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Post by jeremy on Jan 3, 2014 20:54:32 GMT -5
I have some new FETs I can install, Ill remove them first and check, then if the DC is gone ill put the new ones in and re-check
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Post by jeremy on Jan 3, 2014 21:36:49 GMT -5
I pulled the 2 FETs from the FR channel, didn't put any new ones on, just put it back together and checked for DC on the speaker terminals. The receiver comes on, stays on, both power and amp relays click, no smoke coming from the pre-driver board,... but there is voltage on the FR still, and it jumps all over from 1.5v DC to 19v DC quite randomly, the FL also does the same thing only in negative voltage, and it seems to be quite lower from -30mv to -6v DC.
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Post by mastertech on Jan 3, 2014 21:45:39 GMT -5
1 last thing to check and I'm off for tonight. Diode scale test Q33 and D1068. You check them on the other channels also to compare. Q32 and D1067. Q31 and D1066.
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Post by jeremy on Jan 3, 2014 22:21:53 GMT -5
Sounds like a plan, Ill get back to you tomorrow with the results
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Post by jeremy on Jan 6, 2014 10:09:13 GMT -5
Ok back, sorry I didn't reply when I said I would, got a bit busy. Anyway, I went ahead and checked all those parts you asked me to and they all check out fine. I did replace those fets in the FR channel as well as the emitter resistors. They are all soldered in place and the receiver does power up with all the cables plugged in as normal, both relays click on, no smoke from the pre-driver board, but the voltage is still fluctuating on the FR from +0 to +20v DC, and the FL does the same as I mentioned before, only it goes from 0v to +5v and it seems to stabilize back to normal more often than the FR does. I'll give myself one thing, I sure know how to pick the "good ones"  |
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Post by mastertech on Jan 6, 2014 12:18:40 GMT -5
The fluctuating voltage can be caused by various things. A bad cap could be 1. But seeing how you have fluctuating on 2 channels we have to look for a component common to both but not the other channels. So far I only see ic903 and Q946. Can you probe the pins of ic903 and Q946 and see if the readings are fluctuating there also?
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Post by jeremy on Jan 6, 2014 18:42:11 GMT -5
Checked IC903 and Q946. Voltage on IC903 seems stable at +14.5v and -14.5v, on Q946 the voltage is +4.98v on one lead, +0.493 on the other outer lead, and zero v on the center lead.
They don't seem to fluctuate on either of those parts.
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Post by mastertech on Jan 6, 2014 20:41:50 GMT -5
I was more wondering about the other legs of ic903. If possible maybe give me a pin number and voltage reading of each pin.
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Post by jeremy on Jan 11, 2014 19:26:39 GMT -5
MT, sorry I haven't replied in a few days. I've been busy and haven't gotten a chance to get that IC tested. I needed to order some more parts anyway because I'm running low on stuff around here, so I ordered a bunch of the parts that were in the VSX-09TX as well (including those ICs and a bunch of the transistors on the pre driver board).
I'll get back to you on the IC test as soon as I can get some spare time though. I would like to get this receiver finished since I got the rest of the matching components to go with the system now. (and I'm excited to hear it with the rest of the system)
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Post by mastertech on Jan 12, 2014 12:27:09 GMT -5
That's fine. No hurry.
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