A1200 display issues with Dbl and productivity modes

[Betelgeuse]

I have a weird issue with an A1200. Whenever I try to use some productivity and all Dbl modes on a multiscan monitor I get half of the screen or less showing up. When I drag the screen down past the point where there is no image (just background colour) then the image shows up on the bottom half. It's an A1200 1D.1 revision with 2MB RAM and vanilla config Workbench 3.1 and KS 3.1, tried with an 060 board and some RAM and same issue. Monitor and dongle are fine as my other Amigas show the display properly.

[tone007]

Possible bad overscan settings?

edit: though that might not explain why the image shows up after dragging the screen down...

[Betelgeuse]

I had a thorough look at the board and the capacitors around the RGB port have all leaked, there doesn't appear to be board damage but could the bad capacitors cause this sort of issue?

[Thorham]

I had a thorough look at the board and the capacitors around the RGB port have all leaked, there doesn't appear to be board damage but could the bad capacitors cause this sort of issue?

Doesn't matter, because you should get this fixed a soon as humanly possible, or your A1200 isn't going to work for much longer. Easiest way is probably Amigakit (capacitor replacement service).

[Cammy]

There's a bug in the A1200 design which causes this, and although you should replace your caps it might still persist. The cause is sometimes the E123R or E125R resistors. You could try shorting them with a screwdriver while Workbench is running in one of these screenmodes, and see if it improves the image. Some people solve the problem by removing the culprit resistor.

Another solution is to change your palette. The flashing and blanking you're experiencing is caused by the black and white shades in your palette, as well as possibly other shades. 255,255,255 white will do it! The best way around this is to download and install FullPalette and use Rebel's 16 colour palette with it, making sure to lock every pen so it keeps them after a reboot. Just make sure you set your screenmode to 16 colours, you won't need more than this when using this optimised palette.

[Betelgeuse]

I don't think that's the same issue Cammy as there's no flashing or any blinking or anything, it's just half (or less) of the screen shown. I'm aware of the A1200 bug and it's just not the same thing.

[Thorham]

I wouldn't worry about this for now, and just get those caps replaced (or do it yourself .

[LaserBack]

that is not a capacitor issue or timing issue or something like that

it seems there is a problem in workbench config or monitor drivers
also something wrong on icontrol preferences

on the other way the 1.d1 are the worst motherboards ... were done in hong kong some of them comes with bad cias which produces bad cia timers and other timing issues but nothing related to caps

[Thorham]

that is not a capacitor issue or timing issue or something like that

The OP says the caps are leaking in the second post, so I think it's more important to address that issue first, or there will be no more A1200 to fix the monitor issue for.

[Betelgeuse]

that is not a capacitor issue or timing issue or something like that

it seems there is a problem in workbench config or monitor drivers
also something wrong on icontrol preferences

on the other way the 1.d1 are the worst motherboards ... were done in hong kong some of them comes with bad cias which produces bad cia timers and other timing issues but nothing related to caps

It's definitely a hardware issue not a software issue as a clean install of 3.1 exhibits the exact same problem.

[bbond007]

There's a bug in the A1200 design which causes this, and although you should replace your caps it might still persist. The cause is sometimes the E123R or E125R resistors. You could try shorting them with a screwdriver while Workbench is running in one of these screenmodes, and see if it improves the image. Some people solve the problem by removing the culprit resistor.

Another solution is to change your palette. The flashing and blanking you're experiencing is caused by the black and white shades in your palette, as well as possibly other shades. 255,255,255 white will do it! The best way around this is to download and install FullPalette and use Rebel's 16 colour palette with it, making sure to lock every pen so it keeps them after a reboot. Just make sure you set your screenmode to 16 colours, you won't need more than this when using this optimised palette.

Cammy I _think_ to fix the video issue you short  E127R.

and I _think_ the ones you mention are timing fix for accelerators.

I might be wrong, or it might vary by motherboard, but that seems to be what I recall anyway.

[Thorham]

Wow, this persons CAPS ARE LEAKING, and no one seems to be concerned about it. NOT COOL

[LaserBack]

It's definitely a hardware issue not a software issue as a clean install of 3.1 exhibits the exact same problem.

ok but that fault it is not related to caps
it is related to the buggy 1.d1 motherboard and bad cias

the 2 big caps 1000mf near the modulator are to smooth the 5v line and the other smallest near the rf modulator 470mf is the one for composite video
nothing related to that bug
the other small caps are for different functions like 2 of them to smooth the 12v line 1 to smooth the 5v line in the IDE port,other to smooth the -12v line and other 2  are there for the sony chip

to confirm this:

try for example the game "arabian nights" which uses cia timers....
if the game works correctly with music....that's ok
but
if the game crash or works without music...you have a big problem

[Thorham]

Ha ha, you guys just keep on going about the problem, while this persons A1200 is slowly dying. How ignorant can it get? Well, who cares, as long as the problem is solved, the fact that this persons caps are leaking which can kill this A1200 doesn't matter at all

Seriously, this ain't funny Just keep using that A1200, and pretty soon another one will go to waste

[Thorham]

if the game crash or works without music...you have a big problem

I think the problem is a lot bigger than some mobo bug :hammer: