Hey guys, I just aquired this old mobile tube amp. It's a PAL200MDX. Unfortunately I think in my excitement I ended up killing it. I seem to have killed the two transistors that drive the transformer. They are unmarked but the schematic says they are PE250 AKA EF250. They are stud style transistors with a bolt on the collector. I can't find any info on these. They are PNP types. I'm wondering if anyone here has any info about these or can suggest a replacement. Here is the schematic. http://www.firestik.com/Instl-Art/PAL200MDX-dc.pdf When I was setting it up for testing I placed the amp on top of something metal. This shorted the collectors of the two drive transistors on the bottom against the case. Apparently negative from the battery and the amps chassis ground are supposed to be isolated as the transistors are isolated from the case with mica insulators. Schematic doesnt show that but on the amp those two grounds are isolated. When I keyed it up it made a squealing sound but after that it kinda stopped. When I key it up now it stills squeals a tiny bit and puts about 40 Volts on the plates of the tubes but that's about it. Transistors are testing a little bit weird. Not totally shorted, still conduct in one direction on certain terminals but voltage drop reads around 100mv. Weirder still is that even though they seem to be shorted, when I key the amp up they don't get hot at all which I would expect if they where totally dead. I read somewhere that early power transistors of this type where germanium, maybe that's why I have such a low voltage drop reading? Who knows. I would love to get it to work again. Stupid mistake I made. Though in my defense this thing seems extremely vulnerable with those transistors being so exposed like that. With this being a mobile amp I imagine it was often at risk of being put against the metal floor or dashboard of a car.