k200b repair and info [message #2731] |
Mon, 19 May 2003 12:15 |
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A friend of mine had a k200b for a while that he stopped using when he got a fender bassman. I recently took it off of his hands for $50. It sat in his garage for a couple of years while he wasn't using it. I took it home and plugged it up to a 8ohm 4x12 cab. I got a loud hum and a little bit of guitar signal before it went dead. The unit still turns on, but i can't get it to put out any sound at all. There were no loud pops, flashes, or smoke. I opened it up and the fuse was okay. There is some rust on the transformer. and a lot of dust on everything else.
If someone could give me some input on what the problem could be and how to fix it, it would be greatly appreciated.
Also, the plate or sticker that had jack labels and information on the back has been removed. So if someone could clue me in on which output jacks are what and what the min/max ohm loads are it would be help me out alot.
thanks
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Re: k200b repair and info [message #2734 is a reply to message #2731] |
Mon, 19 May 2003 16:27 |
C4ster
Messages: 686 Registered: June 2001 Location: Mukwonago, WI (Milwaukee...
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Senior Member |
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Hi, the cabinet is OK for that head. Kustoms like 4 ohms or HIGHER. I would suspect you have a K200A series amp. As far as the startup failure, my only guess would be a fuse mounted on the circuit board. That fuse is for the speaker output. That would be consistant with what you described. The amp has at least one output transistor that has shorted. The high current through the speaker caused the humming and then the fuse blew. You need to check the 4 output transistors on the bottom of the amp. Good luck
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Re: k200b repair and info [message #2735 is a reply to message #2734] |
Mon, 19 May 2003 21:54 |
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I checked the model number again, it is a k200B-5. I think i have solved part of the problem. I found burn marks on the back circuit board. It's fixable if i can get ahold of a schematic, but then i have to figure out why it fried.
If anyone has any ideas on the problem it would help alot.
thanx
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Re: k200b repair and info [message #2737 is a reply to message #2735] |
Tue, 20 May 2003 09:07 |
C4ster
Messages: 686 Registered: June 2001 Location: Mukwonago, WI (Milwaukee...
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Senior Member |
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Sorry about the K200A reference, but I still stand by the basic answer I gave. The circuit trace acted as a fuse and burned out. Does that trace go to the connector on the right side of the board and then with a blue wire to the 2 1/4" jacks on the back?? If it does then that is your speaker output. I still think there are shorted output transistor(s). You need to check out the transistors before you apply power again.
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Re: k200b repair and info [message #2746 is a reply to message #2744] |
Thu, 22 May 2003 18:40 |
Bill
Messages: 64 Registered: March 2002 Location: Kansas
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Member |
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My K200a-2 has two glass fuses...one for power, right behind the power switch, and one to the right rear near the speaker output. All my B series only have one glass fuse--the one for power. Also has a thermal curcuit breaker.
I got all my parts from Mouser Electronics and/or Radio Shack.
Thrill Bill
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