Friggin Sanwa Monitor Problem-Compromised (SOLVED)

[gokun]

Ok; sorry to bother you fellows yet again, but I have a problem that is driving me batshit here...it's seriously bothering me and I' just can't figure it out so I'm asking for some more help...
The monitor in question is a Sanwa 27" VGA only model 29PF31
It's in a cab which can run either a Naomi or a Namco 256...prior to this monitor there was a d9200 monitor in it which had it's own problems(all of which are now fixed-that being said both systems work and look great with the d9200).
Sooooo, my problem is if the picture fills up the screen vertically(from top to bottom-which it will almost but not quite do-at best there is still a cm or 3 of black bar at the top) then I get a squeezed picture in the top 3-4 inches of the screen. No amount of adjustment of any description will get rid of this short of simply not making the picture go to the edges of the screen vertically(leaving about 1 inch on top and bottom usually makes teh compressed area go away).
My first thought was vertical lin adjustment but that does not make any difference...playing with the vert size and pos will get different results but none of them what I would consider to be acceptable. Just varying degrees of the compressed area or black bars at top and bottom.

I've included pics so you can see what I'm talking about hopefully...
first pic shows the screen with the bars at the top and bottom-no squishing here but those bars drive me nuts i would like for the pic to fill the screen
next pic shows as close as I can come to making pic fill screen...there is squishing present at the top, and also still a small black bar...i could deal with this black bar if the squishing wasn't there...
the next 2 pics are a close up to show the squishing...in the first you see the name is squished up-you can also notice like a lighter line area going across from left to right where it's squished... and in the next pic you see how it should look...

 

 

 
 

this is REALLY driving me crazy...cannot for the life of me figure it out and even sent it back to the guy I got it from (who is generally reputable) who hooked it up to pattern generators, etc and he said he couldn't find anything wrong with it...but the pics don't lie...there obviously IS something wrong with it and it's driving me insane lol...
can somebody PLEASE help me out with this? all help, ideas, etc is appreciated...

[grantspain]

sounds like the b+ is set incorrectly

[gokun]

sounds like the b+ is set incorrectly

Thanks for the reply! Checking on that, but I don't have a schematic or anything...any ideas what the B+ should be on this one? Also there is no visible means of adjusting it(no pots, etc), so what would be the best method for me to adjust it if it's off?
On a side note, something else I noticed was that it doesn't show the symptom until it's warmed up(like 5-10 minutes) in case that makes any difference.
Thanks again for the help!
Why oh why did I have to pick such a troublesome hobby? lol!

[gokun]

Ok, been playing around with this a lot...more pics will be coming soon...I can get a decent pic in the naomi setup, with the main distortion being a slight ripple effect at the top...well, a better description might be that if you have a grid on screen, the top portion vertical lines have an almost "S" shape to them...does that make sense?
I'm assuming this is a symptom of the same problem since it's in the same area, etc...
The B+ seems within tolerable range, baring in mind I have no basis for comparison other than the other monitors I have on hand...so anyways it doesn't seem horribly off by that guesstimation...
I noticed while playing with adjustments, that should you play with the vertical pos pot there is a sort of center point....going above this makes top of screen bigger and bottom smaller...going below this point does vice versa...
never noticed that effect on my other monitors, but then was probably not paying that close attention to those either...so let me know if that is just a normal deal...anyhoo, I'm stumped...still...
sigh....might end up just putting the d9200 back in the cab...which would be a pain since I had to modify the cab to fit the stupid sanyo lol...
[EDIT]
so it almost seems like a trap problem on the naomi and indeed on the namco you can see some of that too...can't be adjusted out...hrmmm...just trying to pinpoint what the problem is as best I can...i'll upload some new pics showing my best adjustments  either tonight or tomorrow...
[EDIT 2]
yeah, pics are still forthcoming, but i still keep coming back to thinking it's some kind of fault with the vertical linearity/deflection/etc....of course that doesn't narrow it down quite enough as it could still be either caps or components that are the culprit...i think i'm going to focus in on things like the vert out put transistors/ics/etc for my next round of tests....maybe check the b+ to them where applicable....maybe check on any caps on the  collector of vert output trans?....just brainstorming here....anyhoo...that's my brief update lol

More pics showing my best adjustment attempts thus far...
first shows the squiggle at the top(geometric distortion?) and the second shows how it bulges, etc towards the top...hard to find the right words to describe it so hoping the pics will help...
    

