Jump to content
IGNORED

Atari 800 XL black screen


alortegac
 Share

Recommended Posts

:) :-D :) :-D :) :-D :) :-D :) :-D

 

 

Guys! Thank you so much for your continuing support along the way of fixing this great machine ! Even putting up with my rants and frustrations so kindly (it is my thought process,,,,, Believe me, I did not mean anything negative towards ATARI, I love my collection!).

 

You are gentlemen and scholars.

 

 

I followed these final steps in this order:

1.- I used my working 5200 as testing board (took the risk). I checked CPU and all OK. (as suggested by 1050).

 

2.- I used my 5200 to check the ANTIC with pole position. It was BAD! 5200 in black screen. (as suggested by jmcorn) (pic#2)

 

3.- I replaced the known GOOD ANTIC in the 800XL board. AND BOOM! Machine booted up!

 

4.- I tested the machine with Pole position and noticed some double picture, minor artifacts and discoloration in title band of the game.... See pic 1 and 3.

 

5.- I suspected GTIA, so I replaced the known good GTIA(5200) in the 800 XL board......AND now all IS PEFECT and WORKING! (pic #3)

 

6.- Strangely, the "bad" GTIA from the 800XL...worked fine in the 5200. (????)

 

7.- I assembled the machine after cleaning keyboard and casing. Pic #5,6

 

8.- I will need to buy an ANTIC chip or harvest it from another broken 5200..to get my 5200 up and running again...... easy peasy.. ;)

 

 

So I learned a lot! How to use the logic probe, about SAMS guides, a process to troubleshoot with a map. And also what NEVER to do with 800s, such as use a suspected power supply, be super careful with the sockets and probing first before touching any IC's.

 

 

AND TO NEVER GIVE UP on an ATARI computer!

 

BIG Thank you again for all your help! (pic #4)

 

PS: I will eventually try to fix computer #2.....but not now. I have too many new games to play!!!!!!!!

post-44601-0-78562600-1536499236_thumb.jpg

post-44601-0-04678500-1536499270_thumb.jpg

post-44601-0-97414600-1536499341_thumb.jpg

post-44601-0-72062900-1536499392_thumb.jpg

post-44601-0-68520600-1536499414_thumb.jpg

post-44601-0-20730000-1536499493_thumb.jpg

Edited by alortegac
  • Like 7
Link to comment
Share on other sites

Great news and great persistence! One of the roughest parts of troubleshooting is when there is, in fact, more than one thing wrong or going bad in a system at the same time. You can get misleading or flat out wrong ideas about what you're seeing from 'scopes and probes because there are multiple parts of the machine acting up. So sometimes you track down a lot of false leads and face frustration when things don't work out.

 

So good on you for sticking it through! :)

Link to comment
Share on other sites

So I learned a lot! How to use the logic probe, about SAMS guides, a process to troubleshoot with a map. And also what NEVER to do with 800s, such as use a suspected power supply, be super careful with the sockets and probing first before touching any IC's.

 

AND TO NEVER GIVE UP on an ATARI computer!

 

Hey, I learned something too: don't remove the initial section of your post that gives the correct answer. :)

 

I had removed it because I saw that I confused the IRQ with the HALT lines, but nevertheless ended up at the correct source of the problem. Here's what he was referring to, for those who wondered how I ended up with credit for the ANTIC diagnosis:

 

CPU pin 6 is NMI signal to GTIA.

Hardware is not my area of expertise, but my understanding is that the ANTIC/CTIA/GTIA gets primary control over the bus and it is the device which has the authority (via hardware) to tell the 6502 to yield for this clock cycle, not the other way around. A high NMI pin on the 6502 seems to tell me that the ANTIC/GTIA is not releasing the CPU to access the system bus (including memory). Is my understanding correct?

 

Personally, I'd focus on the ANTIC chip itself and spread out from there (basic board issues, GTIA, memory, etc).

  • Like 1
Link to comment
Share on other sites

Hardware is not my area of expertise, but my understanding is that the ANTIC/CTIA/GTIA gets primary control over the bus and it is the device which has the authority (via hardware) to tell the 6502 to yield for this clock cycle, not the other way around. A high NMI pin on the 6502 seems to tell me that the ANTIC/GTIA is not releasing the CPU to access the system bus (including memory). Is my understanding correct?

My logic comes from the way code works entirely. The

CPU sets the NMI capabilities in an ANTIC register.

 

But brain fart time - this is not the NMI line itself.

Which runs between GTIA and the CPU only.

Many other mistakes I assumed wrong as well.

Because I was stuck in the wrong place, I was not seeing

the entire picture. Which is why it's best to have

several people looking as someone in the group is

bound to have a better take on what just happened.

 

Well done jmccorm.

 

My comment on this line:

U7 NIM bar, U23 CS2bar and U17 SO, SI, S2 bar still wrong.

