RCA 62287 and Motorola M 025 -- what's that?

coal to newcastle

I may be preaching to the cathedral dean, but I'll open my mouth. When I replaced the burned RCA 4xxxx output transistors in my 1966 design 1972 production ST120, I liked what the NTE60's (1984) did to the highs- believe the increased ft and gain helped the sound a little. Everybody complained in reviews how vile this unit was, I didn't hear it that way. Was burned when I bought it, never heard the before sound. However, in place of the destroyed current regulator circuit NPN to3, NTE60 was regulating at 2.5A Vcc instead of 6.5 per spec. To get the current regulator up to spec, I had to find a really rusty RCA 4xxxx transistor, with low enough gain to make the circuit work correctly. Per Ivey's comments about the hard brightness of MJ15003's in old circuits, I think I would put some base emmiter capacitance across new stuff and maybe a bleed resistor to cut gain. Kind of like the "TIP Mod" did to the ST120, the old type transistors did not have an oscillation problem, but the new ones did.
However, determining if the M025's were germanium or silicon, once destroyed, I suppose one would have to saw the tops off and look for grown bars. I've got some old Delco germanium power transistors from 1972, they were price king about then, if industry wasn't still using tubes. (I was repairing geophysical data acquisition systems) They were in packages like little flying saucers with only 2 legs on the bottom, not 3, and a threaded stud in the middle.
 
Last edited:
I remember such flying sources with 2 legs and a bolt. When I sold them on epay I was surprised how high the price they gone for, for such ancient low-frequency, dirty-die parts!

I've found today 4 of some Bendix transistors, with 10-digit number. Can't find any info in the net.

By the way, that Motorola 025 transistors died nicely: looks like wires inside were made such a way they work like fuses!
 
m025

RCA SK replacement book 1986 has nothing on 62287. M025 and M025 A,B cross to SK3018 and SK3444, which are TO72 and TO39 small signal NPN transistors, obviously wrong. 025 no prefix crosses to SK3027/130, NPN si AF High POwer, TO3 available as matched pair SK3029/130MP. Pt 115 W, Ic cont 15A, Vceo 60V, hfe typical 20-70, Vce [email protected], ft 2 mhz. 2N3055 crosses to the same SKnumber.
 
Last edited: