IC7000 Front panel kills 8 Volt series resistor


 

I have two IC7000 bought at an estate sale and bot were DOA when tested.

I found on one unit the series 4.7 Ohm resistor was bad and replaced it and turned the unit on after replacing it blew again. The 7808 was OK so I fed it a second resistor and tried the front panel from the second radio and the unit quit clicking and shutting down an booted up.

This panel has a bad headphone jack and has no audio out.

I tried the other panel and "tested" the resistor again.

I wonder if anyone else had had experience with this.

The DC resistance on the 8 volt line is 980 Ohms and clipping the lead on the 7805 makes no difference.

Any other thoughts?

By the way to troubleshoot this problem I added two wires to the working front panel to be able to read the 8 and 5 volt levels at the 7805 in that panel.

The bad one zapps the regulator resistor before one can check anything of course.

Any particular parts to look at and save some hacking about?


ThanksĀ 

KE4MD