FRG-8800 Loses Audio

[Kbhall4u]

I have a Yaesu FRG-8800 Communications Receiver with the optional VHF module installed. Unit seems to work fine for about 10 minutes then the audio mutes and the display flashes. Turn unit off and on again, same problem. Unit has to be off for some time, then problem goes away until the 10 minutes. Seems the shorter the unit is off, the sooner the the error returns. Presents as a heat problem.
I took the unit apart and inspected the boards and solder joints looking for the notorious cold joints but all seemed good. No cracks either.
Any ideas where to look next?

 

[Patch42]

In all honesty, if you have to come here to ask that question, it's time to take it to a professional. I wouldn't have a clue what to look for either and likely wouldn't know what to do if I did know what to look for.

 

[techman210]

PLL synthesizer unlocking-

Antique Radio Forums • View topic - FRG-8800 pll lock and flashing display

 

[merlin]

A thermal problem. If you are handy with a service manual and volt meter, you can check supply test points.
If all that is good,,time for a scope.
Often you can find thermally bad parts with a can of freeze mist.
Look for resistors that too much smoke got out.