New cap kit on WG K4921 top rollover?

jtslade69

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So just put a capkit on my MC with a WGK4921 ..

There is a jumpered wire that I replaced prob done by an operator, the wit looks like it has a resistor or diode of some kind I'll take pics when I remove it tomorrow.

After the capkit had some bad blue sparking under the anode which I hopefully fixed by cleaning the glass and anode cup.. The glass was very dirty with black dirt..

The monitor now has rollover at the top.. ImageUploadedByTapatalk1361318768.610476.jpg
ImageUploadedByTapatalk1361318779.319621.jpg

Also the capkit called for a 47uf 250v at C313 but the original was a 100uf @160v.

Per some advice I left the 100uf @ 160v cap in..

Any advice.. ??

Did a later wells Gardner update call for a Change in this cap?

Any ideas??
 
I found this from a 2008 post titled: 4900 Rollover...


....
I have the monitor adjusted to where there is now just a small curl with a slight fold over. The problem is only visible on the menu screen, can't see it at all during game play. I got it to this point by changing C313 to 47uf and C308 to 3.3uf.



Oh, pretty sure where talking about the same chassis version Modessitt.



Thanks for the responses.
 
i have always replaced C313 with a 100uf @ 160v.
never had the need to change it with a different value.

when i have seen this issue it has always been a pot adjustment for the fix.

check over your work for a bridged solder and all the resisters in the V-Height and linearity control circuit.

Peace
Buffett
 
So I removed the wire hack (pic below) and it had no effect on the fold over.
ImageUploadedByTapatalk1361367008.038723.jpg
ImageUploadedByTapatalk1361367041.835043.jpg

Everything else looks good, but I am so new that I could be overlooking something.

Using the v-dampening I can adjust out the fold over but the screen is then 2 1/2 or so inches lower pic here ImageUploadedByTapatalk1361367156.235189.jpg

Is the next step to swap the cap at c313 with the 47uf that came with it?

I need some guidance..
Thank you all for any help.
 
Anything you find on the foil side that looks like a hack is not a hack at all. It is another example of Wells-Gardner's famous UNDOCUMENTED production changes. So leave it alone.

As to the "foldover" problem, have you adjusted the "vert damp" pot?

Also, there was a service bulletin issued about chassis/yoke differences. If the wrong version of chassis was used with the incorrect yoke part number, there would be foldover you could not adjust out:

http://home.comcast.net/~mtpacifico... 4900 series Yoke & Chassis Compatibility.pdf
 
Thank you Ken..

Yes v damp has been adjusted and I have pics a couple of posts back in this post..

The fold over was not there before cap kit from Arcadeshop.com
 
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Wells did update that particular cap value from 47 uf @ 160 volts to 100 uf @ 160 volts. Perhaps Arcadeshop is putting capkits together from very old cap lists?

This is why I usually purchase capkits from either Zanen Electronics or Bob Roberts. They usually update their kits over the years to reflect the latest parts values.
 
I'm trying to get the latest cap kit sheet from Zanen or Bob Roberts to see which caps may be incorrect that could be causing my issue..

I don't want to have to completely redo my entire cap kit with the original caps when it is possibly onlone or two that are incorrect, I'm ok with a little trial and error now that I am getting good at disc hatching and pulling the chassis out of my Missile Command..
 
I'll post a PDF of the cap sheet that Arcadeshop sent me and maybe it will be possible to track down the cause of the top fold over..

Some caps definitely helped the now bright picture , no more bleeding color, dark black..

Just need to figure which ones were. Wrong for the K4921 that I have in my MC...
 
keep us posted on your findings.

i have always used the 47 uf @ 160 and never had any issues.
but there is always a first time.

Peace
Buffett
 
Just soldered in the 47uf @ 250v into C313

Now trying to determine if any of my solders were bad for caps in the vertical section,

Any that I should focus on?

This is what comes with the Arcadeshop cap kit, some differences to the Bob Roberts...
Wells Gardner K4900 Series Monitor

C201 1000u 25V
C205 470u 16V
C301 330u 50V
C303 2.2u 50V
C308 2.2u 50V
C310 10u 160V
C311 4.7u 160V
C313 47u 250V
C315 1u 50V
C351 1u 50V
C352 47u 25V
C354 47u 25V
C506 22u 160V
C507 47u 250V
C701 1000u 25V
C702 10u 160V
 
This is what comes with Bob Roberts kit:

Bob Roberts Kit
Wells Gardner K4900 Series Monitor

C201 1000u 16V
C205 470u 16V
C301 330u 25V
C303 2.2u 50V
C308 2.2u 50V
C310 10u 250V
C311 4.7u 160V
C313 100u 160V
C315 1u 50V
C351 1u 50V
C352 47u 50V
C354 47u 50V
C506 22u 250V
C507 47u 250V
C701 1000u 50V
C702 10u 250V
 
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