Hi everyone,
I'm looking at a pioneer A204A which had badly distorted sound, I probed the input channel from the CD input to the input of IC9163N (analog switch) and inputs on both channels sound ok, but the output on pin 6 was distorted and the other channel sounded slightly better, I checked the chip and power supply( + and -) in is good, ground is also connected. I also checked the other inputs (tuner in) and they are the same. I temporarily bypassed the IC switch with a piece of wire on both channels and now its working on cd, so initially I though it must be a faulty switch, not ordered or replaced yet ( re-flowed the pins and they look good) But here is the question, is the input marked ST the clock that switches or cycles through the inputs? I do not see any voltage changes on this input when I select tuner and then cd. Or on any of the others for that matter, I presume I should see maybe a voltage spike? when the inputs are selected.
Thanks in advance.
I'm looking at a pioneer A204A which had badly distorted sound, I probed the input channel from the CD input to the input of IC9163N (analog switch) and inputs on both channels sound ok, but the output on pin 6 was distorted and the other channel sounded slightly better, I checked the chip and power supply( + and -) in is good, ground is also connected. I also checked the other inputs (tuner in) and they are the same. I temporarily bypassed the IC switch with a piece of wire on both channels and now its working on cd, so initially I though it must be a faulty switch, not ordered or replaced yet ( re-flowed the pins and they look good) But here is the question, is the input marked ST the clock that switches or cycles through the inputs? I do not see any voltage changes on this input when I select tuner and then cd. Or on any of the others for that matter, I presume I should see maybe a voltage spike? when the inputs are selected.
Thanks in advance.
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Search for TC9163N and you should find a datasheet to answer your question. Electronic input selectors have a reputation for requiring good input protection (even if only 2k2 input series resistors) and occasionally blowing up all by themselves. Apparently you can still buy replacements, but how trustworthy those are, I don't know.
Hi, I got it resolved a few days ago, it was nothing to do with TC9163N, I was getting no voltage changes on any of the pins on TC9163N when any of the input switches where pressed, the voltage going to the chip was present, I bypassed the tc9163n with a jumper cable temporarily and the amp worked. Checked around the control circuit IC202 ( can not see the chip P/N the schematic is not the best) Found a faulty super capacitor 5.5V, it had only voltage on one side, I stuck a 100uf normal capacitor in place and it works now. Took me ages to find, was testing continuity on all the wires and tracks, but If I knew straight away this had a super capacitor I would have went straight for it (they go bad a lot), I will know better next time. Its left of the main chip on the diagram
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