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Thanks for the tips -- Sansuii, you're way ahead of me in performance at this point!
Well, the set has now consumed 90% of my free time for 2 weeks, but I finished recapping the last 5 or 6 films, and all the electrolytics. I guess this is where the real fun begins...
I haven't removed the CRT or the speaker, nor have I made any long wiring harnesses yet, so I put the chassis back in the set, and brought it up slowly on the poor man's variac -- assorted series light bulbs, while monitoring the 375V Bus, as its the only one readily accessible on the picture tube when the chassis is in.
Once I got it up to full line, there was still not much going on, Not so much as static on the speaker. The 375V bus topped out at about 445VDC, seemingly indicating that there's an awful lot of something not drawing very much current. (incidentally, I have gone through most of the resistors I deemed critical -- the power supply chain seemed to check out reasonably well). I flipped the audio input switch to Phono, and hooked up an IPOD on an RCA cable. Still Nada.
Peering inside, it looked like the 6K6 audio output tube was showing some haze, like it might have gone gassy. So much for NOS. I poked around, but all I could come up with was a 6V6 -- close enough to try. I popped it in, and Voila! Sound. Albeit pretty faint, even at top volume. After some more digging, I did find another 6K6, and put it in. Moderately better results -- for about the next 25 seconds when the 5U4 gave up the ghost.
I can see right away that I should have stocked up about 5X more on all the tubes. So. There it is. No signs of raster, no signs of HV. Either that or the CRT is dead. The only up side is that the CRT filament is definitely not open.
I'd consider bringing the set up on silicon diodes at reduced line voltage to get the proper bus, but the death of the 5U4 seems to indicate something is pretty wrong. Plus, the filament voltages would be low. When I get some more 5U4's, I'll start by digging into the other bus voltages.
When you guys probe on a bench, do you always do it with the CRT attached? I was thinking of jumping out the CRT 'loopback' pins on the power supply, and just pulling the horizonal output tube to start looking at things. Whats your standard procedures?
Guess I'm taking hte weekend off, since new 5u4's wont get here for a few days.
Alex
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