Wells 25k2193 on the fritz

[Rattanee]

I'm wondering if anyone can help me with a  25k2193 monitor... (gods I hate Wells-Gardner... )

The monitor works, but... no horizontal shift, no width control, and picture has an about 2 inch black "fade-out" on the right side (when facing monitor)... I know that there is a cap that can cause the fade-out on a k7000, but there the transition to black is longer, more gradual. Here it looks like somethign you get when you're looking at a blank raster with an improperly set up chassis or even a chassis runnign with an incorrect tube where only the very edge is totally washed out to black. Also the inability to control the horizontal section suggests a horizontal IC, but I'm not even sure which model's schematics I should be looking at... (See rant at bottom) or an incorrect flyback... Speakign of which, the flyback on this one is weird. It comes from a killer Instinct cab I'm working on, and I'm pretty sure the Mortal Kombat 4 cabs I've been working on had the same chassis, but a different flyback, as the FB on this one has a separate molded plastic component on the HT lead between the flyback and the cup that was bolted to the side of the cabinet next to the monitor.

If anyone can point me to which schematics/manuals I should be looking at, that'd be awesome.

Stop here if you're a fan of WG monitors. Don't want a flame war but I'm pretty pissed atm.

Rant time. I -hate- wells-gardner by now... They should've gone out of business ages ago.
1. No Wells chassis I've met so far (and I've seen a few trust me) was free of burnmarks or cracked traces. Hantarex chassies of the same age 90% of the time look -much- better then the best WG boards I've seen...
2. What the hell is up with identifying monitors? Why the *** can't the chassis just say Wells-gardner K7400 or whatever, why with the stupid code? I understand they have different numbers because of different revisions, but how hard would attaching a simple sticker be? Or at worst a query window on their support site that identifies the monitor and revision from the  25k2193 type numbers... I mean come-on...
3. Manuals... gods... what the hell is wrong with these people? I know Hantarex are equally unreliable in some models (particularily talking about Polos here) but what the hell.. at least they have a decent manual that has -everything- you need to fix the monitor. Wells manuals are split into pieces and the schematics Ive seen 90% of the time don't say anything about the several modifications they made in the factories over each run... not to mention yeah they made some troubleshooting charts... but not one of them has anything for horizontal issues, and even what is given only points you to some general components...

Yeah... one has to wonder how they are still staying in business...

[lilshawn]

1. No Wells chassis I've met so far (and I've seen a few trust me) was free of burnmarks or cracked traces. Hantarex chassies of the same age 90% of the time look -much- better then the best WG boards I've seen...

thats a problem with everything mass produced these days. they rush stuff out, and fix it later when a problem rises up. they would rather get out a few thousand units and hotfix them on site than have to sit and test them. allot of the problems we have seen are due to just plain old bad design (like the 9200 where when the HOT blows up the whole board), and component placement issues. (caps mounted right up against hot heatsinks.)

2. What the hell is up with identifying monitors? Why the *** can't the chassis just say Wells-gardner K7400 or whatever, why with the stupid code? I understand they have different numbers because of different revisions, but how hard would attaching a simple sticker be? Or at worst a query window on their support site that identifies the monitor and revision from the  25k2193 type numbers... I mean come-on...

monitor number breakdowns... shhhhh it's clasified... no acutally, it's something that got lost when they revamped the site a number of years ago, they have kept to it for the most part.

http://www.wellsgardner.com/downloads/MonitorPartBreakdown.pdf

3. Manuals... gods... what the hell is wrong with these people? I know Hantarex are equally unreliable in some models (particularily talking about Polos here) but what the hell.. at least they have a decent manual that has -everything- you need to fix the monitor. Wells manuals are split into pieces and the schematics Ive seen 90% of the time don't say anything about the several modifications they made in the factories over each run... not to mention yeah they made some troubleshooting charts... but not one of them has anything for horizontal issues, and even what is given only points you to some general components...

yup. 


as for your issue, sounds like ALL of your issues are capacitor related. possibly the horizontal IC, but failures there are rare, and often when they are, it's a line. IE total failure.

[Rattanee]

removed the chassis, noted all electrolytic caps, replaced them all, removed some hackjobs after consulting the schematics to try and figure out which ones are factory installed and which aren't...

