For those that repair amps:What brands or problems do you prefer to stay away from? - diyAudio
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Old 31st October 2007, 08:42 PM   #1
spooney is offline spooney  United States
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Default For those that repair amps:What brands or problems do you prefer to stay away from?

Is there any particular brands that you just hate to service or problems that would lead you to turn work away?
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Old 31st October 2007, 10:25 PM   #2
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Many of the 4kw+ amplifiers that have the transistors mounted vertically should be avoided. They have a tendancy to break the leads on the transistors due to poor support of the heavy components.

Many times, the amplifiers will arrive with a single transistor that has a broken leg and it's causing the amp to go into protect. Some people would replace only the 3-5 transistors in the paralleled group of components (and that would be OK on many amps). The problem is... many of the other components have weak leads. If the others begin to break soon after you repair it, you could be married to the amp if you give a warranty because other components' leads will begin to break (and may break during the warranty period).

If you do it correctly and replace all of the weak components, you may have to replace ~$300 worth of parts (actual cost of the parts). If you provide a warranty and the owner blows the amp again, you'll have to buy and replace the parts again.

Some of these amplifiers have 300+ volts across the rails so extreme caution is required when working on them.
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Old 31st October 2007, 11:11 PM   #3
ppia600 is offline ppia600  United States
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Like maybe the new earthquake phd 20000, I wouldn't even think of repairing it if even one output was bad. Maybe if it was something simple like a cracked solder joint in the preamp section or power and speaker terminals, but the earthquake seem to be pretty well made.
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Old 31st October 2007, 11:22 PM   #4
MadMutt is offline MadMutt  Australia
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Reeeeeally old amps, ones that have point to point hard wiring.
Sure as sh-t, as soon as you touch it those wires start breaking, one after the other.

Brands,
none really, they all have their own little quirks for dissasembly, known faults, etc.

Worst I've done was an alpine V12.
Part of the fibreglass board was burnt.
I had to cut out the burnt section (5cm square), lay new tracks, drill holes, replace smd's etc.
Took several days, but the customer really wanted this amp fixed.
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Old 1st November 2007, 03:37 AM   #5
Clipped is offline Clipped  Thailand
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zapco's 3 layer hell...
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Old 1st November 2007, 08:08 AM   #6
grjr is offline grjr  United States
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I personally don't like amplifiers with a lot of smd components in them
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Old 2nd November 2007, 02:04 AM   #7
Clipped is offline Clipped  Thailand
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i'll second that...
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Old 2nd November 2007, 02:18 AM   #8
MadMutt is offline MadMutt  Australia
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Ceramic/hybrid daughter cards. (later rockfords)
Hate them with a passion.
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Old 2nd November 2007, 06:53 AM   #9
Clipped is offline Clipped  Thailand
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i'll second that one too....i have a rockford af4/hd with messed up hybrid cards...
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Old 2nd November 2007, 12:38 PM   #10
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Quote:
Originally posted by Perry Babin
Many of the 4kw+ amplifiers that have the transistors mounted vertically should be avoided. They have a tendancy to break the leads on the transistors due to poor support of the heavy components.

Many times, the amplifiers will arrive with a single transistor that has a broken leg and it's causing the amp to go into protect. Some people would replace only the 3-5 transistors in the paralleled group of components (and that would be OK on many amps). The problem is... many of the other components have weak leads. If the others begin to break soon after you repair it, you could be married to the amp if you give a warranty because other components' leads will begin to break (and may break during the warranty period).

If you do it correctly and replace all of the weak components, you may have to replace ~$300 worth of parts (actual cost of the parts). If you provide a warranty and the owner blows the amp again, you'll have to buy and replace the parts again.

Some of these amplifiers have 300+ volts across the rails so extreme caution is required when working on them.

Quote:
Originally posted by Clipped
zapco's 3 layer hell...

Quote:
Originally posted by grjr
I personally don't like amplifiers with a lot of smd components in them

Quote:
Originally posted by MadMutt
Ceramic/hybrid daughter cards. (later rockfords)
Hate them with a passion.
I agree with all of you. They did all those things to save money and ease construction, and bolster profits
Heres a solution of mine for PPI amps. Lots of work but worth it in the end run...I will have these in quantity shortly. PM me if you have questions or needs

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