In article ,
thanatoid wrote:
Does anyone have any idea what I should do first? I want to
determine exactly /what/ in the chain from the *turntable audio
cables/cable extensions/original RCA plugs and cable/circuit
board* is NG.

Well, I'd say that one of the two standard approaches would work.
Which one you would use, depends on what sort of test equipment you
have available.

Probably the easiest approach is "work backwards". You'd use some
sort of low-level signal injector (something which can create a few
millivolts of audio), starting at the input selector switch (probably)
and working backwards towards the turntable, and see how far back
along this signal chain you can go before you stop getting audio
output through the amplifier.

The other way is "work forwards"... from the cartridge towards the
preamp and amp, using an oscilliscope to see how far along the chain
you can detect audio when you stimulate the cartridge (e.g. playing an
LP, or touching the stylus gently with a brush).

Take all of the appropriate safety precautions, of course!

If the phono preamp is dead, it's dead. The unit is still a
/great/ AM (and decent FM) receiver and line-in amplifier,
handles TWO sets of stereo speakers, and it will outlast all of
us.

In a component of that type and age, I'd suspect one of two things as
the most likely culprit:

- A bad switch in the signal path (maybe in the preamp, or maybe at
the turntable itself - if I recall correctly, some turntables have
anti-thump muting switches which short the signal from the
cartridge until the stylus is playing the groove), or

- Dried out and "open" electrolytic capacitors, coupling one stage
of the preamp to the next.

There could also be a power supply problem affecting the phono preamp
stage.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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