Problem Toei TC252S with Toshiba Tube

[jerryspaghetti]

So after finding a chassis swap solution with my other Toei monitor, I couldn’t find a suitable chassis swap solution to this Toei so bit the bullet and bought a direct replacement Toei TC A252S from China (not cheap)

It was advertised as fully working and looks very clean with no obvious signs of why it wouldn’t work. It certainly did not get damaged in transit.

So I plugged it all in and was met with very green screen which is a bit odd as the guy send video of it working before he sent it.

So I adjusted the RGB pots to get a balanced colour picture but there is serious convergence issues but more annoyingly, horizontal width issues and geometry issues that can’t be resolved using any on board pots.

The pic attached is as good as I could get it. Set jumper to wide. Tweaked B+ but still couldn’t fill horizontally.

This is the specific board to suit this specific tube so god knows whats going on.

2nd picture is the yoke.

Any help appreciated.

 

[Retroman839]

Looks same yoke as mine

What’s the diffrent beteeen
The two chassis ?

Width coil on chassis ?
Neede warming up to adjust them easily broken

 

[eccentric-nut]

This might not be directly relevant to what you are experiencing but I had an issue albeit different on my TOEI chassis and I found it was related to one of the pots on my remote board, I gave the remote board an ultrasonic clean and basically cycled the all pots on the remote minimum to full a fair few times, and it solved my issue. Just a pointer that might be worth checking.

 

[jerryspaghetti]

Thanks guys will investigate further

 

[gunblade]

a few things going there
needs a degauss or putiry rings not set correctly or possible yoke out of home position
vetical size
trapezoid and spc need adjusting, looks like some compression on the horizontal but it could be the test screen
convergence strip required for upper left in photo

 

[jerryspaghetti]

a few things going there
needs a degauss or putiry rings not set correctly or possible yoke out of home position
vetical size
trapezoid and spc need adjusting, looks like some compression on the horizontal but it could be the test screen
convergence strip required for upper left in photo

Cheers I’m going to have a little tinker with it tonight.

Very nervous as never messed with the yoke before. I know to be extremely careful not to neck it!

Is it best to just turn off and on making slight adjustments to yoke or wear rubber gloves and don’t touch the coil?

 

[jerryspaghetti]

So I tinkered and tinkered and tinkered and no joy. Tried yoke/rings adjustments and convergence strips and it’s safe to say I just don’t have the skills or knowledge to sort this one.

@gunblade is this something you could give a once over?

 

[Hexen]

So after finding a chassis swap solution with my other Toei monitor, I couldn’t find a suitable chassis swap solution to this Toei so bit the bullet and bought a direct replacement Toei TC A252S from China (not cheap)

It was advertised as fully working and looks very clean with no obvious signs of why it wouldn’t work. It certainly did not get damaged in transit.

So I plugged it all in and was met with very green screen which is a bit odd as the guy send video of it working before he sent it.

So I adjusted the RGB pots to get a balanced colour picture but there is serious convergence issues but more annoyingly, horizontal width issues and geometry issues that can’t be resolved using any on board pots.

The pic attached is as good as I could get it. Set jumper to wide. Tweaked B+ but still couldn’t fill horizontally.

This is the specific board to suit this specific tube so god knows whats going on.

2nd picture is the yoke.

Any help appreciated.

Looks like a bad case of degaussing and convergence rings to me. Did you change the yoke? Aren't colour yokes never meant to be changed due to the factory setup of each tube? Any case, it's a tube issue and likely not the board.

 

[jerryspaghetti]

Looks like a bad case of degaussing and convergence rings to me. Did you change the yoke? Aren't colour yokes never meant to be changed due to the factory setup of each tube? Any case, it's a tube issue and likely not the board.

Haven’t changed yoke. The problem I’m having more than anything is that I can get the blue and red pretty spot on but the green isn’t possible to line up as the geometry of the green grid is slightly squeezed compared to the red and blue. So you can line the top half of the screen up but the bottom half will always be off or vice versa if you line the bottom half up.

I’m wondering if some lunatic has slid this ring assembly off the neck at some point and put it back on backwards?!!

Might try and flip is as can’t see any harm in trying…

 

[Hexen]

Haven’t changed yoke. The problem I’m having more than anything is that I can get the blue and red pretty spot on but the green isn’t possible to line up as the geometry of the green grid is slightly squeezed compared to the red and blue. So you can line the top half of the screen up but the bottom half will always be off or vice versa if you line the bottom half up.