Guess what? Schematics differ from the actual board in places, and in more then one place in values too...

Nevertheless... did the full recap bar one cap I didn't get (which doesn't have to do with the horizontal circuit anyways) and I got some improvement, but horizontal shift still doesn't work. The horizontal shift pot is wired between ground and the la7850 IC, with very few components. The schematics say there should be a 2.2k resistor here, the one factory installed was 1k, a ceramic cap to ground at 1500pf and that's about it... replaced the resistor which was not open or burned, but it couldn't hurt, then snapped theceramic cap off to see if that was pulling it low, and nada... all that's left is the horizontal IC? Or did I miss something ?  (Probably boned with this one since the la7850 is not available from any sources near me...)

[lilshawn]

removed some hackjobs after consulting the schematics to try and figure out which ones are factory installed and which aren't...

often hack jobs are done by the manufacturer to fix an issue in the design. often they are applied to the solder side of the chassis. (extra resistors , caps, diodes or even removing components or replacing them with wire) it's best to leave things like that unless you obviously know it's something someone kludged on there.

Guess what? Schematics differ from the actual board in places, and in more then one place in values too...

aaaaaall the time. "manufacturer supplied hack job" or MSHJ.

the la7850 is not available from any sources near me..

it's a pretty common chip a lot of places carry NTE parts... if you can find one get a "NTE7086" it's the cross.

but horizontal shift still doesn't work. The horizontal shift pot is wired between ground and the la7850 IC, with very few components. The schematics say there should be a 2.2k resistor here, the one factory installed was 1k,

the change in resistance might be due to a substitute of another component. i wouldn't worry too much. I would on the other hand check at the end of the circuit there is a variable resistance when the pot is changed...to be sure the chip is receiving it.

[Rattanee]

I only removed one electorlytic cap that was clearly put there by someone else... the rest were either noted on the schematics or were in a part of the circuit that was working... so... I'm following the principle "don't fix somethign that isn't broken"...

Guess what? Schematics differ from the actual board in places, and in more then one place in values too...

aaaaaall the time. "manufacturer supplied hack job" or MSHJ.

Not with Hantarex... or at least not in such quantities... WG is the recordholder for "MSHJ"s...

it's a pretty common chip a lot of places carry NTE parts... if you can find one get a "NTE7086" it's the cross.

There's no local source for NTE parts... seems to be an abundant supply in the US but no source in the EU... at least not any place in my country...

the change in resistance might be due to a substitute of another component. i wouldn't worry too much. I would on the other hand check at the end of the circuit there is a variable resistance when the pot is changed...to be sure the chip is receiving it.

Checked the trimpot, works fine, checked continuity to adjustment pcb pins, checked to the other end of the adj board cables,  checked from chassis receptacle pins to the ic... all checks out...
Unless there is something on the output pins of the ic that could stop it from varying position but still allow h size adjustments, I'm pretty sure it's the IC at fault... going to try attaching the adj pcb directly to the chassis just in case, but I doubt there'll be any results...

[lilshawn]

WG is the recordholder for "MSHJ"s...

agreed.

i'll have the plaque, trophy and the metals made up ASAP.

[Rattanee]

So now that we have the trophies handed out... weird stuff going on...

I was testing the monitor without an input signal with a blank raster... turns out wells don't shift the raster left or right, only the image 'inside' the raster... so h-position actually works, just not the way I want it to.

Basically raster is shifted to the left of the screen about 3-4 cms, and every adjustment works on the adjustment pcb with a video signal applied.

How can the raster position be adjusted? I don't see any adjustment for it aside from moving the yoke itself, which is firmly in it's place. What further reaffirms my notion that this is not a tube/yoke problem is that while the right edge of the picture is faintly washed out, the left side has slight overfolding. I've acquired a horizontal IC and swapped it, but no dice. Thoroughly checked the board visually aswell, but could see no problematic spots.

There is however a colour problem aswell. but that should be easier to figure out. Basically I can adjust brightness properly, but the picture itself is dim. If I pull up brightness everything becomes white., so the flyback is healthy, but I only get a picture with the contrast all the way up. Red and green drive pots don't do much, but there is a heavy flickering of colours as I adjust them (slight contact fault inside the pots). Bias pots work well but all three need to be on minomum or I get an oversaturated picture.

Any help's appreciated.