2 issues on Blitz 99 - K7500

craigmack

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Hi Guys,

I'm having 2 issues on a Blitz 99 with a k7500 chassis. First is wandering focus, it looks good for a little bit and then it goes out of focus. From the posts I have read here this is a flyback issue correct?

If it is a flyback, how difficult is it to change on this model? I have not done any monitor work before, but I have done quite a lot in the realm of pinball board repair.

The 2nd issue is that my screen is too wide, and the horizontal width pot on the remote board seems to have no effect.

Is it as simple as replacing the pot on the remote board or is the issue something larger?

Thanks,
Craig
 
I can't speak 100% about your width issue, BUT, the black heatsink in the middle of the chassis should have 2-3 transistors mounted to it. the transistor that's facing closest to the front of the chassis (the part by the tube :)) will either be soldered directly into the chassis, or it will have jumper wires going to a small red (usually) connector that plugs into a transistor that's mounted to another heatsink... verify that this is present or plugged in, it has something to do with width. I recapped a K7500 once and bridged the cap to the transistor (it was hardwired, not jumpered) and it made the screen like half the width. (note I did this on accident, not on purpose, I went back and removed the bridge.)

second, you are correct about the "wandering focus" being a flyback issue. that's the exact same thing that happened on one of my K7500s, along with wandering brightness (as in the Screen pot).

changing them out is very painless, but takes a little creativity since the replacement flyback will not come with an actual connector on the G2 wire, instead it will just be a wire. so when you go to hook that up you'll need to remove the pin in the neckboard for the G2 and simply solder that wire in directly. all the other stuff still applies, opening the neck socket to install the focus wire (make sure this goes in all the way) and hooking up the CRT ground to the neckboard.

you may as well install a cap kit while you have the chassis out too. this could potentially help your width issue, or any other messed up things like jailbars or strange flickery artifacts.

if you have any questions or need help send me a PM.
 
Also If you got a Multimeter,you should check these parts
Listed in the repair Guide!
And check C724,C723,C718,D708,D707
for a short,or out of tolerance.
Try adjusting the width coil.
Pull chassis and check all the parts,your going to need a fly
for the focus issue.
Let us know what you find.
 

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