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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Onkyo receiver/amp model:TX-SV313PRO
Onkyo receiver/amp model:TX-SV313PRO,year:1996 one day the customer
turned the unit on and there was no audio ouput only a burning smell.Upon troubleshooting I found that the following parts were defective: Q507=2SA1695 (was shorted) Q505=2SC4468 (was shorted) R515=8.2 ohm,1/4w (visually burnt and somewhat higher resistance) R531=2.2 K ohm,1/4w (visually burnt) R519=0.22 ohm,5w dual emitter (cement metal) (open on one end,I think) So I replaced all those parts with exact replacements,there is still no audio output on any mode or set of speaker outputs,I noticed that when I turn unit on on the main power supply relay engages and not the ones on the output stages.I measured most discrete passive components with my Fluke series II DMM model 29 on low ohms (diode range) and most parts seemed ok. Anyone have any common repair tips for me from all of those repair tips sites?.Thanks in advance for replies. Sidney Dartmouth,Nova Scotia Canada |
#2
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"Sidney" wrote in message most parts seemed ok. Sidney -------------------- Sidney, You said that "most parts seemed OK" so please describe the parts that did not "seem" OK . Since the speaker relay is not engaging, either one or both of the PO channels has DC present on the output. A quick check will reveal which channel you have to troubleshoot..... the good news is that you can utilize the good channel as a repair guide. If both channels are "bad" then you should suspect things that are common to both such as power supply, stereo amp or preamp chips, etc. If both channels are good and the speaker relay still does not energize then you should troubleshoot the protection circuitry. These are common hints and "standard stuff" for repairs on most models of stereo recievers and amps. Obviously you will want to re-check the new components that you installed to verify that they are still good and not blown out by other, so far undiscovered, faulty circuitry. -- Best Regards, Daniel Sofie Electronics Supply & Repair - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - |
#3
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I presume the transistors you replaced were the large output devices.
the 2 immediately preceding them (electrically) are the most likely to have a faulty/leaky junction and be giving you the offset of DC on the output you will need to check carefully each junction out of circuit for a leak (I always find an analogue meter the best for this, unless you have a transistor tester.) I these 2 are ok then just move backwards through the circuit looking at all the tr junctions and for high/open resistors. a DC offset of more than 0.6v is sufficient to hold the protection circuit on. normally you will probably measure full + or - rail voltage there (midpoint of the 2 way 0.22ohm res) Sorry I can't be more specific, I haven't a manual. AW "Sidney" wrote in message m... Onkyo receiver/amp model:TX-SV313PRO,year:1996 one day the customer turned the unit on and there was no audio ouput only a burning smell.Upon troubleshooting I found that the following parts were defective: Q507=2SA1695 (was shorted) Q505=2SC4468 (was shorted) R515=8.2 ohm,1/4w (visually burnt and somewhat higher resistance) R531=2.2 K ohm,1/4w (visually burnt) R519=0.22 ohm,5w dual emitter (cement metal) (open on one end,I think) So I replaced all those parts with exact replacements,there is still no audio output on any mode or set of speaker outputs,I noticed that when I turn unit on on the main power supply relay engages and not the ones on the output stages.I measured most discrete passive components with my Fluke series II DMM model 29 on low ohms (diode range) and most parts seemed ok. Anyone have any common repair tips for me from all of those repair tips sites?.Thanks in advance for replies. Sidney Dartmouth,Nova Scotia Canada |
#4
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"Sidney" wrote in message m... Onkyo receiver/amp model:TX-SV313PRO,year:1996 one day the customer turned the unit on and there was no audio ouput only a burning smell.Upon troubleshooting I found that the following parts were defective: Q507=2SA1695 (was shorted) Q505=2SC4468 (was shorted) R515=8.2 ohm,1/4w (visually burnt and somewhat higher resistance) R531=2.2 K ohm,1/4w (visually burnt) R519=0.22 ohm,5w dual emitter (cement metal) (open on one end,I think) There's a .47 ohm resistor at pin 2 of Q501, a uPC1298V, and 2 anothers nearby. Can't quite make out the locator numbers, the second one shows to the left of pin 4 in the schematic which I have thoughtfully e-mailed you :-) , and the third looks like R527 to pin 9. Very possible one of these resistors is bad or the driver IC is bad. Mark Z. |
#5
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Thanks Mark,Sofie & JVC Dude,I found that Q501=UPC1298V=NTE7103 is
defective so now I need as many part # equivalents as possible so that I can buy one locally.Thanks. Sidney Dartmouth,Nova Scotia Canada |
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