Amiga 500 Video Problem

[Kadir]

Hi all,

I have a problem with my (stock) A500 tried to show in video at the end of my post.

This problem occurs in some games, but some games works without any problem. Lotus-1 in this video an example of worst one.

Also some games lose picture and black screen after intro menus etc, but sound continues, like James Pond-2 Robocod, some has no artifact like Lotus-1 but resets machine itself when level started, like Pal modded DynaBlaster.

Finally, some games are completely fine, like Agony, Giana, Swiv, PP Hammer, Twintris.

I tried until now:

- Remove all socketed chips and clean them and sockets with Locktite Contact Cleaner spray,

- Re-capped 6 electrolytic caps near the Agnus, Denise and 68k,

- Tried different and more quality ATX power supply, (my Amiga works with PC psu)

- Tried composite out, same problem present here too,

- Sand papered Denise's pins

And problem not solved.

BTW i checked all games in Winuae and all of them ok in emulator,

Also i am using Gotek and SysInfo shows Kickstart v34.5, conected to hp monitor via OSSC; maybe these info helps too.

So, i am suspecting mine Denise or Agnus defected, what are your opinions, advices etc?

Thanks.

[ Show youtube player ]

Edit: Here some pics:

[solarmon]

Was it working OK before the recap?

Use Amiga Test Kit to do some health checks and run a long memory test on it.

https://github.com/keirf/Amiga-Stuff

[torsti76]

Originally Posted by solarmon

Was it working OK before the recap?

Use Amiga Test Kit to do some health checks and run a long memory test on it.

https://github.com/keirf/Amiga-Stuff

Yeah, this looks like some kind of ChipMem problem.

[lesta_smsc]

Very unusual behaviour. Unless it is related to memory allocation and so yes Amiga Test Kit could help...

[Kadir]

Originally Posted by solarmon

Was it working OK before the recap?

Use Amiga Test Kit to do some health checks and run a long memory test on it.

https://github.com/keirf/Amiga-Stuff

No, i decided to recap because of that problem.

Thanks all, i will try that test stuff now.

[DigitalKeeper]

Have a look at the Agnus Socket, coz of contact problem's -> glitches

also possible - check traces to Data Path ICs and Chip RAM ICs

[Kadir]

How to use this memtest tool, it is working about 1 hour and not ends? Should i interrupt it or it will end automatically at one point?

[Kadir]

Originally Posted by DigitalKeeper

Have a look at the Agnus Socket, coz of contact problem's -> glitches

also possible - check traces to Data Path ICs and Chip RAM ICs

Ok i will check againg, thx. But i didnt notice any disconnected or defected trace until now.

[DigitalKeeper]

The most "curious" effects aka glitches, stuck, guru, came from contact failure - i.e. IC Sockets, corroded contacts, corroded solder blob's, corroded traces.

Have a look at dark/black Points on the traces....(I'll take a picture later)

If all is fine and glitches are on the playfield, a possible failure is Agnus; i had a similar failure here, and after a check with cooling spray on Agnus, the glitches where gone; at this point - Agnus was faulty, at my PCB here.

[Kadir]

Originally Posted by DigitalKeeper

The most "curious" effects aka glitches, stuck, guru, came from contact failure - i.e. IC Sockets, corroded contacts, corroded solder blob's, corroded traces.

Have a look at dark/black Points on the traces....(I'll take a picture later)

If all is fine and glitches are on the playfield, a possible failure is Agnus; i had a similar failure here, and after a check with cooling spray on Agnus, the glitches where gone; at this point - Agnus was faulty, at my PCB here.

Are you keeping cool Agnus? When chip is cool, artifacts gone?

[DigitalKeeper]

Yes, that's right (at my PCB here) I've changed Agnus with another one...

[Kadir]

Originally Posted by DigitalKeeper

Yes, that's right (at my PCB here) I've changed Agnus with another one...

Interesting

A friend of mine will send a complete chipset for troubleshooting, and i ordered a PLCC removing tool for replace Agnus again, i dont touch him again with screwdivers because it seems socket will crack this time. I am waiting for now.

[DigitalKeeper]

Be aware with the Agnus Socket

They are "fragile", coz of "Aging"

They would break easy....

[Kadir]

Chipset arrived, i tested one by one but problem does not resolved. Any suggestion from now on? I will continue recapping and search RAM chips (FAST?). Also I do the keirf's test before but was not sure my RAM's ok or not, i wrote it before. Test runned around 90 mins without any error and i think thats ok... Is that right way to test RAM or not? How should i do the test? Thx.

[solarmon]

90 minutes of 512K memory testing using Amiga Test Kit should normally prove that memory is OK.

The main suspect will Agnus, Denise and the video chip - and traces/components associated with it.

You have not swapped out Agnus yet, because you are waiting for the PLCC extractor?

Are you able to try the other video output - like composite (although, it will be in black and white) - to see if you have similar graphics corruption?

[Kadir]

Originally Posted by solarmon

90 minutes of 512K memory testing using Amiga Test Kit should normally prove that memory is OK.

Ok.

Originally Posted by solarmon

The main suspect will Agnus, Denise and the video chip - and traces/components associated with it.

You have not swapped out Agnus yet, because you are waiting for the PLCC extractor?

No, it is arrived too and i swapped the other Agnus (and also whole chipset), but problem is not resolved.

Originally Posted by solarmon

Are you able to try the other video output - like composite (although, it will be in black and white) - to see if you have similar graphics corruption?

Tried, same problem present in composite out too.

How can i test Vidiot?

[Kadir]

Nevermind, it resolved.

The problem was not actually a problem Mine A500 has only 512kB FastMEM and the color-gfx-display glithes i observed in some games was about it. We tried 512kB config @UAE and same thing happened in emulator too. Weird, i dont remember any issue something like this with A500 days from my childhood, or i was bought trapdoor mem expansion bundled with the machine and i always used 1MB A500, i dont remember...

Well, thanks everyone.

[solarmon]

A 'stock' A500 I would assum to mean it only has 512K of CHIP ram, not FAST ram.

Expansion in Emory in an A500 is normally allocated as SLOW ram, not FAST ram.

I'm confused now as to what memory configuration you have in your 'stock' A500.

[Kadir]

Yes my bad, i have stock A500 and it has only onboard 512kB RAM.

[solarmon]

Originally Posted by Kadir

Yes my bad, i have stock A500 and it has only onboard 512kB RAM.

OK, thanks for clearing that up.

So are you saying the video corruption issue for these games is because these games need more than 512K of memory?

What are these games and are they original or crack ones? I can test and verify whether it is happening on hardware and on emulation, if I know the details.

I assume you have Kickstart 1.3?