Punch Out - Need monitor help please

philsarcade

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Donor 2012, 2025
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I have a punch out machine. I attached photos of the monitors, and the label on the back of the bottom monitor. The problem: The top monitor is nice and bright. It looks washed out in the photo, but in person, it looks nice. The bottom monitor is dark. The image is clear, not distorted at all. The whites don't look white though. They look almost brownish white. I have tried adjusting the color settings......I've also tried the focus and screen knobs.

I feel like the color green doesn't adjust. The character that we control in the videogame is green. No matter how low I turn the green knob down.....he is still vibrant green. I'm wondering if maybe the green is turned all the way up, and can't be turned down by turning the knob....thus causing the whites to look dark..........or if any of you know what is actually wrong.
Thank you,
Phil
 

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it almost seems like you are missing blue in the bottom pic.
do you have blue in other screens?


have you capped the monitors yet they will look even better after a cap kit.
wile you have it out re-flow the chassis and the three color transistors on the neck board.

there is 3 brightness adjustments on a sanyo one on the fly one on the remote board and one on the chassis about the center.

and if you have access to a rejuvinator i would test the tube to see it it needs a cleaning.

Peace
Buffett
 
Thank you. I'm very new to this hobby, and have never serviced a monitor. I will dive into this though and see what I can figure out. (and I'll try not to get shocked in the process.)
Phil
 
sounds good.

take your time and be careful monitors are not as scary as everyone makes them out to be.

respect them and you will be fine.

there are lots of threads on how to remove a sanyo from the game and the the chassis out of the frame and off the tube.

and discharge it several times before removing it from the tube and frame.
then discharge the tube again several times after it has been removed to eliminate any residual static build up.

Peace
Buffett
 
Since it's a Punch-Out, you've probably got a bad Blue Color prom on the gameboard, very common problem with these. The monitor itself is probably still fine.
 
Since it's a Punch-Out, you've probably got a bad Blue Color prom on the gameboard, very common problem with these. The monitor itself is probably still fine.

I definitely appreciate the idea, but I think I may have already figured out that this isn't the case. I briefly switched the video feeds for the 2 monitors. The bottom one still looked bad and the top one still looked good. (now the game was being played on the top screen). So I think it has to be that the lower monitor is bad and not the CPU. Like I said though, I'm new....so please correct me if I'm missing something.
Phil
 
No, your logic is correct, there's something going on with the bottom monitor. One last thing you can try is to bypass the 'inverter' board on the flyback cage if you have one, but other than that you've either got a tube or a monitor board problem like Buffet suggested.
 
There is a group of three transistors on the neckboard, one for each colour. The first thing I'd do is swap two of these and see if the problem moves to a different colour.
 
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