Regards to community,

I am having trouble with one of my amigas. Escom A1200 with blizzard 1230MK4 is cosing me some serious graphics problems. When amiga is working in PAL mode everything is working OK, but if I try to use dblPAN, dblNTSC, on lower right part of monitor screen I get artefacts (parts of screnn doubled and blinking). When I use Multiscan productivity, it gets even worse. Whith emerging of artefacts, screen is unusualy dark. I have tried MV1200 scandoubler and blizzard 1230 in my other amiga and everything work perfectly. What could cause these problems, and is it solvable?

I tried installing OS3.1 only, and tried to run T-Zero game from CD so I could see if artefacts are apearing while the game is running, but everything works like charm. So I presume that problem is with higher frequencies?

Thanks for your help!

@amigappc

this kind of problems were common with escom a1200 as far i recall. i have even seen some on display in the store that shown similar behaviour. guess why none wanted to buy them. i believe there is some simple electrical solution to that as to solder an capacitior somhwere or something like that but unfortunattelly i do not recall now. its so long ago..

Last edited by wawa on 07-Oct-2008 at 09:02 PM.
Last edited by wawa on 07-Oct-2008 at 09:01 PM.

@amigappc

Open the case and check the Capacitors see if any are leaking.
Higher frequency artifacts are a sign of improper filtering or bad chip RAM.
See if the errors appear when chip ram get low or if it is just a case of higher scan rates that cause problems.

kgrach

Thought this problem only occured on early C= A1200. I think there is a software fix on Aminet, i'm not really sure what it does but it worked for a friend which had en early C= A1200.

Found this file http://us3.aminet.net/docs/hard/flickerfix.readme hwfix though.

Tried searching for the software fix but i cannot remember what it's called. :/

Last edited by fryguy on 07-Oct-2008 at 09:27 PM.
Last edited by fryguy on 07-Oct-2008 at 09:07 PM.

@fryguy

This sounds pronising, I've just looked inside file and there is picture which doesn't say alot. Does someone knows will this help and does someone have larger picture with exact explanation what to do?

Has anybody here tryed this?

@amigappc

I agree, not much info there. Perhaps you could try asking on amiga.org, maybe someone there knows.

I just opened this A1200, capacitors are in great shape, motherboard is revision 1D4.

I just find this page:

http://www.ianstedman.co.uk/Amiga/amiga_hacks/A1200_Mobo_fix/a1200_mobo_fix.html

Do I neet to try fix from aminet and fixes from this page one of this two?

I dont want to fry this amiga....

Well,

This is the picture I've found:

http://eab.abime.net/showthread.php?p=462797

But as I can see on my motherboard resistor E127R is in place, so do I need to remove it and solder directly (without restistor?

Regarding page with mobo fixes I posted, E123C and E125C are not connected on my motherboard...

Does any hardware guru reads this maybe?

@all who can help

Status on my motherboard regarding upper images:

E126R FILLED
E126C FILLED
E127R FILLED
E127C FILLED
E125R OPEN
E125C OPEN
E123R OPEN
E123C OPEN

Now this document written in russian says:

http://faqs.org.ru/hardw/non_pc/amiga.htm

AltaVista translation:

"Sufficiently known problem Of eSCOM[ovskikh] machines (on The commodor[ovskikh] it practically it was not manifested). Strips appear next to the colors, in RGB which are established 23 bits and more. This is treated as follows: it is necessary to short out resistor E127R and to remove capacitor E127C. They are located on THE LOWER side of pay, approximately under the chip Of alice. If you are not inclined to consider yourselves as that sufficiently qualified for this operation, better you will turn yourselves to someone more experimental."

Is this solution for my motherboard? Remove E127R and connect it directly, and remove E127C?

Any expirience?

Quote:

by amigappc on 7-Oct-2008 22:48:28 @all who can help Status on my motherboard regarding upper images: E126R FILLED E126C FILLED E127R FILLED E127C FILLED E125R OPEN E125C OPEN E123R OPEN E123C OPEN Now this document written in russian says: http://faqs.org.ru/hardw/non_pc/amiga.htm AltaVista translation: "Sufficiently known problem Of eSCOM[ovskikh] machines (on The commodor[ovskikh] it practically it was not manifested). Strips appear next to the colors, in RGB which are established 23 bits and more. This is treated as follows: it is necessary to short out resistor E127R and to remove capacitor E127C. They are located on THE…

Yes, based on the Russian FAQ link you provided. The advice is to short out resistor E127R (and likely also capacitor E127C) located under the chip labeled "alice" on your motherboard's lower side which might be causing striped RGB issues in eSCOM machines, but it suggests consulting someone more experimental if you are not comfortable with this.