Problem with 2 wells 25k7193 monitors: wells chassis & zenith chassis

mrbill2084

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Problem with 2 wells 25k7193 monitors: wells chassis & zenith chassis

I recently picked up two games. One has a wells chassis and the other the zenith. I have recapped both. Both width coils look good.

wells chassis: works, but picture is about 20% too narrow with width ferrite pulled out to max. Putting ferrite in middle makes the image more narrow.

zenith chassis: works but picture displays about 20% too wide with ferrite in middle(image is off the screen).

I was thinking maybe the operator swapped chassis. I don't think its likely as the tray serial number on the zenith monitor matches the one on the chassis. Plus the ground wire from the neck to the frame had never been cut. Zeinth also has a monitor remote control board.

Wells chassis does not match tray serial number and ground wire was cut before. Wells chassis does not have a remote board(but I see to screw holes were it looks like the remote board was probably mounted). So its likely its not the original chassis for this monitor.

I metered and took down the model numbers of both yokes:
wells chassis monitor:
yoke wires meter 7.3 and 1.9

yoke numbers are:
912613
EIA 343
DE 95-53


Zenith chassis monitor:
yoke wires meter 10 and 1.6

yoke numbers are
9A2911-001
9014T

I am wondering if I could swap the 2 chassis and solve both of the problems..
 
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Are both games the same game? Different games will display on the same monitor differently.

To answer your question: you should be able to swap the two chassis around if you want.
 
As long as they are both the same size (19" or 25"), then yes you can swap them. I doubt it will fix your problem.

You most likely need to change the width cap on each...
 
Both chassis are 25".

I will check the width caps on the two make sure the traces are good. maybe swap the 2 to see what happens.

should have known bob roberts would have wrttien somthing on it..
http://arcadecontrols.com/BBBB/width.html

The width caps themselves are fine. It's the value of them that determines the width.

edit: as you wrote in the 2nd bit.

how far off is it?
 
ok, here is an update..

Put the wells chassis on the zenith chassis tube and picture is fine. I am able to adjust the screen to fit. I was going to try swapping pcbs, but it started to rain again.

Put the zenith chassis on the wells tube, and its as wide or wider..
the current cap in c38 on the zenith is:
394j
200

but on the bottom of the pcb, looks like they may have added 1 or possibly 2 more caps. They are not soldered directly onto the the c38, but on the component behind it(they share at least 1 trace). Not sure if they are related to width or supposed to be there. I don't have another zenith chassis handy to comapre it to.

the bigger one is marked:
x32G h (x = to cant read it, but probably a 5)
1.6kv R

smaller one is marked
561J h
1.6kv Q

as for how far off, its displaying about 20% of the image off the screen.

here are pics (Need to buy some more dustoff)
zenith1.jpg


zenith3.jpg
 
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Those two caps were put there by the factory. I have a Zenith k7000a that also has them. The values are:

Big Cap: 862G 1.6kv
Small Cap: 102G 1.6kv

I removed them and replaced them with the cap from a regular WG k7000 to see what would happen (this is a long time ago, so I don't remember the details) and the width shrunk significantly. So those caps definitely play a part in the width.

*edit* found and attached a lousy picture I took a long time ago of the caps on mine.
 

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Those two caps were put there by the factory. I have a Zenith k7000a that also has them. The values are:

Big Cap: 862G 1.6kv
Small Cap: 102G 1.6kv

I removed them and replaced them with the cap from a regular WG k7000 to see what would happen (this is a long time ago, so I don't remember the details) and the width shrunk significantly. So those caps definitely play a part in the width.

*edit* found and attached a lousy picture I took a long time ago of the caps on mine.

So your saying swap the bottom 2 caps off the 7000a and match it to the 7000 and that might help. I might have time to try that on tuesday.
 
So your saying swap the bottom 2 caps off the 7000a and match it to the 7000 and that might help. I might have time to try that on tuesday.

Well, I wouldn't go as far as to say I suggest it. In my case, there wasn't any info on these k7000a's out there at the time I was troubleshooting mine. I assumed those caps were a hack and decided to throw the cap that the regular k7000 schematics show in it's place. The result was that my screen width shrunk considerably. I don't know what the long term results might have been since I immediately put those factory caps back in there place under the board.
I was really just confirming that those caps are factory, and they do play a part in the width.
 
