VintageKustom.com: Repairing Kustom Amps » K-25 C2

Home » VintageKustom.com » Repairing Kustom Amps » K-25 C2 (Reverb)

Show: Today's Messages :: Polls :: Message Navigator

K-25 C2 [message #20869]

Sat, 05 July 2014 10:08

corrdk@aol.com
Messages: 21
Registered: June 2014
Location: California

Junior Member

Hey there Kustom Kool Kats, I bought this K-25 for $40.00 because it did not work. Had no idea what I was doing so I took it apart and found a gizmo (on the back of the circut board two deals look sorta like miniture rolls of dimes) needed to be soldered. It works and sounds pretty darn good except the reverb will not work.Any suggestions? It's black, circa 1968 according to the speaker code (Jensen)and was missing the handle but I found one on Craigslist for $20.00. Looks Kustom kool but no reverb.

Report message to a moderator

Re: K-25 C2 [message #20870 is a reply to message #20869]

Sat, 05 July 2014 10:40

pleat
Messages: 1454
Registered: June 2004
Location: Belding, Mi

Senior Member

Kool find and great price. First question, does the amp still have the reverb tank that is mounted on the back wall of the amp chassis? If so, there may be a problem with the tank itself or maybe the cables that connects the tank to the circuit board.

pleat

Report message to a moderator

Re: K-25 C2 [message #20871 is a reply to message #20870]

Sat, 05 July 2014 10:55

corrdk@aol.com
Messages: 21
Registered: June 2014
Location: California

Junior Member

Yes it still has the reverb unit and I took it off and looked at it and seems to look OK. Also cleaned up the connections. I have a K-200 PA I bought with the reverb "not working" and got an aftermarket foot swith and turned it on and it works great but no such luck with the K-25. I'm pretty good at taking stuff apart and looking but usually don't have a clue if it gets beyond complication factor .05, would the K-25 and the K-200 use the same footswitch?

Report message to a moderator

Re: K-25 C2 [message #20872 is a reply to message #20871]

Sat, 05 July 2014 14:12

pleat
Messages: 1454
Registered: June 2004
Location: Belding, Mi

Senior Member

The footswitch jack on the K25 is a stereo 1/4" that uses the two button footswitch, one for reverb and the other switch turns on/off for the Trem/vibrato. One thing you could check is check the input and output coils of the reverb tank. With an ohm meter each coil should read about 180 to 200 ohms. Other than that, I'd say its time for one of the techs to jump in.

pleat

Report message to a moderator

Re: K-25 C2 [message #20927 is a reply to message #20872]

Sat, 12 July 2014 13:52

corrdk@aol.com
Messages: 21
Registered: June 2014
Location: California

Junior Member

I've checked the reverb tank with an ohm meter and get nothing. Maybe I need the footswitch. Any suggestions where I might find one? Any one have one they want to part with? $$$

Report message to a moderator

Re: K-25 C2 [message #20928 is a reply to message #20927]

Sat, 12 July 2014 16:46

pleat
Messages: 1454
Registered: June 2004
Location: Belding, Mi

Senior Member

If your metering the tank itself and get an open reading at both the input and output, you may have some broken wires inside the tank itself. The coils have a green and black wire going to the RCA jacks of the tank. If they are connected and the two springs between the coils, then You have an issue with the tank being bad. A footswitch is not needed to have the reverb work. The footswitch only would act as a remote off and on.
As long as the reverb control is turned on (the reverb control has a switch off at max counterclockwise). I'd save your money from buying a footswitch and get a replacement tank. Or take what you have to a tech that can trace everything and make sure the rest of the amp is in good working order.
pleat

Report message to a moderator

Re: K-25 C2 [message #20929 is a reply to message #20869]

Sat, 12 July 2014 16:58

stevem
Messages: 4775
Registered: June 2004
Location: NY

Senior Member

Hello!
The first thing to do is to check is what's called the reverb recovery amp.
This is easily. Done by unplugging the RCA cable from the end of the pan that is the greatest distance from the power transformer.
Unplugging this cable and taping the end with the reverb turned up should get you a buzz out of the speaker just like doing this with the end of a guitar cable.
If this checks out then it's time to check the pan itself.
To do this plug both cables back into the pan and with a ohm meter check the resistance of each end of the pan.
If each of the two coils in the pan is good the meter should read anywhere from 175 to 200 ohms.
Do these checks on let use know the results and we can get deeper if need be!

Report message to a moderator

Re: K-25 C2 [message #20931 is a reply to message #20929]

Sat, 12 July 2014 20:35

Kustom_Bart
Messages: 601
Registered: October 2010
Location: Greenville, MichiGUN

Senior Member

Also, any 2 switch stereo 1/4" jack pedal will work, peavey, marshall, Fender, etc. anything that you can pick up for 10.00 will work. No need to spend 100.00 or more for an original Kustom pedal that you most likely won't use anyway. I don't use any of the on board effects on any of my Kustom amps, they do all work, just not convenient if you are playing a bunch of different types of music. You are better off with a multi effect pedal as they have all of the effects built in at your control in one spot or in your patches that you make. Just how myself and others here do it.

