Whoreo's (Rob's) WOPL 400 in for Warranty Work

[laatsch55]

Both channels driven at 20hz, 136mv input...

 

[jbeckva]

Wow.. what if you take the load off? Any bad signal then?

 

[laatsch55]

Hang on Jer...

 

[laatsch55]

The same loaded or unloaded...

 

[jbeckva]

Strange how it's both channels, Lee. Is the 20 and -20 steady under a scope reading, and under an input signal?

 

[laatsch55]

It's steady on the bench, havent checked under load..

 

[laatsch55]

Double checked R23 R/L, R35 R/L, R78 R/L, R79 R/L all good...

 

[laatsch55]

Shouldn't I have minus rail voltage on the collector of Q7??

 

[jbeckva]

Got any spare rev E's to swap in and help rule out the chassis / back wall?

 

[laatsch55]

Oh yeah, got an E ready to go, and that was my next move.....but, it bugs me ....

 

[laatsch55]

I did lose an emitter resistor on the PNP row where the 95 was blown..

 

[jbeckva]

Bugs me too, LOL!! really weird.. hey what about taking the DCP out of circuit.. any change there, or have you tried that already?

 

[laatsch55]

No, haven't done that yet.,..what should I have on the collector of Q7, I'm thinkin minus ral voltage...

 

[jbeckva]

No, haven't done that yet.,..what should I have on the collector of Q7, I'm thinkin minus ral voltage...

Thereabouts, yep. What's on pad 3 L/R ?

 

[laatsch55]

Hold on, had a minus rail fuse blown...jeez and I checked that thing twice, got minus rail voltage now.. Let me get it back on the sciope..

 

[laatsch55]

Now I have positive rail voltage on each speaker out...

 

[laatsch55]

Blown minus Pico fuse on the right backplane..

 

[laatsch55]

Got a relay click, back on the scope...

 

[laatsch55]

53watts out, 22k hz .122 THD & N...

 

[laatsch55]

Interesting that a mius pico fuse being out on the right backplane will cause plus rail voltage on the LEFT speaker out...,