Author Topic: Monitor issue (Read 2274 times)

ZORK2 · « **on:** March 26, 2009, 09:17:14 pm »

I picked up a Simpson's cabinate today. I tested it before I bought it, it ran fine all the way around. Brought it home fired it up, ran fine for about an hour. I went it to eat dinner and left the machine running, came out about a half hour later, the game was running, but the monitor had NO picture!! I looked through the monitor electronics and discovered that the little slow-blow 2A fuse was blown. I replaced it with a regular 2A fuse and fired it up. The fuse blew instantly. I
looked everything over and there was no obvious signs of a short anywhere that I could see? Is there anything that could be causing that fuse to blow repeatedly!?
PLEASE HELP!!

ZORK2 · « **Reply #1 on:** March 26, 2009, 09:35:39 pm »

By the way, it is a Wells-Gardener Model No. 25K7191

Kevin Mullins · « **Reply #2 on:** March 26, 2009, 10:01:37 pm »

Check for bad solder joints. (everywhere)

Check for a shorted H.O.T. transistor. ( Q11 )

Is the chassis secured?
Did it shift or anything while moving it?

Ken Layton · « **Reply #3 on:** March 26, 2009, 10:55:56 pm »

Did any loose screws or metal pieces or coins that might have been rolling around in the cabinet possibly land under the monitor circuit board?

ZORK2 · « **Reply #4 on:** March 26, 2009, 11:05:00 pm »

I'll give it a look for a bad solder joint. And check fora short on the Q11 if I can find it.
Chassis seems to be secured. It doesn't look like anything shifted? I did put it on it's back before I plugged it in so I could remove the bad levelers. Flipped it back upright, played it for an hour or so. Had dinner, came out 1/2 hour later to a dark monitor, the game was running the entire time.
I will check for that too, but I don't think so, I looked underneith it best I could??

ZORK2 · « **Reply #5 on:** March 26, 2009, 11:21:37 pm »

Other than having the usual dust and grime on everything, I don't see anything obvious. No metal or any other debris that I could see on the board? Nothing under the board from what I can tell either.
I'm not sure what this means, but the game has been off for several hours, After I checked everthing this last time, I put a new fuse in it, turned the game on, the monitor still did not come on, I power the game off, checked the fuse, and this time the fuse was GOOD?!
What am I looking for to find the Q11 HOT tran?

Kevin Mullins · « **Reply #6 on:** March 26, 2009, 11:51:27 pm »

Quote from: ZORK2 on March 26, 2009, 11:21:37 pm

What am I looking for to find the Q11 HOT tran?

It's the large transistor mounted to the metal heatsink near the flyback.
(also marked on the chassis as Q11)

ZORK2 · « **Reply #7 on:** March 27, 2009, 12:29:43 am »

I'm not seeing anything labeled Q11 anywhere? Other than being dust and grimey, I don't see anything that looks shorted?

ZORK2 · « **Reply #8 on:** March 27, 2009, 02:31:51 am »

Well I'm not sure if this is it or not, but there is something weird with the wiring on the Isolation Transformer.
Acording to the operation manual, the Isolation Transformer has 3 inputs, 110V, G, O coming from the power supply.
2 outputs going to the moniter board.
This is how its ACTUALLY wired on the machine, 110 from the power supply, goes to the 115 on the ISO trans. That's it. For some weird reason there is an extra 110V coming from the second 110V on the power supply, its just floating around by the "O" on the ISO trans. It almost looks like it could have come off the "O"?? Or maybe it touched the "O" on the iso and popped that fuse?
So what excactly needs to be going into that Iso trans from the power supply? The posts on it are labled "0", "115", "E" I'm confused, What is the difference beteen "E" and "0"?? And why is there a second 110 by that ISO hanging free? I'm confused as to how it was even working earlier with that wire configuration?

