I think I killed my 800XL.

[Laemeur]

Howdy, folks.

 

I picked up an 800XL a few days ago that had some problems. The first problem was a few bum keys, but that was an easy fix since they were all on the same line of the keyboard membrane, and I just used some foil and transparent tape to bridge the broken part of the circuit.

 

The second problem was that the video was having a hard time staying one color. BASIC would go from blue to green, sometimes brown or yellow, even. I poked around these forums for a bit and saw that re-seating chips was a common recommendation for video problems (as well as checking the power supply, which I haven't done yet), so I popped the top and reseated just a couple chips to make sure I knew what I was doing. I powered 'er back up and everything was working, except the video was still having trouble keeping its color. With the power still on, I started (unwisely, I'm sure) just sort of pressing chips down into their sockets to make sure they were well-seated. I got to one of the smaller chips in the column of chips on the left (I assume these are memory) and the video sorta went wild on me for a second, then blanked. I switched 'er off, thinking I'd killed the poor thing then and there, but then I switched it back on and - viola! - BASIC came up in a nice, steady blue.

 

Never one to quit while I'm ahead, I turned the power off and continued to just sorta press the rest of the chips into their sockets like I had been doing before (just for thoroughness' sake, of course). Only, after I'd finished doing that, I switched the computer on and... no BASIC. The screen, after switching on, flashes white once, like it's always been doing, but rather than going to the READY prompt, it just blacks out. I have since gone back and properly re-seated all the chips, but the symptoms haven't changed.

 

Does anyone have a suggestions for what I can/should try to do next?

 

Thanks for any and all help.

[Laemeur]

She boots!

 

I was just monkeying around, popping chips in and out of their sockets, and to my delight, BASIC finally came up when I threw on the power. On top of that, I realize that the whole chip-seating fiasco was probably totally unnecessary since the rather obvious presence of a variable resistor right below the memory chips finally made itself known to me. A few tweaks with the screwdriver and the video color seems to have stabilized.

 

I'm guessing there's still something not-quite-right about the whole situation, though, since that varistor certainly isn't what kept the system from booting. I suspect that one of those memory chips may be a bit dicey. Any second opinions?

[UNIXcoffee928]

The trim pot was probably off by a bit when you got it (this can happen if the system is dropped or banged around)..

 

When you re-seated the chips, an oxidized part of the pin became seated, then the system failed, because the pin(s) had no contact through the oxidation.

 

You fixed the trim pot.

 

When you popped the ICs out then re-seated them, the oxidation on the pin was scraped off, thus providing a good contact.

 

 

So, basically you are good to go.

 

 

PS, ALWAYS re-seat ICs with the power off, & get yourself a ground strap, to avoid static discharge, which can kill chips.

[Rybags]

The alternative to a ground strap is to:

 

- work in bare feet, less chance of starting a static buildup

- with a normal PC, periodically touch a bare part of the chassis, or the outside of the PSU. The equivalent on the Atari would be to touch one of the RF shielding plates (AFAIK these all should be grounded when securely in place). In both cases, the PSU should be plugged in but not turned on.

 

Of course, it's a stopgap measure but better than nothing. Not sure either about places that don't have switched outlets - with a PC ATX power supply, there is standby current going through the motherboard and you don't really want to be working on your machine in that case.

[Laemeur]

That's my optimistic assessment as well.

 

I knew that playing with the chips while the power was on was a stupid idea, and I really couldn't tell you what possessed me to do it. At least as far as static goes, I'm pretty mindful of that sort of thing (I used to build PCs for a couple of years).

 

Thanks for the input. It's much appreciated.

[a8maestro]

The color trimpot is just a resistor film with a contact. Over the years, tarnish will get between them.

 

So, note where the pointer is, then turn the control to each side a few times, then put back where it was originally. Can fix many color flicker problems with only a little tweaking.

 

Rick D.

[a8isa1]

Howdy, folks.

 

I picked up an 800XL a few days ago that had some problems. The first problem was a few bum keys, but that was an easy fix since they were all on the same line of the keyboard membrane, and I just used some foil and transparent tape to bridge the broken part of the circuit.

 

The second problem was that the video was having a hard time staying one color. BASIC would go from blue to green, sometimes brown or yellow, even. I poked around these forums for a bit and saw that re-seating chips was a common recommendation for video problems (as well as checking the power supply, which I haven't done yet), so I popped the top and reseated just a couple chips to make sure I knew what I was doing. I powered 'er back up and everything was working, except the video was still having trouble keeping its color. With the power still on, I started (unwisely, I'm sure) just sort of pressing chips down into their sockets to make sure they were well-seated. I got to one of the smaller chips in the column of chips on the left (I assume these are memory) and the video sorta went wild on me for a second, then blanked. I switched 'er off, thinking I'd killed the poor thing then and there, but then I switched it back on and - viola! - BASIC came up in a nice, steady blue.

 

Never one to quit while I'm ahead, I turned the power off and continued to just sorta press the rest of the chips into their sockets like I had been doing before (just for thoroughness' sake, of course). Only, after I'd finished doing that, I switched the computer on and... no BASIC. The screen, after switching on, flashes white once, like it's always been doing, but rather than going to the READY prompt, it just blacks out. I have since gone back and properly re-seated all the chips, but the symptoms haven't changed.

 

Does anyone have a suggestions for what I can/should try to do next?

 

Thanks for any and all help.

I don't know why this would be true but my 800XL used to have the color blue fade. Not fade out completely but definitely less saturated.

 

Later on I discovered the 800XL could lose power with the slightest touch of the power cable.

 

I didn't see any boken solder joints but when I touched up all the joints of the DIN connector both problems were cured.

 

- Steve Sheppard