Carver Receiver

[FreiherrRitter]

I have a Carver receiver MXR 150 with a dead 5v supply . I have a schematic for a MXR 130 which is pretty close. I am pretty good with digital stuff but not so good with this analog stuff. I am thinking about just installing a LM309 and calling it a day but maybe it is a simple fix. Where is the 5v regulator circuitry exactly . The other supply voltages seem to be OK. Since this amps chassis is not safety grounded what is the best way to use a scope to check it out? Thanks

 

[rayma]

It's also possible that the 5V regulator is being heavily loaded by a defective circuit, and so is reducing its output voltage as protection.

 

[AllenB]

Moved to solid state.

 

[FreiherrRitter]

something smoked and now no 5 volts --I changed out one transistor but no joy --maybe a zener ? Like I said the othe r voltages are OK but I am totally confused by the schematic that seems to indicate that a negative 16 volts is being turned into positive 5.7 volts--black magic ? ha

 

[rayma]

Post the schematic.
It's best to troubleshoot logically, rather than shotgunning.

 

[FreiherrRitter]

I think I have it figgured out --there is a +13 supply from the supply board that goes through 2 transistors with a couple of Zeners and associated caps and resistors to end up with +5.7 volts . I'm not at my workbench right now -just studying the schematic in my study. Will post how I made out soon.