07-01-2016, 10:10 AM
I have basically the same problem with each of these, which is that one of the two decks doesn't power up. The deck mechanism is identical in both models although the associated circuitry duffers, as does the metod of connecting the mech. to the 'motherboard'. In the 505 three ribbon cables (two on the play only deck) are used, whilst in the EX90 a multi-way fixed plug/socket arrangement, plus one ribbon per deck is used. I've checked all ribbons, the microswitches on the deck mechanisms, and other relevant parts though i haven't made any detailed measurements on either machine's 'motherboard' as yet.
Is it possible that faults could occur in components on the motherboards whist the deck mechanisms have been removed pending fitting new drive belts & pinchrollers, maybe due to static electricity. All ribbon cables were completely unplugged from both decks and removed from the motherboards, and not refitted until the belts, etc., had been replaced, which, in both cases was two or three weeks after dismantling the machines. I haven't had this problem on previous occasions when repairing similar SONY cassette decks.
Is it possible that faults could occur in components on the motherboards whist the deck mechanisms have been removed pending fitting new drive belts & pinchrollers, maybe due to static electricity. All ribbon cables were completely unplugged from both decks and removed from the motherboards, and not refitted until the belts, etc., had been replaced, which, in both cases was two or three weeks after dismantling the machines. I haven't had this problem on previous occasions when repairing similar SONY cassette decks.