Report message to a moderator

Re: K-25 C2 [message #20940 is a reply to message #20931]

Sun, 13 July 2014 16:04

corrdk@aol.com
Messages: 21
Registered: June 2014
Location: California

Junior Member

O.K. I tried the above tips with no positive results. I had a reverb tank from a Hammond organ (accutronics) and I wired it to the amp and just like magic it works. Now the question is..should I mount it in the amp or try to find the right one? They are very similar except the Hammond unit has an on/off lever and where the springs hook up on either end the knubs on the back side of the unit are bigger in diameter than the original tank. I could send photos via email if that last sentence doesn't paint a very vivid picture. The mounting holes and unit itself match the original.Most important Thank You everyone for your help so far.

Report message to a moderator

Re: K-25 C2 [message #20941 is a reply to message #20940]

Sun, 13 July 2014 16:51

Kustom_Bart
Messages: 601
Registered: October 2010
Location: Greenville, MichiGUN

Senior Member

Chicagobill or Stevem can tell you what tank that you need and will work for your amp. I wouldn't install the other one. Just order the one you need and be done with it. A lot less messing around. Unless you plan on using the tremolo and reverb all the time it is no biggy to wait for the tank. The reverb and trem are nice. I don't know what you would ever use the trem for unless you only play old surf music, the reverb is nice though in small dosages.

Report message to a moderator

Re: K-25 C2 [message #20943 is a reply to message #20941]

Sun, 13 July 2014 20:42

pleat
Messages: 1454
Registered: June 2004
Location: Belding, Mi

Senior Member

I have a original Gibbs 1122 reverb tank that has a locking lever that pushes the reverb spring channel to the housing for transporting. I think it is something Gibbs did for shipping the tanks from the factory to the amp builder. It would be impossible to lock it once the tank is in the amp. It probably came from a kustom since it has an isolated input jack and the impedence of both input and output is 180 ohms.

First thing that comes to mind with the internal Vibrato/Trem is CCR tone, but then I'm older and as long as it's as easy as hitting a footswitch, saves me a lot of time trying to set that tone with my processor pedal.
pleat

Report message to a moderator

Re: K-25 C2 [message #20947 is a reply to message #20943]

Mon, 14 July 2014 03:47

Kustom_Bart
Messages: 601
Registered: October 2010
Location: Greenville, MichiGUN

Senior Member

Sorry Don, you left the door open, you are older DOH! lol!

Report message to a moderator

Re: K-25 C2 [message #20948 is a reply to message #20869]

Mon, 14 July 2014 07:00

stevem
Messages: 4775
Registered: June 2004
Location: NY

Senior Member

A lot of 70s Ampeg combo amps used the lever that locks the inner pan tray up for travel.
I would use the pan but first do a tweak to it so it does not fail like the original.
To do. this get a tube of clear silicone glue and place a good blob of it on the two coils where the small wires enter it and also on the RCA jack where the wires start off, with that being done at least that. Common failure point is covered!

When you remount the tank you need to make sure that the side of the pan marked OUTPUT is as far from the power transformer as the mounting area will allow.

Report message to a moderator

Re: K-25 C2 [message #20950 is a reply to message #20869]

Mon, 14 July 2014 11:37

chicagobill
Messages: 2006
Registered: April 2003

Senior Member

Locking reverb pans were fairly common in Gibson amps as well as most home organs in the 50s and early 60s. They were meant to protect the fragile springs from damage when they were moved. Personally, I think that they did as much damage to the springs if not more than just letting them rattle. You were supposed to gently push the lever over to push the spring channel into a foam rubber pad. Kinda like the metal front amps. But once the foam melted and the owner was a little too rough in pushing the lever over, the springs would get bent out of shape and lose their ability to transfer the audio waveform across the pan.

If the tank works and you like the sound, you can just use it as is or you can cut the locking lever out.

Report message to a moderator

Re: K-25 C2 [message #20971 is a reply to message #20950]

Sat, 19 July 2014 10:21

corrdk@aol.com
Messages: 21
Registered: June 2014
Location: California

Junior Member

I think for the time being I will modify and mount the locking tank (remove locking lever). What is the theory behind mounting the reverb OUTPUT as far from the transformer as to be allowed? Again, thank you all for your input. Stay tuned for our next adventure featuring a Kustom 100 4-10 Combo that sounds horrible when you turn it on.

Report message to a moderator

Re: K-25 C2 [message #20976 is a reply to message #20869]

Sat, 19 July 2014 14:39

stevem
Messages: 4775
Registered: June 2004
Location: NY

Senior Member

The output side of the will pick up hum from the power transformer just like if you have ever heard the hum made when you place your guitar with the volume turned up on top of a amp where it's power transformer is mounted.

Report message to a moderator

Previous Topic:	Need amp tech
Next Topic:	Major Bass Combo Restoration Project

Goto Forum:

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

]

Current Time: Sat Nov 16 23:48:09 EST 2024