Wells K4900 vertical position pot?

MadPerry

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I have a Wells Gardner k4953 thats image is about an inch, inch and a half to the right and can't be adjusted to the left anymore. I can fill the entire screen with the vertical size pot, but it of course chops off the right side. I was wondering if changing the potentiometer that controls vertical position would cure this problem?
 
V position

Is the monitor sitting in the game horizontaly or verticaly? If it is horizontal there is a jumper wire on the right hand side of the monitor chassis if you are looking from the back. You can move this jumper to 3 different positions depending on what direction you want the picture to shift. There are 3 different terminals sticking out of the chassis. One of them most likely has the jumper wire on it already. Move it around to the other 2 and see what you get.
 
Is the monitor sitting in the game horizontaly or verticaly? If it is horizontal there is a jumper wire on the right hand side of the monitor chassis if you are looking from the back. You can move this jumper to 3 different positions depending on what direction you want the picture to shift. There are 3 different terminals sticking out of the chassis. One of them most likely has the jumper wire on it already. Move it around to the other 2 and see what you get.

The monitor is in the vertical position, but I believe I see the 3 pins you are referring to. They are even labeled. But, none of them have any jumper attached to it. I think this may not help me since I am trying to adjust the vertical position?
 
I'm still hoping to get some assistance on this if anyone knows. I have removed the pot and verified it's resistance range(25K ohm). I tried adding a 10k ohm resistor inline which seemed to do nothing, but it may be in the wrong position.
 
post a pic of the place where the jumpers and posts should be.

i have seen several 4900's that the actual jumper wire was gone.
the crimp post is still solderd in the board but the wire was missing.

you may just need to add the wire.

Peace
Buffett
 
Ill post a pic as soon as i can. I can say that a tiny sub board with only the potentiometer and a transistor are soldered right to the place where the jumper posts are. It looks factory to me. That is why i tested pot resistance at 25k.
 
there is a set of jumper posts behind it as well.

i have seen that jumper missing as well.

we will see what you have when you get some pics:)


Peace
Buffett
 
finally got a couple decent pics of it:

potentiometer_zpsd7c6a3e6.jpg

jumperposts_zps875f9a46.jpg
 
here is where the jumper is soldered to the chassis and where it goes to on the 3 pins adjust the image.

the center pin does nothing. it is just a place holder.

the two outer pins move the image.

only connect the jumper to one of the pins at a time.

Peace
Buffett
 

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here is where the jumper is soldered to the chassis and where it goes to on the 3 pins adjust the image.

the center pin does nothing. it is just a place holder.

the two outer pins move the image.

only connect the jumper to one of the pins at a time.

Peace
Buffett

That wont help me with my vertical position problem. Those posts are the horizontal posts and are even labeled as such. The vertical ones are there too, and labeled, they just have that pot soldered to them. Ill have to dig up a pic of someones 4900 with no pot to show you what i mean.
 
i have all the chassis types here. i can look at them.

what does the 4th wite pot to the rite before the blue pot do anything.

it should not have to be maxed out like that.

center both pots and readjust see what both pots do independently and that hey do together.

does the image split when you adjust anything.

Peace
Buffett
 
that 4th pot does the same thing as the v size pot. widens the image. i've tried all combinations of pot positions, with anything vertical related. the only thing that resembles a split image is when i mess with the v hold.

tomorrow night i'm going to de-solder the blue pot entirely and see what happens.

i should mention a little history in case it is usefull. this was a karate champ original monitor that i have transplanted in another vertical cabinet. it had some slight burn from it's years of being karate champ, and the image is burned showing that this screen has NEVER had anything on the left 1 inch of the screen. been off center since the day it started operating.

and thanks for hanging in there. who knows, maybe i'll get this thing fixed some day.
 
I assume you have already re-capped this monitor?

If so, then the transistor on the vertical position board probably does not have enough gain and should be replaced. This assumes the vertical position pot is ok.
 
I assume you have already re-capped this monitor?

If so, then the transistor on the vertical position board probably does not have enough gain and should be replaced. This assumes the vertical position pot is ok.
yes, i have re-capped. it has a really nice picture and centering vertically is the only issue i have with it. the pot has a full range, in other words, it shifts the image from one end of the range to the other end of the range.

i have no idea how to id a transistor or how to replace it with a higher or lower value...
 
I'm having the exact same issue with my monitor (Gyruss).

When you use the pot, does it actually do anything on screen? No matter what I do with my pot the picture isn't affected - dead pot I presume?
 
Adjusting that pot allows you to center the picture vertically. If it isn't doing anything transistor Q901 on the vertical position board could be bad.

If you need it repaired send it in. Cost to repair $36.00 plus parts and return shipping.

Ed West
 
Is the daughter board removable? I tried to pull it out gently but it won't budge (that's what she said). I don't want to be rough, break something and make things worse.
 
no it does not come off.

it is soldered to the chassis.

test the transistor next to the pot it may be bad.

if you hit a brick wall you are welcome to send it in.

Peace
Buffett
 
Solution

Posting this for documentation that will hopefully help folks in the future.

I had this exact same problem with my Time Pilot (WG K4951) after I installed a cap kit. The vertical postion pot could not get the screen far enough left.

Looked high and low on the internet and didn't find much mention of this particular problem, except for this thread which was kind of left unresolved.

Buffet's last comment about the transistor next to the vertical position pot potentially being bad made sense to me so I researched it and found a modern replacement which I bought here:

http://www.ebay.com/itm/NEW-NTE194-NPN-TRANSISTOR-TO92-ECG194-/262049356461

Installed the new transistor this evening and the problem was solved for $4.18 and about 30 minutes total, including removing the chassis and putting it back.
 

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