It's me again after several years. The Accuphase sounded fine but recently developed first an attenuation on left channel, the a total demise of right channel. Attached the poor state of the output board of the pre (just the portion near the output jacks). It was layered with dust. I sprayed some isopropylic and gently scrubbed with a toothbrush, then applied WD40 contact cleaner. The board (and its sisters) are still dirty. Many jumpers are oxidized and the two large caps have obviuos released their magic goo and desperately need replacement. How is the better way to disconnect the 3-wire flat on the bottom from the black connector? Just pull? I've read that many uses a foam cleaner to remove crud off boards. Any product suggestion? How would you replace jumpers? I only recall that nicer electrolytic caps (perjaps Silmic II) have plated copper terminals but, there are a lot of jumpers... Thanks a lot for any idea.
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Thanks for feedback. Well the earlier problem was not responsibility of the unit but there was a ground loop I fixed.
You are right, I'm not sure it cannot be glue, but it's the only case where I can see such glue applied on the unit's boards.
I'm targeting the "output" board, because the right (otherwise missing) channel is available on headphone output of the pre, and output relays seem to click correctly
You are right, I'm not sure it cannot be glue, but it's the only case where I can see such glue applied on the unit's boards.
I'm targeting the "output" board, because the right (otherwise missing) channel is available on headphone output of the pre, and output relays seem to click correctly
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i just looked at the schematic for the C-222; that's a nice preamp you have there.
if you've got "good signal" at the headphone output but not at the line output, check output relay R4 contacts.
could also might be something bad in the RCA jack + plug + cable.
even degraded solder joints in the path from relay contacts to output jack.
good luck!
if you've got "good signal" at the headphone output but not at the line output, check output relay R4 contacts.
could also might be something bad in the RCA jack + plug + cable.
even degraded solder joints in the path from relay contacts to output jack.
good luck!
Please read the thread:
https://www.diyaudio.com/community/...-and-others-diagrams-repair-etc.211108/page-2
https://www.diyaudio.com/community/...-and-others-diagrams-repair-etc.211108/page-2
I too was almost sure there was an issue on R4, but it seems to click fine, so I will for sure check the signal path from R4 to jack. Meanwhile will check the caps and the resistors... Let's seei just looked at the schematic for the C-222; that's a nice preamp you have there.
if you've got "good signal" at the headphone output but not at the line output, check output relay R4 contacts.
could also might be something bad in the RCA jack + plug + cable.
even degraded solder joints in the path from relay contacts to output jack.
good luck!
Here's the update for my missing channel. As a reminder, it had vanished after I had thought of cleaning the unit first with isopropyl alcohol and then with a somewhat oily contact cleaner. This operation clearly triggered the issue. First thing I did yesterday was to test C27 and C28 and they seemed ok. Then I examined with a better light the status of all of the jumpers on the output board and found a couple of them flooded with crud. So I decided to remove as much crud as possible from anywhere, together with the residual contact "cleaner", with a good amount of isopropyl alcohol. I looked at a couple of suspect solder joint and retouched them with fresh solder. After drying it, I played a 1KHz signal tone and checked for DC. I first started by looking for reasonable values of DC offset (around 0.20 mV) by setting the trimmers on the output board, then fine tuned it by acting on the equalizer board. I got values around 0 DC. Only thing I have a little imbalance (would say roughly a 10% value), i compensated with the balanced pot. I realize I might have to work on trimmers for the phono stage, too, but my deck is still off... Anyway this morning the system sounded quite well to my ears, much more "clean". I swear that removing the dirt not only restored the channel but provides a better sound. Is there any suggested effective foam to clean the boards? In the afternoon I used a foam cleaner for car seats/interiors. Of course I didn't dare to apply to my Accuphase, but something similar might perhaps work...?
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For foam cleaning look here :
https://www.diyaudio.com/community/...xtremely-dirty-amp.370742/page-2#post-6612229
The brown substance under the right side caps in post 4 is deteriorated glue. It is corrosive.
https://www.diyaudio.com/community/...xtremely-dirty-amp.370742/page-2#post-6612229
The brown substance under the right side caps in post 4 is deteriorated glue. It is corrosive.
Great! I think I will definitely try the oven cleaning foam on these boards. Indeed, I'm already an "alternative" user of this product while using it to safely strip varnish from fragile plastic miniatures (Subbuteo teams, FWIW), without destroying them. Will try on some less valuable boards before to tune times.
I cleaned it (not perfectly) with isopropyl, cotton-fioc cleaners and a lot of patience.
I removed the degraded glue and the caps - I didn't remove them - seems healthy from the values displayed on my DMM. I retouched again all the soldering for RCA out but the issue was still intermittently there (no issue with headphones).
Finally found the culprit and it is indeed the ugly RCA plug assembly which is faulty and sometimes work (almost), sometimes not. Now it passes sound, but I have a feeling level on one channel is weaker. I'm figuring out how to remove this assembly without making any damage around and either use new RCA receptacles or hard wire RCA output cable (like in old philips cd players... ).
I'm blatantly ignorant. In case channel level don't match, is there a trimmer should I work on for level? VR1 and VR2 of equalizer ***'y? I couldn't find any service manual aside from the pdf with the scheme (and some resistor values don't match...)
Thanks,
I removed the degraded glue and the caps - I didn't remove them - seems healthy from the values displayed on my DMM. I retouched again all the soldering for RCA out but the issue was still intermittently there (no issue with headphones).
Finally found the culprit and it is indeed the ugly RCA plug assembly which is faulty and sometimes work (almost), sometimes not. Now it passes sound, but I have a feeling level on one channel is weaker. I'm figuring out how to remove this assembly without making any damage around and either use new RCA receptacles or hard wire RCA output cable (like in old philips cd players...
).I'm blatantly ignorant. In case channel level don't match, is there a trimmer should I work on for level? VR1 and VR2 of equalizer ***'y? I couldn't find any service manual aside from the pdf with the scheme (and some resistor values don't match...)
Thanks,
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under
https://www.accuphase.com/cat/c-222en.pdf
is to find on page 2 a simplified schematic without values and without mode select switches.