Atari 800 and 800XL Restore Questions

[pentad2k]

I have been restoring both an 800 and an 800XL and had some questions:

 

Atari 800:

 

The restore went great and everything works! I purchased an an Atari monitor cable (w/YRWB RCAs) and one of those cheap AV2HDMI boxes from Amazon. The display looks terrible and I wondered if there was an upscaler you folks recommend?

 

Atari 800XL:

 

This was filthy when I got it. I believe it was in a barn or garage or something. I was able to clean it up so it looks almost new. However, it has a type 4 keyboard (with the mylar) so I could only get the function keys to the right to work. I did run the diagnostics and all the memory passed so I happy. I disassembled the keyboard and gently wiped the mylar with a damp cloth and then dried it with a micro-fiber cloth. The mylar was filthy but came out clean when I was done.

 

However, now the 800XL gives me a black screen when I turn it on with the mylar plugged in. I can't even get the diagnostics to start. If I remove the keyboard the computer boots to ready without issue. I believe the mylar is bad and I was going to replace it. Would that be everyone's next step as well?  If there is another step or suggestion I should take I would be grateful for the advice.

 

Finally, the AV2HDMI looks terrible on the 800XL. Though, I believe the chroma line is not connected when I check the logic board.

 

Also, if someone here has a mylar for sale or knows a good place to purchase one I would be grateful for that advice too! 

 

 

Thanks for all the help!!  :-)

 

 

[Beeblebrox]

Hi @pentad2k

 

Welcome:)

 

Firstly where are you based?  (PAL or NTSC Atari's?) Knowing which you have for both machines will help.

 

Also what is your TV/display? More info and images of them running will help the forum members a lot.

 

The 800XL - if stock and not an 800XLF (an 800XL with a Freddie chip essentially), won't have had Chroma hooked up in the factor so on S-video you'll get a black and white image. If you want to use S-video you'll need to hook chroma up inside. Dead easy, see here:

https://forums.atariage.com/topic/352274-best-video-output-option-for-an-800xl/?do=findComment&comment=5269990

 

You want to start with the best output signal before it goes into an external conversion box or upscaler. A lot of the cheap ones are awful. It's been discussed a hell of a lot over the years here on AA, but the most recent post which might help for both machines is here:

https://forums.atariage.com/topic/352839-atari-800-to-hdmi/

 

Interestingly the 800 has Chroma hooked up from the factory so you can use S-video cables from the outset. Usually you get a good image from a stock 800. (Incidentally the smallest Atari 8-bit computer in the family (the 600XL), has by far the best stock image. I just fixed one earlier this evening where I hooked up Chroma and on S-video the output is stunning. Anyway, I digress ).

 

Goes without saying that RF is the worst image quality, then AV composite is better and S-video the best. Also some AV composite cables are pretty awful and are prone to interferance, which muddys the output quality.

 

Not entirely sure what has happened since you cleaned the mylar but I suspect aside the mylar need replacing it's not the mylar causing the dead system. Double check when the keyboard is plugged in that there isn't something shorting something. For example the keyboard's back plate might be touching something.

 

what power supply are you using with the 800XL?

 

Pictures of yout 800XL's keyboard from the back and also the XL's motherboard would be very useful. (hi res)

 

Mylar replacements are available but again would be helpful to know where you are

Edited July 14, 2023 by Beeblebrox

[pentad2k]

Here are some photos of the 800XL motherboard, the label on the keyboard plate, and the mylar sheet.

[Beeblebrox]

@pentad2k

 

Thanks. So I see it's an NTSC 800XL. If you want to use Svideo chroma will need hooking up.

 

If you coud also provide answers to the remaining questions as still need those bits of info.

 

quote::

 

Double check when the keyboard is plugged in that there isn't something shorting something. For example the keyboard's back plate might be touching something.

 

what power supply are you using with the 800XL?

Edited July 15, 2023 by Beeblebrox

[+kheller2]

I can see on the keyboard ribbon that it looks like one of the contacts on the connector has worn in half, that might not make contact when inserted.  But that doesn't explain the behavior you are seeing unless things were shorting.  Don't screw the plate on too tightly just gently snug.  You can also test it unassembled and plugged in, gently touching the keys should do something.  

