HELP! Shutdown on an WG Monitor???

Tighe

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Here are the symptoms:

Turn the game on and it work great with a beautiful picture for about 60 seconds then the monitor goes black and I can hear clicking from the chassis board.

The monitor has a previous repair tag that says it had shutdown before.

I really don't want to do a whole cap kit on this monitor since the picture is perfect. What is the minimum I can do to repair this. I have 4 other projects and I just want to get this working because my son loves this game.

The ironic part is that I bought this game just for the monitor to fix another game. I ended up getting another monitor to fix the other game.

I can't tell what model this monitor is by the cryptic Well Gardner tags, so I so here are some photos:

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

http://homearcade.org/BBBB/mon70.jpg

This comes with crap capacitors from the Wells-Gardner factory. Best to do a full recap on it. K7400 series.

http://homearcade.org/BBBB/caps.html

Thanks! Sigh, but not what I wanted to hear. I was so hoping it was just one. :D

Last time I did a cap kit from Bob Roberts I turned working K7000 (albeit dim and blurry) into a non working K7000. The worst part is that I installed all the caps correctly and I do electronics repair all the time, obviously not professionally, but enough that I am confident that I am doing things right.

I guess I will order the kit and replace the caps one at a time and test (pain in the ass) that way I will know when I make a mistake. I don't have a test rig so it means putting it back in the cabinet each time. Discharging the monitor each time.... :004_ssad:
 
http://www.wellsgardner.com/downloads/MonitorPartBreakdown.pdf

http://homearcade.org/BBBB/mon70.jpg

This comes with crap capacitors from the Wells-Gardner factory. Best to do a full recap on it. K7400 series.

http://homearcade.org/BBBB/caps.html


Do you know if that monitor needs an isolation transformer? It would make it 10 billion times easier if it didn't. Although I have one sitting in the bottom of my Capcom Vs SNK since I switched to a monitor that does not need one in that cab. I guess I should pull it and build myself a test rig. I can use an old AT PC power supply to power a JAMMA board right? That half busted pirate Double Dragon board will come in handy. :D
 
Do you know if that monitor needs an isolation transformer? It would make it 10 billion times easier if it didn't. Although I have one sitting in the bottom of my Capcom Vs SNK since I switched to a monitor that does not need one in that cab. I guess I should pull it and build myself a test rig. I can use an old AT PC power supply to power a JAMMA board right? That half busted pirate Double Dragon board will come in handy. :D

I know that you and I have seen applications where people have converted PC power supplies for use in video games (most notably for Sega 3.3V replacements) but the fine print they typically mention is that the PC units are capable of pushing more amperage through the lines, which could damage some game boards.

not saying it can't be done, but I'd save myself the trouble and just get another new arcade unit than go through the trouble of hacking a PC one and having to install fuses and shit inline on the 5 volt line.
 
OK I have the kit...

But it doesn't include this cap:

2mdgpd2.jpg


Is it not necessary?

Also is shutdown caused by bad caps? I know it isn't a guarantee, but could it be something else?
 
That is the filter cap, and usually isn't included in cap kits because they rarely ever fail and are expensive.

Caps CAN cause shutdown, but so can other things like cold solder (causing your B+ to go up), a blow HOT, bad flyback, etc...
 
That is the filter cap, and usually isn't included in cap kits because they rarely ever fail and are expensive.

Caps CAN cause shutdown, but so can other things like cold solder (causing your B+ to go up), a blow HOT, bad flyback, etc...

Thanks! I will be looking for cold solders. what is a "blow hot" and how would I test a flyback?
 
meter the HOT, if I'm not mistaken you put your black probe on the middle pin, then meter the outers with the red probe. then flip them around. I think if they come up shorted or open, then the HOT's no good. but considering that you have a picture for a period of time and then it goes out, the HOT should be fine.

on the K7400, I wanna say the HOT is the middle transistor on the large heatsink in the middle, but I don't know for sure.

I had a K7500 do the same thing yours is doing, it turned out to be a mis-adjusted B+. I can't remember the value it's supposed to be off hand, I wanna say within 118-120V, that sounds too easy. lol if the B+ is significantly higher than that, that will cause high voltage shutdown. the BITCH of the B+ on these is that Wells-Gardner generally blobbed them with a shitload of epoxy and the epoxy is known to actually damage the adjustment pots (notably the B+ adjustment and the Xray Shutdown pot ... either of which when gone flaky will turn the monitor into click-click-click mode) and breaking the epoxy off can be a challenge as well... I wound up breaking a B+ pot in the process, luckily I had some donors off other parts chassis laying around.

