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Old 25th July 2007, 02:34 AM   #1
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Default Capacitor Help

I have the older Adcom GFA 545 amp and need help with replacing a capacitor. The cap is located on the bottem of the two circuit boards, there in not anything else located there. This cap is fairly large in size, it's black and flat, has radial leads, the only numbers are 100v/1k 6502.

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Old 25th July 2007, 12:52 PM   #2
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It sounds like 1000uF/100V to me, but sometimes the k stands for the tolerance (10%), in which case it could be 1uF/100V, with the 6502 being the batch code. Can you provide the physical size, as that will give a clue. Also is it polarised (any markings of + or - on either end), or any branding?
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Old 25th July 2007, 02:56 PM   #3
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Thanks for the reply, the only thing else is, there is a T with a circle around it (T). The size is 3/4" wide 1/2" tall 1/4" deep. I am trying to locate a service manual for this amp, but have not had any luck as of yet.

Here is a picture
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Old 25th July 2007, 04:02 PM   #4
anatech is offline anatech  Canada
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Hi MorePower7701,
This isn't the input coupling capacitor is it? Why do you need to change it?

Your missing picture (probably to large) would help answer this question. I have repaired a number of these amplifiers but I am working off memory here.

-Chris
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Old 25th July 2007, 04:40 PM   #5
AndrewT is offline AndrewT  Scotland
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Hi.
could the T be short for MKT = terephthalate = metalised film.
As said "k" could be tolerance
Size seems a bit big for 1uF unless 6502 means polypropylene, but that should be even bigger than those dimensions.

As Anatech asked, "why change it"?
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Old 25th July 2007, 04:43 PM   #6
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I was told this could be the reason I getting a strange noise when I power the amp off. I changed two caps on the board and it improved a great deal, but I still have a slight noise.
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File Type: jpg 002.jpg (59.2 KB, 163 views)
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Old 25th July 2007, 04:49 PM   #7
anatech is offline anatech  Canada
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Hi MorePower7701,
No, those are pretty good input capacitors. I think the advice you were given is faulty.

Have you considered having your amplifier professionally serviced? I suspect the repair may be beyond your ability. I'm not trying to say you can't fix amplifiers, but I have an idea what the problem may be. If you don't get it serviced, it will become more costly to repair.

Is there an older authorized Adcom service center near you? A good audio only service shop? TV shops are normally not mentally prepared to service audio properly.

This is one of the better sounding amplifiers in that series, it would be a shame to ruin it while following poor advice.

-Chris
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Old 25th July 2007, 05:17 PM   #8
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There is not an Adcom authorized repair shop, but there is a great higher-end repair shop. There is only one shop I feel that has the knowledge and ability, but they laughed when I asked about having it repaired, they said "it's not the quality amp we repair, it best to throw it away and get something worth repairing".

I delt with another shop like this when it came to repairing a set of floorspeakers I had. The foam surrounds needed replacing, the shop aggreed to replace them for $60. I recieved a call after three weeks that the speaker were ready, the guy said "you will not believe the difference". The speakers did sound great, but the repair cost was just under $400, the shop replaced the woofers, midranges, rebuilt the crossover and polished the cabinets. The guy told me that original woofers were good, not great and the midranges left a lot to be desired, and rebuilding the crossover to closer match the freq was nessary. These are the problems I have ran into, the shop eather does not feel your equipment is worth there time, or do as they please with modding your equipment.

I have not lived in Knoxville very long, there might be a few shops that I do not know of.
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Old 25th July 2007, 07:41 PM   #9
anatech is offline anatech  Canada
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Hi MorePower7701,
Quote:
There is only one shop I feel that has the knowledge and ability, but they laughed when I asked about having it repaired, they said "it's not the quality amp we repair, it best to throw it away and get something worth repairing".
Well, then they only think they are a high end shop. Ignore their existence because I have a feeling they also think they know everything as well. A true high end shop would not have said that to you.

Just to give you some idea, I ran a high end service shop for many years. We did warranty work for Adcom along with many other brands. Adcom amplifiers were pretty good and better than some of the other "High End" brands out there. I honestly don't believe in degrading a customer's equipment like that.

Quote:
The speakers did sound great, but the repair cost was just under $400
Did you get an estimate??? I get the feeling they took advantage of you. Wow! I hope you did after so many component changes!

Do try to find a good Adcom shop. The repair you need is involved. Please call Adcom directly and enquire. Your PCBs likely need to be removed and given a special wash treatment along with some component changes. I'm up in Canada and it does not make any sense for you to ship the amplifier up here.

-Chris
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