4" Flat BW CRT , can't flip image vertically

[samu]

Hi ,
I'm working on a project that will use one of those 4 inch B/W CRTs sold on aliexpress that were made for Chinese door phones.

It works great normally, but my project requires that I mount the CRT upside down and flip the video vertically (like is done in the 4" sony watchman models). I know that this is usually done by swapping the vertical yoke connectors. I swapped my vertical leads, which had a resistance of 15.1 ohms between them while the other two (horizontal deflection) leads had a resistance of 2.2 ohms.

However, this produces a completely white screen with no discernable image, and no amount of fiddling with pots has changed this. Moving pots around (vert/horiz size/position etc.) randomly does sometimes produce some change, but only in that the purely white screen sometimes gets darker in certain areas.

Movement in the video input is discernable, for example when changing menu screens in a game, a dull sweeping movement can be made out. It almost seems like the image is just extremely out of focus, to the point where the entire screen is just displaying a white mass and only movement is sometimes discernable. Still, adjusting the focus pot does nothing.

Swapping the vertical leads back and swapping the horizontal leads instead produces the desired horizontal mirrored effect with no problems, but this isn't what I need.

I guess it has something to do with the weird angle that a flat CRT like this is forced to project at.

Has anyone had any experiences with something like this? Any ideas of what I can do to fix it? Unfortunately software is not an option. I'm new to CRTs, sorry if I'm missing something.

[HelloVoltage]

I have experience in this matter from repairing a few arcade cabinets with reflectors.
Please provide all available information on the crt, and the video source.

Welcome to videokarma.

[samu]

Originally Posted by HelloVoltage

I have experience in this matter from repairing a few arcade cabinets with reflectors.
Please provide all available information on the crt, and the video source.

Welcome to videokarma.

Thank you,

The video source is composite, coming from a Nintendo Wii.

It's hard to find information on these, it seems like there are many variations of these Chinese versions of the 04JM Sony tube.

My CRT is marked model no. YC-103A, but nothing comes up online for that.
Most other images I find online have their board marked with either Sony or Tosho, mine only says YC-103 with no manufacturer name.

Here's a site that has a lot of information on similar products. ( https://geeseang.wordpress.com/exper...lat-4inch-crt/ )

My model has an LA7806 IC controller, which could be important as I believe this is what drives the deflection coils?

Only other information I could find that seems to be from a potential manufacturer is here ( http://www.hanseelec.com/product/vie...CRT-002&ku=CRT ) , but again, not a perfect match to mine.

I'll attach some pictures of it.

[zeno]

I dont know about lolly pop tubes but THINK the beam is scattering &
not hitting the screen directly. On many sets @1975 this could happen
A vert out would short
DC got on the yoke
This caused the beam to shift off the screen & you would get
a dim blank foggy pix. from the scattering. When you turned it off
you would see a flash with a vert problem, either missing the
bottom or top half for a second.

73 Zeno
LFOD !

[Electronic M]

Don't these tubes use electrostatic vertical deflection? Could you be mixing up one of the vertical plate pins with the focus pin?

[jr_tech]

Originally Posted by Electronic M

Don't these tubes use electrostatic vertical deflection?

The early ones did...later versions, with the curved screen were magnetic in both axes.

jr

[HelloVoltage]

I request that, for troubleshooting purposes of your display you don't use a wii, as the video output is subject to config settings. I recently spent an hour trying to get a tv to work at a local gaming event thinking the issue was not having the proper remote before I remembered that about the original wii.

[samu]

Originally Posted by HelloVoltage

I request that, for troubleshooting purposes of your display you don't use a wii, as the video output is subject to config settings. I recently spent an hour trying to get a tv to work at a local gaming event thinking the issue was not having the proper remote before I remembered that about the original wii.

I don't really have any other composite out devices, and the Wii output is fine. I have another CRT right next to this one that I'm checking the output with and all is normal. It also works perfectly with the original vertical coil pin order. I know what you mean though with the Wii having settings for interlaced vs progressive, aspect ratios etc. that can mess things up.

[samu]

Originally Posted by zeno

I dont know about lolly pop tubes but THINK the beam is scattering &
not hitting the screen directly. On many sets @1975 this could happen
A vert out would short
DC got on the yoke
This caused the beam to shift off the screen & you would get
a dim blank foggy pix. from the scattering. When you turned it off
you would see a flash with a vert problem, either missing the
bottom or top half for a second.

73 Zeno
LFOD !

Thanks for the help,

That sounds a lot like what I have here, but I don't quite understand how simply swapping the vertical coil leads can cause all of this. It works fine if I swap them back to normal.

As for the flashing and missing of half of the screen when turning it off, it doesn't look that way in person. I'll link some videos I took of it both swapped and normal.

Here's the menu sweep with no vertical swap: https://youtu.be/Q9U8DVKnXiU
Here's the menu sweep (it's a little hard to see) with the swap: https://youtu.be/V4hkpaW4GHM
Here it is turning off with no swap: https://youtu.be/FNcV1TAB-LQ
Here it is turning off while swapped: https://youtu.be/_4dOJMq9uhI


Maybe that gives some clues... idk

P.S. If anyone else has a 4 inch flat CRT unit like this that's just sitting around, I would greatly appreciate it if you wanted to try swapping the vertical leads and see what happens.
Just take care to check the resistances between the leads and only swap between leads that have continuity (the higher resistance leads at about 15ohms are the vertical ones).

[zeno]

If you have a scope look at & compare the wave form & DCV on
both swapped & unswapped wires. may be a clue there.

Zeno

[JeffB]

Try rotating the deflection yoke 180 degrees to match the flipped vertical.