Crosley Model ??

[Doug66]

Another problem has developed. The horizontal is very unstable. Sometimes, I cannot even get it to sync even though besides the hold control, there is a trimmer for a horizontal lock, drive, freq, and a coil for the horiz lin.
I left the set on for 20 min while I was troubleshooting, and the width shrunk and no sync was the result. See pic

[Doug66]

I have now lost the raster completely. I finished replacing the mica caps in the horiz osc section as well as resistors. Voltages on the 6SN7 check ok. Tried another 6Sn7 as well as a 6BG6 output and 1B3. Any ideas? Here is the horiz section on the schematic.

[Eric H]

Well if it quit after you changed the Micas I see two possibilities.
1. You got something wrong.
2. The values are different from the originals, possibly because the originals were bad, now the frequency is so far off the oscillator won't run. Try adjusting the H Osc coil.

[Doug66]

Eric, that post was confusing. The raster quit while the set was playing. I then replaced 3 micas hoping one of them had gone bad.
First, the horizontal lost stability, then I lost sync altogether. Next the pic shrunk (see pic 2 posts ago) then I lost the raster completely.

[Eric H]

Originally Posted by Doug66

Eric, that post was confusing. The raster quit while the set was playing. I then replaced 3 micas hoping one of them had gone bad.
First, the horizontal lost stability, then I lost sync altogether. Next the pic shrunk (see pic 2 posts ago) then I lost the raster completely.

Oh okay, I though it quit after replacing the Micas.

I've used a 5U4 in place of a 5V4 Damper temporarily, it worked fine but I was advised not to leave it in permanently.

[Electronic M]

If you Have a scope check and calibrate (by comparing the freq to video synch) the osc. If that don't fix it check voltages on the H out tube, and if those are fine check the damper tube. A shorted or weak damper will kill the raster.

[Doug66]

I don't have a scope, so I checked the voltages on the 5V4 Damper. Pin 2 is low about 45V. I don't have another 5V4, but my tube substitution guide says a 5U4 will sub. I want to make sure of that, then I will try a 5u4 in it's place.

[Electronic M]

My Dumont uses a 5U4 for a damper, and this set seems to be a dumont inspired design so it will probably work.

[Kevin Kuehn]

A 5U4 pulls an extra amp on the filament supply.

[Doug66]

After a break, I have gotten back on this and found a mistake I made. An 8200 ohm resistor was going to pin 5 instead of pin 6 of the 6SN7 horiz osc tube. Correcting that now gives me a partial raster as shown.

Any ideas on why only 1/2 of my screen is lit, and where to start troubleshooting?

[Doug66]

I've gone as far as I can. I think the horiz is running off frequency. I can see what looks like a blurred overlapping image on the screen. I checked the horiz hold control, and it's fine. The horiz lin control measures good. I even replaced the 56pf cap on the yoke for the horiz. I posted most of the schematic, but the hoirz and HV section can be found on PG 2 of this thread at post 10 that starts as "I've completely lost the raster." It wouldn't let me repost the same pic again.

If someone recognizes the problem or has any ideas of that's wrong, please advise me as I'm about to give up on it.
Thanks
Doug

Also, this set has 3 trimmer caps. Horiz lock, horiz drive, and horiz freq. Lock and drive have to be screwed in almost completely or I lose what raster I have. Freq seems to make no difference.

[David Roper]

I'd sooner use 5Z4 (preferably) or 5Y3 as a temporary sub if I had to.

[Doug66]

I briefly tried a 5U4, and that didn't help. Pin's 2 and 8 should have 300V and both have about 255. Pin 8 has a fuse (which is good) that goes to the horiz lin coil. I put the HV probe on the cap of the 6BG6. No HV, but when the probe touches the cap, I can hear it cackle in the speaker.

[Kamakiri]

Get rid of those two candohm resistors underneath, no matter how they test. I just went through hell with a somewhat similar issue.

[Eric H]

Judging by that picture it appears to be scanning top to bottom, not side to side.
Is it possible the yoke has been turned 90°?

If that's the case then the vertical is short, not the horizontal, though that may be off frequency.