Fender Roc Pro 1000 - Output is SUPER low

[slow6i]

Yes, power amp is good.

Alright, I have finally gotten time to redo the pop test on the op-amps.

Results can be found https://docs.google.com/spreadsheets...it?usp=sharing

Im still only getting +- 25 volts at U7 (pins 4 & 7), which is low compared to the schematic of +- 40V thought im not sure what this is telling me.

This was dont with volumes all the way up, mix all the way up. and a guitar plugged in with its volume up.

Next steps?

[g1]

+/- 25V at U7 is correct, look at TP17 & TP20 near U7.
Were your pop tests on the chart done with clean channel selected? If not, please redo with amp set to clean channel. Also set mix to 'dry' if you are not using the FX return jack.

[slow6i]

+/- 25V at U7 is correct, look at TP17 & TP20 near U7.
Were your pop tests on the chart done with clean channel selected? If not, please redo with amp set to clean channel. Also set mix to 'dry' if you are not using the FX return jack.

Finally got some time to redo the test.

https://docs.google.com/spreadsheets...Azg/edit#gid=0 This spreadsheet is now up to date with the current information. I also included all my knob settings, and this was done with a cable plugged into the input jack.

Thanks for all the help!

[g1]

That says the mix is set to 10. If you are using the input jack you need the mix pot set to dry, which is 0.

[slow6i]

That says the mix is set to 10. If you are using the input jack you need the mix pot set to dry, which is 0.

Ok, RE-re-did the tap tests, and updated the results on that sheet.

Im starting to think that I should just take it somewhere...

[nickb]

It looks like the signal is not getting thru Q7. Did you do the tests with something plugged in to the input? If you did, then measure the voltages at Q7 gate, CR20 cathode and CR21 cathode. If not then plug in and redo.

[slow6i]

It looks like the signal is not getting thru Q7. Did you do the tests with something plugged in to the input? If you did, then measure the voltages at Q7 gate, CR20 cathode and CR21 cathode. If not then plug in and redo.

Yes, the test was done after plugging a cable into the input jack. For confirmation, I unplugged it as I was measuring your suggestions:

Q7 Pin 1 is the "top" of the D shape looking down at it.

Pin 1	Pin 2	CR20 No Stripe	CR20 Stripe	CR21 No Stripe	CR20 Stripe
2 mV	17 mV	220 mV	5.69V	27 mV	7.95 V
0 V	-15.24 V	-15.84 V	-16.22 V	15.83 V	7.95 V	Cable Unplugged

Thanks!

[nickb]

With those voltages Q7 should be enabled. If Q7 were bad it would explain the clean channel volume but there would have to be a second fault to explain the overdrive signal that comes through Q6.

So, more data is needed. Select the o/d channel and measure the voltages on CR15 and CR17 both sides with the input plugged in. Also measure the voltages on U5 pins 5 and 7, they should both be close to zero.

[slow6i]

With those voltages Q7 should be enabled. If Q7 were bad it would explain the clean channel volume but there would have to be a second fault to explain the overdrive signal that comes through Q6.

So, more data is needed. Select the o/d channel and measure the voltages on CR15 and CR17 both sides with the input plugged in. Also measure the voltages on U5 pins 5 and 7, they should both be close to zero.

Thanks for the response, here are the latest results.

Yellow Distortion Channel CR15 Stripe: 6.48 V CR15 No Stripe: 37 mV CR17 Stripe: 5.70 V CR17 No Stripe: 41.2 mV U5-p5: 0 V U5-p7: .2 mV

Red Distortion Channel CR15 Stripe: 6.49 V CR15 No Stripe: 38.3 mV CR17 Stripe: 5.70 V CR17 No Stripe: 42.6 mV U5-p5: 0 V U5-p7: .2 mV

Notes:
- When measuring the stripe side of CR17, the voltage started at ~10 V, then worked its way down to ~5.7 over the course of about 2 seconds, kind of like a Cap discharging or something.
- All settings are exactly the same as the google sheet save for the distortion channel selected.

[nickb]

Hmm. Well that checks out and I'm not buying that Q6 and Q7 are bad until proven. Please double check: select clean, clean vol up, plug into the input jack and do the noise touch test on U1 pin 5 again. Also measure the DCV on I1 pin 7 (should be about zero) .

Put you meter on ACV and measure the ACV on U1 pin 7 while you strum your guitar or connect a signal generator or music source - whatever works for you. Do you get and significant change in ACV reading when you play? If you do I'd say that U1B is OK and the problem is later. In that case try bypassing Q7 by linking CR19 stripe to U5 pin 6. More likely you'll get nothing in which case I'd replace IC1.

[slow6i]

In that case try bypassing Q7 by linking CR19 stripe to U5 pin 6. More likely you'll get nothing in which case I'd replace IC1.

Do you mean bridging it with a piece of wire or something on the underside then measuring U1 again? Or checking to see if I get amp output with my instrument? Comfortable with both, I just want to make certain I understand what you mean.

Also:
U1 pin 5: 0 Vdc
U1 pin 7: -5.5 mVdc
Pin 7: 3.2 acV (strumming with tone knob at 10, using bridge pickup, clean vol. at 10 on amp.)

[nickb]

Well U1B is OK.

Yes, bridge with wire. You should be able to do this from the top without removing the board. I would use a piece of wire wire ez-hooks. But first let's do some more ACV testing. Turn all the tone knobs to max and measure the ACV on U1 pin 5 and R24 with the strum test.

[slow6i]

Well U1B is OK.

Yes, bridge with wire. You should be able to do this from the top without removing the board. I would use a piece of wire wire ez-hooks. But first let's do some more ACV testing. Turn all the tone knobs to max and measure the ACV on U1 pin 5 and R24 with the strum test.

On U1 Pin 5 with all tone knobs (amp and guitar) maxed: 0 V on all channels (clean, dist. 1, dist. 2)

R24
Band 4 Side (Gold)	Band 1 Side (Brown)
1.1 acV	1.0 acV	Clean
1.1 acV	1.1 acV	Dist
1.2 acV	.9 acV	Dist 2

Again, I really appreciate your help with this back and forth!

[nickb]

Well I'm feeling kinda dumb. I'd already got you to test the ACV at U1 pin 7 but I simply forgot. That meant we didn't need to do the last test. I was obsessed with finding a common cause for all modes failing.

So, in clean ONLY, bridge Q7 as we talked about and see what happens. Also check the DCV on U6 pin 1.

[slow6i]

Well I'm feeling kinda dumb. I'd already got you to test the ACV at U1 pin 7 but I simply forgot. That meant we didn't need to do the last test. I was obsessed with finding a common cause for all modes failing.

So, in clean ONLY, bridge Q7 as we talked about and see what happens. Also check the DCV on U6 pin 1.

I get normal amp output in clean channel after bridging as we talked about (CR19 stripe to U5 pin 6)

I have 0 V at U6 pin 1 with input plugged