| Parts Identification [message #29482] |
Tue, 11 March 2025 13:37  |
KustomGeorge
Messages: 21
Registered: February 2025
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Junior Member |
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I recently purchased a 250-4 amp and was told the tremolo section was dead. I went ahead and bought the amp thinking I could get that section fixed. When I received the amp, the tremolo effect was dead, however, the volume on the effect channel was more than half of the non-effect channel. I just received a call from the repair shop and was informed it looks like the issue was with the pre-amp section on the effects channel. The tech did not go any further in his diagnosis and then me told the schematic does not describe the parts listed on the schematic with respect to the parts. The transistors are just listed by a Kustom part number. The same with the diodes. Any help would be greatly appreciated. I am technically challenged and need a qualified person to do the repair and do not want to fry the amp by trying!
Thank you.
KustomGeorge
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| Re: Parts Identification [message #29487 is a reply to message #29482] |
Wed, 12 March 2025 15:47  |
chicagobill
Messages: 2017
Registered: April 2003
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Senior Member |
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I would suggest that before you start replacing any parts, please check all of the Molex connectors on the cables that run from board to board.
Sometimes they will oxidize and loose connection or will just vibrate loose. Worst case is when the connectors break the solder joints that hold them to the pc board. I use a contact cleaner called DeOxit, but any quality cleaner made for electronic contacts will work fine. I do not recommend WD-40 or any other oil based products for this purpose.
Spray a little cleaner on each of the pins and then push and pull each connector on and off to burnish the contacts.
If this doesn't fix any of the problems, then trace the signal path to see where the problem might be.
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| Re: Parts Identification [message #29488 is a reply to message #29482] |
Wed, 12 March 2025 16:19 |
stevem
Messages: 4828
Registered: June 2004
Location: NY
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Senior Member |
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Have your son-in-law look at the schematic for the 250-1.
On that note the jumper between pins 1 and 2 on J1 on the 5066 preamp board.
This jumper closes off the signal that would go to the effects board on the 250-4 amp and sends it right to the output board.
The output signal from the 5067 preamp board goes into the 5066 boards 14 pin IC chip.
This means that if you unplug your connector from J1 and then jump pins 1 and 2 you will have then bypassed the effects board completely.
Then you can judge where the problem lies .
Like Bill posted your whole issue might be just tarnished up aluminum connectors in those plugs.
[Updated on: Wed, 12 March 2025 16:23] Report message to a moderator |
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| Re: Parts Identification [message #29512 is a reply to message #29482] |
Sat, 26 April 2025 07:32 |
stevem
Messages: 4828
Registered: June 2004
Location: NY
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Senior Member |
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Well now your down to troubleshoot by checking voltages shown on the schematic.
Note that all Kustom schematics for the metal face amps state the voltages with all the controls at minimum and no speaker load on the amp.
[Updated on: Sat, 26 April 2025 07:36] Report message to a moderator |
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