Something else that makes me think there is definitely a component amiss somewhere (even though they all check out ok thus far) is that if you start it up cold it seems fine and you can adjust it to a nice pic with no distortion, but once it has warmed up after about 5-10 minutes the problem shows...sigh...I just dunno...I'm gonna take it out and put it on my test rig this weekend so it will be easier to muck with...looks like the wg is going back in the cab after all...anyways would greatly appreciate any advice anyone has to offer on this one...

[LAST EDIT] [PROBABLY lol]
Ok, so i'm admitting defeat on this one...all the parts check out, all the voltages check out, all my test boards and systems check out...everything tests absolutely fine every friggin time.....sooooooooooo.....
here is my thought....
I've read both here and elsewhere the experts saying time and time again that certain monitors were simply made for certain systems. period. So i'm thinking that is, at least to some extent, the case here. I can get a 98% good picture on the naomi system and a 99% good picture on an atomiswave, but not on the namco system 256.
So I've basically admitted defeat and compromised. I removed the namco system from that cab and replaced it with the atomiswave. I then put the namco system in the cab the atomiswave came out of, in which the namco system has no monitor issues whatsoever. thus everything is working with a decent picture now(minus a little rewiring i will have to do to get the namco system up and running peoperly in its new home), and I am left dumbfounded.
I tried literally everything I could think of and nothing else worked for me....
so in summary i'm going to have to classify this sanwa as a piece of crap overall lol! ;p
and i sincerely hope it's makers die knee deep in a pool of their children's blood. 

[gokun]

UGH!!!
Well I just can't win....
so it turns out that after a couple of days of good use, the problem is just as visible now on the atomiswave and naomi...still not quite as pronounced as it was on the namco system, but very close to it at this point. As before cannot be adjusted out, etc....
so decided to do some checking while it was running and warmed up good(figured what the heck-it's already broken lol)...and I really only noticed one thing I found overly suspect...
there is one chip on the other side of the big metal heat sink the hot(well what I believe to be the hot) is on...
it looks like a hot itself actually, but due to its position could not read the numbers off it etc and with no schematic it's hard for me to tell exactly what it is(hard enough for me even with a schematic lol)...
ANYWAY...the point is that this chip in question gets SO hot that it will literally burn your finger if you touch it...
that just doesn't seem right...i've never had another monitor with a chip that ran that hot...
I'll try to get the numbers off it tomorrow if I have time to pull the chassis again...my wife and I are going on vacation monday so may not have time to though...
anyways, opinions more than welcomed as I'm just being driven crazy by this thing...still

[EDIT]
Ok, so after MUCH mucking about I'm 99% sure it's the vertical output IC chip(la7838)....vertical foldover as it turns out...just not what you would expect it to look like typically...
so anyway i'm gonna replace that ic and see if that fixes it...will prolly replace some caps, etc while i'm there just to be thorough...

[gokun]

Well turned out to be fixed by a combination of things...replaced la7838 with a new one and it helped a good bit. changed out the vert size pot with a bigger one again, as well as the vert lin again and that helped a little more...
Then, and this may sound silly but it worked, mounted a fan atop the heatsink which the 7838 is attached to...that seemed to be the last piece of the puzzle...for the record i had also replaced all the caps but that didn't seem to help in the least...still never hurts to do it anyways i suppose...
some things I found about this monitor for furture reference...
The Model # is 29PF31 but the underside of the chassis is screened 29E31S...it is basically a modified version(e.g. crappier version) of the e31s...
it's vga only 31.5khz
+/-0.84 dot pitch
+/-1.0-4.0vpp
45mhz vid band
640x480
120-220 vac
50/60hz
115 watt power consumption

there are 2 factory mods on the underside of the chassis board, one of which is connected to a leg of the vert connect and prolly has something to do with the problem i was having lol
supposedly it can take seperate or composite sync but I could never get composite working on it...the sync wires are on the little 3pin plug on chassis
that's all i can think of right at the moment will add more if i notice anything worth mentioning in my notes later...hope this helps somebody some time...i still hate this monitor lol


hrmmm...just realized...now i need another monitor to play with hehehehe...guess i never learn lol

[grantspain]

i am thinking that you may have found a fix there for a production problem-I am sure I saw another few people with this problem on other forums