New road blasters problem.

THEDJ

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I have been working on an atari road blasters.
When i turn it on, The graphics are all messed up, see photo.
road blocky, and car all messed up.
all the words look fine, anly the graphics messed up.
sound all works.

i have buit my own power brick, as the game did not have one.

new transformer for the ar board.
transformer for the monitor.
switching power supply for the pcb board.

i did not hook up the - sync wire, or the - sync. as i was told they are not needed. and i am not sure where they hook too.
voltages all at 5, and now, i am working on cleaning/seating chips, so far not working.

any ideas?

thanks
chris
 

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Sometimes you might need to go over +5 due to voltage drop. 5.10 - 5.2. Cleaning and reseating the chips is a start.
 
I apologize for the necro bump but......

My Roadblasters is now doing the same thing as the OP's. It worked as it should several months ago but exhibited the above when I booted it up last week. Has anyone dealt with this issue and resolved it? Any help would be appreciated.

Thanks

Bob
 
I apologize for the necro bump but......

My Roadblasters is now doing the same thing as the OP's. It worked as it should several months ago but exhibited the above when I booted it up last week. Has anyone dealt with this issue and resolved it? Any help would be appreciated.

Thanks

Bob

Have you tried booting it up with the test switch on to see if you get any ROM errors?

The ideas already mentioned still apply: Most importantly - check the 5v rail at multiple locations around the boards.
Re-seat the entire ROM cartridge (clean the edge connector if needed).
Try re-seating the ROMs on the cartridge.
 
I too am having this exact problem with a cockpit. I have already tried reseating all the chips and ribbon cables, all of the 5v test points are reading 4.9v, with the power supply set at 5.1v. Test mode does not produce any rom errors. Has anyone found an answer to this?
 
There are four identical graphics chips on the daughterboard that are called SLAGS chips in the schematics. They are large, maybe 40 pin chips. You can tell them from the eproms or masked proms because they don't have the game number and a sequential number

like 136030-010
That would be one of the eproms.

Anyway, something wrong with one of these SLAGS chips will wonk out the display and keep the game running. You can swap them from socket to socket and the graphics issue will usually differ from the original position.
 
Looking at the schematics, I can't find anything referred to as a SLAG chip. I have found several breeds of chips with 40 pins. There are 5 that are labeled 137419, then a dash followed by 101 to 104, and there are two 102's, one of which looks to have been hacked. Anyway if I try switching these around there is either no difference, a blank screen or the game simply won't boot.
 
OK I see them. They arent 40-pin though, looks like 32. Either way swapping those around makes no difference.

Heres a video I made if that helps any. Skip to about 6:00 or so and you can see what the screen looks like.
 
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If this is, in fact, a board issue, are we sure that its just the Roadblasters cartridge or could the problem lie somewhere in the system pcb? Anyone fix this problem and can offer some insight.
Any/all help is appreciated.

Bob
 
After checking and adjusting the power supply, cleaning contacts and reseating every chip on the RB Cart (with no change to the graphical problem) I bought a replacement today. We'll see how it goes. I'll give you all an update when I have one.
 
If this is, in fact, a board issue, are we sure that its just the Roadblasters cartridge or could the problem lie somewhere in the system pcb? Anyone fix this problem and can offer some insight.
Any/all help is appreciated.

Bob

It's possible a PROM may have failed. There are two at the bottom of the cartridge by the edge connector. The one at location 6A feeds a decoder for the graphics EPROMs.

Pulling this PROM on my board makes the graphics look exactly like your video.
 
When I pulled the PROM at 6A I noticed a change. While it didn't solve my problem (my issue is less about missing graphics and more about distorted ones)I did notice that pulling the chip caused many of my graphics to disappear (pretty much everything but colors and words...no car, opponents, turrets, etc.)

Since I was in the neighborhood, I pulled the PROM at 5A just to see. When I did the jagged and blocky graphic issues that I have been experiencing went away. Unfortunately, so did some of my colors. Clearly this chip at 5A is imperative to the graphical function of the machine, but I feel that since my original issues went away after pulling it I may have a faulty PROM in there.

So.... the removable PROM at 6A (there's a soldered chip sharing 6A as well but I assume that the removable is the one that warerat was talking about) seems to control the placement of many of the graphics including cars, and the like. If you are experiencing missing graphics of this sort, this chip could be your issue.

Pulling the chip at 5A seems to stop the jagged and blocky graphics(around the track for example) but also removes colors and creates a scan-line effect in the graphics.
For my case, this PROM might be the culprit but I suppose I won't know until I can compare it to another board.

BTW...looking at Keith's video again, that cab seems to have both blocky and missing graphics so there may be more than one chip on there that giving you trouble.

Sorry for the run-on here but in my searches for a solution to my problem I've seen many dealing with a similar issue. I get a sense that we are finding the source of these problems. Hope this helps...at least to find the area on the board that is acting up.

Cheers
Bob
 
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Resolved my issue today. Got a replacement board from Atari Force (fellow KLOVer...thanks Brian). While the untested board was not working all the way i was able to swap SLAG and other graphics chips until I found the culprit. For me it was the SLAG at 5H on the board (the chip furthest from the edge connector).

Suckers working like a charm. Now if I could only find a nice burn-free replacement monitor...hmmmmmmmmm.
 
Is that on the main board or daughter board? I have a lead on a working daughter board from an upright and am wondering if parts from it might solve my problem.
 
I was going to say it had to be a eprom or maybe even a scratch on the board. But since you had removed the 1 eprom and changed the effects we knew it was a eprom. I would have then pulled every eprom and verified them with the original MAME roms.
 
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