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OK, R41 checks out at .21...

here is the impacted R25. Thanks for the help!

Well, I'm back, did you miss me? hahaha. So here is where I am at. The PL400 with PL14 board. I have now replaced the transistors with new 96's, (bottom row are 410's). My DC offset on both channels is almost undetectable. The Bias on the left channel is set at .360, however the right channel...

Good going Gene. Did you go with white? PS I think I have this pl400 tamed after going through and replacing all the 10W resistors, and the .001 capacitor. I went ahead and installed the WA output relay, and the DBT has quit lighting up. My final challenge is the right channel has .350 bias...

3V bridge rectifier? Smarty pants! LOL

The part by part testing will resume this evening while watching NCAA basketball. For now, it's 60 degrees outside, and I have a 71 Norton Commando that needs some road time.

Dang it. false reading. Replacing the resistor did not fix the issue. Square one squared

I didn't say Saint! hahaha

You're my hero Gene!

Got it! I found the R39 10 Ohm resistor was reading 15 ohms in circuit. Replaced it and now have 11.9 ohms in circuit, the other 3 are reading 11.5ohms in circuit, so close enough. and the problem went away! I just noticed I've been upgraded to journeyman, is that because I read all 228 pages of...

both check out...

Replaced D14, D15, and the Q7's. Arg. Nothing changed. Yes, that's an Oxford comma.

next up I'm going to pull and test q7

Progress I think. I removed each transistor one by one. The DBT went out on only one. The bottom transistor in row one [Lower right by transformer]. I replaced the transistor with another, and the DBT still lit up, and went out when I removed the transistor. The DBT did not go out when I removed...

Narrowed in on the issue. Removed both rail fuses and the dbt does not light with speakers attached. Replaced right fuse (as viewed from back of amp), and dbt does not light up with speakers attached. Removed left fuse, and BDT lights up with speakers attached. With left fuse still installed...

done. thanks!

I lifted the legs on d9 and d10. No change

Working on a PL400 (different than the one with the DBt issue) and would like to replace the Q1 and Q2 TIS97 transistors as recommended by the manual to correct high DC offset. Mouser and Digikey both list the TIS97 as obsolete. Although Mouser lists a substitute, the specs for the sub don't...

Good thought, that would explain the problem being on both channels. I'll give it a shot, Thanks for the idea!

Has me befuddled too.