[DaveWM]

did not get to more tube swapping but did notice some odd voltage on the video amp (6aw8). the screen was way high, like 210 vs 180 and the plate was low 110 vs 150. I checked the voltage divider on that tube and found the 15k was 11k and the 56k to ground was 65k. Not a lot but in those direction it would add up to too much screen voltage. I went ahead and replace those two ( had some old school 2watt carbon comps on hand) and check it again, much better screen at 178 and plate at 138. Seemed to help the video out, brighter and the contrast control is not as sensitive anymore, but still has a good range.

this all stemmed from what I thought was a bit dim of a pic, I started with checking out the video out, then moved to the video amp. Interesting effect of the change was before the fix I thought I had a slight tracking issue, as increased the contrast, the green highlights seemed to worsen (was checking by watching a B&W program. I just assumed it was a CRT issue. After correcting the video amp tube (and the contrast seems to work "better") I don't notice the green highlights happening. I spent a LOT of time trying to setup the the CRT drive pots to get rid of problem before. Perhaps it just not as much drive at the CRT cathodes, but it def is better.



Its fun to check things out, make a few changes check again, to slowly see improvements. I think it may add to overall trouble shooting, by being able to see direct cause effect. Not perfect, and certainly no substitute for good trouble shooting technique, but fun non the less.