 

The nomeclature in the schematics show them with a bar above the name of the signal, I think it means signal was inverted or flipped. Apologies for my lack of correct naming.

Ahh, thanks for that clarity. The bar is important

for determining active signal polarity. It represents

a negative polarity as the active state or signal

asserted state.

 

So a high /NMI would mean a Non Maskable Interrupt is

not being used.

/FORWARD SLASH can be used to type it on systems that

can't do bar over label. A standard label as typed

in uppercase then would be a positive asserted logic.

 

Not the top level hardware man myself, I can only

suggest that the /NMI line is used to tell the CPU

to get off the pot because the big boys need to use

it asap. And this is backwards to what I suggested

before as to who tells who what.

 

Logic probe = useful (in the right hands)

  • Like 1
Link to comment
Share on other sites

Great news and great persistence! One of the roughest parts of troubleshooting is when there is, in fact, more than one thing wrong or going bad in a system at the same time. You can get misleading or flat out wrong ideas about what you're seeing from 'scopes and probes because there are multiple parts of the machine acting up. So sometimes you track down a lot of false leads and face frustration when things don't work out.

 

So good on you for sticking it through! :)

Link to comment
Share on other sites

Great news and great persistence! One of the roughest parts of troubleshooting is when there is, in fact, more than one thing wrong or going bad in a system at the same time. You can get misleading or flat out wrong ideas about what you're seeing from 'scopes and probes because there are multiple parts of the machine acting up. So sometimes you track down a lot of false leads and face frustration when things don't work out.

 

So good on you for sticking it through! :)

Thank you so much! I feel good, a good job. Thanks for your support and feedback!

Al

Edited by alortegac
Link to comment
Share on other sites

OK the fact you get the Red screen with no OS would suggest the main IC's (GTIA, ANTIC, CPU, POKEY) are probably OK, and RAM is where to concentrate now... I'm not sure you can test much with a multimeter for RAM, maybe with a logic probe. Others would have to pipe in about that.

 

Does it have Mt RAM chips? Those are notoriously bad. When the system has been on for a few minutes, feel if any of the 8 get hotter than others, if so that's likely your bad one. One trick mentioned on these forums is to lightly spray isopropyl alcohol on the chips while on and look for ones that evaporate faster than others.

Thank you so much for the ROM and your help!!!

Edited by alortegac
Link to comment
Share on other sites

Thank you so much for the ROM and your help!!!

Very welcome - spares are always nice to have on hand for the next one. :) and at least the 2nd ROM I included with Hias' highspeed patch should be a nice simple upgrade to make loading off SIO snappy. I'm impressed by yours and others troubleshooting depth to narrow it down!

  • Like 1
Link to comment
Share on other sites

  • 2 weeks later...

Thank you so much all!! Your support throughout this process has been tremendous!!!

 

Computer #1 (originally with all black screen of death). Is now Alive and well!!!

 

See pictures.

 

Nazgar, Again, many thanks for your help with the rom ic. It is installed, works great!

 

After ruling out RAM with new chips, GTIA and Antic with my 5200, U5, 26,27, U2 and U30....the last and final suspect was U29. And it was the sole culprit apparently. Why did it fail? I do not know. All seems ok now.

 

2 for 2 = 100% success in this rescue op! Thanks so much all!!!

 

Al

post-44601-0-14096800-1537560505_thumb.jpeg

post-44601-0-35700500-1537560529_thumb.jpeg

post-44601-0-54166100-1537560553_thumb.jpg

post-44601-0-63139000-1537561115_thumb.jpg

Edited by alortegac
  • Like 1
Link to comment
Share on other sites

  • 3 years later...

I have a brand new in the box 800 XL, still in the plastic wrap. anyway I just opened it up to try it out on my composite monitor... and is DOA! Black screen. I wonder if it could be caps? well this thing is NEW so i probably should just put it back in the box... Always something...

Link to comment
Share on other sites

5 minutes ago, sideburn said:

I have a brand new in the box 800 XL, still in the plastic wrap. anyway I just opened it up to try it out on my composite monitor... and is DOA! Black screen. I wonder if it could be caps? well this thing is NEW so i probably should just put it back in the box... Always something...

That's the danger of new old stock.

Link to comment
Share on other sites

1 hour ago, sideburn said:

I have a brand new in the box 800 XL, still in the plastic wrap. anyway I just opened it up to try it out on my composite monitor... and is DOA! Black screen. I wonder if it could be caps? well this thing is NEW so i probably should just put it back in the box... Always something...

Did you get a power light ?  Testing with a known good supply, or the one from the box ?  Watch out for the deadly ingot (search the forums if you are not familiar).

 

Link to comment
Share on other sites

1 hour ago, cwilbar said:

Did you get a power light ?  Testing with a known good supply, or the one from the box ?  Watch out for the deadly ingot (search the forums if you are not familiar).

