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Kasino U100-P repair - HELP!

Started by LJN, December 09, 2014, 07:02:40 PM

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LJN

Hi, all. I have a 1973 Kasino guitar amp that needs some work. I've had it for a few years now. I got it at a pawn shop for $40. The guy couldn't tell me if it worked or not. It did (after some tinkering) for about 9 months. Then, one day it stopped. I found the problem, but haven't been able to find the part to fix it with. It was a germanium transistor with only two leads, and the number 61008 on it. Is there any way to repair this amp? Or, should I just write it off as junk? Thanks
If it sounds good, USE IT!

Epiphone Les Paul, Kasino U100- P, Sears 125-XL

nosaj

ljn wrote:
I'm pretty sure the part in question was a PNP germanium transistor. It only had two leads, though.


Then it isn't a transistor.
From another site same question......


U100... Isn't that the "Club", right? You know that Kasino amps are largely just Kustom amps in different cosmetic appearance. They recycle largely the same PC board modules. Club, according to my references, holds PC105 (preamp), PC803 (reverb & f/s control) and PC900 (power amp & +/- 8VDC regulators).

You can verify pretty easily what board numbers are of interest.

I can find a crossreference to 61088, which is a 1N3754 diode, but not a reference to 61008.

Another useful resource:
http://www.vintagekustom.com/literature/Tech/tech.html

LJN

#2
Thanks.I have posted about this in another forum. Part of what you said was also written on there, but not all of it. Thank you. I'll have to try and find one of those, although it's extremely unlikely that I have one. And yes. I'm aware that it's just a rebranded kustom. That's why I wanted it in the first place. I'm a CCR fan. That being said, I constantly played through it until it died. The reverb was amazing. I never even put a grounded cord on it, either. I was going to, but couldn't find one that was long enough.
If it sounds good, USE IT!

Epiphone Les Paul, Kasino U100- P, Sears 125-XL

J M Fahey

1)  yes, Kasino was rebranded Kustom, owner had some Divorce trouble, inside they were exactly the same.

2) I very much doubt they used germanium for anything at all, specially in a Kasino which came later.

3) please post a picture of your mystery transistor, I'm just guessing you refer to a TO3 (or TO66)  metallic transistor, which of course "has 2 legs" .

4) what exactly is the problem, symptoms, and why you think that particular transistor is the problem?

Look for PCB labels and post a couple pictures, it certainly must match some regular Kustom amp, specially because of their modular construction ... which I find an excellent idea..

LJN

Thanks, Juan. I can't get a picture of the transistor because I lost it. It had some kind of fluid leaking out of it, which I noticed once while working on the amp. Shortly after, there were intermittent popping sounds, and loss of output when the amp had been on for a certain amount of time. Then one day I turned it on and ...nothing.  The part had a clip that it sat in, and when I moved it to get the number from it, the leads broke off. I tried to keep it, but it was eventually lost. I read that this amp is supposed to be identical to the Kustom K 100 (internally) . When I get the chance, I'll try and get some pics.
If it sounds good, USE IT!

Epiphone Les Paul, Kasino U100- P, Sears 125-XL

J M Fahey

2 legs / mounted on a clip points to a diode, probably a biasing one.

Post a picture anyway showing where it used to live, of the clip (and measure its diameter, as in , sometimes you don't have the girl but the bra gives you an idea of size) and both sides of the PCB where it was originally connected.

That way we might guess a little more accurately.

And of course the goldmine would be to have PCB codes matching known Kustom ones  :cheesy:

LJN

Thanks,Juan. It was exactly the same size as the metal can germanium transistors. I'll try to get some pics, if I get a chance. Thanks again
If it sounds good, USE IT!

Epiphone Les Paul, Kasino U100- P, Sears 125-XL

J M Fahey

That nails it.

It must be the then very famous and popular 1N3754 , "the king of biasing diodes" ;)  ... or so they thought.




LJN

That looks just like it, except for the number. I can't get those pics yet, but I will as soon as possible.  I don't really feel up to moving the amp right now. Thanks again, Juan. :)
If it sounds good, USE IT!

Epiphone Les Paul, Kasino U100- P, Sears 125-XL

g1

  Someone on ebay selling those 1N3754 has the spec listed as:
100 PIV, 125mA, Vf = 1.0-1.1V
Does that sound right?

LJN

Quote from: g1 on December 12, 2014, 08:30:44 PM
  Someone on ebay selling those 1N3754 has the spec listed as:
100 PIV, 125mA, Vf = 1.0-1.1V
Does that sound right?
Thanks, but I have no idea about any of the specs for the original part. I guess the amp may just have to sit there and look pretty for a long time. I appreciate your help, though.
If it sounds good, USE IT!

Epiphone Les Paul, Kasino U100- P, Sears 125-XL

DrGonz78

We can clearly see that the 61088 diode refers to an IN3754 diode, see attached sheet(kustom semiconductor infomation 2). That semi-conductor reference is clear back in 1971 and is from Kustom, which we know is possibly the same amp. Here is the data sheet for the RCA IN3754 diode too. Seems like your closer than you think. Attached is the Kustom K100C and perhaps that relates to this amp, I don't know. There is one IN3754 in there and a special note that it clips on to chassis, CR902*. 61088 was a house number perhaps and the actual name of that part is IN3754. Just throwing it out there... :tu:
"A person who never made a mistake never tried anything new." -Albert Einstein

J M Fahey

Quite possible and thanks for posting  :dbtu:

I would be very surpriseed if Kasino K100 were not Kustom K100  :o

I remember unsuccessfully trying to get 1N3754 in Argentina ... and eventually replacing it with plain old 1N4002  :o

In your case, maybe a fatter 1N5402 will fit that clip , although its legs will be too fat for original PCB holes if direct soldered.

In that case, use 1N4148 or 1N914 which have skinny legs but you'll have to epoxy it to the heat sink to have some thermal coupling.

That said, a blown bias diode usually means certain death for outputs and drivers ... check them.

LJN

Thank you both very much. I've tried several diodes in there, but got a distorted sound and alot of heat coming from the amp, so I had to shut off power very quickly. I became somewhat disenchanted after several attempts, and left it alone. Externally, the amp looks great other than a bit of rust on the corner caps. I wonder if someone had been driving the amp too hard over the years. Thanks again guys.
If it sounds good, USE IT!

Epiphone Les Paul, Kasino U100- P, Sears 125-XL

DrGonz78

So we can't blame a plain old vanilla diode for these types of problems. As Juan stated the diode being bad typically indicates other greater problems. Are you running this amp on a light bulb limiter when you are testing it?
"A person who never made a mistake never tried anything new." -Albert Einstein