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Kustom 100 Head, Model 2-12A-2 [message #17005] Fri, 27 April 2012 21:17 Go to next message
gomusicstl is currently offline  gomusicstl
Messages: 3
Registered: April 2012
Location: St. Louis
Junior Member
Hi guys,

I'm new to this forum and hoping you guys can help. Judging from the other forums and posts, I think I'm in good hands...

Anyhow, I have a vintage Kustom head. The front panel says "Kustom 100" like you'd expect, but the tag on the back says the model is "2-12A-2". The pots date to 1968, and the board inside is labeled "PC 104".

The problem is with the reverb. For some reason the reverb is always on, no matter how the footswitch is configured. The footswitch is a 2-button TRS-ended unit, and I've checked it and it works perfectly. On the inside of the amp, the reverb tank is in good shape, and I don't see any obvious blown-out parts on the board, though some parts have been replaced.

Also, the reverb doesn't really seem to get mixed into the signal until you're at about 8 or 9, when it kicks in really quick for that down-a-well sound.

The tremolo circuitry works perfectly, and all of the other functions seem to work well too. No weird distortion, nothing strange at all.

The only schematic I can find is for board PC 104, revision 4 (from 1970?), and it's not quite the same as the board in this unit.

If you guys have any thoughts or suggestions, I'd greatly appreciate it. I'm handy with a DMM and solder, but I'm no electrical engineer (yet).

Joel @ GoMusicSTL


Joel @ GoMusicSTL
Re: Kustom 100 Head, Model 2-12A-2 [message #17006 is a reply to message #17005] Fri, 27 April 2012 21:55 Go to previous messageGo to next message
pleat is currently offline  pleat
Messages: 1452
Registered: June 2004
Location: Belding, Mi
Senior Member
It sounds like you amp never had the revisions made to it starting Feb 9-1968. It deals with that down the well sound you mentioned. I'll send you the revision page, to change out some part values.
pleat
Re: Kustom 100 Head, Model 2-12A-2 [message #17007 is a reply to message #17005] Fri, 27 April 2012 21:59 Go to previous messageGo to next message
pleat is currently offline  pleat
Messages: 1452
Registered: June 2004
Location: Belding, Mi
Senior Member
PM me and give me your email address.
Pleat
Re: Kustom 100 Head, Model 2-12A-2 [message #17008 is a reply to message #17007] Fri, 27 April 2012 22:11 Go to previous messageGo to next message
gomusicstl is currently offline  gomusicstl
Messages: 3
Registered: April 2012
Location: St. Louis
Junior Member
schadjo at gmail dot com

Joel @ GoMusicSTL
Re: Kustom 100 Head, Model 2-12A-2 [message #17012 is a reply to message #17008] Sat, 28 April 2012 13:10 Go to previous messageGo to next message
gomusicstl is currently offline  gomusicstl
Messages: 3
Registered: April 2012
Location: St. Louis
Junior Member
Thanks for the information. That said, any idea why the reverb won't shut off? The reverb-down-a-well thing doesn't bother me, but the unswitchable reverb has been hard to figure out.

Joel @ GoMusicSTL
Re: Kustom 100 Head, Model 2-12A-2 [message #17013 is a reply to message #17012] Sat, 28 April 2012 17:47 Go to previous message
pleat is currently offline  pleat
Messages: 1452
Registered: June 2004
Location: Belding, Mi
Senior Member
It's hard to say what might be the cause. The amp is about 44 years old, and unless you've owned it since new and know of any repairs or modifications, I would suggest have it serviced by a qualified tech. Changed out reverb pan, caps drifting in value, or another component failing might cause the reverb from not turning off with footswitch.
pleat
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