Kenwood TW-4100 Problem

[christmegatron]

I have just acquired a kenwood tw-4100. I have been experiencing an odd problem with the unit. When I turn it on the display will come on but there will be no backlight. Also while all functions appear to work no signal can be received not even static. I have performed all resets and all adjustments suggested by the manual. I have taken the unit apart and found the the audio frequency preamp and/or another nearby IC are heating up almost as soon as I turn the radio on.

Now occasionally if I leave the radio unplugged for a day or so it will begin working again. The back light will light, I can receive signals, and the ICs are not heating up.

The backlight is a voltage sensitive device according to the manual and that combinined with the heating of the ICs suggests a short. The fact that being left unplugged for awhile suggests to me a capactitor.

I am writing mainly to see if anyone else has had a similar problem and knows how to fix this issue.

Thanks for your help
_chris

[christmegatron]

Okay I fixed the receive. A bad voltage regulator was shorting out and causing the problem. Now however I found that I also have no transmit. Pressing the PTT button generates a carrier wave but speaking into the microphone does not cause any modulation of the carrier wave. I am wondering if anyone has suggestions about the likely source of this problem.

Thanks