Kevin Mullins · « **Reply #9 on:** March 27, 2009, 04:03:47 pm »

Quote from: ZORK2 on March 27, 2009, 02:31:51 am

For some weird reason there is an extra 110V coming from the second 110V on the power supply, its just floating around by the "O" on the ISO trans. It almost looks like it could have come off the "O"??

Nothing weird about that.... you should have TWO 110v lines and an Earth ground going to the tranbsformer. Sounds to me like one of you 110v lines ( O ) came off.

Quote from: ZORK2 on March 27, 2009, 02:31:51 am

The posts on it are labled "0", "115", "E" I'm confused, What is the difference beteen "E" and "0"??

115 = 115v
O = 115v
E = Earth Ground

Quote from: ZORK2 on March 27, 2009, 02:31:51 am

And why is there a second 110 by that ISO hanging free?

Once again, sounds like it fell off or broke off the "O".

If you can snap a picture of the entire setup it might be easier for us to just "point" at stuff.
And if you have a dedicated Simpsons cabinet..... the schematic in the manual is color coded.

ZORK2 · « **Reply #10 on:** March 27, 2009, 04:41:31 pm »

Kevin thanks!
I take back all those bad things I said about you!

I have a feeling that is why its no longer blowing that fuse? I'll bet when I hook that second 110 back up, it'll blow again? Strange thing is nothing was ever hooked to the "G"? What's up with that?
That is the same schematic I have. The wiring isn't original so the color coding doesn't help much.
Let me hook that up and try it again. I bought a can of air, and some board cleaner and cleaned up the board on the monitor. You can at least see things in there now.
I've just started the restoration process on the cab. Hope to post some pics of the process soon on another post.

ZORK2 · « **Reply #11 on:** March 27, 2009, 04:52:32 pm »

Yeah hooked up the 110 to the "0" and grounded the "G", Fuse blew.......

Kevin Mullins · « **Reply #12 on:** March 27, 2009, 04:55:13 pm »

See if you can grab a couple pics from the power supply to the isolation transformer to the monitor.

Did you get a chance to check that H.O.T. yet?

ZORK2 · « **Reply #13 on:** March 28, 2009, 06:47:29 am »

I had some problems uploading some pics last night. I'll try and get some posted today.
Having a difficult time locating the HOT? I'll give a closer look tonight when I get home. Just looking over the board in general, nothing looked damaged?
Here is how it is wired now

Power supply 110V to Iso Trans 110V
Power supply 110V to Iso Trans "O"
Iso trans "N" to ground

Out put from "110" and "0" go to the monitor board.

ZORK2 · « **Reply #14 on:** March 28, 2009, 09:45:40 am »

This is a pic I found on the net of an identical board......

http://www.jstookey.com/arcade/WG_25k7191/WG_25K7191_pot_zoom_out.JPG

ZORK2 · « **Reply #15 on:** March 28, 2009, 11:49:35 am »

This has proven to be very helpful. It says if the fuse is blown check the Q11 and IC4 for a short. Found them on the "Main PC Board Layout". Now that I know where both are excactly I'll check them both when I get home this evening.
Curious if this thing is toast, where would one find a replacment board for a 25K7191???

ZORK2 · « **Reply #16 on:** March 28, 2009, 12:17:24 pm »

http://www.jstookey.com/arcade/WG_25k7191/wg-k7000.pdf

SirPeale · « **Reply #17 on:** March 28, 2009, 08:37:31 pm »

Quote from: ZORK2 on March 28, 2009, 11:49:35 am

Curious if this thing is toast, where would one find a replacment board for a 25K7191???

Rarely are K7000s completely toast. And they're excellent monitors, usually easily repairable.

ZORK2 · « **Reply #18 on:** April 01, 2009, 12:34:56 am »

I bought a new monitor board on Ebay. I'm going to swap it out and see if that does the trick. I could find no visible problems with the old one.

SirPeale · « **Reply #19 on:** April 01, 2009, 02:27:54 am »

You probably wouldn't see anything, unless it died violently. You need a multimeter to test the components reliably.


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