A500 Plus graphical glitches

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dougal

dougal

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I noticed it in Lethal Weapon in Whdload mostly. Sometimes it can do it in Workbench too.

I also tried Lethal Weapon disk and same problem.

Disconnected 1MB ram expansion
Disconnected A590
Removed Indivision
Removed 68010 and put 68000
Replaced Denise with another one from another 500 Plus
Replaced Kickstart with another one
Replaced one of the CIA's (Left one)

Does not fix the problem.
 

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The glitch seems to show up rarely in Workbench and almost always in Lethal Weapon and it isn't always exactly the same/as much
 
I would suggest loading this game from floppy as it might be a SLAVE issue.

Also ensure that NOCACH and other options are turned off - I would even suggest trying to load it without PRELOAD but I believe thats all default now.

If you are still having a problem then I would humbly suggest cleaning the Agnus socket and if that doesn't alleviate the issue it might be a good time to replace the capacitors - should that still not yield satisfactory results then its time to replace the CHIP RAM.
 
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It's very clean and I had removed the battery at the very beginning of leak. Motherboard looks undamaged. I'll try cleaning the 8375 socket first as you said.
 
I had a similar problem with a late ECS A500, turned out to be a dodgy Agnus chip in the end.
 
I'd run a memory test to see if chip ram is good or not. Those glitches look like memory read errors which could happen either in the RAM chips, Agnus or other interface ICs.
 
Well I can try the Agnus from a damaged 500 plus I have and run a mem test using the A590 disk. Will post back

---------- Post added at 19:56 ---------- Previous post was at 19:48 ----------

Agnus!!! Thanks :)
 
This is what happened to my A500 with the dodgy Agnus
picture.php
 
Does mouse cursor show corruption in WB? It practically guarantees broken Agnus chip if it also happens with Indivision.
 
dougal has confirmed in his post above that swapping Agnus has fixed the issue, I just posted my pic to show how bad mine was when I had the same problem.
 
Thing is on mine the problem hardly ever showed in WB and almost never showed up in nearly all games except Lethal Weapon and maybe once or twice in Risky Woods and Alien Breed Special.

Would it eventually get worse ?
What causes the Agnus to go bad ?
Is it possible to program a CPLD as an Agnus ?
 
dougal said:
Would it eventually get worse ?
What causes the Agnus to go bad ?
Is it possible to program a CPLD as an Agnus ?
Click to expand...
IC's mainly gets worn by heat. So the longer it has been running, the sooner it will fail. It could also be ESD, although Agnus is not close to any connectors (maybe an ESD zap on the trapdoor connector could reach Agnus?).
It is very possible to replace Agnus with a programmable IC, but it is not likely very cost effective to do that. :) If you look at Minimig, they have Agnus implemented in the FPGA, although that is together with all the other ICs.
 
Hmmm I think I need to be more careful when working on my Amiga's. Need to start wearing my anti-static wrist strap etc..
 
Keeping one hand connected to ground (bottom shield or floppy housing if connected to motherboard) while you work on it will also provide some level of protection, although a wrist strap is a little more convenient. Also don't wear synthetic clothes or wool.
 
While I agree that we should all take precautions, the Agnus is not statically sensitive, so it might be overkill to ground yourself during your work.... unless you wear nylon tights of course ;)

As mentioned above its HEAT thats the problem and the end to all integrated circuits.

With exception to one 8370, I am yet to come across an Agnus that has failed without other fault on the board - be that incorrectly inserted or battery acid.

Give it a good clean with IPA, ensure the socket is also clean, and then install the Agnus and see what you get. I suspect that this is a CPU/SLAVE/CACHE issue before I go and blame the Agnus.

you wouldn't happen to have FBLIT installed / active?

Remember its best to do the simple (non-costly) things first before costing out for parts and upgrades ;)
 
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Scratch that bit about upgrades...


Upgrades are cool! you should get them ;)
 
Zetr0 said:
you wouldn't happen to have FBLIT installed / active?
Click to expand...

No FBLIT installed here.

I won't be throwing the AGNUS away, like you said i'll give it a good clean and test it again. I've also got another spare 8375 and 8371 which i think don't work but i'll give them a good cleaning too.

Also bought another 8375 (for A500 plus) from the other bay just to keep as a spare. Jeez they have shot up in price in recent years.
 
Men with tights

Men with tights

Zetr0 said:
While I agree that we should all take precautions, the Agnus is not statically sensitive, so it might be overkill to ground yourself during your work.... unless you wear nylon tights of course ;)
Click to expand...

That explains then...
 

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