A Tale of 2 800XLs

[Classic Pac]

Some might recall me posting about a 800XL a friend gave me. It had issues 1st up was it needed cap replacement. A another friend who is a PC Tech offered to do the job, which turned out perfect. It turned on with zero issue, except it goes into Test Mode. I wish I could say the same about the keyboard. We thought it was bad, so later on I went to Ebay and bought a fully reconditioned one. Sadly same issue, we didn't learn until that Midwest Vintage Computer show that it is possibly the POKEY chip that controls the keyboard possibly went bad. Still am not 100% certain. Either way it can play carts, just not anything that requires typing.

 

Then last weekend my PC Tech friend and I went to an estate sale where I picked up a fully working 800XL in perfect condition for $50 

 

As to the 1st one again I am not 100% certain what to do know, and that extra keyboard which we aren't certain if it's 100% or not it fully works. You can see why we are unsure, so right now I am just getting into Atari 8 Bit many carts for now. But I might get eventually one of those modern storage devices so I can play what was originally on floppy.

[mimo]

The keyboards can be tested on the working 800xl.

You could also swap the pokey chips over (might have to de-solder them though) 

Put the suspected faulty pokey in the working machine rather than the other way around so you don't kill a good pokey

[BillC]

The 4051 MUX chips are another potential point of keyboard failure, they are located between the keyboard and POKEY in the circuit.

[+kheller2]

You have a fully working 800XL...   you can now troubleshoot the bad one.

If you swap tops/keyboards with each other, what happens?

I think we discussed this before where you said certain keys did or did not work.  That leads to the 4051s.  First, let's make sure you have two fully working keyboards.

 

[_The Doctor__]

and so ended the journey, but yet we still worry about our 800XL compatriot, does he still yet need TLC?