Your information is too vague. There are literaly many hundreds of
solder connections, as of many of them can cause your unit to not work.


Proper troubleshooting would be necessary to service your init.

The first thing to look for are visual faults, such as visible cold
solder connections, and or broken parts, burned parts, or bad
connections.

The next step is to verify that all the power supply outputs to the
various areas on the boards are working properly.

The final step would mean following it through with a DVM, and a
scope, to follow through the signal processing.


Jerry G.
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