Problem with my Atari 260 st

[talrek]

Hi,
i just bought a 260ST without power supply.
It is a 1MB modified , with internal german Tos.

I manage to connect an Amiga power supply to the Atari 260ST st power connector : GND, +5, +12 and -12
I posted picture , and the video is on its way on youtube.

When i power up the computer it makes a lot of black lines, and then i can see the floppy drives boot and it reads datas (on the video you can see it even loads a screen) but the the St craches...
This may be remind a specific issue to someone ? i checked things like memory, tos etc. with the diagnostic cartridge (see the picture below) ad it seems to be fine.
The only thing is that i don't use an original supply. I want to have advices before buying an expensive "original" power supply for nothing...

Thank you a lot.

 

[talrek]

Hi,

i feel stupid...

The 260ST works well now. When i put my tv on composite, it works well, when i put it in RGB, it doesn't work anymore.

So problem soldev, i didn't know 260ST were not RGB.... But i still don't understand why it works when a cartridge is inserted...

[exxosuk]

If RGB is going out of sync, then it sounds like this type of issue...

 

http://www.exxoshost.co.uk/atari/last/STFMSYNCFIX/index.htm

 

I've had white backgrounds go screwy, but darker ones like the desktop green work fine.

 

Though don't forget the video timings are a bit iffy with some monitors anyway.

[talrek]

Great !

I don't have all capacitors, but i have to order other components. So i'll try your fix, make pictures and post them here to see the result !

 

Thank you !

[English Invader]

If RGB is going out of sync, then it sounds like this type of issue...

 

http://www.exxoshost.co.uk/atari/last/STFMSYNCFIX/index.htm

 

I've had white backgrounds go screwy, but darker ones like the desktop green work fine.

 

Though don't forget the video timings are a bit iffy with some monitors anyway.

 

Very useful information. I have an STfm that gives me a grey screen on boot and flickering text in the GEM desktop when I use RGB or composite. The issue is cleared up when I use RF.

 

I've also been running my STe on a flatscreen (composite and RGB) and even when there is no power going into the ST the inputs cause a humming sound and when I fire up the computer there is a horizontal transparent line running down the screen. The ST is otherwise usable but I'm worried that continued use with those issues would damage either the ST or the television. Would you be able to clarify if it's safe to continue using it like that or whether I should look to rectify the issues in some way?

 

I should also add that the STe runs just fine on my CRT without issue.

Edited February 20, 2017 by English Invader

[exxosuk]

Monitors vary in tolerance of what they accept signal wise, more modern monitors tend to be more fussy about the ST's video signals. My fix does help to solve such issues. I'm not aware of any damages being done being used in such ways, likely it would damage the monitor before the ST, but modern LCD's I doubt would be damages anyway. Older CRT's if they start flashing black and white a lot can strain and die, though old CRT's generally won't show up the problem anyway. ST's are failing in many respects, they are 30+ years old now, so fixes will have to be done at some point anyway.

 

Grey screen doesn't sound right, there are a lot of cables about, possible yours has resistors added in the RGB lines ? If so, then value could be to high. It could also contribute to odd video problems as well.