Glitchy Moon Cresta Cocktail

SavageMind

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I picked up a moon crest cocktail table. It has a nifty glitch in need to sort. I plays the demo no ships, just letters and number in thier place. I cant get any buttons to respond even in free play mode. Still need to dive into it more.

Video shows the glitch.

 

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Start with verifying the roms, then look into the voltages.
The voltage regulator is attached to the back wall of the cabinet, under the monitor.
 
Start with verifying the roms, then look into the voltages.
The voltage regulator is attached to the back wall of the cabinet, under the monitor.
Waiting on my reader/writer. I plan to use a test rom I found in the forum. The only one rom has a number MB8516 the rest I can;t verify. However, the maker of the Test rom suggests a 2716 are these compatible with each other?
 
So I got a GQ-4x4. I found out there is no device profile for MB8516. Looking at the datasheet shows it is compatible with 2716. So installed the test rom from :Galaxian-Moon Cresta Test Room Post. and I fired it up but got pure garbage. I verified the file vs the eprom and it matched. I dumped the roms and put them on new eproms and the game is back to playing quiet, with glitchy graphics. So at least I can write to a eprom correctly. Not wanting to give up for sure, I'm going to explore memory next. Any help in the right direction would be appreciated.


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Soooo. I traced everything back on my board and tested at each connector. You can see the rail on the left hand side that seems to be a place the wires are soldiers together in common. 5v is reading 4.87v 12v is reading 9.43v with no change anywhere on the line. So I'm going to look into another power supply. By the looks of the schematic, I can remove the transformer and keep the rest of it to keep the monitor powered. Still researching to make sure. What I am trying to figure out is where the -5v is coming from. There is no connection from the power supply that is -5v. However, there is a -5v test point on the board. Naturally low -2.7v. Any input would be awesome, still learning.

.Railpic.jpg
 
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It's not likely a power supply issue. Don't go modifying what's there unless you know for sure that the game Pcb isn't dragging down the voltage.

Pull the game board out, hook it up to a different 5v source, and troubleshoot it on a bench.
 
It's not likely a power supply issue. Don't go modifying what's there unless you know for sure that the game Pcb isn't dragging down the voltage.

Pull the game board out, hook it up to a different 5v source, and troubleshoot it on a bench.
I traced the lines back to the power supply at that junction from the PCB. There is is low voltage in all the lines both on the board all the way back. There is no voltage difference in between. So it is not the pcb, wires, or their connectors. However, I will test the board with another 5v supply.
 
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I traced the lines back to the power supply at that junction from the PCB. There is is low voltage in all the lines both on the board all the way back. There is no voltage difference in between. So it is not the pcb, wires, or their connectors. However, I will test the board with another 5v supply.

+4.87v is plenty good enough for that board to run.
The +12v is only for the Audio Output, which will also run fine at +9.43v.

My machine has low +12v also, not a big deal.
Try flipping the switch that's located next to the fuses so that it points away from the fuses. See if that helps your voltages.
It shouldn't make your Game PCB have graphical issues, though.

By the looks of the schematic, I can remove the transformer and keep the rest of it to keep the monitor powered.

You can't pull the transformer for the monitor out. You can pull the 9V transformer out, and replace the +5V & +12V with a switching power supply and a custom wiring harness. You would pull AC from the Line Filter, and wire the DC voltages to the correct pins on header 12P.
(again, this might not solve your graphical issues. you should test this before puling the transformer and hacking up the original wiring.)

EDIT: Now that I think about it, mine only has one transformer with two windings. It does both the monitor and the 9v, which means that you can't remove the Transformer anyway. You can bypass it, but you'd need to find another spot for the switching power supply.
 
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+4.87v is plenty good enough for that board to run.
The +12v is only for the Audio Output, which will also run fine at +9.43v.

My machine has low +12v also, not a big deal.
Try flipping the switch that's located next to the fuses so that it points away from the fuses. See if that helps your voltages.
It shouldn't make your Game PCB have graphical issues, though.



You can't pull the transformer for the monitor out. You can pull the 9V transformer out, and replace the +5V & +12V with a switching power supply and a custom wiring harness. You would pull AC from the Line Filter, and wire the DC voltages to the correct pins on header 12P.
(again, this might not solve your graphical issues. you should test this before puling the transformer and hacking up the original wiring.)

EDIT: Now that I think about it, mine only has one transformer with two windings. It does both the monitor and the 9v, which means that you can't remove the Transformer anyway. You can bypass it, but you'd need to find another spot for the switching power supply.
Thanks, I'll pull the board and start searching more. So far I have changed out some of the memory, fix a cold solder joint and got sound back, tried new set of ROMs, I'm getting to a level that is becoming out of my depth. I'm determined to fix this bloody thing though. Thanks for your input. It really is appreciated even if my frustration is coming out.
 
Well tried a test Moon Cresta Test ROM. It went through the tests it got to the end it says Ram Stuffed0. It also had a solid tone running the whole time. It passed Ram, ORam and VRam but said RAM Stuffed0 at the end.Ran the test a second time makes it through the RAM, ORAM and VRAM. The it gets flakey, runs what I assume a sprite test there are no sprites, just numbers and it never ends, it keeps going. Not sure what that is about. BTW.. This is a weird board SMC-2FJ, Which is supposed to be a Super Moon Cresta. I'm not sure the MC-1 Schematics completely Line up.

 
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