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Post by u2nmg93 on Sept 25, 2017 16:27:09 GMT -5
I have an Onkyo TX-SR353 that shows no signs of life. Fuses all check good, transformer checks out, but still no power or response when pushing the power button on the unit or the remote. I have 3.3v at pins 80 and 62 on the CPU IC203, not really sure where to go from there. PM me with your email if you want a copy of the service manual.
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Post by mastertech on Sept 25, 2017 18:40:30 GMT -5
Lets start with ic203, pins 71 and 85. Get me DC voltage.
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Post by u2nmg93 on Sept 25, 2017 20:21:41 GMT -5
I've got 3.3vdc at pins 71 and 85
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Post by mastertech on Sept 25, 2017 20:45:00 GMT -5
ok. voltage on the following pins:
5____
16___
38___
49___
54___
55___
56___
72___
88___
98___
100___
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Post by u2nmg93 on Sept 25, 2017 21:55:14 GMT -5
Pins 16 and 98 I have 3.3vdc
5,38,49,54,55,56,72,88,100 I have 0vdc
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Post by mastertech on Sept 26, 2017 13:42:03 GMT -5
Check pin 75 for 3.3v which it should have. Press the "power on" button while testing and see if the voltage drops significantly.
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Post by u2nmg93 on Sept 26, 2017 14:53:05 GMT -5
It has 3.3v and drops to essentially 0 once the power button is pressed.
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Post by mastertech on Sept 26, 2017 15:26:28 GMT -5
Well like the last one everything seems to be there. Just check pins 86,87,89,90,91,92 for 3.3v and if all are there then either crystal or CPU.
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Post by u2nmg93 on Sept 26, 2017 15:36:37 GMT -5
86 and 87 have 0v
89,90,91,and 92 have 3.3v
Still points to crystal or cpu?
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Post by mastertech on Sept 26, 2017 17:10:30 GMT -5
ok, looks like 86 and 87 are not powered until unit is on so it all looks correct. So yes, most likely crystal or CPU.
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Post by mastertech on Sept 26, 2017 17:12:03 GMT -5
Have you tried holding down the stereo and standby/on button for 3 to 5 seconds?
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Post by u2nmg93 on Sept 26, 2017 22:13:15 GMT -5
Doesn't do anything unfortunately. Tried Enter and Standby/On too and nothing shows on the screen. Also followed their flow chart for "No Power" and it leads to replace CPU assembly. I'll order a crystal and hope that fixes it or I'll have to invest in one of those hot air stations. I tried calling Onkyo to buy the whole board and they don't sell parts to individuals only "authorized service centers". Called my local service center and they told me the same thing but I could send it in for repairs. Somehow that takes all the fun out of it.
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Post by u2nmg93 on Sept 29, 2017 8:24:49 GMT -5
Replaced the crystal, still no signs of life. Guess it's on to the CPU? Could this be done with a heat gun or one of these (http://www.ebay.com/itm/858D-Soldering-Rework-Station-Iron-Welder-Desoldering-Hot-Air-Gun-Tool-3-Nozzles-/192010037941?epid=2222976326&hash=item2cb4b0aab5:g:u2kAAOSwo4pYDbcS) and oven similar to the DTS Chip reflow justgreg did just removing and replacing the the chip?
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Post by mastertech on Sept 30, 2017 16:50:32 GMT -5
I think the biggest problem here would be finding a CPU from Onkyo. A CPU off the shelf would not have any firmware so it would not function.I think.
The service manual is missing the digital main section so can't quite be sure where the main firmware is held.
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