 

[pentad2k]

Hi BeebleBrox!

 

First, let me apologize for my last message. I actually replied with long message replying to your questions. I clicked Submit Reply which it then told me my message would have to be approved. I then took photos and returned and posted again. I have no idea what happened to my first message.

 

I am very grateful for your help and I didn't want you to think I was being rude or a jerk by just posting those photos.  :-)

 

Let me try this again:

 

 

Quote

 

Welcome:)

 

Firstly where are you based?  (PAL or NTSC Atari's?) Knowing which you have for both machines will help.

 

Also what is your TV/display? More info and images of them running will help the forum members a lot.

 

 

I am in the US (Indiana) and using NTSC as you can see now.  :-) I have a 27" monitor I use for my desktop computer so I thought I would use it for my ataris as well. It has two HDMI ports on it.

 

 

Quote

The 800XL - if stock and not an 800XLF (an 800XL with a Freddie chip essentially), won't have had Chroma hooked up in the factor so on S-video you'll get a black and white image. If you want to use S-video you'll need to hook chroma up inside. Dead easy, see here:

https://forums.atariage.com/topic/352274-best-video-output-option-for-an-800xl/?do=findComment&comment=5269990

 

You want to start with the best output signal before it goes into an external conversion box or upscaler. A lot of the cheap ones are awful. It's been discussed a hell of a lot over the years here on AA, but the most recent post which might help for both machines is here:

https://forums.atariage.com/topic/352839-atari-800-to-hdmi/

 

Interestingly the 800 has Chroma hooked up from the factory so you can use S-video cables from the outset. Usually you get a good image from a stock 800. (Incidentally the smallest Atari 8-bit computer in the family (the 600XL), has by far the best stock image. I just fixed one earlier this evening where I hooked up Chroma and on S-video the output is stunning. Anyway, I digress ).

 

Goes without saying that RF is the worst image quality, then AV composite is better and S-video the best. Also some AV composite cables are pretty awful and are prone to interferance, which muddys the output quality.

 

 

Thank you for the links. After reading through them I think I'll try the s-video to upscaler with the Chroma mod on the 800XL. I had no idea how difficult it was getting these vintage computers to work with modern monitors.

 

Quote

 

Not entirely sure what has happened since you cleaned the mylar but I suspect aside the mylar need replacing it's not the mylar causing the dead system. Double check when the keyboard is plugged in that there isn't something shorting something. For example the keyboard's back plate might be touching something.

Mylar replacements are available but again would be helpful to know where you are

 

 

I might have caused the black screen issue myself. Do you think this might be a problem: After I disassembled the keyboard to wipe the mylar I did not put the keyboard back together. I plugged the mylar directly into the 800XL and turned the computer on. I thought I could test the different points directly on the mylar without attaching anything else. Does the mylar need the metal plate attached to work? Maybe for grounding?

 

 

 

 

Quote

what power supply are you using with the 800XL?

 

I felt I got lucky with the power supply and the motherboard.  The chips are all socketed and the power supply is the beige and brown model that is repairable. I was able to remove the four screws, clean the inside, check the capacitors, and measure the voltage. It all tested within specs.

 

Again, thank you for your help and I apologize if you thought I was being rude. I'm not sure where this message went before, but hopefully it comes through now.  :-)

 

 

[Beeblebrox]

@pentad2kAh no worries, didn't think you were being rude at all.

 

So firstly maybe get the converter box first which has composite inputs (and for later ensure it also has a 4 pin mini svideo input) and an hdmi output to test.

 

If you want to now - or at a later stage - I'd do the chroma mod and get a din5 to svideo cable which has an audio out.

 

Note: Hdmi signals when using these things will likely only carry the video signal through so you'll need to get the audio from the machine separately and feed it into your tv's audio or some separate speakers, (ie powered desktop speakers). Hence the Din5 to svideo with audio out. 

 

An alternative to a custom din5 to S-video w/audio out cable is detailed here by fellow AA member and electronics guru Mytek:

 

Note: If you do go down the svideo route and use a modern lcd bare in mind there is one more recommend mod internally to do to eliminate composite interference. I can tell you about that as and when you cross that bridge. 

