Did I just fry a GTIA chip?

[Pfaffa]

Hi, I recently bought a 800xl which I am attempting to get working. We accidentally powered the system on with the GTIA off by one peg (to the right) . Did we permently damage it?

[+DrVenkman]

Well, if the system was powered and your power supply was producing the expected +5V DC, you just put that voltage into the A0 line of the address bus. Kind of hard to be sure if you damaged anything that way or not.

 

Do you have any kind of tools or test equipment to help you repair this system, or are you just chip-swapping?

[Rybags]

The only way to find out is put it in properly and see if it works.

Generally a fried chip won't hurt the rest of the system.

[Pfaffa]

Just trying to get the system up, we are getting either a black or red screen (we are colorblind and the lcd is old). I have a voltmeter with discontinuity checking and that is about it. We were pulling up chips and reseating them to see if that fixed the system.

[+DrVenkman]

1 minute ago, Pfaffa said:

Just trying to get the system up, we are getting either a black or red screen

A red/green screen usually indicates that the SALLY, ANTIC and GTIA are okay but something is preventing the system from booting up. Often it's the OS ROM but it might be any number of other things as well.

[+mytek]

Well behaved chips should have their I/O set to inputs when first powered up. So there is a good chance that the GTIA is ok. And as it has already been suggested, best way to know is to properly re-install and see.

 

[Pfaffa]

Still working but we made to the system test screen

[TGB1718]

11 hours ago, mytek said:

Well behaved chips should have their I/O set to inputs when first powered up.

If it's one pin out, it's not going to power up 🙂

[+mytek]

2 hours ago, TGB1718 said:

If it's one pin out, it's not going to power up 🙂

Yes you are correct in that being one pin offset will not power-up the chip (VCC not connected to 5V).

 

Edited August 18, 2020 by mytek
Deleted completely wrong presumptions

[Pfaffa]

Everything is working thx everyone. We still need to adjust the POTs to the correct image, I am getting everything setup for it right now. I am happy to have a working Atari, a 400 was my first computer.