Pincushion problem with wells monitor

[mamerocks87]

I have an older wells gardner standard resolution arcade monitor. It is a 27". Im having problems with my screen bending inward like it needs pincushion adjustment.  My monitor doesn't have an adustment on the remote. What can I do? Its pretty badly bent inward.  Has a new cap kit. Please help,

-Kyle

[hiperco]

Do you know if it ever had a good picture?  I understand that pincushion can be caused by a deflection yoke with an impedance that is not a good match for the board.

I'm sure one of the guru's will post shortly with information that is more helpful

[mamerocks87]

Im not sure i bought the monitor off ebay.

-Kyle

i have never seen it with a good picture.....is there a manual way to adjust the pincushion without having to discharge my monitoR?

[hiperco]

Oh, and I'm sure the guru's will want to know what chassis it is, and a picture of the chassis is often very helpful

[mamerocks87]

I uploaded some pics of the monitor to my server. Check them out

Here is the model number for the monitor:
www.debutvm.com/arcade1.jpg

here are 2 pictures of the monitor:
www.debutvm.com/arcade2.jpg
www.debutvm.com/arcade3.jpg

Here is a picture of the romote that is on my monitor:
www.debutvm.com/arcade4.jpg

thanks ,

-Kyle

[hiperco]

A couple of observations. 

-I don't think that barcode in picture #1 is the chassis model number.  It should be something like 25K7184 (for example).  (By chassis I mean the circuit board in the back, not the tube etc)

-Are you sure that a cap kit has been installed?  And it was the correct one for your monitor? 

[mamerocks87]

I think this is what your wanting....
 Tell me if its not



27k7401

Yes there are new caps on it, however i didnt put them in so I can not say for sure if they were for the right monitor.  Im almost positive they would be because it was a reliable seller.   Thanks,

-Kyle

[hiperco]

Thats the one 

Now for a guru to chime in and give you some expert advice.

[Ken Layton]

The k7400 series is a current production model. I don't think there's a capkit released for this model yet. I agree that your pincushion problem is pretty bad. I don't have a schematic or service manual for any sizes of the k7400 series. It might be a good idea to phone the tech support department at Wells-Gardner about this problem.

[mamerocks87]

What all do i need to ask them?

-Kyle

[mamerocks87]

I just emailed the Wells Technician support, so maybe I should here something soon. I will post what they send me when I get it.

-Kyle

[mamerocks87]

Heres the response from wells:

HI KYLE
 
             YOU'R MONITOR FROM THE PIX YOU SENT ME LOOKS ALMOST LIKE A 60 CYCLE HUM. BUT YOU CAN TRY ADJUSTING THE PIN CUSHION WITH THE CONTROL ON THE PIN CUSHION BOARD, WHICH IS MOUNTED ON THE MAIN BOARD.GIVE IT A TRY TO SEE IF THEIR IS ANY RESPONSE FROM THE PIN CUSHION ADJUSTMENT.
---------------------------
Sorry im such a newbie but which board is the main, and where would i find the pincushion adjustment?

-Kyle

[Ken Layton]

Since I don't have a 7400 manual or a 7400 monitor in front of me I can't do you much good.

In general, Wells-Gardner uses optional small plug-in boards for optional things like a pincushion correction circuit. Look on the monitors main (largest) circuit board. There is probably a small circuit board plugged into it (and standing vertically). I'm thinking that would be your pincushion correction board. I strongly advise ordering a k7400 service manual from the parts dept at Wlls-Gardner.

[mamerocks87]

I found the pincushion adjustment.  It helped some, i guess, there is still noticable boeing.  Here are the pics after adjusted..... Could my pincushion control thing, be needing replaceing? What about the 60 cycle hum, he was talking about?? Whats that??

www.debutvm.com/pic1.jpg
www.debutvm.com/pic2.jpg
www.debutvm.com/pic3.jpg


Thanks,

-Kyle

[Ken Layton]

I think he meant there's a slight hum bar in the picture (probably caused by some failing caps in the monitor power supply).

This may be an instance where a capacitor ESR meter would be handy to check the capacitors in this monitor.

[mamerocks87]

Where can i get a capacitor ESR meter to check them? Which ones might it be? Im freightened to discharge my monitor, is it nessasary in order to change a capasitor? Just point me in the right direction.


-Kyle

[Ken Layton]

Visit this site: www.eds-inc.com/products.html and purchase the CapAnalyzer88A capacitor tester. Well worth every penny---I use mine nearly every day.

Having not worked on a k7400  (and not having a manual) all I can tell you is to start with the electrolytic caps in the power supply section. Of course if it were my monitor I would check EVERY electrolytic cap in the monitor.

[mamerocks87]

I cant seem to find a price on the cap tester. How much does it run? Do i have to discharge the monitor to do change a capacitor? Where can I get a discharge tool? How do i change the capacitor?

-Kyle

[Ken Layton]

I cant seem to find a price on the cap tester. How much does it run?

$179. and you can also purchase it from one of their distributors like MCM Electronics (www.mcminone.com) as MCM # 72-6508



 Do i have to discharge the monitor to do change a capacitor?


Yes, since you need to remove the circuit board in order to get to the capacitors on it.


 Where can I get a discharge tool?

MCM Electronics (www.mcminone.com) part number 72-6530 ($75.) or 73-520 ($92.). You can also check Bob Roberts' site and build the 'safeback' discharge tool yourself (cheap & dirty, but it works).



How do i change the capacitor?

Tutorials on Bob Roberts' site. Same for Randy Fromm's site.

-Kyle

[mamerocks87]

I have been thinking of going to Randy's arcade school. Is it pretty in depth?? Sorry that this is so off the subject.

-Kyle

[Ken Layton]

Randy's arcade school is worth every penny. I've heard nothing but positive comments.