800XL video problem

[Forrest]

I've recently dug the old 800XL out of the closet and am trying to get it working. It does bootup from a floppy drive, but the video is just black and white on a composite monitor. I've confirmed it's not the monitor cable, as I get a color display from a 130XE. I tried pushing down on all socketed chips, but this didn't fix the problem. The 800XL has an ICD RamboXL 256K upgrade. Any ideas on how to fix it, or a recommendation for a shop that still works on these machines?

[+Stephen]

I've recently dug the old 800XL out of the closet and am trying to get it working. It does bootup from a floppy drive, but the video is just black and white on a composite monitor. I've confirmed it's not the monitor cable, as I get a color display from a 130XE. I tried pushing down on all socketed chips, but this didn't fix the problem. The 800XL has an ICD RamboXL 256K upgrade. Any ideas on how to fix it, or a recommendation for a shop that still works on these machines?

 

IIRC, some models of the 800XL do not have the chroma (color) lead hooked up to the monitor port. It's a simple fix if you don't mind opening the machine and soldering one wire.

 

Check http://www.atariage.com/forums/index.php?showtopic=64241 for more info.

 

Stephen Anderson

Edited July 30, 2006 by Stephen

[re-atari]

I've recently dug the old 800XL out of the closet and am trying to get it working. It does bootup from a floppy drive, but the video is just black and white on a composite monitor. I've confirmed it's not the monitor cable, as I get a color display from a 130XE. I tried pushing down on all socketed chips, but this didn't fix the problem. The 800XL has an ICD RamboXL 256K upgrade. Any ideas on how to fix it, or a recommendation for a shop that still works on these machines?

 

If you had this specific cable fully working on the 800XL in the past, it might just be that trimpot R38 (left-down corner of the PCB) has gone off through the bygone years of inactivity. Trim it a bit left and right to see if it has any effect (of course after marking it's original position on the PCB with a feltpad).

If that doesn't fix it, you might want to check your power supply. I've heard reports of errors similar to yours that were due to dried out capacitors in the PSU prohibiting it from reaching its nominal voltage. If it works o.k. on the 130XE, it should be fine on the XL as well.

 

re-atari

[puppetmark]

I've recently dug the old 800XL out of the closet and am trying to get it working. It does bootup from a floppy drive, but the video is just black and white on a composite monitor. I've confirmed it's not the monitor cable, as I get a color display from a 130XE. I tried pushing down on all socketed chips, but this didn't fix the problem. The 800XL has an ICD RamboXL 256K upgrade. Any ideas on how to fix it, or a recommendation for a shop that still works on these machines?

 

The power supply is always the first thing to check. Also, the color signal comes from the GTIA chip at pin 21. You can swap your GTIA from the 130xe and put it into the 800xl in order to make sure you have a color signal to begin with. I would also certainly check the color potentiometer. After that, you will most likely need to look at one of the color amp transistors. Q5, Q4, Q2.

 

Edited July 31, 2006 by puppetmark

[Forrest]

Thanks for the help, a small adjustment to the R38 trimpot was all it took to get the color back.