Traynor YCV-40 No Reverb

[ca7922303]

Generator display shows a frequency of 10000 Hz = 10kHz (much too high for amplifier tests and DMMs).
Output level is 10Vp corresponding to 7.07Vrms (too much for amp inputs).
Use 140mVp = 0.14Vp for instrument input and 1.4Vp for PA input. DMM should read 100mV(rms) and 1V(rms) respectively.

I guess the generator just stores the last settings.
Read the manual!

Do you have 12VDC (without signal) at U1A pins 1 and 3?

Yes, 12vdc @ U1a pin#1/#7 no signal.

[Helmholtz]

Yes, 12vdc @ U1a pin#1/#7 no signal.

Good.
Now adjust signal generator to 400Hz/0.3V output
Feed signal to PA IN. You should see around 0.6V (rms) signal at both ends of C3 with DMM
Same signal should be on both ends of C7.
What is the signal at both ends of C9?
Tank should be connected for measurements.

[ca7922303]

Yes, 12vdc @ U1a pin#1/#7 no signal.

Meant to write 12vdc @ U1a pin#1/#3*

[ca7922303]

5

Good.
Now adjust signal generator to 400Hz/0.3V output
Feed signal to PA IN. You should see around 0.6V (rms) signal at both ends of C3 with DMM
Same signal should be on both ends of C7.
What is the signal at both ends of C9?
Tank should be connected for measurements.

C3(2.7mv &0.00), C7(2.7mv & 1.0mv), C9(5.1mv &0.00).

[ca7922303]

5

C3(2.7mv &0.00), C7(2.7mv & 1.0mv), C9(5.1mv &0.00).

Correction: C3, C7, C9 all positive ends of cap are 0.00mv.

[Helmholtz]

Now please measure signal (i.e. AC voltage) at both ends of C6.
What does the signal generator display show?

[ca7922303]

Correction: C3, C7, C9 all positive ends of cap are 0.00mv.

Removed dmm negative lead from chassis and getting C3(20mv), C7(20mv), (20mv).

[Helmholtz]

Removed dmm negative lead from chassis and getting C3(20mv), C7(20mv), (20mv).

Measurements done with only one meter lead will show useless "ghost" voltages.
Negative meter lead must be connected to amp ground for real measurements.

[g1]

ca7922303 can you please post the serial number of the unit. Also any board numbers and revision numbers from the circuit board.

[ca7922303]

ca7922303 can you please post the serial number of the unit. Also any board numbers and revision numbers from the circuit board.

Serial number 7011482WR, board#m581.

[ca7922303]

Now please measure signal (i.e. AC voltage) at both ends of C6.
What does the signal generator display show?

C6(+61mv, -3.5mv), C9(+55mv, -5.8mv), C7(+64mv, -2.5mv), C3(+59mv, 2.7mv)photos attached of settings.

[g1]

Serial number 7011482WR, board#m581.

The M581 board should have a version or revision number on it somewhere. Like maybe rev. or V. something? Or post some pics of the board if you can.
There are several different schematic versions for the YCV40 and I'm not sure that we are using the correct one.

[ca7922303]

The M581 board should have a version or revision number on it somewhere. Like maybe rev. or V. something? Or post some pics of the board if you can.
There are several different schematic versions for the YCV40 and I'm not sure that we are using the correct one.

I'll have to remove the board again to get to the component side, trace side is only showing the number I gave you. I'll get to it asap, work m-f 0600 to whenever. Thanks for your help

[g1]

C6(+61mv, -3.5mv), C9(+55mv, -5.8mv), C7(+64mv, -2.5mv), C3(+59mv, 2.7mv)photos attached of settings.

You have your meter set to a DC volt range. The straight line with 3 dashes under it is the symbol for DC. The AC symbol is ~ .
It looks like that meter only has a 500 and 200 volt AC range. Try with the 200AC range.

[Helmholtz]

All these signal levels at the caps make no sense.
Was the amp even turned on?

Your picture shows the meter in 200mV DC range. Not suitable.
You need AC range for signals.

I have a similar looking cheap DMM.
It doesn't work for low level signals.
Also it doesn't isolate DC from AC, which is essential for these measurements.

For a meter test, directly measure the output of the signal generator.
And measure a 9V battery in AC range.