I capped the faulty monitor I was tinkering with last year, didn't solve the problem it had on its own, but at least I know that monitor's good for a long time now.
 
That is great info! Thanks! I need to find a manual for the monitor. I took off the flyback clip and the clip was all bent to hell, and the wire to the degauss thing was cut and horribly soldered, but I doubt it would cause the problem. I think I am going to fix those two things first and try it out. Also the flyback is a replacement (it had a part tag hanging from it) so there is a good possibility that when it was replaced they didn't solder it well.

Flyback clip:


Degauss wire:


meter the HOT, if I'm not mistaken you put your black probe on the middle pin, then meter the outers with the red probe. then flip them around. I think if they come up shorted or open, then the HOT's no good. but considering that you have a picture for a period of time and then it goes out, the HOT should be fine.

on the K7400, I wanna say the HOT is the middle transistor on the large heatsink in the middle, but I don't know for sure.

I had a K7500 do the same thing yours is doing, it turned out to be a mis-adjusted B+. I can't remember the value it's supposed to be off hand, I wanna say within 118-120V, that sounds too easy. lol if the B+ is significantly higher than that, that will cause high voltage shutdown. the BITCH of the B+ on these is that Wells-Gardner generally blobbed them with a shitload of epoxy and the epoxy is known to actually damage the adjustment pots (notably the B+ adjustment and the Xray Shutdown pot ... either of which when gone flaky will turn the monitor into click-click-click mode) and breaking the epoxy off can be a challenge as well... I wound up breaking a B+ pot in the process, luckily I had some donors off other parts chassis laying around.

I capped the faulty monitor I was tinkering with last year, didn't solve the problem it had on its own, but at least I know that monitor's good for a long time now.
 
replace the flyback then, most of these U5000/K7x00 generation chassis I've come into contact with had dying or shitty flybacks anyway.

your ground wire (the black wire you called the degauss wire) doesn't need to be overly fancy. most people with K7000s cut that wire roughly in half and reattach it with wire nuts when they reinstall the chassis. there just needs to be some kind of connection there, otherwise all kinds of detrimental shit can ensue without it. lol

when you install the new flyback, you'll find the red G2 wire will not have a connector on the new one. just desolder the G2 pin from the neckboard and hardwire the new one in. after all the work you're gonna do on this thing you won't need to pull it for a long time anyway. :p

the focus wire (the white one, or it may even be grey) is very easy to install. just stick a small flathead in the side of the neck socket where the little door flips open to open it and lift up. the wire will pull right out then. install the new one the same way, make sure it's all the way in. then close the little door.

done.
 
when you install the new flyback, you'll find the red G2 wire will not have a connector on the new one. just desolder the G2 pin from the neckboard and hardwire the new one in. after all the work you're gonna do on this thing you won't need to pull it for a long time anyway. :p
I hate how many new flybacks don't come with those connectors. What I've started to do is just use female molex pins and attach them that way. It is unlikely you'd have to remove it again, but I like having the flexibility just in case. :)
 
meter the HOT, if I'm not mistaken you put your black probe on the middle pin, then meter the outers with the red probe. then flip them around. I think if they come up shorted or open, then the HOT's no good. but considering that you have a picture for a period of time and then it goes out, the HOT should be fine.

on the K7400, I wanna say the HOT is the middle transistor on the large heatsink in the middle, but I don't know for sure.

I had a K7500 do the same thing yours is doing, it turned out to be a mis-adjusted B+. I can't remember the value it's supposed to be off hand, I wanna say within 118-120V, that sounds too easy. lol if the B+ is significantly higher than that, that will cause high voltage shutdown. the BITCH of the B+ on these is that Wells-Gardner generally blobbed them with a shitload of epoxy and the epoxy is known to actually damage the adjustment pots (notably the B+ adjustment and the Xray Shutdown pot ... either of which when gone flaky will turn the monitor into click-click-click mode) and breaking the epoxy off can be a challenge as well... I wound up breaking a B+ pot in the process, luckily I had some donors off other parts chassis laying around.

I capped the faulty monitor I was tinkering with last year, didn't solve the problem it had on its own, but at least I know that monitor's good for a long time now.

I pulled the chassis board and found the B+ pot. Where should measure the B+ voltage?
 
B+

Since I don't have a manual for this monitor I need some help.

There is a test point right next to the B+ pot (TP 104), is that where you can measure B+?

9swb2q.jpg


Also any tips for getting the goop/glop/glue off the pot without destroying it?
 
If I recall correctly, the B+ test point is in the area I circled, tucked between some caps. TP202

Your best bet is to gently chip away at that glue.
But really there is no "good" way, and no guarantees you won't break the pot.
 

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