WG 25K7191 problems

[abzman2000]

So, story time.  I started this arcade project a long time ago (and yes, feel free to laugh at my original timetable) but I'm almost done.  I have everything aside from the front plexi and final calibration of the monitor done.  I didn't compromise (much) on the contents of the machine and I still want to add coin-up buttons and at least a hidden 'esc' key (unless I configure the software a bit differently).  I may also add external USB ports and an aux input to use it as a set of speakers, but that's after I declare it done.  I will update this post with pictures (and maybe video) after I get home today, but for now I'll just have a text description of my issues. 

I have been working on this monitor almost as long as the cabinet itself and I thought I had the issues sorted but it's still got something up. 

What I have done:
1. Cap kit
2. new pot on control board
3. reflow solder
4. new flyback

I haven't tested any resistors (that I remember) or other capacitors.  I haven't checked the HOT, or any other relevant parts because I thought the issue was gone. 

The problem is this:
The monitor looks beautiful on initial power-up but within minutes goes completely out of focus The focus control on the new flyback can't bring it in (and can barely be seen to do anything) and I can't tune up the colors until I have a stable picture.  I have been using my Simpsons board as my gold standard to check if it's the signal I'm giving it or the monitor itself, but I splurged on one of those VGA to CGA converters floating around on e-bay so I think the signal form there's pretty solid (even does color bars when it has no signal which is cool).  As an electrical engineer I can imagine a loose high voltage wire being the problem where over a long time (electrically speaking) a charge can build up and it appears ok to start with, but it drifts out of focus.  I will admit I have a limited knowledge of CRTs, and I can dig more into what these symptoms mean at a component level if need be, but I figured that someone with experience could point me at something obvious (except to me). 

Secondary symptoms include the monitor developing a high static charge on the tube (I know some CRTs just do that, but I thought I remember it not doing that after I replaced the flyback).  Crackling a lot on startup and shutdown (same situation, maybe it's supposed to but it doesn't sound "good").  There's also a clicking (I hope not arcing) at a fairly regular and quick pace (maybe 30 HZ, I can check) and the picture bobs up and down slightly (maybe with the clicking) and has a slightly perceptible intensity wave move up it (I seem to remember). 

Like I said before I will update this with pictures and video, but I can't for now. 

Any help would be greatly appreciated,
Evan Allen

[grantspain]

sounds like,
crt socket or focus wire is not soldered correctly

dag earth is no connected

[abzman2000]

ok, it turns out I had the focus pin bent in the socket, it wasn't making contact with the neckboard.  That's fixed.  I did screw up the grounding too, a cheater fixed the crackling and static-y monitor, but there's still an inescent ticking and throbbing of the picture. 

[ed12]

inescent ticking and throbbing of the picture

would u please explain this a little more?
much like when it throb's dose it pull in from the side's
and or start's to pull up from the bottom and down from the top
much like that please

ed

[abzman2000]

ok, I'd change my description from 'throbbing' to 'bouncing'

[ed12]

first i would turn the screen down
and adjust the foucs.,unless that is your camara ?
buzzing can be a few thing's
your degauss coil,to chk just unplug it >with power off<,un-plug coil then plug monitor back in
or it could be a bad filter ?,but i am leaning toward's the deguass coil first

ed

[abzman2000]

not the coil (just unplugged it) and I tuned up the color and focus, but in that video it's displaying a fuzzy picture partially because I haven't tuned it well, but mostly because it's going through a crappy VGA-CGA converter and scaling something like 1024x768 to med res.  I don't plan to have it like that forever, but I'm fixing one thing at a time.  I still have a bouncing picture and a buzzing.  I appreciate your help so far, hopefully it's nothing too major. 

[ed12]

ok lets start from the very start
bring this unit back to it's native rev.
then tweak it up/down >control wise< as u must to get it near perfect picture..
then we will on to a few b+/hv chk's.ok ?

ed

[abzman2000]

ok, the bouncing is gone (maybe I can attribute that to the converter) but there is still the buzzing and a wave that seems to roll over the picture.  (video forthcoming)

[ed12]

the wave u see,is it a ghost wave
ie light in the back ground, or is it a dark wave?
or is the full picture waving?
this will lead us to where we need to go.
good to see the degausse coil is not doing it

ed

[abzman2000]

it's the picture waving.  I'd say maybe insufficient shielding on a long video cable, but it's the stock cable it came with. 

[ed12]

ok 1 step at a time
lets chk the cable >replace it with a good 1<
next we go to grounding

i see it is pulling in a tad  >like old days 30hrz hum<,main filter leaking?,
but is still doing 1/2 its job..so maybe the power supply u are feeding the conveter with is
just not up to snuff?

btw the picture look's 100% better

ed

[abzman2000]

So that video is of an actual arcade board which is designed for that monitor (and all the cabling is stock, something I can't really improve on).  I agree it might be insufficient power filtering, and I'll see if I can dig up a replacement filter. 

[ed12]

what bug's me is u say it is going through a converter?
why the converter if it is all native ?
look all i am trying to do here is ask u a outside q,which i would do
until i can dedouce the exact problem
1=are u using this with another setup ?
2=is there power supply up to snuuf?
see i got to throw these out there for u,because u are about 90% there now

ed

[abzman2000]

the first video has the signal from my computer going through a converter which converts the vga to the native res of the monitor, the second video is of a stock pcb to eliminate any possible sources of contamination from what may not be a quality converter.  I can 'scope out the power rails on the Simpsons PCB in the morning, but for now it'll have to wait. 

[ed12]

ok,perfect
i do tend to agree with u on 2 of 3 points
but let's have at a scope image of the
a=main power supply after the filter but before the regulator's
this will say where we are going..
i still have to look back at 1 of your post's,that tell's me u are ol school


ed