Motorola ts18 contrast control

[timmy]

Originally Posted by earlyfilm

First, I agree with B. Anderson, to check for voltage differences between the problem set and the correctly working TS18.

Tim, from what you describe, I'd be more likely to suspect low high voltage, which on an electrostaticly deflected CRT often looks more like a weak and gassy CRT, but on a magnetically deflected set, it usually shows up as image bloom.

First verify that the feedback coil on your 1B3 is in the correct place. If it is a round coil spring, it centers with the bottom folded lip of the 1B3 plate. If it is a flat band, the bottom edge matches the bottom edge of the 1B3 plate. Older 1B3s have a much longer plate than the newer ones, so the sweet spot won't be in the same place on all 1B3s.

If no improvement, borrow the 1B3 and 25L6 HV Osc tubes from the better performing set, and retest.

Since the B++ only feeds the sweep, HV Osc and Video Amp, confirm that is is working correctly by measuring the voltage from the high end of the Brightness control to Ground on both sets.

Also check the voltages on the video output tube on both sets and try substituting that tube.

A final check would be to check the value of four resistors in the HV cage. Ozone can cause resistors to change value.

(The above trouble-shooting tests are listed in the order of probability.)

James

the hv is a solid 5 kv weather the bright is up or down my other sets are at 4.5 kv and they are fine. But it's possible that these tubes are not as good as the ones in my other sets. I tried the crt in my other set but the lines were Bearly there at full brightness but at full bright it was Alittle washed out suggesting possible gas in the tube as the other tubes are at full bright and they are bright with no lines. But if I can find something or a reason why the lines are stronger on this set rather then the other ones it would be nice to get rid of even 90percent of them.