[Kenwood] Troubleshooting TS-820S

[cemilton at aol.com]

An elderly ham friend has asked me to "take a look" at his 820S since it abruptly quit receiving.  I have no service manuals, but did pull enough info off the web to look at each of the modules in the rig.  Power supply is fine.........all voltages are nominal.  All connectors were re-seated and the usual re-torque of all screws was done.  All switches and rear plugs were verified as o.k. and since the rig is his original.........and never been modded, etc. ---------------- I suspect that a discreet component has gone south.  Especially an electrolytic cap or transistor.

I discovered that the relay (RL-1) pulls in at power on!  Reading the schematic on my computer screen is a bit tedious, but tracing the RL lines out brought me to the FIX-VOX module (and others).  I'm suspecting Q-9 or another component as the culprit.  I can see where the schematic shows "0" volts on the collector of Q-9 but I can't distinguish if that is a transmit or receive measurement condition.  I'm measuring approx. 24v at that point.  (Didn't write down the actual figure)

Any comments?  Am I on the right track?  I work on tube-type gear only and thus have no solid state repair parts to speak of.  With the large number of electrolytics in this rig and given its age, I find it easy to consider one or more of them going bad. I would hate to order out one or two components and find they were not the problem.  An expensive way to do a repair, IMHO.

The rig is too nice to just let it go and I'm not certain he wants to spend much money repairing it.  He uses it primarily as a receiver.

Thoughts and comments are welcomed.

73
Chuck
W4MIL

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