Quote:
Originally Posted by Electronic M
I'm a little late to the party on this observation but sometimes when focus voltage is good but proper focus is unobtainable and picture is bright (especially if previous owners have been monkeying with it) it can be because the CRT G2 AKA screens are set too high...I had that on a Setchel Carlson monitor and was chasing my tail till I turned G2 down...That brought the HV way up and I had to readjust the regulator.
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I set the G2s in service mode for a barely visible line, so I believe they're good. I did have slight blue retrace lines at first, so they may have been set too high. I don't think I touched the focus after that though so maybe it needs a touchup. The good news is that it didn't take much to get a line on all 3 guns, not even half, so the CRT looks to be happy! I should get the HV set when it's straightened out, that's a good reminder. It's supposed to be 25KV, and it was 26 before I even worked out the focus and adjusted the G2s.
Quote:
Originally Posted by zeno
That looks pretty damn strong. The green may be a little off though.
Contrast looks good, almost as if its at max. Keep in mind these sets
wont show the high contrast of newer sets & keep a good pix.
They are meant to be used in a dimly lit room & not driven to the max.
BTW we used ECG sticks. ECG was a good quality sub line almost all
the time.
BTW#2 Flipping a set on its side will throw off the purity, thats normal.
73 Zeno 
LFOD ! |
I think the picture exaggerates the contrast. I'm almost certain it's too low. In any case, the contrast control has no effect whatsoever, so something is wrong there. I took some voltage measurements around the video output tube, and the values on the schematic vs. the actual readings are below.
All readings vary w/ brightness control, and Contrast control has little to no effect on any reading:
Pin 1 (connected to contrast pot) shows 10.5V. It's 10.7-0.5
Pin 2 shows 5.5v. It's 5.8-(-19v)
Pin 7 shows 300v. It's 280-390
Pin 8 shows 130v. It's 187-273
There are 2 electrolytics in the vicinity that I didn't touch yet. Can they cause an unresponsive contrast pot?