help finding a transistor

[rayma]

used another meter and I am getting the same results, I even tried useing the little PNP, NPN slots on the meter but that didn't prove to be any help

If it's really 0 Ohms, then the transistor must be shorted.
See if you get the same reading by just shorting the two test leads together.

 

[jimmy74]

yes I do so the meter is a cheap one, using the other meter I get a 0.2ohm difference between testing the transistor and shorting the test leads

 

[rayma]

yes I do so the meter is a cheap one, using the other meter I get a 0.2ohm difference between testing the transistor and shorting the test leads

That's normal enough. Start looking for another transistor, though.

 

[jimmy74]

yes I started off this post to try and understand what transistor would replace it

 

[rayma]

yes I started off this post to try and understand what transistor would replace it

I think you haven't got the right number, look carefully again.

 

[jimmy74]

there are other 13 transistors of the same type throughout the whole organ, they all have the same script TJ729H with motorola's symbol infront of the letter T.

 

[rayma]

there are other 13 transistors of the same type throughout the whole organ, they all have the same script TJ729H with motorola's symbol infront of the letter T.

Seems like this may be a "house " number, because I can't find it anywhere. Is there a schematic?

 

[djk]

Because it's the best currently available part for driving TO-220 outputs, rated for up to 80V.

I have used it in my commercial designs to drive same.

 

[jimmy74]

there is a schematic but it doesn't show these transistors, I'll try and post it up today

 

[jimmy74]

this is the original schematic of the power amp section:

https://www.flickr.com/photos/73835524@N00/14674643600/