Quote:
Originally Posted by AdyH
Many thanks for this - I’m struggling with the quiet left hand side channel so will have to come up with a solution to that now before anything else.
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Ady
This doesn't necessarily have to stop you doing the Bluetooth conversion... if you go ahead with this, then this balance problem may reveal itself once you're working on the unit and checking connections and swapping components etc.
There are several tests you could do:
* Is it quieter on one side no matter the input - eg - radio or cassette? If you bought a BT unit and plumbed it in at the right point, this would give you an input to test the volume of each side.
* If the stereo is out of the car and on the workbench, could you connect the outputs straight from the back of the car stereo, (which are 'pre-amp' level) - into another amp to test output levels - eg I used a small cheap phone/ipod type speakers with a bat powered amp. This was useful anyway when working on the stereo on the bench. You can see markings on the circuit board next to the 6-pin round connector to say what the 4 audio out signals are - eg - Front Left (FL), Front Right (FR), Rear Left, Rear Right etc - you can solder wires at these points to bypass the 6-pin connecter.
This would tell you whether the outputs are the same coming from the stereo, which would indicate problems with the amp or speakers in the car.
* I have in the past had hi-fi amps where one channel was quiet or not working, and it was from the balance knob potentiometer being dirty/knackered, or the volume knob pot might be bad, or even the fader. You could use a contact cleaner spray, and give the pots back-and-forth movement because they may not have been used for a long time.
* Without seeing it I can't say, but bad electrolytic caps in the signal path might be causing one channel to be quiet or dull. Unfortunately testing caps can be laborious because you really need to unsolder them individually and test them off-board with an ESR meter. But 're-capping' is a thing with vintage hi-fi repairers, who will order replacement caps for practically every elec cap in a unit - using good-brand caps, and this rejuvenates the circuit. I did this with my TD-603 - and many of the caps - particularly the smaller elecs - still 'worked' but after 30 years were drifting well out of spec, including the ESR being too high. When I replaced these caps (it cost around £20-25 for parts from bitsbox and took 8-10 hours ish) the stereo just worked well, sounding as good as it would when new, plus, the new caps will last another 20-30 years. Your problem may be gone if you did this.
John