JBL LSR 6312SP test point voltages doubled

[BrianJSiegel]

I'm working on two JBL LSR6312SP powered subs that were buzzing. I recapped them both, fixing one and not the other.

I couldn't manage to find a service manual or schematic but I did see some test points on the amplifier board and they all read at almost exactly double the voltage of what the tests points say they should be. I feel as though there is a somewhat obvious answer that I am just not experienced enough to figure out quite yet on my own.

I'm about to check the voltage regulators and large resistors to see if I can find a faulty component causing the test point voltages to read so high.

Any assistance as to what it could be, would be very much appreciated. Hopefully someone has encountered this issue or something similar and will have some words of wisdom to share. Thanks in advance for any helpful tips.
-Brian S.

 

[TwentyTrees]

...double the voltage...

Bipolar rails and you're measuring between + and -, rather than +/- and 0V?

 

[BrianJSiegel]

Bipolar rails and you're measuring between + and -, rather than +/- and 0V?

I have the black lead connected to ground on that board, and the red lead touching the test points. I did find a couple resistors that were burnt up (100ohm I think) so I replaced those and also a nearby pair of 2N3904 transistors since I had some spares. I haven't powered it back up just yet.

What else should I look for before powering it up and re-testing the test point voltages? Thank you for your help btw.

 

[TwentyTrees]

Without a schematic, anything I could suggest would be just a shot in the dark. I see you've already recapped the units, which would have been my next suggestion - if one of the old caps had failed, that could perhaps have caused the resistors to burn out. But from the sounds of it, you've got a working unit as well as your misbehaving unit - an absolute boon for troubleshooting, as you can compare and contrast to hone in on the issue.

Good luck!