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Please help me identify a K100 part [message #8501]

Thu, 05 April 2007 15:16

swwhit
Messages: 6
Registered: April 2007
Location: Windsor, CT

Junior Member

Hello:

I have an original Kustom 100 from the late 60's I managed to pull the wires off a part: it is a small metal cannister-shaped part 3/8" long X 3/16" diameter, located in a metal clip between two large transistors on the bottom of the chassis.

The part is made by RCA: N3754. There might be a "1" in front of it, the lettering is smudged.

There is also the text "8L" on it.

If you have any suggestions regarding how to identify and/or find such a part, I'd appreciate it. Meanwhile, I'm interested in ordering a schematic. I don't know whether I have a K100-1 or K100-2. The Model# label on the head is unreadable, but the s/n is 34966. PC board has the letters: KEI-1 PC104 on it.

Can you tell from this info which model this is? Maybe there are other distinguishing features that would help me identify it.

Thanks in advance for your help.

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Re: Please help me identify a K100 part [message #8502 is a reply to message #8501]

Fri, 06 April 2007 06:43

stevem
Messages: 4733
Registered: June 2004
Location: NY

Senior Member

Hi,That semiconductor you broke is a diode, and its part number is 1N3754,.It is used to sence the two output transistors running temperature and adjust the output stages current as needed.
You can get a replacement from mouser electronics in the NTE line they carry,their part number is NTE5801.
You will also need a tube of heat sink compound to dab a blob on the new diode before you place it back in its mounting clip, and the clip must fit tight on atleast 2 sides of the diode.
The new diode will have a plastic case not a metal one like the original.

The k100-1 head is 2 channels, the k100-2 head is one channel with reverb and tremolo, so depending which amp you have the schematic part number will be CR102, or CR106 in the K100-2 model.
Why where you messin around down in that part of the amp, does it have a problem?

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Re: Please help me identify a K100 part [message #8507 is a reply to message #8502]

Fri, 06 April 2007 14:15

swwhit
Messages: 6
Registered: April 2007
Location: Windsor, CT

Junior Member

Stevem: thanks for the excellent information! I think I saw that part on mouser but wasn't sure if it was the right one.

I was messin' around to see if I could find the source of it's reverb & trem problems. It also had a hum; I think the diode was hanging on by 1 lead so maybe that was the culprit.

The reverb feeds back waaaay to easy. I opened up the head a few years ago and the tank had a kinda fiber cover on it that was coming apart. I reglued it but no difference. The springs were springy and didn't seem overly loose but I'm no expert, and the tank is original, so ... ?

The trem has practically no depth.

The footswitch isn't controlling them correctly; I forget exactly what it does or does not do. When I replace that diode I'll fire the thing up again and can give you a better description.

thanks again,
Scott

... almost forgot, I've got a single channel (2 inputs) with reverb & trem so it must be a dash-2

[Updated on: Fri, 06 April 2007 14:18]

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Re: Please help me identify a K100 part [message #8513 is a reply to message #8501]

Mon, 09 April 2007 06:40

stevem
Messages: 4733
Registered: June 2004
Location: NY

Senior Member

When you replace that diode, be sure to put the clear tubing back on the leads so they do not short to anything.
As far as the reverb problem goes if you look at the inside of the pan you will see where the wires come off each jack and go to a small transformer, they should not beable to move on their 2 leged metal core, but most times they work their way loose so get some thick gap filling super glue and let it drip down into the gap between the cores frame and the nylon winding bobon to hold it in place.this should help to one degree or another with the feedback.
The pan also has to be installed the right way, if the output marked side of the pan is near the power transformer than when the reverb is turned up you will get more hum than you should.
Some hum with the reverb up is normal though!

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Re: Please help me identify a K100 part [message #8517 is a reply to message #8513]

Mon, 09 April 2007 11:38

swwhit
Messages: 6
Registered: April 2007
Location: Windsor, CT

Junior Member

Dynamite, can't wait to try it!

thanks again

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Re: Please help me identify a K100 part [message #8550 is a reply to message #8517]

Thu, 19 April 2007 08:54

swwhit
Messages: 6
Registered: April 2007
Location: Windsor, CT

Junior Member

Hello Stevem:

I received my NTE5801 from Mouser yesterday. Just to make sure it's the right part: it says "Industrial Rectifier, Axial Lead".

The part has a "cathode band" ring on it. Is polarity an issue here? If so, can you tell me where to connect the lead with the cathode band?

thanks,
Scott

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Re: Please help me identify a K100 part [message #8553 is a reply to message #8501]

Thu, 19 April 2007 13:11

stevem
Messages: 4733
Registered: June 2004
Location: NY

Senior Member

Hi, the cathode, or banded end of the diode goes to the 4700 ohm resistor that goes to another 4700 ohm resistor that is in parallel across a cap that is a 68 mfd at 35 volts.the other end of your doide goes to another doide that is in serise with yet another diode.
Hope this helps.

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