OK, I'm working in unfamiliar territory... and since there seem to be a lot of video experts of late, this seems like the time and place to ask... I'm working on an H-89 that seems to have a problem in the horizontal drive on the video board. The unit powers up from cold to a good display, properly sized, and stable. After the unit operates for 10-15 minutes, the video breaks down, first by jittering slightly for 30-60 seconds, then it goes to a single vertical line on screen that fades to black. At this time, the filament on the CRT also stops glowing. If I leave the unit off for 20-30 minutes, it comes back with good video for a bit, then repeats the above. If I turn the unit back on right away without a cool down, there's no display/no filament glow. After tracing the (good) horizontal output signal from the terminal logic board into various part of the video board, and checking voltages where I felt I could reach safely in a hot set, I discovered that if I shot horizontal output transistor Q217 with cold spray I'd get video back right away. This unit is the one I posted about on cctalk a few days ago with the NOGDS board... when I got it, it had a AA battery inside for a clock board that leaked down onto the flyback transformer. The leak didn't appear excessive, and most of the "material" on the flyback must have dried long ago and was brushed away easily, leaving only a slight tarnish on the aluminum heatsink it's mounted to. My questions... 1) Although the flyback _appears_ OK, could the leak have caused some unseen damage that is now causing excessive current through Q217 and shutting it down? My limited understanding of flyback construction is that they are sealed units. It takes several minutes (10-15) before the failure is observed. Could a flyback failure allow operation for this long? How do I test this thing? 2) If I proceed under the assumption that the flyback is OK and Q217 is not... Q217 is a BU500: 1500V, 6A, 75W, SI-NPN. I normally buy from Mouser, DigiKey, and Jameco, but none of them seems to have this part, and I wasn't able to turn up anything useful Googling. A possible dealer or two in the UK, but for a $2-3 part I was hoping for a more-readily-available source or an equivalent. The closest I can find in the family is BU508A, which is 1500V, 7-8A, 120-125W (depending on whose specs you believe). Is that OK or too far out of spec? Does anyone know of US source for the real McCoy? Thanks for any help/advice! --Patrick