Atari 800 XL black screen

[Bryan]

Really, the only sure-fire way to troubleshoot these machines is to have 2 of them, or to have extensive diagnostic equipment. It's easier to swap components into a working machine and isolate the bad parts.

[Meall]

I think your best bet is to watch ebay for a junky looking machine that goes cheap for parts. All 600XL's I've seen were socketed and they contain the same chips (except for the RAM). IIRC the XE's are never socketed. As long as the machine doesn't do anything, it's a crap shoot which chip is bad. I don't think I've ever seen a Pokey get even warm.

 

Completed 600XL that went for $20+shipping:

http://www.ebay.com/itm/Atari-600-Xl-Untested-or-for-Parts-/112013257013

 

 

Nice idea, but getting another non working computer "for parts" may be as much difficult to diagnose than the only one I have. Unless I can find one locally.

 

For the same price, I better order the chips and test them one at a time...

[Meall]

I finally got in touch with the guy my friend's got it from. He tested the PIA, GTIA, Sally and Antic chips, and they were all working fine.

 

He also tested Pokey, and confirmed this one is not working on my 800XL. He also tested his Pokey on my board, but this test proved that something else on the board is faulty because he got the black screen too. He stopped testing at that point.

 

This means it could be the MMU or RAM that is faulty in addition to the Pokey itself. He should validate if the MMU and Ram are socketed on his computer, and I'll try to investigate further with him if we can meet together.

 

Great so far. I've got further down the path of a resolution...

[Meall]

Ok, now I know better what can be wrong with my 800XL:

 

- the guy tested the GTIA, PIA, ANTIC and Sally chips in his working 800XL, and they worked

- he tested Pokey, and it failed. Putting his good Pokey on my board failed, so another component is bad

- he tested the RAM and was fine

- he could not test the MMU or RON chips as they are soldered on his board

 

I contacted Best Electronics for pricing of components:

 

CO12294 Pokey U$D 20.00

CO61598 OS U$D 12.00

CO61618 MMU U$D 14.00

8 CO60612 Ram chips U$D 12.00

 

Or I can buy a working 800XL main board for $70.

 

Probably my best bet is to buy a working board with sockets and clearly identified the bad parts as the price will be similar in the end.

 

I'll also need to buy some joysticks, any recommendations on theses? And Atari and Commodore have compatible joysticks?

[Roydea6]

 

 

EPYX 500 XJ

Edited July 9, 2016 by rdea6

[Meall]

EPYX 500 XJ.jpg

 

 

EPYX 500 XJ

 

Thank you,

 

Best Electronics are selling them $30 apiece:

 

http://www.best-electronics-ca.com/quickguide.htm

[Meall]

Hi

 

I finally ordered a new 800XL board from Best Electronics, and received it today. I installed it in my 800XL and it starts normally.

 

With one exception: the keyboard is sending the "F" letter constantly, which prevents me from using it normally.

 

Any suggested path of investigation you can suggest?

[shoestring]

I had this with my 800xl.

 

I took my keyboard apart and found one of the small springs under the keys to be rusted on one end so I reversed the spring.

 

Fixed my problem but I don't know if this is your problem.

[Meall]

It is finally working.

 

The issue was weird...

 

I removed the F key and the white plastic to look at the springs. Nothing wrong there, but the F key was still repeating.

 

I tried cleaning it with compressed air and alcool, nothing worked...

 

So I remove the ~10 screws that maintain the keyboard to the metal plate, and connected the membrane only to the computer, and the F key was no longer repeating. By typing on the membrane itself, all keys were working as expected.

 

I then reinstalled the keyboard to the metal frame with the membrane, tested it, and it worked...

 

Basically, I thing it was some small thing stocked between the keyboard and the membrane doing a false contact. By just removing the keyboard from the membrane it freed the culprit item and now I have a 800XL like new.

 

I just need to ket software now and start using it.

 

Thank you all

[Mattingly]

Hi everybody!

I also have a "black screen" problem with my Atari 800 XL (PAL/NTSC).

In fact, i encounter multiple random screen issues in addition to the black one each time i power it on!

I've searched everywhere on the internet and also in technical service manuals, and i understand that the causes are numerous.

Initially, i only had a black screen problem, and i decided to replace the C061598B-01 ROM chip, but nothing had really changed except that now, i mostly get black screen but sometimes i also get various type and colored screens (some are frozen and some are flashing)..

I also tried to boot with the "Star Raiders" game cartridge, but it doesn't work.

