other end of the 5 meg pot regardless of the pots positin , is this correct
if it is it sounds like a bad pot, because the voltage changes then you turn the pot

A bad pot would show either full voltage or nothing (ie open circuit). Unless you have connected the body to GND and one of the legs is shorting to GND (against the front panel etc)

 

[a2d]

ok well I'm going to call it a night on this ,,,, I'll look again in the morning I still don't see anything wrong with the wiring or any shorts around pad 19,
Thanks Gswan