I’m wondering if some lunatic has slid this ring assembly off the neck at some point and put it back on backwards?!!

Might try and flip is as can’t see any harm in trying…

Has the tube taken a bump or been heavily handled?

 

[Hexen]

Haven’t changed yoke. The problem I’m having more than anything is that I can get the blue and red pretty spot on but the green isn’t possible to line up as the geometry of the green grid is slightly squeezed compared to the red and blue. So you can line the top half of the screen up but the bottom half will always be off or vice versa if you line the bottom half up.

I’m wondering if some lunatic has slid this ring assembly off the neck at some point and put it back on backwards?!!

Might try and flip is as can’t see any harm in trying…

The rings have the line of paint - the only thing would be physical misalignment of the gun assembly or mask through shock. I'd suggest a proper degaussing first, then a potential ring adjustment. Degaussing with a degaussing tool though, and not just the outer coil - which will be difficult if the tube's been shocked.

 

[jerryspaghetti]

The rings have the line of paint - the only thing would be physical misalignment of the gun assembly or mask through shock. I'd suggest a proper degaussing first, then a potential ring adjustment. Degaussing with a degaussing tool though, and not just the outer coil - which will be difficult if the tube's been shocked.

Could have had a bang in its past but wouldn’t know for sure.

I’ll order a degauss tool.

Pic 1 below is the Green and Red only. You can see the actual grids are different sizes so no amount of moving each colour around will line it up.

Ditto Green and Blue in 2nd pic although this isn’t as bad as Red and Green.

 

[Hexen]

Could have had a bang in its past but wouldn’t know for sure.

I’ll order a degauss tool.

Pic 1 below is the Green and Red only. You can see the actual grids are different sizes so no amount of moving each colour around will line it up.

Ditto Green and Blue in 2nd pic although this isn’t as bad as Red and Green.

A very odd situation. The attached picture shows a convergence issue that can be sorted by ring adjustment, if yours is displaying each colour at different sizes, then I'm sure the yoke rings won't do much. At this stage, it's definitely a problem with the tube and as you say, you have nothing to lose. Experiment.

 

[Hexen]

Also, take each of the drives down to mid-way, all identical.

 

[Retroman839]

Seems strange you have some
Blend green to blue up the side

But a perfect cut of on the side
Between Blue to white ?

That can’t be magnetic or colour would blend / blend

 

[Retroman839]

I would say you don’t have green or red at that point ,
But they stop perfectly. Question is why ?

coincidence it’s a perfect straight line up the middle of the grid ? I don’t know but seems odd if it is …

Red and geeen guns have narrowed their beam width ?

Has monitor been knocked perhaps ?
Shadow Mask moved ?…

If blue is the center gun
Red and green on the outsides

And the shadow mask was to fall back or forwards ..
Perhaps this would stop the coloured Photons at the extremities reaching it’s target

 

[Hexen]

Seems strange you have some
Blend green to blue up the side

But a perfect cut of on the side
Between Blue to white ?

That can’t be magnetic or colour would blend / blendView attachment 37615

Notice how it lines up to the centre of the screen and diverges to the top and bottom? Of course, the top left corner will be sorted by degaussing the mask.

I suppose the rest *could* be down to rings, but there's a lot of movement. Maybe a small Neodymium magnet, a LONG way 45 degrees from the back and side of the tube neck, and brought in extremely slowly to observe any differences? Nowhere near the front and not nearer than about 30cm. The way the electron gun assembly is fitted inside the tube generally means that movement would be near impossible. Near.

 

[Retroman839]

I don’t to understand the clean
Break between the colours ?
Almost digital ?

Why is this ?
I thought the colours would bleed fade into one another ?

 

[Hexen]

Seems strange you have some
Blend green to blue up the side

But a perfect cut of on the side
Between Blue to white ?

That can’t be magnetic or colour would blend / blendView attachment 37615

The blue is 'behind' the red and green (white) and the R/G are truncated. I love this problem. It would be a joy to diagnose.

 

[Hexen]

I don’t to understand the clean
Break between the colours ?
Almost digital ?

Why is this ?
I thought the colours would bleed fade into one another ?

Only with a dodgy undegaussed mask. This is like there's a 'something in the way of the R/G guns' problem.

Definites are:
degaussing needed
alignment/convergence needed