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Should be able to use a piece of 4mm or 5/32" ID brass tubing, and heat shrink the outside. Probably could just leave it in there and not have to worry about finding custom probes ever again until you find the originals! (though having them stick out is kind of annoying...)

Unfortunately those lithium primary batteries are indeed very high dollar to size*weight ratio and excellent ROI for theft :( I'm going to continue using dollar tree batteries for my meters wherever possible, however... they work long enough. Should check my Eico again, but I figure it's still...

Next time someone needs reverse banana plugs and can't find any, here's an option: buy some MC4 connectors, throw away the plastic part, and use the female connector... should fit! Just need to insulate it, a few heat shrink tube layers should do the trick! Dang...mad... I was at a hamfest and...

Though you can try soldering/welding a new wire to the stub I'm more concerned about melting the plastic seal there... do it fast or do put it in the trash :( I would not try to use high melting point solder here, have to spot weld if you have the tools (still very hard to do!), else try to...

Also check of C71 is dried up... though you probably checked already since electrolytic capacitors in equipment of this age should all be checked for drying out!

Did you end up replacing the rectifier, for grins? Is the original really a selenium rectifier (assuming that's why it's labeled Se)? Maybe that is what's causing the hum.

fidelity of this radio probably wasn't very good to begin with, but either way it's not easy to swap with silicon and still get the same audio performance. You can just put in silicon and deal with the additional sound degradation...

So if the original resistors weren't FL-PR00F does the replacements need to be? :D

trying to learn something here, grid current should be pretty low (less than 1mA), and well for tubes, plate current should also be fairly low (hundreds of mA at most) at least compared to semiconductors. Basically socket weakness provides additional resistance but usually it's only a few ohms...

The battery (SLA) should have gotten hot if you charged with too high of voltage (and the psu was able to supply the current needed to sustain that voltage). Cheap chargers put a resistor in series with the output and this by itself causes the "sag" when connected to a battery to charge it -...

good catch, yeah the transistortester schematic is indeed wrong. Probably made an assumption that it's drawn the same way as NPN but that's an error -- it should be opposite, anode connected to collector in pnp versus cathode to collector on npn. Funny thing is sometimes you can't even trust...

Nice thing about those modern transistortesters like the one you have in the picture actually shows that diode connected -- and you should "see" that diode with your DMM! That diode is very common in power transistors in general, most modern transistors will have one integrated. Especially...

Package is probably the more important issue actually if this transistor is being used as an emitter follower. These plastic transistors are just not very good at getting rid of heat, and if your heatsink that you're trying to mount on is not suitable for the plastic component, it will not...

Experimentation is sometimes necessary and well, at least for me, I keep a variety of components to try. TBH I would not swap parts with a working channel in case the guess was wrong and fries another component. I would have just removed Q605 and see what it does, then test with a cheap tester...

something isn't quite right here. transistor looks okay. Perhaps there's a loose resistor nearby... R637 still good?

Exactly what is your transistor tester reporting for the suspect BC556B(Q605) and 2SD669-D(Q607)? What kind of transistor tester do you have? If the tester solely reports hFE this is probably insufficient. What happens if you just remove one of Q605 or Q607 by itself, will the output drop back...

Sus because since B is higher voltage than E (lower, if we were talking about npn but this is pnp) this transistor should be cut off. If this transistor is truly cut off, Q607 must also be shut off and not pull its emitter to 25.6V. So I think either Q605 or Q607 is shorted/stuck on if the...

re-measure Q605 voltages/test Q605 ...readings look sus here, but maybe I just can't read the way too small numbers anymore... Bad electrolytic caps usually don't cause voltage railing in analog gear, usually ends up passing 60 cycle hum along or stops/distorts the signal.

The nice thing about having touch screen is that they can change the text under each button. The horrible thing about having touch screen is that they can change the text under each button.

Are the terminals shaped differently? Can't tell due to the angle but is one terminal rounded or the hole in the terminal rounded (have to look closely), perhaps that's the 50µF section.

The 50µF section has something to do with a circle on the capacitor somewhere ... but yes if you can find the bridge rectifier and trace it to the capacitor, the schematic says it's connected to a 100µF capacitor, whether or not it's this you'll have to look at the radio...

Just remember if you want to bolt to a metal case, it too needs to dissipate, and thin metal chassis are insufficient as well. Also make sure you don't forget to insulate the metal tab from the chassis with shoulder washer and all - usually for low programming current adjustable linear...

you should be noticing the heatsink getting quite hot, that heatsink is probably marginal for the 10W or so that needs to be dumped. 10W is a lot without a fan, did you allow enough space for at least some convection? Redesigning the circuit to spread the 10W across multiple regulators/larger...

A higher voltage may be fine, should check the tube's plate voltage maximum and make sure you're not dissipating more heat than the tubes can handle.

In case anyone's looking at this in the future or finding an answer in the past (seems the OP was a theoretical question rather than a practical/device repair question), again, AC is generally for distribution of power and regulation is difficult, so it's not very tight. Yes, keeping a steady...