WG d9400 d9800 color bleed

[castlesteve]

Ok, so I have a 27" d9400 (aka d9800) flat tube monitor.   I was able to revive it and did a cap kit on it as well. 

Everything works except the green gun was bleeding just slightly only after white objects.    I adjusted the gain and advanced factory controls to try to get the bleed turned back, but it just seemed that perhaps the tube was aging.

So I swapped with a newer tube and ported the yoke etc.  Now it is brighter and requires much less gain etc (so yeah, the tube swap was worth it).... but I am still getting the slight green bleed.   

The only caps that did not come are the 1uF 160V NP caps, one for each drive color on the neck board.   I swapped the green with the red, and I THINK it got a little better.  But it is hard to tell.   I have new ones on order but it will be a bit for them to come in.   

Anyone ever swap these out with new non-polars to fix this issue or perhaps something else?    I also swapped the drive transistor with RED just in case it was saturating to easily but that didnt do anything.


stumped

[grantspain]

now i could be wrong but i think there are small jumpers on the video interface pcb to set it to either vga or cga/ega-it may be worth checking they are on the correct setting although i would have thought this issue could have been adjusted out on factory menu anyway

in the factory menu did you check the cut off levels for each colour

[castlesteve]

I think the jumper is a dont-care for VGA input on that board.    Looked into it... think it just adjusts the input level for the inline connector.

Yea... i adjusted about every possible service menu gain and cutoff.   Its definitely a saturated transistor or bad cutoff on the neckboard in my opinion.   I think ill have to start swapping parts in that area now as it otherwise works fine.   grr

[joelbob]

What did you end up doing? I'm seeing similar things on mine.

[lilshawn]

ZOMBIE THREAD WANTS BRAIIIINS! 

Usually this color bleed is one of 2 things in these neckboards... the video amp IC or the non-polarized caps.

if it's not one, it's usually the other. the NP caps in this voltage range are impossible to find. they are basically made for CRT units and well... they don't make CRT's anymore so nobodys making parts for CRT.

I contacted a manufacturer in china to get some... and the minimum order was 10,000 units. so likely they where going to just make up a batch. but I just wanted like 100 not 10,000.

I've successfully used 2 regular polarized caps to make 1 NP (non-polarized) cap though.

you need 2 for each cap (6 total) that are DOUBLE the capacitance of what you are replacing. so to replace a 1uF 200v NP capacitor, you need TWO 2.2 200v caps. it's not exactly 1uF (it's 1.1) but close enough and better than what's in there.

take the 2 caps and bend the negative legs at a right angle to each other and solder them together... then place the 2 left over positive legs in place of the NP cap. it's not ideal, but it seems to work ok. Done quite a few of them like this now. I bought a pile of high quality Panasonic (Matsushita) capacitors to use for this purpose. (they happen to be 2.2uF 400V)