JCM 2000 DSL no output

[g1]

The amp still works when you go into the FX return?
Use that side of R73 as ground for your black meter probe.
See if you can get a DC voltage reading at R71.

[sweatyk]

R71 = 518v, 519v

[g1]

Good. Continue using that point as ground.
Take readings at both sides of R71, R63,R62, R61.

[sweatyk]

R71 = 518v, 519v
R61 = 452v, 428v
R62 = 449v, 456v
R63 = 456v, 516v

[g1]

Now you can check if you get the same results using the main ground you were originally using. If so, you can continue using that ground.
Then check voltages at R19, then pins 1&6 of V1,V2,V3,V4.

[sweatyk]

R9 = 0V, 0V
R20 = .1mv, voltage jumping around settling near 3mv
R21 = .1mv, .1mv
R51 = .63V, 26.03V
R52 = 1.35V, 19.06V

[g1]

power supply & power amp schematic:
JCM2-60-02 (2001) iss7.pdf

[g1]

R9 = 0V, 0V
R20 = .1mv, voltage jumping around settling near 3mv
R21 = .1mv, .1mv
R51 = .63V, 26.03V
R52 = 1.35V, 19.06V

Sorry, I deleted that post as it referenced the wrong schematic.
Please see post #80

[sweatyk]

All measurements relative to earth....

R19 = 433V, 421V
V1 pin1 = 264.7V, pin6 = 191V
V2 pin1 = 298V, pin6 = 330V
V3 pin1 = 453V, pin6 = 246V
V4 pin1 = 291.5V, pin6 = 295V

[g1]

How about either side of R24 and recheck pin 1&6 of V2.

[sweatyk]

R24 = 408V, 429V
V2 pin1 = 295V, pin6 = 328V

[g1]

So far all the DC voltages seem good. Check that the +15 & -15 supplies are good (at pin 4 & 8 of any 5201 IC).
Beyond that it will be time to inject a signal and trace it through the circuit to see where it is getting lost/weak.
Do you have or have access to a scope?

[sweatyk]

I'll check those in the next couple of days. Mr. Sandman is calling right now......lol. I do not own a scope nor have I interjected a signal before. Those are uncharted waters to me. I'm kinda stuck in the basics. I wish I had a good local mentor to experience these things and learn more. I'll check the +/- and get back to ya.

[DrGonz78]

I do not own a scope nor have I interjected a signal before. Those are uncharted waters to me. I'm kinda stuck in the basics. I wish I had a good local mentor to experience these things and learn more.

Yup I know that feeling well. Sometimes you just have to jump in head first and take the plunge. Injecting signal is very simple today and you can even just use an audio program like Audacity(which is free) to use as a signal generator. You just plug the signal into the input of the amp and then you can trace a signal. You don't NEED a scope at first to trace a signal. There are many simple devices that you can build that can be used as a signal tracer. One of the most simple versions is where I started when I built one. Just make sure you use a coupling cap that is rated for high enough voltage when testing on tube amps, 600v rating is great. Even when you have a scope it is still beneficial to have a simple signal tracer around as to hear the amp. I tend to just plug my signal tracer into a practice amp that I have laying around but you could use even old computer speakers etc...
Simple Circuit Debugging
or better yet http://www.tdpri.com/forum/attachmen...r_injector-jpg

Also, putting a resistor in series with the signal tracer will help if you ever test a very strong signal that might overload you amp. In this example there is an extra parallel resistor bleeding to ground as well.
http://www.musicfromouterspace.com/a...nal_tracer.gif

Lastly you can watch some people on youtube that have videos explaining how to trace audio signals with these tracer probes. Start simple and even just trace signal on a low voltage device before you jump into the tube amp.

[sweatyk]

Checked the IC 5201
pin 4 = -15.5V
pin 8 = 15.5V

Currently working on building a test probe. Largest city in the united states and not one decent place to get the capacitor I need.