No where in any of your previous posts above do you state that number or any other manufacturer's number.

But, here is how you second source a transistor:

1) Enter the PN in the search engine and start looking for it's data sheet or electrical specs.

2) once you know the key specs of voltage rating, collector current rating, gain and case style you go to transistor makers like motorola and shop for a power transistor similar to it.

If you can't identify the number, you estimate the needed specs based on surrounding circuitry, load current, etc.

BTW: on the schematic, there is an actual part number listed under the part labeled R265A device which is: 2N1309

I can't find any transistor on the schematic labeled R256A, which is the number you list above.

EDIT TO ADD: the 2N1309 is a germanium power transistor. I don't even know if germanium transistors are still available?

http://pdf1.alldatasheet.com/datashe...TC/2N1309.html

 

Sorry Bountyhunter, I thought I mentioned it. I post on two electronic forums so that explains why I thought that. Please accept my apologies! As for the transistor, it is gernamium. I tried looking up the datasheet, but I couldn't find it.

 

You didn't measure the transistor correctly. A Vbe tester (multimeter etc) won't return a Vbe reading of 12v.

How did you go measuring the voltages on the powered-up PSU and comparing them to the voltages clearly marked on the datasheet (as i said in a previous post)?

 

I found the bad transistor, it is circled in red. I substituted a PNP power transistor for it and it worked fine, except that it's a silicon transistor and I need a gernamium one. Does anyone know of a substitute for it?

Attached Thumbnails

 

 

The transistor you circiled in red is wired in parallel with the one just above it in schematic. Those MUST be the same type of transistor or you will have serious problems because one will hog current and cook itself under load. Whatever transistor you installed in the red circle, put one in the above location as well.

 

I already know that transistors should be the same if wired in parallel. What I've noticed, is that the transistors in the actual hardware are the same, but in the schematic they aren't. Also, the transistors they suggest, aren't identical to the ones in the schematic.

 

The schem shows both of the two paralleled as 2N2147 if I read it correctly. They must be the same type. The one above those two can be different because it is not in parallel, it is their driver.

 

Right, but guess what transistor is actually in the hardware? The 2N2869 is used instead of the 2N2147.

 

Heathkit often substitutes similar parts. I suspect those are similar germanium devices. I couldn't find them in my ancient books, but they probably interchange.

 

There is a Recommended Heathkit Update to This Supply!
Go to The Yahoo Groups Heathkit Group and Look under Files for the IP 27.