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Post by mastertech on May 10, 2022 21:29:46 GMT -5
So I am assuming the unit still shows no signs of life. While it is plugged in and booted up try a manual reset of ic151 and see if anythings changes.
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Post by serafis on May 10, 2022 21:34:25 GMT -5
No change, no signs of life (other than green LED and mains relay on as before).
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Post by mastertech on May 10, 2022 21:39:06 GMT -5
Try putting the eeprom back in and see if any change. Do reset again also if no response.
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Post by serafis on May 10, 2022 23:04:28 GMT -5
Reinstalled eeprom, no change. Reset, no change. Reconnected the severed tracks, no change. :-(
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Post by mastertech on May 11, 2022 9:16:20 GMT -5
Yea, things are not looking good. About the only other thing I would check is the "remote in" line, ic151 pin 6 and see if it is a steady @ +5v.
I am assuming RN64 is not populated?
Also, is WF105 a harness that can be disconnected on either side. If so, disconnect it and try unit startup again and see if any life.
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Post by serafis on May 11, 2022 15:25:40 GMT -5
IC151 Pin 6 is steady at around 3.3V once the mains relay clicks. When I press a remote key, I get a series of square wave pulses as in the screenshot below, so looks like the IR signal is getting to IC151.  RN64 *is* populated, marked '101' and each of the four resistors reads correctly. WF01 is a flat ribbon cable. No change when disconnected. In fact no change if the entire HDMI board is disconnected / removed. |
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Post by mastertech on May 12, 2022 8:27:38 GMT -5
Well I guess then you are pretty much done at this point. Parts seem to be very hard to get, even if possible.
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Post by serafis on May 12, 2022 15:23:16 GMT -5
Yes, destined for the landfill now, after I salvage anything useful from it. Thanks for your help though, I really appreciate it.
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Post by mastertech on May 12, 2022 17:04:36 GMT -5
No problem. Just so you know, the Harmon Kardon 2650 is internally almost exactly the same. I saw a functioning processor board on ebay for 79.99 free ship. Guy might even take less. But I am sure the ic151 firmware is different and dont know if a firmware update would change all firmware info or not. It would be a big gamble but a fun experiment. www.ebay.com/itm/324124638868?hash=item4b77557e94:g:cdgAAOSwS~Reh13s |
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Post by serafis on May 12, 2022 18:11:21 GMT -5
Thanks, that's very interesting - presumably HK and Arcam are related in some way. I didn't know that, although I'd noticed on Google that HK service manuals came up when searching for the Arcam eeprom part number.
Anyway, the board looks similar but not identical, and with shipping it comes out too expensive an experiment for a unit that only cost me NZ$100 to buy. I'll salvage the transformer, the capacitors I put in and any other useful parts for future projects, and I've learned a bit more about fault-finding, so not a total loss. And I have a few more good, but faulty, CD players and receivers and an old 100MHz oscilloscope on their way from our local online auction site to feed my "repair anything" hobby!
BTW the VSX-920K I fixed back in February (which also only cost me NZ$100) is still working flawlessly as the centerpiece of my main home theatre setup, so win some, lose some. Thanks again for your help, no doubt I'll be back here again next time I get stuck.
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