a600 video fault

[elmasta]

Hi! this a600 was the one I have had for over 16 years now. It had some problems with leaking capacitors which prevented the machine from booting. But, I changed the problematic ones and it worked.

However, when playing games, for example project x, the main sprite (the ship), the background and pretty much anything that moves flickers horribly. Its annoying as hell, and prevents me from playing any games

This graphics corruption happens only in games. Not in workbench. Also, the machine runs stabily with no crashes whatsoever. I find it puzzling and I have no idea what can it be.

I recorded these videos:
http://video.google.es/videoplay?doc...04101842&hl=es
http://video.google.es/videoplay?doc...22255698&hl=es


Thanks

[alexh]

Possibly a RAM fault. You sure these games EVER worked on this A600?? Have you upgraded the Kickstart?

[elmasta]

The games worked before, yes, it's the same machine I had when I was a kid.

If it were the RAM, wouldn't the computer be unstable? because I don't experience any random crashes.

No I didn't upgrade the kickstart.

[DDNI]

Are you using a PCMCIA SRAM card?

[orange]

there are several utilities on aminet for testing RAM

[elmasta]

Thank you for your suggestions and help.

When I recorded the video, the machine had only the floppy disk connected, and no extra ram. Just the 1mb chip. The behavior is with Proyect X (not SE) disks.

I ran a mem test with an old program I had, let it for 1 hour or so, and it did not report any problems.

Could it be a capacitor problem? because I didn't change all of them.

Then I connected the HD and the 1mb trapdoor expansion, and I ran Project X SE with WHDload, the behavior was worse than with Project X normal edition disks.

I did some more testing with other WHDload games but I could not reproduce this behavior. Note that the other games I tried werent so graphically intensive. I tried Alien Breed TA, Dyna blaster, and one intro and they ran ok.

[rkauer]

Yes, it can be a capacitor problem. Specially those near the video port.

[alexh]

And you 100% sure that this game, these particular disks, worked fine on this Amiga before?

[elmasta]

Originally Posted by alexh

And you 100% sure that this game, these particular disks, worked fine on this Amiga before?

Yes 100%. Were the same disks I used to play with back when I was a kid.

I think it's not a problem with the disks because when run it with whdload from harddisk (with downloaded image disks from projectx se) the video fault persists. And it's even worse with PX SE. There are changes in the colors of the pallete, making it completely unplayable.

However, it seems strange to me that other games run perfectly fine. I haven't tested much games for this defect, but I will.

Moreover, I did an exhaustive list of all electrolitic capacitors in the motherboard and checked the circuit they were part of in the schematics. But I can't find any link between the video fault and the suposedly faulty capacitors.

I am out of ideas regarding what this can be, any help is appreciated.

[FOL]

Originally Posted by elmasta

Yes 100%. Were the same disks I used to play with back when I was a kid.

I think it's not a problem with the disks because when run it with whdload from harddisk (with downloaded image disks from projectx se) the video fault persists. And it's even worse with PX SE. There are changes in the colors of the pallete, making it completely unplayable.

However, it seems strange to me that other games run perfectly fine. I haven't tested much games for this defect, but I will.

Moreover, I did an exhaustive list of all electrolitic capacitors in the motherboard and checked the circuit they were part of in the schematics. But I can't find any link between the video fault and the suposedly faulty capacitors.

I am out of ideas regarding what this can be, any help is appreciated.

Out of interest, whats turrican2 like (if you have it). Cause I have seen this type of corruption before, when testing with turrican2 CDTV version, on my real amiga. I had that problem cause I was trying to run it on kickstart above 1.3 and I removed the rmtm files from the startup.

As you say it happens on only certain games, it can be a bit confusing to decide wether its the machine or not. What about downloading, another version of ProjectX and see if that works. In theory, if its the machine, it shouldnt matter if you tried 10 different versions, they should all play up the same.

[alexh]

You can get a replacement A600 motherboard off ebay for £4.99

[FOL]

Originally Posted by alexh

You can get a replacement A600 motherboard off ebay for £4.99

At that price, proberly be simple to get it and rule it out completely.

[Damion]

Originally Posted by FOL

At that price, proberly be simple to get it and rule it out completely.

Careful though, the one I bought had caps that had leaked and destroyed pads and traces... this despite my asking beforehand about visible cap leakage

[elmasta]

@FOL
I have tried with downloaded games, Project X se was downloaded.


Here are two more vids showing sensible soccer, and body blows galactic.
(The quality is horrible because google vids re-encodes the material)
http://video.google.es/videoplay?doc...85380848&hl=es
http://video.google.es/videoplay?doc...11599110&hl=es

[FOL]

Originally Posted by elmasta

@FOL
I have tried with downloaded games, Project X se was downloaded.


Here are two more vids showing sensible soccer, and body blows galactic.
(The quality is horrible because google vids re-encodes the material)
http://video.google.es/videoplay?doc...85380848&hl=es
http://video.google.es/videoplay?doc...11599110&hl=es

Does seem odd, I would go with alexh's comment about getting another mobo. Unless you can see any damaged capacitors, and able to replace them.