A1200 graphics corruption

11 November 2013, 21:51

hi!

I recently bought an A1200 on Ebay (no fastmem or any expansion board) and unfortunately it has some graphical issues

Right after booting Workbench, there is a "mirrored" mouse pointer (see screenshots), not only in WB, but in Theme Park and other games too. I tried Zool 2 (original disks came with the package) and it is messed up too: I try to move but in some seconds the graphics become corrupted.

What's this error? Is it repairable?

Any suggestion appreciated!

voyager · 11 November 2013, 23:00

I don't know why but my gut feeling thinks its a memory corruption. You can download a memory checker and let it run overnight

jimbob · 11 November 2013, 23:25

A coder who knows the hardware well can probably tell you better but it looks like sprite data for the mouse pointer is being copied to a bunch of lines it's not supposed to be on. Suggests a custom chip fault to me.

A couple of things to try just to see if the behavior changes.

Try some different screen modes in workbench, see if the fault changes or goes away.

See what happens when you use the mouse pointer prefs program to change the pointer graphics.

Loedown · 12 November 2013, 09:34

Check the power rails and certainly the voltage level on the pins of Lisa and also the noise content. Less likely to be Alice as it's a sprite problem mostly.

Also check the state of the capacitors near the video stage ( top left board corner ) and also the ram could also cause similar faults but with that you would more likely see faults across the board ( no pun intended or implied ) as in problems writing disks and corruption errors.

It could also be a bad joint but this is more unlikely.

All errors are repairable but it's just how much time and effort it will take.

Szia!

13 November 2013, 08:33

I tried to change the screen mode, tried with another PSU, but graphics still corrupted, probably Alice, chipram or capacitor problem as you said. Try to find an expert who can fix it.

Thank you all!

Loedown: szia! :-)

Loedown · 13 November 2013, 10:28

Closest to you would be Tomcrazy66 ( Croatia ) or Stachu100 ( Poland )

I could do it too but live 16,000 km away and postage costs are astronomical too / from Hungary.

11 November 2013, 21:51	#1
aboy Posts: n/a	A1200 graphics corruption hi! I recently bought an A1200 on Ebay (no fastmem or any expansion board) and unfortunately it has some graphical issues Right after booting Workbench, there is a "mirrored" mouse pointer (see screenshots), not only in WB, but in Theme Park and other games too. I tried Zool 2 (original disks came with the package) and it is messed up too: I try to move but in some seconds the graphics become corrupted. What's this error? Is it repairable? Any suggestion appreciated! Attached Thumbnails

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Graphics corruption on scrolling	demolition	project.WHDLoad	3	11 November 2012 23:50
A1200 Graphics Corruption	darkwave	support.Hardware	10	07 November 2011 18:10
Graphics corruption on Lotus 2	azy	support.Games	4	15 November 2006 14:49
Graphics corruption	Minuous	support.WinUAE	9	21 July 2005 17:42
Graphics Corruption	DW7	support.WinUAE	3	09 November 2003 01:45

11 November 2013, 23:00	#2
voyager The show must go on. Join Date: Dec 2010 Location: Alkmaar Nederland Posts: 269	I don't know why but my gut feeling thinks its a memory corruption. You can download a memory checker and let it run overnight

11 November 2013, 23:25	#3
jimbob Registered User Join Date: May 2006 Location: Kilmacolm Age: 46 Posts: 632	A coder who knows the hardware well can probably tell you better but it looks like sprite data for the mouse pointer is being copied to a bunch of lines it's not supposed to be on. Suggests a custom chip fault to me. A couple of things to try just to see if the behavior changes. Try some different screen modes in workbench, see if the fault changes or goes away. See what happens when you use the mouse pointer prefs program to change the pointer graphics.

12 November 2013, 09:34	#4
Loedown Precious & fragile things Join Date: Feb 2009 Location: Victoria, Australia Posts: 1,946	Check the power rails and certainly the voltage level on the pins of Lisa and also the noise content. Less likely to be Alice as it's a sprite problem mostly. Also check the state of the capacitors near the video stage ( top left board corner ) and also the ram could also cause similar faults but with that you would more likely see faults across the board ( no pun intended or implied ) as in problems writing disks and corruption errors. It could also be a bad joint but this is more unlikely. All errors are repairable but it's just how much time and effort it will take. Szia!

13 November 2013, 08:33	#5
aboy Posts: n/a	I tried to change the screen mode, tried with another PSU, but graphics still corrupted, probably Alice, chipram or capacitor problem as you said. Try to find an expert who can fix it. Thank you all! Loedown: szia! :-)

13 November 2013, 10:28	#6
Loedown Precious & fragile things Join Date: Feb 2009 Location: Victoria, Australia Posts: 1,946	Closest to you would be Tomcrazy66 ( Croatia ) or Stachu100 ( Poland ) I could do it too but live 16,000 km away and postage costs are astronomical too / from Hungary.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)