 

It's got the white power supply but I am using my own USB power and composite video cable. I have a working 130 XE that I use those with.

Yes I get a power LED. but no sound when typing keys or powering up while holding down option, then select / start...

 

From what I can remember, the XL also boots into basic so i would hear the sound at start up and also beeps from the keyboard right?

 

I put a pole position cart in it as well but nothing.

 

I just opened it up and it is pristine and ALL chips are socketed and in their sockets tightly with no sign of aging at all.

I re-seated the CPU and the one in the middle but i didn't bother with the rest. I also see data on the chips when I put a scope on them.

I am not sure if any chips on my XE are compatible. So this makes troubleshooting it pretty tough without a toner board.

 

Link to comment
Share on other sites

If you have RAM socketed, replace it. It is a common cause of such behavior. But it actually can be anything else. At least you may say that GTIA is working (since you get a black screen). 

Link to comment
Share on other sites

Posted (edited)
9 hours ago, sideburn said:

I have a brand new in the box 800 XL, still in the plastic wrap. anyway I just opened it up to try it out on my composite monitor... and is DOA! Black screen. I wonder if it could be caps? well this thing is NEW so i probably should just put it back in the box... Always something...

 

Check your av cable, test the computer with an rf cable and in a different tv. Rule out any connections issue.

 

Testing your power supply. It should +5v. Electrolytic capacitors are old now, maybe dry or shorted. 

 

If all good, now it is time for measuring voltages. Check for 5v. Start with The on/off switch.  Check all electrolytic capacitors, one could be shorted.  

if all ok, Then “re-seat” all the chips in their socket. Push them down gently but firmly in place.


Then let it run for some time, “feel” the chips, check if any is really hot, specially RAM chips. 
 

if you still haven’t found any issues,  it is time to pull your logic probe, voltmeter and sam’s. 
 

Black screen is a common failure, but can be caused by many things. Sometimes, multiple things. 
 

it would help if you have another 800xl, testing one chip at time in a known working machine. Some of the chips in the 130xl are compatible, but they may not all be socketed. 

it is important only doing one thing at the time and observe any changes.

 

Hopefully, this is helpful. I have now fixed 30 or 40 machines, they are all repairable, don’t give up. 
 

If you would like me to repair it for you at no charge only parts, Send me a pm. 
 

 

Best!

Al

 

 

 

Edited by alortegac
Link to comment
Share on other sites

9 hours ago, sideburn said:

and is DOA! Black screen. I wonder if it could be caps?

 

 

When you say you have a black screen, do you have a dead screen, as in no video output signal, or a black screen is being output? There is definitely a difference. Also, I'm not sure about the Pole Position cartridge, but I know Star Raiders doubles as a diagnostics cart and, depending on whether or not it will run, it will help narrow down possible issues. Try that one if you happen to have one. I'm not sure if running Star Raiders from a multi-cart will work the same, but that may be an option if you have one. Does anyone know if this works the same as using a real Star Raiders cartridge?

 

Link to comment
Share on other sites

11 minutes ago, bfollowell said:

 

When you say you have a black screen, do you have a dead screen, as in no video output signal, or a black screen is being output? There is definitely a difference. Also, I'm not sure about the Pole Position cartridge, but I know Star Raiders doubles as a diagnostics cart and, depending on whether or not it will run, it will help narrow down possible issues. Try that one if you happen to have one. I'm not sure if running Star Raiders from a multi-cart will work the same, but that may be an option if you have one. Does anyone know if this works the same as using a real Star Raiders cartridge?

 

Star Raiders bypasses System’s rom. Therefore, it is a good cart for ruling that out.

I would think a Epprom based cart would work as an original, but a multicart with menu, like UNO, will not.


 

 

 

 

Link to comment
Share on other sites

3 hours ago, Peri Noid said:

If you have RAM socketed, replace it. It is a common cause of such behavior. But it actually can be anything else. At least you may say that GTIA is working (since you get a black screen). 

Yes all socketed. Problem is I only have a 130 xe. How much of the xe is compatible with the xl to use as a parts doner to test with?

Link to comment
Share on other sites

50 minutes ago, bfollowell said:

 

When you say you have a black screen, do you have a dead screen, as in no video output signal, or a black screen is being output? There is definitely a difference. Also, I'm not sure about the Pole Position cartridge, but I know Star Raiders doubles as a diagnostics cart and, depending on whether or not it will run, it will help narrow down possible issues. Try that one if you happen to have one. I'm not sure if running Star Raiders from a multi-cart will work the same, but that may be an option if you have one. Does anyone know if this works the same as using a real Star Raiders cartridge?


it’s definitely sending a “black screen” signal to the tv so it’s alive. 
 

don’t think I have a star raiders cart. I’ll look. Multicart wouldn’t work. You’d have a black screen before you could navigate to star raiders in the menu. 
 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...