|
long term update. been watching MEtv, last night all of a sudden gets very contrasty... 1st check was the video amp tube, subbed, no change, next up was the AGC tube, a multfuction compactron, again no change. So I go to the AGC and reset it. Ok now I get the pic back but its VERY VERY touchy on the AGC either snow or blacked out and no sync over a range of only a few degrees...
Flip the TV on its side, remove the service saver bottom, start with a shot of tuner cleaner on the agc pot (the set has a lot of dirty pots). No real help.
Jumped a .15 AGC filter cap, no change, jumped the 4uf cathode bypass, bingo normal AGC. I replaced it by doing some pig tails on the new cap, atttaching to the cliped lead from the old. For fun I put the old cap on the cap tester, nada, wide open. This is one of the little tube electro used in zeniths, black body with a red end. The set is all orig but for the disc cap in te pic cushion and now this little electro. I know I could have avoided it by just shot gunning the whole set, but I enjoy finding problems and learning symptoms and fixes. So next time I run into a hyper critical AGC you can bet I will be checking the cathode bypass on the sync tube 1st.
The set still has a tint issue fully CCW is purple, but when CW rather than green the color just seems to say about corrent for tint but weaker. Fortunity the tint is fine, that is I dont need more green, but there is something wrong. I did notice I could get the green to work somewhat when the set was tilted up on its side (when I was checking for the AGC issue) Thats odd. Not sure why having it on its side would effect the tint control, unless just the flexing of the chassis or wire harness that connect the tint to the chassis had some corrosion where the plug harness connects up. Not going to deal with that for now. got to get the shop cleaned up.
|