Wells Gardner D9200 - Weird problem (flickering/contrast) [[[FIXED!]]]

[gokun]

Hello again, I've got another odd problem...I seem to get a lot of those lol....anyways, here is the short version of the story...got this monitor when I got my system 256...was paying for the sys 256 so didn't care about the cab but figured since it was a vga monitor what the heck I'll keep it....

obviously that was before I had read all the threads about this model here lol!

So anyways, it had been working relatively well but has recently developed an odd problem....well there are several problems, but I think they're all related so let's just tackle the big one for now...
first just let me say that the monitor works...it powers up and there is picture...
the screen will, for lack of a better way to put it, flicker slightly...if the screen is blank you can see little balls of light flash momentarily in random places and occasionally a line will momentarily flash all the way across horizontally...as this happens, if there is a picture, you will notice that the focus seems to go slightly blurry, then snap back into sharp focus. This happens constantly, not sporadically. I have also noticed a sort of faint buzzing noise, which is not constant, but seems to randomly happen for random amounts of time...as best I can tell, this seems to be coming from the flyback...

so, after reading through 14 pages of threads about problems with this monitor type let me tell you what I've done thus far...

I've replaced the major caps, I've reflowed solder on both the main board and neck board, I've tried all available adjustments(including factory mode), I've tried different power supplies, I've tried different boards and systems, I've tried no boards or systems, I've tried vga mode vs cga/ega mode, I've deguassed, checked my grounds, etc, etc, etc. Basically all the very basic stuff I've checked and the problems persists...

Soooooo...I'm thinking based upon what I've read that this is a flyback problem and replacing it should be the obvious fix here....does that sound correct to you guys?

At any rate, looking for opinions, verifications, input, etc. and as always, am extremely grateful for any and all help you guys might care to offer...thanks!

[qrz]

check the integrity of the focus lead on the crt socket.
a poor connection here can produce the described symptom.

note : the skt itself can develop internal corrosion - fouling spark gaps, and intermitent connections

[gokun]

Ok, thanks for the advice...everything seems to be in order with the focus lead(I re-did it just to be sure though), and as for the socket, as best I can tell it seems to be ok too...also the pins on the tube appear ok as well....
so assuming I did a halfway decent job of checking(which is probably assuming a lot lol), this would lead me back to the flyback as suspect, right?

[gokun]

Well crap....so I changed out the flyback with a new one and it worked for a few minutes(albeit with no change in the original problem) and then this happened...



Also, occasional buzzing I mentioned before...it's now constant...still hard to exactly pinpoint but definately coming from the flyback/hot area....
I'm pretty sure I didn't muck anything up when replacing the flyback...
is this collapse or something?
ideas and suggestions greatly appreciated!

[grantspain]

ooo,wierd fault-looks like something to do with the vertical deflection.i would seriously check the traces on the flyback first

[gokun]

will do; thanks!

[gokun]

Ok, so I had some time to play with this again after work today(thank goodness for fridays!)....
and apparently something is wrong with the new flyback I got in...

after checking every single trace on the board and finding nothing wrong, then checking the hot, ics, etc as best I could and coming up empty, I decide to test the b+ in a few places and get what I thought were odd readings...high in some places low in others neither being appropriate to the spot in question...

so I decide on a whim to put the old flyback back in to see what happens(after all, since the new one worked long enough for me to see the original problem was not fixed by the replacement logic would dictate that the old one still worked-at least to some degree)....and guess what??

The monitor works again!?!

So, ok, I am certainly happy it ain't dead...but what the #@$%^?? That was odd...
so anyway, yeah, I got the new flyback from ebay, which probably wasn't the best place, but the guy is reputable and it was supposed to be new......the part numbers do match up and everything(I double checked) so I can't think of any other explanation for that weird happening...I can only assume there is something wrong with it...

