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phc_joe

130XE Green Screen: Diagnostic Process?

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Hi; So I hauled out my 8-bit collection (that has been modded for various reasons back when I used it heavily back in the '90s). I have forgotten soooo much!  This 8-bit stuff got me through a dissertation, online database searching and early attempts at running a profession-related BBS before the Internet was ubiquitous.

 

Current problem. I'm trying to efficiently figure out what to do to resurrect a 130XE that currently only boots to a blank green screen.  I noted that a different computer (Also Atari 8-bit) booted to green screen when the ribbon cable for the keyboard was badly inserted (a corner was folded over itself...straightening that out allowed it to boot correctly, but that was not the problem with the unit at hand).

 

First question: I have a pretty horrid/beat up 65XE that I was thinking I might scavenge for parts/chips, BUT other than memory are the 65XE chips the same as the 130XE?

 

Next question: Is there a step-by-step logical process for teasing out the most efficient process for diagnosing/repairing the green screen issue?

 

Thanks

 

 

Stuff I have on hand...

CSS Black Box with Floppy Board (Bob Puff was my main go-to guy back in the day!)

SpartaDOS X with R-time-8 cartridge

130XE with 320 RAM upgrade/Multiplexer OS (in good working order)

130XE with a ROM board/switch that can switch/boot between 3 different chips (this is the machine with the problem) 

800XL standard/good working order

65XE with horrid case and keyboard with many dead keys (I might be brave/foolhardy enough to try and desolder this for parts).

1050 disk drive

XF551 disk drives (2)

Hard drive with various Sparta/MyDOS boot partitions and utilities.

Various game cartridges and 8-bit software mostly on 5.25 disks.

 

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see if any of the ram chips get hot

if you have any loose compatible ram chips you can piggyback them on to the fitted chips locate a culprit

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A green screen on power-up indicates that the machine isn’t booting properly. However, the fact that you have a stable video signal means that the clock crystal, GTIA and ANTIC are probably working just fine (and yes, these chips are interchangeable with other Atari computers). Can’t say yet about the other chips, but green screens often come down to a bad OS ROM, bad MMU or bad DRAM chip(s).

 

As noted above, see if any of the DRAM chips gets hotter than the others - if so, that’s likely bad.

 

But first, another quick question: what power supply are you using? I don’t have my usual go-to PSU photo that I post, but beware the “Ingot” power supply! It can produce over-voltages that kill systems and produce symptoms like you see. If you can post a photo of the power supply that would help eliminate that as an issue. 

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Nice collection of hardware. You'd be surprised with that 65XE if it's not damaged then it'll clean up nicely and a new mylar to fix the keyboard sounds like what you need.  Remove the case shell and clean it with a spongey dish scrubber with Dawn dish detergent. The keycaps can be removed and cleaned with a damp rag.  The other green screen thread is a good place to start as mentioned.

 

Oh and your beard is too short.

 

 

  • Haha 2

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Since the machine in question is the "130XE with a ROM board/switch that can switch/boot between 3 different chips" I would personally primarily suspect the ROM's have failed, at least two are likely EPROMs that might have suffered bit-rot over the years.

 

Does it fail with and of the three options selected?

 

If it was upgraded, it likely has had a socket installed on the motherboard for the OS ROM - I'd try swapping in a known working OS ROM from another system. An 800XL will most likely have socketed chips out of the factory and might be a good donor.

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