Restoring a heavily modified 800XL to stock

[svhovater]

Somewhere/sometime within the last 38 years, I acquired this 800XL (CA061854REV D DOT 454) .

 

Someone (not me) did a 256k memory upgrade, and added an omniview.

 

While it does appear to be working (the extra RAM is recognized by SDX), I'm contemplating a U1MB and potentially a 

Sophia2 upgrade, but the existing mods make me a little skittish. 

 

On the one hand I have an 800XL that's mostly working (video is a little flakey). I would like to bring it into this century.

 

So, my approach would be to remove the existing wires, reconnect the lifted pins from the 74LS158. Then we come to the

memory - 4256's.. Which are (thankfully) socketed. I could probably scare up 8 4164's, but does it matter? Without the

extra control circuitry, would they be seen as 4164's ? I haven't decided about the omniview. I haven't used it

other than to verify that it's working. (My current video situation makes the 80col completely unreadable.)

 

Oh, and the keyboard LED isn't coming on. I verified that the LED is good. Symptom of..?

 

Thoughts/advice?

Steve

[svhovater]

looks like removing the RF modulator solved the video instability issue.

[R.Cade]

It looks like a decently-installed mod. If it were me, I would leave it and find another 800XL (or 600XL) to mod.

 

[xrbrevin]

41256 drams as a drop-in replacement can function fine as 4164s

keyboard LED - probly poor pin contact in the ribbon socket or degraded mylar within

[svhovater]

xrbrevin - you had it pegged WRT the LED. I cleaned the ribbon cable connectors and voila!

 

[svhovater]

I decided to keep it as is and not rip out the mod. I did, however, do the chroma mod, and svideo looks considerably better.