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Just acquired a 250/4-whats it meant to sound like [message #7986]

Mon, 08 January 2007 19:05

dess
Messages: 2
Registered: January 2007
Location: England

Junior Member

Hi, I've just bought a 250/4 and 4 x 12 cabinet, along with the footswitches and the boost pedal. My problem is that I can't tell if the foot switch for the boost is working properly,(all the lights are blown in the footswitch). It seems that I can't bypass the boost tone control,it appears to be active all the time, is this correct? I don't have the user manual and over here finding information, or even someone else that has a Kustom Tuck'n'Roll is pretty near impossable. Anyway I thought that one of you might be able to help me out. Thanks Des.

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Re: Just acquired a 250/4-whats it meant to sound like [message #7989 is a reply to message #7986]

Tue, 09 January 2007 06:55

stevem
Messages: 4754
Registered: June 2004
Location: NY

Senior Member

Hi,My guess would be that you have a problem with the connector at the end of the foot switch cable or the switches themselves. My 2 250s only have vib and reverb, and I do not need a foot swtich to turn them on, only to turn them off.If the same wiring layout works for the boost and fuzz, which it looks like it does from the schematic for that circuit then if you short pin 2 and 3 on the amp side to ground on at a time you should be able to turn those effects off and prove out that the foot switch connector is at falt.All it would take would be a bad ground pin connection with that cable and you will have no foot switch lights and no control of any of the effects.

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Re: Just acquired a 250/4-whats it meant to sound like [message #8017 is a reply to message #7986]

Fri, 12 January 2007 17:03

dess
Messages: 2
Registered: January 2007
Location: England

Junior Member

Thanks Steve, after taking the footswitch to pieces I found that one bulb still worked, it was completely out of it's socket: the boost switch is working, so with the assistance of a service manual off ebay I'm going to pass the amp to a tech to check it over.

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Re: Just acquired a 250/4-whats it meant to sound like [message #8032 is a reply to message #7986]

Mon, 15 January 2007 07:02

stevem
Messages: 4754
Registered: June 2004
Location: NY

Senior Member

While the tech has your amp have him check this.If your amp is a early 1971 there was a change made in the mid May production of the amps that effected the preamp board PC 5066 for more gain.
Resistor r16 was changed from 2200 ohms to 3300 ohms
resistor r28 was changed from 15k to 8200 ohms
resistor r29 changed from 8200 ohms to 4700 ohms
and c21 changed from .01 uf to 100pf.
Also some of the big orange drop caps on the preamp boards have had solder connections that I have had to redo.
Most of these amps have a schematic glued to the lid of the amp, which is one of the things I leave off my 250 heads that I play out with as they run much cooler with it off, and then every 2 years I slid it out of the case a blow it out with a can of computer air blast.

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