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Sony CDX-C5000 head unit, TUX-020 tuner module failure

Hi.

I have 2 Sony Car Audio head units both with faulty tuner modules. The module is labelled TUX-020, and is listed online simply as "mounted circuit board", it is also no longer available. I am able to get schematics for the main unit, but this does not include any details of the tuner block at all. I suspect Sony regarded it as a "black box".

One of the units tunes to AM stations fine, but FM reception is extremely faint, barely audible behind the background noise. The tuning voltage does sweep when I do a seek, and since the local stations are faintly audible I suspect some failure in the front-end.

The second unit does not tune at all, though noise is present and changes when an aerial is inserted. On this one the tuning voltage remains high and does not sweep at all, obviously no reception on any band.

Car aerial has been confirmed good with a working unit. I have swapped the tuner modules between the head units and the fault travels with the module, confirming that the fault is with the module itself.

Does anyone have a schematic for this module? Failing that does anyone have an old head unit with a good module (possibly one with a faulty CD mechanism or output stage)? Or possibly some idea of where to start fault finding? There are a lot of models from this vintage (around 1999) which appear to use this module. If it's any help in identification, the unit is a face-off with CD/MD changer control.

I would just buy a new head unit, but I have a 10 disc CD changer fitted to the vehicle which is in good working order.

Reply to
Clyde
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band.

From my experience on

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probably not the TUX but some sort of firmware problem or a problem on the front panel if its like those Sony XR-C5300 cant help more than that , its a "repair" job that got away

Reply to
N_Cook

Hi!

A friend of mine was repairing a radio using a similar TEA-series IC. I don't recall the exact details, but the IC "seemed" to be doing most of the right things while reception just never happened. When audio did come through the set, there was a lot of hash and other noise in the signal. Every other piece of circuitry checked out.

He replaced the IC and the radio sprang immediately back to life.

William

Reply to
William R. Walsh

I have to say I am suspicious of the i.c, as initial comparisons between the 2 modules don't show any notable differences in component values. The i.c itself seems to handle virtually everything aside from the tuned circuits. I am suspicious that I have 2 faulty chips, one with an RF amplifier or AGC fault or something along those lines, the other with a fault in the tuning section.

I may well see if I can grab the i.c. and try it if it's cheap enough. It may be difficult soldering up since there are quite a few large components around it, which may make access awkward.

Thanks for the info

Reply to
Clyde

Reply to
JR North

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