I just thank goodness I had the good sense to pull the plug quickly(Ironically I try to always have the camera ready when I turn one back on after repairs just in case lol! see everything I broke on my pentranic if you really wanna know why i do that now lol! but i digress...)or who knows what could have been fried out...

so back to the original problem, maybe a problem with the chassis ps area?
I'm gonna check around there this weekend and see if I can find anything...then I'll prolly try another flyback when I get a proper one just to be sure...

in the meantime suggestions welcomed!

[gokun]

Ah damnit!! While waiting for my replacement flyback(cause I still think there was something wrong with that one)...I believe I finally found the problem....and it's crappy....the focus pin was actually broken...all that was holding it together was some glue someone put in there...that probably explains the flickering and focus problems mostly....crap...
unless I've been reading things wrong, that means the tube is toast, right?

[grantspain]

is the pin broken off at the base

[gokun]

yeah; it was broken off in the glass...
but I was able over the past few days to eventually get it soldered back(well, had the help of some glue too lol)...
I took a exacto blade and used the tip to very carefully scrape what was left in the glas until I felt it was roughed up good, then put a drop of flux paste in, then I used a pin i cut off a cap with solder on it to get some solder down in the hole and onto the pin...once that was done I tinned the broken off piece and held it in place with needlenose pliers then applied heat with the soldering iron for a few seconds then glued it down on top on that...
now THAT was a pain, but things are looking up I suppose...
now the picture has lost the original symptom and instead it now wobbles slightly, like it's underwater. It's not too bad, and definately less annoying than the original problem, but I'd still like to get that worked out if I can...reading up on it now...
any hints in the meantime?

[grantspain]

wobble could be caused to proximity of a mains transformer,noise on the ac line-i had a jenn shinn chassis wobble until i wired it through an iso transformer and the manufacturer states that an iso is not required

[gokun]

hmmm....i'll have to check on that...I did shift around the test bench when I hooked it back up to the monitor so something on there could be causing it...will definately check that; thanks!
[EDIT]
You called it!
Moved my test bench away from it and the picture is almost perfect!
So, all said and done, the original problem is fixed-woohoo!

Now that brings me to one of the final issues(believe it or not I managed to fix most of the other minor issues I had originaly alluded to in the original post-lol)...so if we can get this one then all is well with this monitor it will be good as new-yay!
Ok,ok...at any rate, the final issue right now is that the screen is slightly rotated...maybe 5-10 degrees...to the left
Now, I found an adjustment on the board for rotation, but it seems to have little/no effect on the problem. I've already replaced all the caps and the HOT(although, and please correct me if I'm wrong here, it looks like this chassis has more than one--and I only replaced one of them), I've reflowed all solder, etc. and gone through the basic stuff...so I have read others mention adjusting the rings manually, but I'm not 100% sure that's the issue...what do you think?
I'll continue to read up on it in the meantime and see if I come up with any bright ideas...hehehehe

[grantspain]

if your crt has a rotation coil fitted you will see a small coil around the crt yoke area-otherwise you will need to twist the yoke a fraction

[gokun]

I once again bow down to your superiority master!
Turns out, it did have the rotation coil fitted, however, it was not connected and I had previously assumed it to be part of the degaussing stuff...so I checked the schematic and put a new plug on it and plugged it back in. Then degaussed just to be sure lol! Anyway, after a little bit of tweaking I got the picture straightened back out again. Oddly, once it was plugged back in the raster rotation pot started working again hehehe. At any rate, I have siliconed the neck card into place as I realize the re-soldered on focus pin will have to be babied from now on and everything seems just fine(well the tube could honestly use a rejuvination but I don't think I'm quite ready to tackle that just yet). So once again, let me just sincerely thank you for all your help and advice! It really means a lot and I greatly appreciate it! Here are some pics of the repaired monitor working on my test rig:
  
lol! just noticed you can see the reflection of my mirror in the reflection of the monitor in both pic lol!
Everything said and done I did the following:
Replaced ALL caps on board and neck cards
re-flowed all solder on both where deemed needed(so basically all of it lol)
re-soldered broken focus pin on neck and glued it down
re-attached rotation coil
replaced 1 of the 2 HOTs
still using original flyback though