Joust and Galaga problems

Joshuart311

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Ok, so I just aquired a joust and a bosconian galaga. Lets start with the joust. It has the usual battery problem. everything else looks good and complete. When I fire it up it the three led lights on the board come on and it displays and 8 in the digital display. Anyone have any idea what that means? On to the galaga. The galaga comes up and now is displaying a split screen with random garbage. it has a bootleg galaga pcb in it. i checked my roms and 3j was not found. The first time I turned it on, it had shown a full screen of random garbage. Then it went to a screen that looked that stars in the background. It displayed at the bottom

Ram ok
Rom FE

It was showing it upside down.
Any help will be greatly appreciated. Also shout out to Gsrogers for selling me these machines. I can't wait to be able to play them
heres a pic of what it did the first time it was turned on(galaga)
 

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If reseatiing the ribbon cable doesn't help. Pull the ROM card and if you have a ROM burner, verify the ROMs. On power up the default is to have all LED segments light up (just to verify that none are burned out). They should go out and the RAM test (the "rug" pattern on the screen) should start. If the LED is not going out and the RAM test isn't starting, either one or more of the ROMs are bad or the CPU chip is bad or it is locked into reset mode by the watchdog circuit freaking out.

You can check the watchdog circuit if you have a logic probe. Test pin 37 (NOT RESET) on the CPU chip. If it is pulsing, you need to debug the watchdog circuit. If it is high, you should be good. Press the reset button while you have the probe on the pin and it should go low for 1 sec then high again.

ken
 
I tried the ribbon cable. No change. Checked all my Roms on romident and they were good. I have ordered a logic probe but it hasn't come in yet. So I guess there's nothing I can do til the logic probe arrives.
 
ok, so while im waiting on my logic probe to arrive. I've decided to check out the galaga. I pulled some of the custom chips. They are in terrible shape and most have leg rot. So on a couple of them the legs are missing. Do I have to repair these legs, or is there a place I can buy these chips? Would I have to buy a complete board and rob the chips?
 
ok, so while im waiting on my logic probe to arrive. I've decided to check out the galaga. I pulled some of the custom chips. They are in terrible shape and most have leg rot. So on a couple of them the legs are missing. Do I have to repair these legs, or is there a place I can buy these chips? Would I have to buy a complete board and rob the chips?

Those custom chips can be repaired..provided they are not in too bad a shape. Not sure these days on finding custom chips...when I ran into this problem years ago, I had no luck finding just replacement ones....maybe that's changed. Good luck.
 
If reseatiing the ribbon cable doesn't help. Pull the ROM card and if you have a ROM burner, verify the ROMs. On power up the default is to have all LED segments light up (just to verify that none are burned out). They should go out and the RAM test (the "rug" pattern on the screen) should start. If the LED is not going out and the RAM test isn't starting, either one or more of the ROMs are bad or the CPU chip is bad or it is locked into reset mode by the watchdog circuit freaking out.

You can check the watchdog circuit if you have a logic probe. Test pin 37 (NOT RESET) on the CPU chip. If it is pulsing, you need to debug the watchdog circuit. If it is high, you should be good. Press the reset button while you have the probe on the pin and it should go low for 1 sec then high again.

ken

Ken, I tested pin 37 and it was low. I'm looking now for some joust schematics. Any Other suggestions?
Thanks
 
found I only have 4vdc coming to the galaga pcb. going to install a switcher on it in a few days. that should fix it right up. also i tested the joust power supply. im only getting 3.86 volts to the pcb. i can unplug it from the power supply and test power supply pins and have 5vdc. when i reconnect it is only the 3 at the board. is it a bad power supply dropping voltage under load or is it a bad wire?
 
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Check your wires and reflow your connection pins on the PCB

I checked the wires last night they look good. I even ohmed them out. If I unplug the harness from the joust board I have 5v. But when I plug it in and test the board or even just the 5v wire it drops voltage. I will try to reflow those pins today. It snowed here and it shuts this town down. So I have all day to play with my games.
 
I checked the wires last night they look good. I even ohmed them out. If I unplug the harness from the joust board I have 5v. But when I plug it in and test the board or even just the 5v wire it drops voltage. I will try to reflow those pins today. It snowed here and it shuts this town down. So I have all day to play with my games.

9 times out of 10 this is caused by a bad header or bad connector
 
If you have the small caps handy, try replacing the small caps. The other thing to check are the fuse clips. I have had power supply boards in the past that would do that and I finally traced one back to a cap that would partially short when it was under load (IIRC it was C16, a 100mfd 25V cap).

Most of the others were traced back to a bad fuse clip. Corrosion or a fuse being loose in the clip will not allow enough current to flow and the voltage will drop to compensate.

ken
 
Update

Galaga is now fully functional with the exception of the player one start button not working.
I'm going to order the power supply rebuild kit for my joust and also all the connectors. I feel that is a good place to start. I will update as soon as I get my parts installed.
 
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