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I currently am working on a Bally Game Maker with a monitor problem; the monitor is a Tatung VS 1428. I caped the monitor and brought some life back to it but I am still having some additional problems that have me a little puzzled.

When the screen is collapsed the picture and resolution is great. However, when I try adjusting the picture to fill the screen I am getting some distortion on the top of the picture.

Are there any suggestions to my problem?

I got  a Monitor Repair Guide from Ken Layton Web Sight and made followed the Monitor repair guide (caping out the Monitor)

I will include pictures of what I am talking about.

Here is one more picture to look at..........

Can you post a picture of your monitor board?  :211-

Here is a pictuer of the chasie before I cleaned it.......  If you need more pictures let me know

I'd look at the resistors in the vertical circuit. Looks a lot like a resistor that's changed values

I'd look at the resistors in the vertical circuit. Looks a lot like a resistor that's changed values

Thanks for the headsup. However would you please be a little clearer....

Thanks.....

Seem to remember back when I was repairing tv's that there was a 1 ohm resistor off the flyback that would change value, increase, and cause this problem. If left to fail it burned the vertical output. Capacitors can cause it to, but you've changed all those and a bad yoke is highly unlikely. It really looks like a vertical size problem which is most likely a resistor going bad. Trace your circuits between the flyback and vertical output and check values on the componants along those circuits. As far as I remember, RCA was the only one that had resistors that only failed under load so if you've got a bad part there it should show up without having to apply power to the circuit.  Anyway, check that with a digital multimeter and see what you find

Thanks cowboygames,

I will check this out Monday after work......

I will keep you all posted

Thank you for the info.
Mike

So I cleaned up the monitor chaise and checked a few resistors (2 watt .47 ohms around the Fly Back) Everything checked out OK on the bench, So I was able to disassemble the monitor apart and run it from the Slot Machine and noticed one of the Parts with a heatsink attached to it and it runs too hot to touch.

I don believe this is the culprit to my problem since the problem starts with the monitor ice cold.

I am including a few more pictures with the chaise cleaned up....

In this picture I identified the part that runs too hot to touch

part on the heat sink is your vertical out put pack and it's getting hotter than it should(though they do run a little warm anyway)because you're having to over-drive it to get a full size raster. Again, it may not be a resistor, but you've got a bad componant in the vertical circuit. Did you replace all caps in the vertical circuit? Check all diodes? If you can, get the part # off the output and I'll try and find pin outs and voltages you could look at while it's running to help nail it down

If power to the vertical circuit is fed off the flyback, replace the high speed rectifier diode that supplies the DC power. If the diode is leaking you'll get oddball things happening in that circuit and it'll run hot.

RJ

Thanks for the info about the leaky diode, however I am not sure if you are speaking about the LA7837

I found a Schematic that has some reference to the problem I am currently dealing with and will first try the resistor and if that does not work I will let you all know....

I will attach the mocked up diagram.....

What is feeding C706 and C720? Are they fed by a tap off the flyback?

C714 is bad.  It is a mylar cap, 104pf, 100v.

Sorry for the delay, thanks to all that gave me the suggestions based on there experience....

The winner was:

AnotherTech,  :131-

Attached is the fixed Monitor Chaise

I'm glad you got it going.

I'm Back......

After a few months of playing my Monitor decided to take another dump on me..... Any Suggestions?

When I worked on it last I caped it out Replaced the IC7 (ran HOT) and a leaky and replaced (C714, a Mylar cap, 104pf, 100v).

Here is a picture of what I have now.