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Originally Posted by Electronic M
I'd stick to the same video driver transistor as original for now and maybe increase heat sink size if practical*....those old metal can transistors don't always die of overheat.
* Remember most of those metal can transistors the can is connected to one of the leads so make sure the heat sink don't touch anything that could short the transistor.
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Anything to elongate the life of the set on the cheap. I'd rather spend some money now to keep it working later. It's in very nice cosmetic shape.
What style of transistor are these? I'm trying to find heat sinks for this package, but I'm not up to date on my solid state stuff. The tiny little fins get hot enough after just a few minutes to almost burn the skin - I think they're either being severely overdriven or the heat sinks are way too small.
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I know this is basic, but did you clean the contacts of the tuner? A dirty tuner can wreak all kinds of havoc....IIRC some 70s sets had issues with tuner fets shorting...If you have a transistor tester those may be worth checking. I doubt you have access to a tuner subber or a B&K TV analyst (which have IF outputs you could use to confirm the IF is working (don't mess with it unless you know it is dead or you have a working TV sweep marker generator and want to learn the dark art of TV IF alignment)...if your video modulator happens to be a blonder tongue AM series or something with an IF jumper often that IF is a standard 44MHz TV IF signal you could inject for troubleshooting.
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Actually, that was my first thought too. I took it out to clean it, took the can off and sprayed electronic cleaner (worked wonders for some radio tuners in the past) and let it dry before reassembling. No change.
Decided to hose the entire thing down for the heck of it. The tuner completely stopped working after it had dried by that point, I was no longer picking anything up on any channel.
Just now, I heard a crackle and it came back to "life." I was picking up a wobbly, fuzzy resemblance of a picture when the speaker popped and I got a decent picture on the screen again. Still the complete wrong channel, but I got the LCG-388 to show up:
Color demodulation is working perfect, too. Everything is working except the green channel, which I know is bad, and the tuner, which is also obviously bad.
Unfortunately, I made the mistake of passing up on a B&K 1074 a while back. I picked up a 1465 scope and the LCG-388 instead for the same price... Probably should have gotten the analyzer.