I have a Fender Jazzmaster Ultralight that won't turn on. They have a power amp /DSP board with surface mount components including the low voltage regulators. I have 40VDC output from the power supply to the power amp board. I unplugged the preamp boards from the power amp board and measured the low voltage supply voltages.
The -15VDC supply is good, but I'm getting only 2 VDC at the output of the 7815 and 7912 regulators. The 5VDC supply also reads only 2V and comes from it's own transformer windings according to Page 2 of the schematic:
http://support.fender.com/schematics...ight_59000.pdf
So now what? See if Fender sells the board complete? Removed the power transistors and see if one is shorted? They are mounted to the underside of the extruded aluminum chassis top behind the power supply board.
I guess I'm looking for advice whether to abandon the quest (don't have the capability to work on surface mount boards), buy a replacement board if Fender has any, or dig deeper into the power amp.
Thanks
The -15VDC supply is good, but I'm getting only 2 VDC at the output of the 7815 and 7912 regulators. The 5VDC supply also reads only 2V and comes from it's own transformer windings according to Page 2 of the schematic:
http://support.fender.com/schematics...ight_59000.pdf
So now what? See if Fender sells the board complete? Removed the power transistors and see if one is shorted? They are mounted to the underside of the extruded aluminum chassis top behind the power supply board.
I guess I'm looking for advice whether to abandon the quest (don't have the capability to work on surface mount boards), buy a replacement board if Fender has any, or dig deeper into the power amp.
Thanks
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