I purchased a Parasound HCA 2205a off eBay that was listed as used, in good working condition, but when I plugged it into the outlet, it sparked at the receptacle and inside the chassis. I opened up the chassis and found this:
Now all five channels are in standby mode. I took it to an Authorized Parasound Service center and the tech quoted the fix at $275. He looked at it for about 10min. I figure replacing the cap and fuses would probably fix the problem. What do you guys think?
Now all five channels are in standby mode. I took it to an Authorized Parasound Service center and the tech quoted the fix at $275. He looked at it for about 10min. I figure replacing the cap and fuses would probably fix the problem. What do you guys think?
Attachments
Most likely not the cap. 🙁 looks like one of the to-92's (transistor) let out a little "magic smoke" . 😀 Appears to be an input board failure -causing DC on one of the channels , amp's dc detect puts whole unit into standby.
OS
OS
What about the pinsize hole on the side of C91, 22uf 50v cap? If it is the input board, how would I fix it?
Mine is in standby too but nothing is blown like in your pics above. Power caps are a bit sweaty so will replace all 10 of them but that couldn't be the standby issue.
Could I detach a single amp without causing issues so to determine where the issue is?
Anybody any thoughts?
Could I detach a single amp without causing issues so to determine where the issue is?
Anybody any thoughts?
Before hacking into amplifier, you could start by looking at DC voltage at the output of each amp. That's measured with respect to audio ground right at each power amplifier output itself, before the relay(s) or other switching, etc. If that's not within 100 mV of zero when there is no signal or load applied, you have a serious problem with that amplifier.
There's five amps, and you can easily find which is/are causing the protection to kick in and stay there, without breaking any connections. If there is not enough DC to be concerned about, like <30 mV, then the problem is elsewhere, maybe even in the protection circuit itself.
There's five amps, and you can easily find which is/are causing the protection to kick in and stay there, without breaking any connections. If there is not enough DC to be concerned about, like <30 mV, then the problem is elsewhere, maybe even in the protection circuit itself.
Anyone that has this amplifier schematic, should share it for simulation and fault finding aid?
I could find only HCA-1205(attached).
Thanks
I could find only HCA-1205(attached).
Thanks
Hi Ian, many thanks for the feedback! I will get on it asap. It's great to have a lead 🙂
@R_Merola: check Service Manual finder | Elektrotanya (don't mind the language) for many Parasound schematics (unfortunately not the 2205 but they seem to be rather similar).
@R_Merola: check Service Manual finder | Elektrotanya (don't mind the language) for many Parasound schematics (unfortunately not the 2205 but they seem to be rather similar).
So I've measured all 5 amps before the relay. Once the amp was stabilized they all measured around 0.5-2mV DC. Some started at +100mV DC, another started at -100mV DC, but they all end around 0.5-2mV DC.
Next step is to check the control circuit. Visually it looks to be ok ..
Next step is to check the control circuit. Visually it looks to be ok ..
@R_Merola: at the aforementioned website, check the schematics of HCA-1205A.
From what I've seen the protection circuit is similar to that of the HCA-2205A.
From what I've seen the protection circuit is similar to that of the HCA-2205A.
I've requested a schematic at Parasound and asked them for some thoughts. Maybe they are happy to help a bit ...
So far I've been unsuccessful to locate a fault on the control circuit.
All 5 connectors from the amps to the control circuit give the same values. Hence why I think the amps are fine (each connector: all leads are 15 volts except the load is about 2mV).
Think .. think .. think ..
So far I've been unsuccessful to locate a fault on the control circuit.
All 5 connectors from the amps to the control circuit give the same values. Hence why I think the amps are fine (each connector: all leads are 15 volts except the load is about 2mV).
Think .. think .. think ..
I have identified a 1/4 broken bridge rectifier (RC202) on the control circuit board. There are two of these and I will replace both. Hopefully this will fix the issue 🙂
The fix will need to wait till the weekend though ..
The fix will need to wait till the weekend though ..
Yes it did. Both rectifiers have been replaced (the broken one and to be sure the other one too). Thanks for asking 🙂
Did u ever get the service manual for it? I am looking to buy one. Wondering what outputs they have and what rails this runs off.
I am having what seems like similar problems with my HCA 2205A that you had. I turn it on, the amp clicks and clicks and the amp doesn't switch to "Standby" but doesn't have any sound. I did take it to a Parasound repair shop in Oregon and they said it was the relays and told me they repaired it. I was so happy, but when I recently moved to Hawaii and turned it on, it went back to what was happening before, with an added "plus." Now I will also get a high temp warning light on Channel 3 on occasion.
This has gone on for years and now that I'm in Hawaii, I can't find a way to fix this unless I get help to do it myself. Sending it to SF is out of the question. Would cost me $500 to do so. I want to keep this amp.
This has gone on for years and now that I'm in Hawaii, I can't find a way to fix this unless I get help to do it myself. Sending it to SF is out of the question. Would cost me $500 to do so. I want to keep this amp.
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Similar issue
Mine has randomly had this issue for years, I normally just leave it powered up because when I restart it it looks like it should be working, but non of the amps work. I will let it sit and sound eventually works... it could be an hour or a day. It is the strangest electronics issue I’ve ever had.
Mine has randomly had this issue for years, I normally just leave it powered up because when I restart it it looks like it should be working, but non of the amps work. I will let it sit and sound eventually works... it could be an hour or a day. It is the strangest electronics issue I’ve ever had.