KBA40 Amp Schematic [message #10484] |
Sat, 14 February 2009 22:22 |
jessicaandtrent
Messages: 5 Registered: February 2009 Location: Alabama
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Junior Member |
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I have a KBA40 Bass amp and I need a schematic for it so I can figure out what part melted when I hooked it up to a 15" sub and over heated it. I know that it is black and has 3 prongs on it but that's all I know abouth the part. but the schematics should tell me what I need to be able to fix it and get the amp working agian. It has two seperate boards. One for the controle knowbs (mounted on the front plate) and the ther for power input/ effects return and send/ headphone jacks (mounted on the back plate. The power converter is mounted to the speaker box. The box has a 12" sub and it is ported. I would like to just get this amp fixed. Please help.
The Circuit board says 50 watt power amp on bottom of board.
Trent
[Updated on: Sat, 14 February 2009 22:28] Report message to a moderator
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Re: KBA40 Amp Schematic [message #10489 is a reply to message #10485] |
Tue, 17 February 2009 21:18 |
jessicaandtrent
Messages: 5 Registered: February 2009 Location: Alabama
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Junior Member |
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It is not an IC I beileve because it was never attached to a heat sink. It stands alone in front of two tall round black things that has 2200uf50v on them it might of had 4 prongs on it a plus on one side and a neg on the other. I had taken it off so I could try to find it a few years ago and I have lost it since, but I remeber what it looked like. You just couldn't read anything but the +/- on the blob of black. It was rounded on the ends and about an inch long. I marked to board before I took it off and the plus side was soldered to the neg strip on the board and the neg end soldered to a srtip that went to one of those tall round black things.
Trent
[Updated on: Tue, 17 February 2009 21:26] Report message to a moderator
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Re: KBA40 Amp Schematic [message #10491 is a reply to message #10490] |
Wed, 18 February 2009 22:03 |
jessicaandtrent
Messages: 5 Registered: February 2009 Location: Alabama
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Junior Member |
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The fuse did not pop. And a question that I have is if I buy one of those bridge rectifyers and solder it on the board and that is not what needed to be there will it mess up the board and also the board is not marked on which side is pos and neg does it matter if it is soldered in backwards?
Trent
[Updated on: Wed, 18 February 2009 22:09] Report message to a moderator
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Re: KBA40 Amp Schematic [message #10494 is a reply to message #10493] |
Thu, 19 February 2009 09:35 |
jessicaandtrent
Messages: 5 Registered: February 2009 Location: Alabama
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Junior Member |
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I did note which way it was facing and I marked on the board where the pos and neg was but it didn't make much since to me. The pos side of the bridge was soldered to the ground circuit on the board. But it was working fine for years like that until I blew it. And how do you tell which side of the cap is pos and neg?
Trent
[Updated on: Thu, 19 February 2009 09:38] Report message to a moderator
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Re: KBA40 Amp Schematic [message #10497 is a reply to message #10494] |
Thu, 19 February 2009 18:39 |
chicagobill
Messages: 2005 Registered: April 2003
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Senior Member |
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The bridge rectifier will either be in a flat package with all 4 leads in a row, or in a square configuration with the 4 leads at the corners.
Two of the pins need to go to the power transformer secondary wires. The other two leads are the positive and the negative voltage outputs.
Check the pc board. Two of the holes will connect directly to the power transformer.
Follow the traces of the other two holes. Where do they go? In most cases they will connect to the main filter capacitors.
These can be mounted on the pc board or can be mounted directly to the chassis. See if you can find them. Most amps will have two, but your amp could have only one. They will be marked with something like 2200uF or 4700uF. They will also have a marking showing which end or which terminal is positive and which one is negative.
If you have two then each one will have one of it's terminals connected to the main circuit ground. You can tell the ground connection because somewhere it will connect to the metal chassis. It may be connected by a screw that holds down the pc board, or it may be a wire to the input jack.
Come back and let us know what you find out.
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Re: KBA40 Amp Schematic [message #10499 is a reply to message #10498] |
Fri, 20 February 2009 10:49 |
chicagobill
Messages: 2005 Registered: April 2003
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Senior Member |
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Steve:
My example of 2200 or 4700 was only a guess at what could be in there. I'm surprised that it fell right in between my two guesses.
So if there isn't a bridge rectifier then I would assume that the blown up device he's talking about is a power transistor, thus the three legs.
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Re: KBA40 Amp Schematic [message #10503 is a reply to message #10500] |
Fri, 20 February 2009 19:42 |
jessicaandtrent
Messages: 5 Registered: February 2009 Location: Alabama
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Junior Member |
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I bought a bridge rectifyer that was a 4 amp x 400 volts and now it is up and running just like it was before. Thanks for all of ya'lls help.
Trent
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Re: KBA40 Amp Schematic [message #10524 is a reply to message #10484] |
Mon, 23 February 2009 12:07 |
stevem
Messages: 4748 Registered: June 2004 Location: NY
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Senior Member |
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Well, all that matters is that its up and running again, although I can not belive that the amps fuse did not pop!
I also would love to know why their are two vastly different versions of this amp and the Kustom repair dept did not ask me for a serial number or something!
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