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Toshiba PF & PD-1843 no picture / video (it's becoming a trend!)

Its probably frustrating dealing with a problem like this makes you start constantly worrying and checking stuff.
This is what I would do because you ruled out its not a chassis issue.

- Buy a demag wand and use that on the tube see if you can fix up the color impurity
- investigate the neck and yoke for possible shifts or changes (may not be something thats able to be spotted)
- Find the ring that is responsible for purity on the back of the neck with the convergence rings. Take a sharpie or paint pen mark its original spot if needed and play around with that.

I think its possible to add magnets in key locations to try to clean up bad purity but im no expert in that and I dont actually know for sure.

---- last resort efforts ----
- remove the tube from its framing and put it on another frame or find some way to run it without using the original frame (the frame could be magnetized and its causing impurity in the corners)
- loosen the yoke and ring assembly from the neck. Move the yoke laterally forwards or back and see if it makes any differences.
- bump the tube around and see if you hear the mask/grill inside excessively rattle or see the picture wobble oddly/excessively, or makes the purity move around or change and stay in another spot.
- last ditch effort with demag hit the demag wand from different angles repeatedly (the implosion band or internal mask/grill could be magnetized)
- swap the yoke or convergence ring assembly entirely if you can or want to. Maybe the yoke or the purity ring is bad or damaged

RIP
- take a hammer to the neck and salvage all salvagable parts or donate the tube to someone / recycle the tube

Dont give up hope yet.
 
I checked the screws on the clamps next to the rings and the yoke, they both seemed pretty on there. I was able to make an extra quarter turn or so but nothing that would suggest they were excessively loose.

I poked around at the yoke with the handle of a wood hammer and tried to push and wiggle the yoke, didn't seem to move at all. I would be surprised if it's not on there all the way or loose somehow. I marked the rings with a grease pen, then moved them back and forth, everything seems okay as far as I can tell? Seems quite easy to move them around though, I imagine bumping around during shipping could've easily knocked these out of alignment!

I banged the front of the CRT with a closed fist, not too hard obviously, and I also shook it back and forth a bit. Didn't hear any concerning sounds or anything suggesting the internal mask/grill might be broken. I haven't been able to hook a PCB back up to test with it on (long story), but I will try to do that this week and report back.
 
Best of luck to ya! So far sounds like its probably not a worse case scenario atm
 
So you have a big purity issue there, the last ring set placed on the neck of the tube, the ones most near the yoke should cure this but if do Not and a degauss do Not fix, then the shadow mask is dislodged due to an impact..really I hope this is not the case.
 
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Interesting, I'd be curious to learn more about how that works. At the moment, they spin freely all day with minimal resistance. It's entirely possible I just lack understanding of how this is supposed to work.
 
I think the lock ring set might just be glued down.

The two rings closest to the yoke adjust purity.
 
kazuo said:
Interesting, I'd be curious to learn more about how that works. At the moment, they spin freely all day with minimal resistance. It's entirely possible I just lack understanding of how this is supposed to work.
Click to expand...
It takes a lot of mucking with to get a real feel for any of it making sense. The guide on AO is really helpful.
 
I dont think they glue those rings tbh they might put glue on the ring to hold it to the plastic one one single point but thats it.

Heres a good question when you say the rings move pretty freely. You say ring(s) Are they all moving at once?? cause if so that is an issue. I feel im reading into that too much.

Theres a pretty good pdf document called A Guide To Setup and Adjust The CRT of an Arcade Color Monitor by Ingvar Karlsson that has some really good info and reference diagrams. Highly recommend checking that out a little if you can.


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Been talking with GeekMan about this on and off on Discord; long story short, I got things to improve somewhat, but the corners are still out of whack. I can't determine if this is an issue with the internal mask being damaged, a magnetization issue, or a convergence/purity issue. I spent several hours over the past few days trying to adjust convergence/purity, working over the tube with a demag wand and multiple large magnets, and trying to adjust the yoke (which is extremely glued on), and not really having any significant progress. I'm basically throwing in the towel and putting this up for sale. Maybe someone else will have more success than me, or otherwise be able to determine if this is still a viable tube.

Thanks everyone!
 
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