Moto M110 2ch VCO problem

[G0FHM]

Hi Guys,

I have just taken delivery of a German built Motorola M110 (MAU34EZA3J22AK), and it appears to have a TX VCO issue.

On first TX, the VCO reading reads dead on 6.0v (as far as I'm aware, that's what it should be - According to the Storno CQM-5500 manual that came with it), but after a few seconds the TX drops and the VCO voltage drops to 1.24v and the radio sounds the 800Hz intermittent (VCO out of lock) tone through the speaker.

It seems to be thermal related, as when the radio is cold, it will take about 10-15 seconds for it to drop out. The more I TX, the shorter time it takes to drop out. When the VCO drops, it will not return to RX until the PTT is released (as it should be).

Any pointers on what could be at fault? I did find the power socket pin to PA board solder joint had failed, and put it down to that causing a problem. But it appears not to be!

Any advice appreciated!

Cheers,

James G0FHM