Kustom K100 2 Schematic

[cjlectronics]

Does anyone have the schematic for a Kustom K100 2. I have one that smokes the 1 ohm resistor as I slowly increase the mains voltage with a variac. I have found one of the drive transistors shorted between the base and collector but it is a blasted NTE part. I want to use the original part number.

Any help is greatly appreciated.
CJL

[Enzo]

What is the PC board number? SOmething like PC5033.

CHances are the driver is a 40409 or a 40410. The NTE cross shows the right current and voltage, but it lacks the integral heatsink of the real part. Yet another reason never to use NTE.

[cjlectronics]

The board number is PC104.

[Enzo]

Well damn. My thick Kustom manual lists the amp and shows that board in it, but both K100 amps while listing the board, omit the board schematics from the collection. I am not missing it, it was never part of the book. How odd. Got PC105 though.

Sorry

[Enzo]

The original RCA 40409 and 40410 types were favorites of Kustom. They were TO39 with a rectangular heat sink included on the part. If the wrong parts in there now are TO39, I suspect the 40409 was what was there first. Or alternatively look up 40409 or RCA40409 in NTE and see if it crosses to what is there now. Bet it does.

[cjlectronics]

I don't see how you answer so many questions in this forum and still run your business. Do you have 4 arms?

First, the two main power transistors in this unit are 2N3055s. They measure good. One of the two drive transistors is marked 2N3058 (the last number is an 8 or 3?). The other transistor is an NTE129 and this is the transistor with the collector to base short.

I looked up the 40409 and it crosses to an NTE128
I looked up the 2N2058 and it crosses to an NTE159
I looked up the 2N3053 and it crosses to an NTE128

Are the two drive transistors supposed to be complimentary if the power trannys are both NPN type?

Thanks for your help Enzo,
CJ Landry

[cjlectronics]

Enzo,

I'll take the PC105 schematic if this is all I can get.

Thanks!!

[52 Bill]

The drivers are complimentary, one NPN and one PNP. The power supply is bi-polar so the dual NPN outputs work there.

As Enzo pointed out, the other transistor to look up is RCA 40410, the compliment to the 40409.

[Enzo]

PC105 is a preamp card for a different amp.

[Twist]

I don't know if you want to go to the trouble but I've pulled the drivers out of those square heat sinks and with a little care you can press new ones back in the heat sink.

[Enzo]

Or buy new TO39 sinks.

I have a small stash of real 40409.40410 that I hoard like gold. No I won't sell them.