TS-850S/AT Troubleshooing

[KE4QCT]

Assistance in troubleshooting a Kenwood TS-850S/AT HF Transceiver.....When turning the set on, the frequency display works for about 2 seconds, then goes blank. A Morse Code signal "UL" is sent after the readout disappears. If the frequency is changed, the display reappears, but again, disappears after 2 seconds.  Appreciate any help....This set has giving trouble free operation for many years.....Mike

[WB2WIK]

UL = "unlocked," indicates the phase lock loop has lost lock.

Needs PLL/VCO service.

Is the rig sitting in a cold room?  These rigs can lose lock if the room temperature gets too low.  If it's in a cold room, try heating it up a bit and see if lock is restored.

WB2WIK/6

[W9SZ]

There's a very knowledgeable group of people at this Yahoo group:

http://groups.yahoo.com/group/TS-850_450_690

Feel free to join!

The TS-440 is notorious for its VCO unlock problem due to a contact cement Kenwood put on the VCO part of the circuit.  I successfully repaired mine by taking every component off that board and cleaning off all the glue.  Very tedious, but worked fine afterwards.

The TS-850 has a similar problem but it hasn't happened to mine yet.  I think it's due to some other cause, as there's no contact cement on the VCO circuits in the 850 AFAIK.