Joust - Garbage Text

advans13

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joust garbage, and/or corrupt? text. background - i was testing a robotron rom board in the joust, to verify it was the robotron rom board in that unit that was effing it up....now that it was i replaced it with another.

i go to reinstall my joust rom board, and i put connector 2j4 (goes to the sound interface board) down by one pin, effectively putting pin 1 on pin2 and leaving the last pin off the header. i didn't notice the problem until i turned the machine on and was greeted to corrupt text - including i believe all systems operational in garbage font :). i proceeded to the game mode fine, as well as playing the game fine to see where else the problem was.

again, all sprite graphics were good....except the text characters (score, words, etc) in all aspects of the game. the only graphic sprite based glitch was when you die, and come back the energy field do-dad that surrounds you is unrecognizable. sounds are all good as well. machine was reading "0" on the led display via the rom board. as far as the game was concerned it was fine.

i first thought i hosed a rom, so i swapped one by one with a pre-burned ste and powered up the game with no change from each swap. i also swapped the special chips, decoder proms and cpu for fun with no changes.

i then suspected the rom board cable, and noticed that pin 40 on the cpu side (header) was bent and not inserted in the female side of the cable. went to correct the pin and it snapped off. i think pin 40 is the ground? game still plays with no issues.

things i havent done and will be doing tonight; swapping in a working robotron rom board to test if its the cpu or rom board issue, and vice versa with the cpu board. additionally, was the problem really caused by the 2j4 mishap?

any ideas in the meantime?
 

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Unless you are getting Rom errors detected during startup, I do not think a Rom board replacement is going to help. Try to get into the test setup and walk thru the tests.

Kirk S.
 
Unless you are getting Rom errors detected during startup, I do not think a Rom board replacement is going to help. Try to get into the test setup and walk thru the tests.

Kirk S.

i can get into test fine, i just can't read anything =p....looks like pin 40 is not the ground according to the schematic.
 
so pin 40, i salvaged a pin from another ide connector, heated it and pushed it in the header. temp fix, but the corruption is gone.
 
pin-40 from the ROM / blitter board is the #WINHU (write inhibit upper) line from the upper blitter chip. A very critical pin! I don't see how the sprites would be unaffected since the blitter draws all text and movable graphics (sprites). Could be a side affect of the way the graphics are laid out and how the pin behaved when it was floating (not connected).
 
yup, i saw that after i read the schematic more clearly....but i couldn't make out what it said on the online copy.

i swapped in my robotron cpu board and the problem went away. so i did the pin hack until my new header comes in..... temp fix still was going 3-4 hours in last night.

yup, the sprite thing was odd...except for the one that was tweaking.
 
The only other time I have seen this was when someone had reseated the DMA chips on the ROM board and had bent one pin under.

ken
 
I'm having this same issue. I've got continuity from pin 40 (2J1) on the back of the ROM board to ground on the the CPU board...does that mean I can rule this out as the cause?

Yellowdog, which are the DMA chips?

Additional info: when this first started happening, the game could warm up and the issue would go away. Now it doesn't matter how long it warms up, still garbage text. I've also got a new switching power supply installed. As well as 4164 RAM with Bob's adapter.
 
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The DMA chips are the two 40 pin chips on the ROM board. Stargate doesn't have them.

If you have a switcher installed, check the voltages at the RAM chips. Then adjust the PS to 5.0V at the RAM chips.

ken
 
The DMA chips are the two 40 pin chips on the ROM board. Stargate doesn't have them.

If you have a switcher installed, check the voltages at the RAM chips. Then adjust the PS to 5.0V at the RAM chips.

ken

Voltage was at 4.98 and 4.97 for all 12. Adjusted it to 5.01...no difference.
 
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