GRAVITAR - Strange display

jetusenet

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Hi;
I have a Gravitar that worked until I fixed it!

The display is garbled and instead of the usual coming up slowly when powered up, the display is dark then the display "pops" up, already bright etc......

Anyway, it has a Clay AVG replacement board and D102 is bright when the game is fired up but D101 is dim.

I poked around the PCB on the bench and found C110 broken, so I replaced it and IC A/B11-7 was bent underneath the IC so I straightened that out as well. Funny how the game worked even with those 2 components not quite right.......

I think that maybe the AVG PCB is bad, as indicated by the dim LED but before I replace that with a good one and possibly damage that one, I would like to get some opinions on why the one LED is dim.

Thanks much
Jeff
 

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Monitor shots

These are the pics of the display...........
 

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To claify what I had meant by "fix it"....

I rebuilt the power brick, the A/R II, replaced the line cord and rebuilt the Monitor. I tested the monitor on a SD and it worked fine so that is not the problem......

Jeff
 
What happens if you jiggle the power connector?

Sometimes mine comes up with some jaggled/jumbled/jumpy vectors and it straightens out if I power down/back up.
 
Which connector are you taking about?

My concern is that the one LED on the AVG PCB is not as bright as the other and I feel that it indicates a problem somewhere.....
 
I was talking about the PCB edge connector. I don't recall if it was the long or the short one. I just use the power switch to cycle it if it starts off bad now.
 
I came across a Black Widow that did that once, I would cycle the power and it would clear up....
But unfortunately, it does not work in this situation, I tried several times.
I will check the edge connector but I feel that the LED on the AVG PCB is trying to tell me something.
Thanks for the suggestion though.
Jeff
 
Need to isolate which part is the problem:
PCB, AR2, power brick (I see you already verified the monitor is good)

I know you are dialed in on the PCB already. But since you made changes to both the AR2 and power brick, it would be a good idea to verify that your focus on the PCB is the right direction.
 
This is one for the history books........
It seems that it was not me after all, it had something to do with the monitor/PCB combo, they will just not work together!

I swapped the A/R II and power brick with known good working and still had the same problem.
I hooked up the monitor to another Gravitar cab and it worked fine.
I put the Gravitar PCB in question into the same cab and BAM, it no work!
I replaced the deflection PCB - NG.
I replaced the HV cage - NG.
I swapped monitors and BAM - it works!

So...... what I had to do was to replace the PCB in question with the replacement, use the original rebuilt monitor, A/R II and power brick and now everything works proper.

Has anyone else ever had a PCB that was incompatible with a monitor before!?!?!

Very weird.....

Jeff
 
Could it be that there is a weak component on the Gravitar PCB which prevents that specific game board from providing a "good enough" signal to the monitor??
 
Could it be that there is a weak component on the Gravitar PCB which prevents that specific game board from providing a "good enough" signal to the monitor??

...Just thinking out loud.....Maybe a pin(s) have backed out a bit, inside the big square Amp connector, that connects everything to the monitor. I know I've had odd vector display issues (color and black & white) driving my crazy......only to find a pin slightly backing out of that connector. Maybe the swapping around of stuff moved thhe pin back into place.

Edward
 
...Just thinking out loud.....Maybe a pin(s) have backed out a bit, inside the big square Amp connector, that connects everything to the monitor. I know I've had odd vector display issues (color and black & white) driving my crazy......only to find a pin slightly backing out of that connector. Maybe the swapping around of stuff moved thhe pin back into place.

Edward

Edward;
That has happened to me as well on an occasion or two but this is different.
PCB "A" just will not work in Cab "A". I pulled PCB "A" and replaced it with PCB "B" and then it works.
Also once I placed PCB "A" into Cab "B", that worked as well.
It is a very strange situation......
Thanks for the suggestion.
Jeff
 
Could be one of the Op Amps in the output section.

Do you think that a weak OpAmp on PCB "A" would cause a certain monitor not to work right but then allow another monitor to work correctly?

For example, PCB "B" works with both, Cab "A" and "B" monitors BUT.....
PCB "A" only works correctly with the cab "B" monitor.

Strange.........

Jeff
 
Well, I would not expect it to behave any differently. I was only suspecting that because they are kinda the "interface" layer, and would be susceptable to enviromental changes... Assuming both monitors present the same input impedance, they should be identical. If you have a scope, you could look at the outputs of the bad board in both cabs, with the monitor connected, then disconnected, and see if it had any effect. It also could be in the power supply thats on the board itself.
 
Thanks for the suggestion regarding the scope and I did not mean my reply to be anything other than my complete exhaustion from this (another) arcade video game enigma.
These machines have a never-ending requirement of human-interface time which I am having less and less of............
 
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