Replacement Peavey CS-800 Power Transistors?

[K-amps]

Here is the NOS (or maybe "NOS"??) Motorola

Seems about right for a MJ15025.... fakes are often much higher gain. What is the capacitance on EC and CB junctions using your TC1?

 

[777funk]

Seems about right for a MJ15025.... fakes are often much higher gain. What is the capacitance on EC and CB junctions using your TC1?

CB capacitance is around 520pF and CE is 300pF.

 

[K-amps]

Looks legit…. Try the NPN. One of them should read higher like 600-700pf

 

[777funk]

Looks legit…. Try the NPN. One of them should read higher like 600-700pf

These are the NPN part (MJ15024).

 

[wg_ski]

500 pf CB is spot on for legit 15024. PNPs are higher (pretty much universally).

 

[wg_ski]

Excellent! That's what I see here also. Looks like the RCAs may??? be original part numbers. I don't know the accuracy of this cross reference (attached).
Taken from here:
https://www.audiolabga.com/pdf/PV_Semi_Cross_Ref.pdf

That IS RCA’s MJ15024 then. They did make one for a few years - it is in one of my old data books. Spec is exactly the same as the Motorola.They are parallelable if they are close in vbe at the same current. Better if they are all the same wafer lot, but in the old days there was more variation within a silicon wafer than there is lot to lot months apart today.

 

[HighTec]

Well, there is another solution. Take a hacksaw and decapitate the sucker. Let's see his guts !

😉

 

[steveu]

Not a great idea to replace failed transistors with the same thing again. As I recall, it's important that the driver is a fast transistor, or it will oscillate. There was a 10MHz 10A switching transistor I used years ago but there should be something better today.