No no no - leave the caps on the bottoms of the chassis there. These were factory installed to help correct minor issues with final testing before shipping. If you take them off, or change their values, the monitor may not work to it's fullest potential...
 
ok, here is an update..

Put the wells chassis on the zenith chassis tube and picture is fine. I am able to adjust the screen to fit. I was going to try swapping pcbs, but it started to rain again.

Put the zenith chassis on the wells tube, and its as wide or wider..
the current cap in c38 on the zenith is:
394j
200

but on the bottom of the pcb, looks like they may have added 1 or possibly 2 more caps. They are not soldered directly onto the the c38, but on the component behind it(they share at least 1 trace). Not sure if they are related to width or supposed to be there. I don't have another zenith chassis handy to comapre it to.

the bigger one is marked:
x32G h (x = to cant read it, but probably a 5)
1.6kv R

smaller one is marked
561J h
1.6kv Q

as for how far off, its displaying about 20% of the image off the screen.

here are pics (Need to buy some more dustoff)
zenith1.jpg


zenith3.jpg

this aint it, but in ther last pic there, do you have a solder joint with no damn solder just under that large cap? you might want to take care of that now vs later.

id be willing to bet that thanks to zenith and thier wonderful design, that c38 has been eating thr heat of those diodes right next to it and that large resistor to the left, and its prolly chaned value. Id get a width kit from bob and change 38 till its right, and leave the caps underneath alone for now.

If you plan on owning more then 2 games, invest in a cheapie air compressor. You only need a few cfm and thats enough to run a air blower( way better then dustoff in a can), and run a hvlp sprayer, etc.

sell it to the mrs as a way to air up car tires and bike tires, footballs, etc. :D
 
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this aint it, but in ther last pic there, do you have a solder joint with no damn solder just under that large cap? you might want to take care of that now vs later.

id be willing to bet that thanks to zenith and thier wonderful design, that c38 has been eating thr heat of those diodes right next to it and that large resistor to the left, and its prolly chaned value. Id get a width kit from bob and change 38 till its right, and leave the caps underneath alone for now.

If you plan on owning more then 2 games, invest in a cheapie air compressor. You only need a few cfm and thats enough to run a air blower( way better then dustoff in a can), and run a hvlp sprayer, etc.

sell it to the mrs as a way to air up car tires and bike tires, footballs, etc. :D

no, that solder joint has solder. Lousy pic. I will order the kit from bob and do it right.. good point on eating the heat, I will try swapping it with a one off a donor board to see if it makes a difference while I wait for bobs kit..

I swapped boards in the cabinets. The monitor that was displaying too small of a pic is a board issue. Picture was perfect with street fighter. Put it with area 51 and the pic was small..

I dug out another working wells 25" k7000 chassis and the pic also displayed small.

I do have a semi protable air compressor. Just too much a hassle to dig it out...
 
Problem fixed yet? If not, try resetting the b+ voltage to spec if the voltage is off.

This has actually fixed alot of geometric problems for me as well.
 
no time to mess with them today. Sold the dedicated smash tv today and someone is coming up from LA to pickup star castle and star wars on thursday. Probably get to it on friday...
 
id be willing to bet that thanks to zenith and thier wonderful design, that c38 has been eating thr heat of those diodes right next to it and that large resistor to the left, and its prolly chaned value. Id get a width kit from bob and change 38 till its right, and leave the caps underneath alone for now.

:D

Thanks for all the help! I had a little time today and fiixed it.

The winner is: heat damaging the c38 cap. I pulled one off a DOA K7000 chassis. Works fine. Never seen that one before, but then I have not had many k7000a's either...

I hit the tube with the rejuvenator and it looks great! This is the 3rd tube I used it on that I have seen positive results. My only concern is that I can't seem to get the bk490 to work like the video I saw on youtube. It seems to me that after about 5 to 10 seconds of holding down the rejuvenate button on a gun, the needle seems to be stable (no longer going down) towards .5.

I have gone as long as another 15-20 seconds with it being stable above .5 before I chicken out.. But the results have been good. Only once has it gone partially according to the video. I think 2 out of the 3 guns on a g07 actually dropped to .5 using the rejuvenate button.

Seems like when I use the clean/balance it works normal going gradually to the .2. Not sure what to make of it. The results are good.
 
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