Peavey XR600B no sound

[Enzo]

The 400 B/G and 400 BH were very similar and more or less interchangeable. They could have mounted either one. The rear panel was printed for BH because most of them used that one, but if there was a production shortage, the other could be used. They have the same ratings. Believe what it says on the board.

SOme of the part numbers differ, and there are subtle differences. I posted the 400BG on www.ampix.org in the Enzo gallery.

When a part reads open like that, reverse tour ohm meter leads and measure again. If this time it reads "negative resistance," then there is voltage present - usually just charge in a cap. It is sufficient to lift just one end of a part to test it.

You don't have to remove parts to test them. A shorted component is not going to read as not shorted from being in the circuit. If it reads shorted, then pull it and retest. After all, if it is shorted it has to come out anyway. There are often parallel circuit paths that result in lower readings than the part itself. A look at the schematic usually reveals those cases.

Start at the start. Use the right schematic for your board - the 400BG apparently - and verify all the DC readings on the schematic are reasonably similar.

[dentsinger]

Thanks for your patience Enzo. I could simply have given up by now and taken it in to the nearest tech. I know this is important though for me to work through it. It's already helped fill in some gaps in my self taught electronics knowledge.

The 400B/G schematic makes much more sense to me now and I appreciate that. Things I'm still a little cloudy on are correlating the trace drawing to the schematic drawing for figuring out where to start or where I should be doing VDC testing. I was able to test the +-15 point after you pointed out the plug and it's location. I can see some points showing + and - 52 a 26 and such, but I'm still unsure when I should be testing VDC or for current which if I'm correct I have to pull a point and test in series.

[Enzo]

Look at page 2 of the 400BG drawing. That is the parts layout. Now page 1, see that +26v by R20 and the +1.17v by the base of Q2? Those are test points. The layout helps locate the parts. the points are the component leads themselves, there are not actual test points sticking up.

Ground your meter black lead to chassis, set it to DC volts, and wwith the red probe check every spot the schematic labels with a voltage. 1.17 volts is way more accuracy than is warranted. We aer looking for avout 1 volt, that's all. 1.3 or .97 would be OK, but +10 or -14 would not. No one will ask for a current reading as a rule. Current is inferred by labelling a voltage across a resistor, as they did at R62.

[dentsinger]

Don't know what happened, but now it doesn't seem to power up. No LED's lighting, etc. I might have narrowed it to the output board. I'm getting +/-52vdc at R28, R29, R30, R31, but not the other side at R60, 61, 62 and 63.

[Enzo]

You sure your meter is connected to ground? There should NOT be much of any DC voltage at R28-31, adn there SHOULD be -50VDC at R60-63.

By the way, since you have a 400BG and you also now have that schematic, can we use that schematic for this repair instead of the 400BH? They are close, but part numbers differ. For example The last row of resistors should be R62,64,65,66.

[dentsinger]

Right, the meter was connected to ground and the resistors are the same as you mentioned on the correct schematic. I have the B/G schematic but the drawing of the output board (not included on the B/G) looked the same so I used that...obviously wrong to do.