Archive for July, 2011

h1

Fender Passport info

July 7, 2011

Fifth, there are some easy and quick things to look for inside, such as inline fuses in the power supplies (if they are present), and obvious short circuits. If Fender is willing to share the schematics, which I think they are, try to confirm the presence of the power supply voltages. Beyond that point, you are going to be hauling it to a tech or finding a cheap box mixer to use with the speakers. With a bit more experience, you can guess where to test the power supplies (look for big capacitors) without a schematic. But having the schemo is always a good thing. Now we get into a bit more difficult territory — definitely at the varsity level in terms of necessary experience. The “protect” circuit probably involves a relay on the speaker lines. It is a stereo amp. If one channel is blown, the other might still work, but is not available due to the relay being open. If you can find the output signals before they go to the relay, you can test whether it is one channel or both that are blown. Also, a DC level on either output of more than a few tens of mV is an indication of a dead power amp plus a clue as to a blown output transistor. Or if both channels are good, then the protect circuit is malfunctioning.

 

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