Hi Fred,
yep - you are correct about the input transformers - they go open
circuit, and are a real ******* to replace, as you have to pull apart
the bandswitch mechanism, which usually generates its own set of nice
little problems.

I've done up 2 of them now - a nice little radio, and not too badly
made or designed, all things considered. Synthesiser is noisy, but hey,
its the technology of the time - and not as bad as some others of that
period! But can be really fiddly around the rf front end area. Things
like bandswitch wafers have run out as spare parts, most other things
are still available.

They are getting a bit old now, so have probably been through a few
owners - and if it has been "fiddled" with, can be a bugger to get all
the faults out - but usually worth the effort in the long run.

The CAL oscillator in any radio is also used as a crude signal
generator - so it gives a "quick and dirty" indication of where the
fault is - in this case, its as deaf as a post on 20m.

The loose wires around the bandswitch are a dead giveaway as well -
probably, someone has been in there in the past stuffing around. -
would look for a damaged switch contact as that might explain the loose
wires as well - someone was trying to fault find. Its unlikely to be
the input rx rf transformer as its common to all bands. The switch
wafers can USUALLY be brought back to life with some TLC - you need
more subtle tools than a big hammer, and the patience to do it tho.

73 de VK3BFA Andrew.

ps - this vintage radio is EMMINENTLY fixable at home - no custom VLSI
ics, common parts, simple design, reasonably accessible layout, NO SMD
"things"................ - if you can get a "good" one, go for it.


Fred McKenzie wrote:
In article .com,
"Andrew VK3BFA" wrote:

Fred - its irrelevant here - you are quite correct, but its irrelevant
in this context. The S meter on the ts120 shows different readings on
each band on its OWN cal. oscillator. This is what the oscillator is
designed to do (among other things)

Andrew-

Perhaps I was a little off base. It has been a long time since I had a
TS-120S, and I don't recall the calibration oscillator. I loaned the
service manual to someone several years ago, so I can't check it out!

Since I wasn't aware of the utility of the calibration oscillator, the
only sure evidence of a malfunction was a reference to smoke that seemed
unrelated to receiver sensitivity.

For what it is worth, there is a service bulletin about replacing an input
RF transformer that might have been damaged by static discharge. I don't
know if it applies equally to the TS-120 and TS-120S.

73, Fred, K4DII