Thank you very much for your help !🙂

[Beeblebrox]

@MattinglyFirstly you either have a pal or an ntsc machine. Unless you are running a combo of ntsc and pal graphics chips. Stock XL Atari's are either one or the other. 

 

I'd say initially it looks like a bad Antic chip combined with possible bad ram chip issues. The latter is very common on most a8s. They are 40 years old after all. Plus chips can fail or die at any time. 

 

Have you got a socketed 800xl or a non socketed one?

 

Can you post some images of the motherboard so we can see what we are dealing with.

[Mattingly]

Thank you very much for your answer.

 

So here is a picture of my motherboard. It is a socketed one and i suppose it is a PAL one too.

 

In the red circle there is a diode which was unwelded on one side, so i welded it back but maybe it has damaged something while it was unwelded.

 

 

[Beeblebrox]

15 hours ago, Mattingly said:

Thank you very much for your answer.

 

So here is a picture of my motherboard. It is a socketed one and i suppose it is a PAL one too.

 

In the red circle there is a diode which was unwelded on one side, so i welded it back but maybe it has damaged something while it was unwelded.

 

 

Hi, So it's a PAL 800XL but it isn't socketed. All chips are soldered to the board. 

 

Can you provide a close up of the component you circled?

 

Also a close up of the lower 40 pin chips, in particular the ones 2nd and 3rd from the left, which is the Antic chip and cpu respectively. Also a close up of all the 8 x ram chips.

 

Do any chips run very hot to touch when on for a while incidentally?

 

 

[Beeblebrox]

....plus also someone has removed the rf modulator at some stage. I wonder if, therefore, anything else has been modified or worked on by a previous owner?

 

Worth uploading an image of the underside of the board also.

Edited April 10 by Beeblebrox

[Mattingly]

Ah yes, you're right! It is soldered, not socketed, except my new ROM (translation mistake 😅) 

So here are some detailed pictures. Hope it can help.

And I didn't notice any hot chips while running even after several minutes. 

[Beeblebrox]

Thanks

So next I'd look at the 800xl schematic and the component you highlighted looks like c52, which is a Ceramic - 100pF - 50V - axial capacitor. 

 

There is no polarity orientation needed here for that component, but they are very delecate so it could be it is  damaged. Plus given it's location/proximity to the 4050 chip and video circuit, it could be causing issues if damaged. 

 

More qualified people than me can comment here. 

 

 

Edited April 11 by Beeblebrox

[flashjazzcat]

Micron DRAMs. Socket and replace as a matter of routine, and if that doesn't fix it, delve deeper.

 

[aeberbach]

And be careful what you get to replace them. Just bought 30 "MN4164P-15A". They all bear exactly the same stamp on top in exactly the same font on the same suspiciously even and flat plastic top but the position markings are varying styles (whole chip through, short, long, missing entirely and dimple/no dimple) and the markings on the underside are different or absent. The first 8 I tried in an 800XL did not work, the second 8 did and appear to be passing a memory test.

Did Matsushita manufacture these chips in all of Singapore, Malaysia, Korea and Japan? No. eBay sellers are sanding off 16-pin DIPs of varying kinds and stamping and selling them as the kind people are buying, and they only work sometimes. Without a RAM tester I don't know what I actually have here but they are probably sufficiently different in timing or refresh requirements that some will not work in an Atari. Of course I knew this went on but I really didn't think it would be worth doing for a chip that is individually so cheap.

Edited April 12 by aeberbach

[aeberbach]

And I did get a refund on those RAM chips, and no return was asked for. And of course the seller is still selling them with no action from eBay 🙄

 

Looks like the TL866-II does not test this DRAM. I see a Jan Beta video about an Arduino DRAM tester. Is it worth getting a tester or just keeping a stock of chips and painfully swapping to identify bad ones?

[Beeblebrox]

3 minutes ago, aeberbach said:

And I did get a refund on those RAM chips, and no return was asked for. And of course the seller is still selling them with no action from eBay 🙄

 

Looks like the TL866-II does not test this DRAM. I see a Jan Beta video about an Arduino DRAM tester. Is it worth getting a tester or just keeping a stock of chips and painfully swapping to identify bad ones?

I mentiond this on this thread a year or so ago, but I got this dram chip tester and it's been very useful in the past. 

 

Here the DRAM ALWAYS goes in the right hand socket - (if it goes in the left it'll get fried!!!😞

Dynamic RAM (DRAM) Tester 4027/4096/4116/4516/4816/4532/3732/4164/4128/41256/etc

https://www.ebay.co.uk/itm/124726020732