Joust color problems

boogiemanspud

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Oh my... I am beginning to see arcade games are a "labor of love"... :(

I fired up my Joust today, played a game, and got distracted with something else. Anyway, it has been on for several hours, probably 8 hours. I went to play another game just now and the colors are messed up. Basically, anything that was black is now red, meaning red background on the game. The high scores screen now has a blue background.

Does anyone have any ideas on this? I hope this is in the right category, I wasn't entirely sure if it was general repair or monitor.

I did a conversion several days ago to 6164 ram using the Bob Roberts adapter. I don't think it has anything to do with it since it worked fine for several days. I just wanted to add that since the chips are different voltages.
 
Turn the game off for about an hour and let it cool off. Turn it back on and see if it corrects itself until it warms up again. Could be caps failing on the monitor.
 
Turn the game off for about an hour and let it cool off. Turn it back on and see if it corrects itself until it warms up again. Could be caps failing on the monitor.

I had it off all night, just checked it this morning and the colors are all still messed up.

If a cap fails completely, would the colors be messed up even when it was first turned on?
 
Get the meter out and check the voltages to the MPU board. IIRC, the video circuit uses the +12V and if that flakes out the colors go wonky.

If those check out, try adjusting the red gain and the red cutoff pots on the monitor (normally on the neckboard for G07s & WGs).

ken
 
Get the meter out and check the voltages to the MPU board. IIRC, the video circuit uses the +12V and if that flakes out the colors go wonky.

If those check out, try adjusting the red gain and the red cutoff pots on the monitor (normally on the neckboard for G07s & WGs).

ken

Please bear with me... The MPU is the one with the ram bank right? If so, where do I need to check for 12v? I have all the drawing sets but to be honest, I don't know what I am looking at on the drawings.

EDIT: I tried the red cutoff on the monitor, no real change besides the red changing colors/levels.

Is this 12v, the one coming from the PS to the board, or is it an output?
 
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Please bear with me... The MPU is the one with the ram bank right? If so, where do I need to check for 12v? I have all the drawing sets but to be honest, I don't know what I am looking at on the drawings.

EDIT: I tried the red cutoff on the monitor, no real change besides the red changing colors/levels.

Is this 12v, the one coming from the PS to the board, or is it an output?

The 12V coming from the power supply to the MPU board (the large board with the CPU & RAM on it).

One other thing to try would be to unplug each end of the video cable and reseat it. Sometimes just enough corrosion creeps in to mess the colors up.

If you have a spare monitor, try plugging the boards into it. That would help pinpoint game boards vs monitor. no sense in spending a lot of time checking the game boards if it is a monitor issue and vice versa.

ken
 
At the power input on the MPU I get 5.05V, 5.05V, and 14.49V. Keep in mind I am using the 4164 ram adapter cable.

It looks like the 14.49V could be the problem (not certain but logically...)

I also checked at the switching PS, and it is similar high voltages on the 12V post. The PS has only 12 hours or so on it, could it just be a defective one? I can't see any way to adjust the output. There is one knob on the front, but it adjusts everything, the 5V and 12V. Even with this knob I cannot get it much lower than ~13.5V.

Any thoughts on this? Is this the problem?

EDIT: I don't have a spare monitor.
 
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Since you did the 4164 mod, you are not actually using the +12V on the MPU board. So that should not be the problem.

Do you know if the adapter you are using is running the +12V to the sound card or is it just running the +5V? If the sound card is not running on the switcher, then it is not pulling a load and it will tend to run high.

ken
 
Since you did the 4164 mod, you are not actually using the +12V on the MPU board. So that should not be the problem.

Do you know if the adapter you are using is running the +12V to the sound card or is it just running the +5V? If the sound card is not running on the switcher, then it is not pulling a load and it will tend to run high.

ken

The sound card is/was ran from the switcher. The only thing not from the switcher is the coin door/start button lights. So I suppose this would make sense it running higher without the load from the sound card. But could that be the difference in the colors being messed up? It ran fine without the sound card until I left it on that day.

I am gonna say it's gremlins. Damn gremlins :mad:

EDIT: Just re-read that. That makes sense since the 12V was only used on the MPU for the 4116 RAM if I follow correctly. I could start checking voltages at components, but I don't really follow which part of the drawings have that. I will study them more. It would be really handy if they said things like that. For example, the MPU board... I assume it needs certain voltage going out to the monitor control, but on the "Interboad Wiring" diagram (page 1) it doesn't say what voltage should be expected there... It just says colors.
 
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Try bringing up the color screens in the diagnostics. The color bar pattern should help you adjust the monitor, if it is the monitor.

ken
 
I would adjust the 5v to 5.15v. Then I would uplug, clean and plug back in the ribbon cable and header. Then I would carefully clean all the legs on the ROM chips.
 
I just tried the color diagnostics, it's not that the colors are bad monitor wise, its like they are messed up on the boards. I tried reseating/cleaning and nothing changed.

Well... I don't know. I may just end up sending it to someone who works on them. It's just beyond my scope at this point. I really appreciate the help, its just I think I have the boards from hell or something!
 
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