12 replies to this topic

[Gandor]

Hi,

I received my Atari 800XL today from an ebay auction (eBay Auction -- Item Number: 190631022856 I won but it doesn't boot up.
I tried both the RF and the monitor port and the tv is detecting something but no picture is shown.
I also don't hear any sound that I normally hear when I boot up an Atari.
I'm looking for some suggestions to determine what might be wrong with it.
I did open it up and it looks in good condition.
All chips are in sockets and I pushed down everyone to make sure they weren't dislodged during shipping but this didn't help.
One thing I noticed is that 2 ram chips get really hot. Could this prevent the unit from booting up?

Any advice would be helpful.

Thanks

[kheffington]

Do you have the right power supply. Too much juice will burn out the ram.

[Gandor]

kheffington, on Thu Feb 9, 2012 8:39 PM, said:

Do you have the right power supply. Too much juice will burn out the ram.

I used the power supply from my other 800XL.
Part no: CO 61982
output +5v DC 1.5A

[Rybags]

Unless the machine's screwed really badly you should still get a picture, a black screen at least.

Without test equipment, another machine to swap chips with or a diag cart it's kind of hard to diagnose.

But those couple of hot memory chips could be the problem.

[Gandor]

Rybags, on Thu Feb 9, 2012 8:57 PM, said:

Unless the machine's screwed really badly you should still get a picture, a black screen at least.

Without test equipment, another machine to swap chips with or a diag cart it's kind of hard to diagnose.

But those couple of hot memory chips could be the problem.

I do get a black screen just nothing else.
Never seen a diag cart for the 800XL. I've seen one for an XE on ebay eBay Auction -- Item Number: 140696136668

[Fox-1 / mnx]

http://www.atariage....l-black-screen/

[Rybags]

Diag carts are fairly universal. There's images around that can be flashed to Atarimax carts.

Some games run in "diag" mode - if you've got a Star Raiders cartridge, try that.

But by your description you've probably got some bad RAM. You could try swapping those 2 suspect chips into a known good machine, although only 800XL and early 65/130 XE use the 64k x 1 RAMs.

[AtariGeezer]

On two different 800xl's I received with black screens, one had a bad CPU and the other had a bad PIA...

Jay

[Gunstar]

Bad OS chip here on an 800XL, just a black screen.

[Gandor]

Quote

Diag carts are fairly universal. There's images around that can be flashed to Atarimax carts.

I just happen to receive my order of 8Mbit Atarimax flash carts yesterday so I will definitely try that.
I also own the Atarimax myide + flash cart. Never used the flash part of it.
To run diagnostics, shouldn't I at least have a picture?

Quote

Some games run in "diag" mode - if you've got a Star Raiders cartridge, try that.

I happen to have this cart but I still only get a black screen.

Quote

But by your description you've probably got some bad RAM. You could try swapping those 2 suspect chips into a known good machine, although only 800XL and early 65/130 XE use the 64k x 1 RAMs.

I have a fully working 800XL but I'm hesitant to remove the RAM from it because it's working great. I don't want to end up with 2 non working 800XL
Could a couple of bad RAM prevent the machine from booting up?
I would expect it to boot up in self-test mode and run the memory test but It doesn't even get that far.

Thanks

[Rybags]

A single bad RAM is enough to cripple the machine because each chip supplies 1 bit per byte accessed.

Diag cart at least might verify the CPU is OK and maybe indicate that some RAM is bad.

Swapping a bad RAM chip into a good machine shouldn't hurt the good RAM. It's a quick way to verify if the chip isn't good.

Booting to Self-Test generally requires the machine to be at least partially working. Bad RAM generally means the system might have trouble getting that far.

[sloopy]

Pull out the DRAMs that are getting very warm, and try running the machine with those sockets empty, and see if you get something besides black, also try with no ram at all...

If you get something different, specifically a red screen, then the issue is in the DRAM circuit (commonly the DRAMs, but could also be the 74x158's).

If you continue to get a black screen, then although the DRAM maybe bad, there is evidently something else wrong also...

sloopy.

[russg]

Gandor, on Thu Feb 9, 2012 8:51 PM, said:

kheffington, on Thu Feb 9, 2012 8:39 PM, said:

Do you have the right power supply. Too much juice will burn out the ram.

I used the power supply from my other 800XL.
Part no: CO 61982
output +5v DC 1.5A

I believe that power supply (C061982) is the infamous 'ingot' supply. It is known to go
too high voltage and fry memory chips. You might want to check the voltage outputs,
should be +5v (somebody give the right range). Get another PS and you may have
to replace some DRAMs.

(from the comp.sys.atari.8bit FAQ)

http://mcurrent.name...61982-Ingot.jpg

Edited by russg, Sat Feb 11, 2012 11:12 PM.