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

"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
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

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

"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.

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