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K200A-1 ID missing transistors [message #6119]

Sat, 27 August 2005 18:06

jackchapman
Messages: 12
Registered: August 2005
Location: Harlingen,Texas

Junior Member

I have acquired a K200A-1 amp. and there are two missing transistors in the power amp board PC702. I am hoping someone has this same amp and can identify the missing part numbers. The lower one has a metal heat sink and the upper one is a standard type. Can you help? I have pics of the board with the missing part locations flagged. Please e-mail me achapman@rgv.rr.com

Jack

[Updated on: Sun, 28 August 2005 02:55]

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Re: K200A-1 ID missing transistors [message #6125 is a reply to message #6119]

Tue, 30 August 2005 12:22

stevem
Messages: 4774
Registered: June 2004
Location: NY

Senior Member

Hi, I only have a 703 schematic, but I may have a 200a head I can look at tonight and let you know in the morning.You may also have some bad output transistors, seeing as your board is missing a heat sinked driver transistor.

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Re: K200A-1 ID missing transistors [message #6126 is a reply to message #6125]

Tue, 30 August 2005 15:30

jackchapman
Messages: 12
Registered: August 2005
Location: Harlingen,Texas

Junior Member

Thanks a million! I have checked the outputs and had to replace one of them....Just about all transistors in the pre-amps are shorted. Must have been a shorted speaker lead or something......sure did a number on the transistors! Thanks again...Jack

Jack

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Re: K200A-1 ID missing transistors [message #6127 is a reply to message #6126]

Tue, 30 August 2005 15:59

chicagobill
Messages: 2006
Registered: April 2003

Senior Member

Jack:
Welcome to the board!

If all of the small transistors in the pre-amps have been shorted, they have probably been subjected to too much voltage. Be sure to check the power supply, and especially the voltage regulator circuits before you power up the amp again.

Bill

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Re: K200A-1 ID missing transistors [message #6128 is a reply to message #6127]

Tue, 30 August 2005 18:21

jackchapman
Messages: 12
Registered: August 2005
Location: Harlingen,Texas

Junior Member

Thanks for the tip! I am going through everything checking all of the transistors, caps, diodes, etc. Have only found one bad cap, but lots of small transistors that are shorted. I hope to make this dragon breath fire again.

Jack

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Re: K200A-1 ID missing transistors [message #6129 is a reply to message #6119]

Wed, 31 August 2005 12:07

stevem
Messages: 4774
Registered: June 2004
Location: NY

Senior Member

Sorry, no 702, just a 703 but it may be of some help. I can fax you a copy, so let me know.

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Re: K200A-1 ID missing transistors [message #6130 is a reply to message #6129]

Wed, 31 August 2005 14:09

jackchapman
Messages: 12
Registered: August 2005
Location: Harlingen,Texas

Junior Member

Yes, please. I should be able to figure out what to do with the missing stuff. I will set my computer to accept the fax..........956/423-8866.
Let me know of the phone charge and I'll pay you for any expenses. Thanks. This will be a great help.

Jack

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Re: K200A-1 ID missing transistors [message #6132 is a reply to message #6130]

Fri, 02 September 2005 11:38

jackchapman
Messages: 12
Registered: August 2005
Location: Harlingen,Texas

Junior Member

Steve,
Thanks for the schematic. It is not very close to what I have, but I think I can come up with something. I have figured out the one with the heat sink......now for the other one. Thanks!

Jack

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Re: K200A-1 ID missing transistors [message #6134 is a reply to message #6119]

Fri, 02 September 2005 12:45

stevem
Messages: 4774
Registered: June 2004
Location: NY

Senior Member

If you can not work it out, call bob monday at SSI manufacturing.513 761 7757.He may have the schematic you need.

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Re: K200A-1 ID missing transistors [message #6156 is a reply to message #6134]

Fri, 16 September 2005 14:51

jackchapman
Messages: 12
Registered: August 2005
Location: Harlingen,Texas

Junior Member

Bob sure was a great help with the missing transistors. Now that I have installed them, I am getting smoking 100ohm resistors near these transistors. Sure wish I could find a schematic and board layout of this amp.....Does anybody have them???????? All the transistors read good on the Sencore tester that I am using.

Jack

[Updated on: Fri, 16 September 2005 14:53]

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Re: K200A-1 ID missing transistors [message #6158 is a reply to message #6156]

Sat, 17 September 2005 15:54

jackchapman
Messages: 12
Registered: August 2005
Location: Harlingen,Texas

Junior Member

Success!!!!! After replacing the burnt resistors and re-checking the driver and output transistors, I found two outputs and one of the driver transistors damaged. After replacing them the amp powered-up without anything smoking or blowing!!!! I found two 3x15 Kustom cabs. in Seattle and when they arrive on tuesday I will be able to give the amp a good testing. Also, I found that the schematics and board layout for a PC704A from a 400 watt amp to be very close to the PC702 in this K200A. Thanks everyone for the tips and help I received. You guys are great!!!!

Jack

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