Output transistor for Sylvania CR2742 Motorola 526 002-3 ?

[DewayneP]

Thanks in advance for any help anyone can provide. I am working on a Sylvania CR2742 Receiver and have a couple burned up NPN power output transistors. I don't have the manual for this unit but I do have it for the CR2743. This is the 25WPC little brother to the 50WPC CR2743. The output transistor only has these markings: Motorola "M" no circle and 526 on one side and 002-3 on the other side of the face of the transistor. Anyone have the manual for the CR2742 so I can try to cross the Sylvania part number or have an idea of a good cross? Thanks.

 

[chazix]

manual for the CR2742

In one sense, you won the AK lottery today! Relevant page is attached.

In another sense, I'm not sure how far this will get you toward a choice of replacement. I would guess you'll want to figure out how to fit a TO-220 part, and there are lots of possibilities. Maybe MJE15028 or 15030?

 

[DewayneP]

That will help immensely, thanks chazix.

 

[redk9258]

That is so cool how B C E is stamped into the leads!

 

[DewayneP]

If my understanding is correct, those are gold plated leads too!

 

[chazix]

This is probably TMI for what I think is a pretty straightforward substitute search (IF a TO-220 package will work)...

...but I was just doing a download cleanup, and came across a datasheet for BD911. These have the 90W (!) dissipation rating that the Sylvania manual specifies. (The On Semi MJEs I mentioned have a mere 50W rating, which I think is plenty for this application, but might as well "go big".)

 

[DewayneP]

Yes, the to220 package is exactly what I need. I’ll get some of the BD911 too.

 

[Tom B]

Those Motorola transistors are the same type Electrol Voice used in their early receivers from the early 70's. like the EVR1, EVR2, EVR3 etc
Typical power out was probably 20 to 35/40W RMS per channel. The power amps were completely direct coupled, and prone to catestrophic failures if the speaker leads were accidently touched together. The transistor characteristics were not high voltage, but pretty high current ratings. I'll look and see if I have any cross references for them as they were usually stamped with EV specific numbers like 43120
I have a bunch is you want to try some.
Yes the leads and heatsinks were gold flashed.
And yes the leads were usually stamped with B, C, and E
The were usually paired with motorola drivers and pre drivers that were epoxy, with mini heat sinks on top

 

[DewayneP]

The Motorola MJE15030 are installed and working perfectly. Now I just need to find out why the right channel is weak on FM, AM and Aux. Thanks everyone for your help and expertise.