Peavey xr-600

[Enzo]

2N5400 or 2N5401. Those are higher voltage parts than comon 2N3904.

Here is a trick, if you don;t have those handy. Just swap them. Put A where B was and B where A was. Even if one of them was bad, the amp would probably still not work, but it would be a different symptom. If it doesn;t change anything, they are probably good. Same with those two 430s.

Generally I believe my meters and such, but in the repair game, people are paying me a dollar a minute to work on stuff. SO how much time would I want to spend testing 20 cent parts? I can walk to a drawer and find almost any part I would ever need for one of these things. I realize your situation is different, so consider that when taking my advice.

TIP30C and TIP31C are good general purpose TO220 3 amp transistors. Always get the C version - the 100v version - it will also work fine anywhere the A, B or plain versions are spec'd, but the 40.60. and 80v versions are less versatile.

Did you follow my crude and simplistic description of how the left side of the circuit works?

[cbass]

Yes Ifolowed your dscription thanks for the help.I'm still trying to take it all in.
I mostly like to work on tube equipment its simple. I can understand it.
I am slowley starting to catch on to this solidstate stuff.I'm only about 50 years behind

I've been checking voltages and Everything is pretty close i think except where the -20volts is being injected.
The 4k7 resistor on the posivtive rail after the 430 driving the output.It shows I should have25vdc there I am onlygetting around 10vdc.The resistor test almost exact.I am assuming this voltage is low because of the negative voltage being injected.
On the negative rail i am getting close about -25vdc after the 4k7.It doesn't list voltage as negative on the schematic but i assume it should be.
I've tested almost all the diodes ones that didn't test right i pulled out of the circuit and tested.Same for resistors.Haven't found anything there.

I nstalled a used tip31c I found laying around.It tested good.But when installed for the suspect 430.I ended up with -45vdc on the speakers.When i put the old one in it went down to back around -20.

I cant thank you enoughfor taking the time and being so patient in helping me.

[Enzo]

Just for grins, see the 50uf/50v cap below the 2k 5w? (See how helpful part numbers would have been?) try lifti8ng that cap from the circuit.

[Enzo]

Go over to Solid State Guitar Amp Forum | DIY Guitar Amplifiers - Index, and in the first category - the general amp discussion - one of the sticky threads up top is a book on solid state written by member Teemu K. It is there for free download. Perhaps download that and read through it when you can. Might help provide a general background for this type of circuit.

[cbass]

lifted one end of the 50uf/50v no change in voltages.

[cbass]

Swapped diify pair and the 430s around still same voltages

[cbass]

Not that it really matters but someone had replaced the 3642 and 3638 xsistors.Ichecked to make sure they were installed right.

I guess i'm gonna replace all the small transistors and those 2 430's

[Enzo]

Well, we seem to be miissing something, but what? Replacing those parts at least tells us if they were bad or not. And if all resistors check out, we can start looking for cracked traces.

Speaking of...

Uuuhhhhh..... did we ever disable the limiters? Right in the middle, the 3642 and 3638? There is a diode connected to each. Disconnect an end of each diode and lift it from the circuit. ANy help? We really should have taken that step earlier. My bad.

[cbass]

lifted both diodes .still no change. Iknow there is probaly something stupid I'm overlooking.this thing is starting to frustrate me

[Enzo]

When you find yourself going over and over the same ground and getting nowhere, then the best thing to do is to set it aside for a day or two to get it out of your head. You might be surprised how many times you come back with a fresh outlook, open it up and smack your forhead - it was (whatever) all along. I admit being guilty of slogging on no matter what, but sometimes you need to clear your thoughts.

[cbass]

doh I didnt ceck fo +16 at the 5w resistor just the voltAGE at the speaker out.Should i lift them and check again

[cbass]

you right I'm gonna crack open a beer after my boys foot ball game toniteand do some work around the house tomorrow.That I should be doing instead of jackin with this thing

[tkeo]

Enzo,

I have Peavey XR 600 G. The light, clips and everything else worked fine except there is no sound coming out from Main or Main/Monitor jacks to speaker. Can you help me figure it out? Thanks

[Enzo]

Sure, but why don't you start a new thread for yours instead of adding on at the end of a thread that died three years ago.


First, at the top of input channel 7, there is a mute button. ANy chance it got pushed in?

For now, turn all your master volumes up midway. Connect a speaker and cord that you KNOW works into each amp output, like normal. Now: Plug a signal into the power amp 1 input, any sound? Now plug it into the other power amp input jack, any sound there?

If either of those power amps works, then plug a spare cord from MAIN OUT to POWER AMP IN. ANy sound?

Does flipping the power amp assign switch do anything?

[tkeo]

First, I am sorry (new here). I tried what you told me, nothing. Could it be one of the circuit board?