KTN-2001 / Galaga

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I'm currently working on a KTN-2001 monitor which requires a new horizontal output transistor. I tested it after pulling it out just to make sure. The horizontal output transistor that was in the chassis was labeled J6808D H05. I've looked through some of the more reliable websites but nothing in stock. Recently, I ordered a batch of 2SC 5149 with damper diodes (which are comparable to my understanding) from a Canadian distributor but they are all testing bad so I assume either I'm testing them incorrectly or these "new" transistors have counterfeit parts.

This is the diode test that I'm performing:
1750821583737.png

Please correct me if I'm doing this incorrectly or if you could direct me to more reliable parts/pieces.

These are the "new" HOTs that I ordered (with damper diodes):
1750821781759.png


This is the original HOT that I pulled from my Galaga / KTN-2001 chassis:

1750821817704.png
 
That procedure is for standard NPN transistors (the kind of HOT that you find in a K7400 or a Hantarex) but these are like the K7000 ones, with a built-in damper diode and a resistor across base and emitter. They test like this (OL when you reverse the probes):

transistordiode.jpg
On B-E you can only read the resistance or a very low reading on diode test (polarity doesn't matter).
 
Also to tack on, that is an inferior transistor that was probably replaced.
On the schematic they show a D5072 H.O.T. - 800v, 5a, ~8 Gain. (NO DAMPER DIODE)
and the 3-4 I've worked on have had a D1880 800v, 8amp, 8-10 Gain and damper diode.
The J6808D is only 750v (probably ok but I wouldn't go with a lower voltage), 8 amp and 4.5-7.5 Gain and damper diode
And finally the 2sc5149 is only 600v, 8amp, and 8-25 gain also with damper diode.

You should replace it with either a D1880 - 800v, 8amp, 8-10 gain or an FJL6920 - 800v, 20amp, 5.5-8.5 gain both with damper diode.

And one last thing, when you remove the hot, check for shorts on the desoldered pads to notify you of something else possibly shorted on the chassis.

-Pat
 
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