substitute tube for sanyo 20EZ

[robotype]

the monitor of my popeye cabinet does not show green color
after checking pcb and chassis it seemed the problem is the tube itself
I brought it to the TV repair guy and he said the green color is exhausted
so I had to find a similar tube but since in Italy we do not have those
nintendo cabinets it is impossible to find a sanyo crt
so looking at the specifics I thought the hantarex mtc-900 would do
and I brought it to the TV repair guy who swapped the yoke and
found the tube working but still missing the green!
so he said the green color is exhausted in the hantarex tube as well
I must find another tube to swap it again...
it sounds kind of weird to me but the man seems to know his stuff...
anybody knows any other 19" tube that I can use with the nintendo chassis?
thank you!

[grantspain]

unlikely both tubes have dead green guns,
have you done the usual checks like swapping colour inputs,is the colour inverter board o.k,have you checked the drive transistors
i just can't believe 2 tubes are doing this

[Kevin Mullins]

I agree, the odds of you pulling TWO tubes that have the same exact color gun bad is highly unlikely.

Have you tried that game on a known working monitor of any kind?
The colors will look wrong, but at least you should see all of them.

is the colour inverter board o.k

He doesn't need the inverter board. The inversion is done on the chassis itself. The inverter board is for NON-Nintendo games to be able to work on the 20EZ.
Alot of dedicated Nntendo cabs didn't even have those on the monitor at all.

[robotype]

thanks for the replies
yes I did all the tests to determinate the green is gone in the tube...
about the hantarex tube the TV guy took care of it but I want to trust him

Have you tried that game on a known working monitor of any kind?
The colors will look wrong, but at least you should see all of them.

no because I don't know which models are good, 20EZ tube does not exist in Italy
so I must find another make that has the same pinout on the neck.
The hantarex seems to work but has the same green issue...now I am looking for another (same model mtc-900) to double check this problem.
If I knew which other tubes would work I would try to look for one but in Italy we mainly have  hantarex, orion, philips 19" crt. I wonder which models are worth to try swap the yoke again.
question: is the sanyo 20ez a generic tube used in other consumers electronics or was it dedicated to the nintendo cabs only? I mean, the color inversion is operated by the chassis, not the tube,  right?

[Kevin Mullins]

the color inversion is operated by the chassis, not the tube,  right?

Right.

Have you tried looking around for old television sets that have a 19" tube?
If you find one with the right neck tube pinout.....you could just do a tube swap using the Sanyo chassis and yoke.

[robotype]

I have better chances to find that crt in old arcade storages, it was the most common here in italy. I really hope that it will work swapping the yoke...I don't want a sanyo tube shipped from usa it would be quite expensive...
btw is it hard to move the yoke? can I try by myself or should I ask somebody experienced?

[grantspain]

yoke swaps are difficult for experienced engineers,the physical moving of the yoke is easy its the setting of the purity rings that can be very time consuming,but there again you may be lucky and have a good matching tube
best to get a professional in for this,just in case you crack the tube

[robotype]

old tube (sanyo)



new tube (from hantarex mtc-900)




finally I could fix it but the colours are not perfect yet; if you notice the left area of the title (around POP) and the roofs are not completely red. I tried to move the yoke and the rings everywhere but that's the best I could get...any suggestion?

[Kevin Mullins]

Does it seem to degauss properly when you first turn it on when it's cold ?

[Jeff AMN]

The Popeye lettering discoloration looks like a degauss issue to me. My DK had that pink invasion on the red high score lettering until I rotated the cabinet 90 degrees to the right. I didn't have to degauss, but that would have fixed it too.

[robotype]

the degauss doesn't seem to work...but how can I test it?
I used the degaus from the original sanyo crt to save some time because the new one had a different connector, should I use the degaus that came with the crt?
anyway I tried going near the screen with a magnet and I can fix the colors temporary but when I remove the magnet it goes pink again.

[SirPeale]

You're going to need a degauss coil to fix it. You may be able to use an electric (corded, not cordless) drill as it generates the same kind of magnetic field, just not as strong.

[robotype]

I swapped the degauss with the other one and nothing happened, so I tried disconnect the degauss plug from the chassis but nothing changed, maybe the degauss problem is in the chassis pcb? can I test it with the multimeter? how? anyway I will try with a drill or look for a degaussing coil, thank you!

[robotype]

using the drill I fixed all the wrong colors! now it is perfect but still I don't understand what's wrong with the degauss in the chassis.

[SirPeale]

Likely nothing.  It just isn't strong enough to clear up those extra bad spots.  Thats why they make manual coils.

[robotype]

anyway thanks to all of you I could fix it!