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stefuel
Joined: 07 Mar 2006
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Location: Green Harbor MA USA
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 Link Posted: Fri Mar 15, 2013 9:02 pm Post subject: Yo Ron, AKA the man with a thousand manuals |
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Classe CA-400
Got one coming with a intermittent hum.
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Chip
A Barco is only a AmPro with training wheels
Card carrying member of the AVS chain gang.
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gjaky
Joined: 05 Jun 2010
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Location: Budapest, Hungary
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stefuel
Joined: 07 Mar 2006
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Location: Green Harbor MA USA
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| Link Posted: Sat Mar 16, 2013 10:56 am Post subject: |
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Thank you, I'm being asked to do someone a favor and this should help.
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Chip
A Barco is only a AmPro with training wheels
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 18051
Location: Langley, BC
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| Link Posted: Sat Mar 16, 2013 3:49 pm Post subject: |
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Shameless post steal. Ron or anyone else, find me a schematic for THIS:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=350741825810
Got it off the recycler the other day, spent an hour trying to figure it out. No success. A buddy would really like this, if I could get it to fire up.
All voltages are present, all crystals are oscillating on the CPU board located under the buttons on the front panel. Apparently these units going dead are a fairly common problem according to my buddy, so there's got to be some common issue that's killing these...
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Phoenixed
Joined: 13 Oct 2011
Posts: 462
Location: The mitten
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| Link Posted: Sat Mar 16, 2013 5:09 pm Post subject: |
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Construction workers being the problem
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Sony G90
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stefuel
Joined: 07 Mar 2006
Posts: 3205
Location: Green Harbor MA USA
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| Link Posted: Sat Mar 23, 2013 10:52 am Post subject: |
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Still waiting for this amp to show up. This manual will help some but it doesn't go much deeper then full board replacement. The only parts list is full board. Given it's age, I think after looking at all the obvious things, a full electrolytic cap job will be in order. I've seen this amp model mentioned in posts dating back to 1994.
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Chip
A Barco is only a AmPro with training wheels
Card carrying member of the AVS chain gang.
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gjaky
Joined: 05 Jun 2010
Posts: 923
Location: Budapest, Hungary
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| Link Posted: Sat Mar 23, 2013 4:46 pm Post subject: |
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The audio amplifiers are not so difficult to troubleshoot for a trained service personel with the schematics, so the most manufacturer don't care to make a precise circuit description.
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NEC 6PG xtra
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flipdog
Joined: 22 Dec 2011
Posts: 143
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| Link Posted: Sat Mar 23, 2013 10:11 pm Post subject: |
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| stefuel wrote: | | Still waiting for this amp to show up. This manual will help some but it doesn't go much deeper then full board replacement. The only parts list is full board. Given it's age, I think after looking at all the obvious things, a full electrolytic cap job will be in order. I've seen this amp model mentioned in posts dating back to 1994. |
Other then a few ic's the parts and values are identified in the schematics. Is the hum in 1 or both channels? What would you like to know?
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stefuel
Joined: 07 Mar 2006
Posts: 3205
Location: Green Harbor MA USA
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| Link Posted: Sun Mar 24, 2013 9:30 am Post subject: |
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| flipdog wrote: | | stefuel wrote: | | Still waiting for this amp to show up. This manual will help some but it doesn't go much deeper then full board replacement. The only parts list is full board. Given it's age, I think after looking at all the obvious things, a full electrolytic cap job will be in order. I've seen this amp model mentioned in posts dating back to 1994. |
Other then a few ic's the parts and values are identified in the schematics. Is the hum in 1 or both channels? What would you like to know? |
I got the impression that ithe "HUM" was in both channels when it does it. I have also been told that the "intermittent" problem started a couple of years ago and has been getting gradually worse. When it gets here I will do the obvious visual thing first although I'm not expecting to see much as it has been on two other benches before mine. If it is in fact on both sides when it does it, I will start from the power supply and work my way in.
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Chip
A Barco is only a AmPro with training wheels
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gjaky
Joined: 05 Jun 2010
Posts: 923
Location: Budapest, Hungary
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| Link Posted: Sun Mar 24, 2013 9:37 am Post subject: |
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An oscilloscope could be handy to track down where the hum is originated.
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NEC 6PG xtra
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