Edit: see here:https://forums.atariage.com/topic/332130-source-for-5-pin-din-to-svideo-cable-for-a800/?do=findComment&comment=5032598

 

I do this mod all the time and the difference in quality is instant. It only occurs on 800XL machines when using svideo on a modern lcd screen btw. 

 

OK, back to your question :

 

Quote:

I might have caused the black screen issue myself. Do you think this might be a problem: After I disassembled the keyboard to wipe the mylar I did not put the keyboard back together. I plugged the mylar directly into the 800XL and turned the computer on. I thought I could test the different points directly on the mylar without attaching anything else. Does the mylar need the metal plate attached to work? Maybe for grounding?

 

I think the main issue here if you are resting an exposed mylar on top of the exposed pcb you are likely shorting something. 

 

Question, is the pcb's metal shielding removed? If you are leaving any part of the upper or lower sheilding in place be sure it's not shorting anything on the pcb. 

 

You can have the keyboard assembled and plugged in but not screwed into the upper casing whilst the computer is open. However trying to test the mylar plugged in exposed and completely separate to the rest of the keyboard is unlikely to be the best way to test the mylar as it needs to be evenly sandwiched as it is when it's between the keyboard upper and it's metal back.

 

Not 100% sure about grounding and the metal backplate. I'd say no, it shouldn't stop the computer from booting if the metal backing plate isn't present. 

 

Either way if you have the keyboard just make sure if plugged in it's not just resting loose on the PCB. The metal backplate could in that instance be shorting components on the PCB. 

 

(BTW please tell me if you know these things. As you'll appreciate it's hard to gauge things in terms of person's level of understanding from initial posts. If you are opening up the psu I assume you have a pretty good level. (Probably better than me heh heh).

 

Might I suggest you take some more photos of exactly what you are doing with the mylar currently so we can see exactly what you have been doing to date. Wide shots will help. I always find images really help. 

 

As long as the machine boots without the keyboard plugged in I'd say you've unlikey to caused any damage. 

 

Question: do you have a game cartridge you can plug into the cart bay? Joystick also? 

 

 

Edited July 16, 2023 by Beeblebrox
Adding extra info

[pentad2k]

Hi Kheller!

 

Thank you for the reply!

 

 

Quote

I can see on the keyboard ribbon that it looks like one of the contacts on the connector has worn in half, that might not make contact when inserted.  But that doesn't explain the behavior you are seeing unless things were shorting.  Don't screw the plate on too tightly just gently snug.  You can also test it unassembled and plugged in, gently touching the keys should do something.  

 

Great observation with the contact. I honestly didn't see it until you pointed it out.

 

Currently, I'm holding the mylar in my hand with it plugged into the 800XL and then turning it on. It goes to black right away. If I remove the mylar it boots to the ready prompt.  I took some photos of how I am holding it so you and Bleeblebrox and see how I am holding it.

 

Thanks!!

 

 

 

[pentad2k]

Here are some photos of how I am holding the mylar keyboard when turning the 800XL on. I am careful not to make contact with the computer.

 

[pentad2k]

Beeblebrox,

 

I posted some photos for you and kheller to see how I am holding the mylar when I'm turning the 800XL on.

 

Quote

 

You can have the keyboard assembled and plugged in but not screwed into the upper casing whilst the computer is open. However trying to test the mylar plugged in exposed and completely separate to the rest of the keyboard is unlikely to be the best way to test the mylar as it needs to be evenly sandwiched as it is when it's between the keyboard upper and it's metal back.

 

Not 100% sure about grounding and the metal backplate. I'd say no, it shouldn't stop the computer from booting if the metal backing plate isn't present. 

 

Either way if you have the keyboard just make sure if plugged in it's not just resting loose on the PCB. The metal backplate could in that instance be shorting components on the PCB. 

 

(BTW please tell me if you know these things. As you'll appreciate it's hard to gauge things in terms of person's level of understanding from initial posts. If you are opening up the psu I assume you have a pretty good level. (Probably better than me heh heh).

 

 

Please assume I'm a newbie!  :-) I appreciate all the advice and suggestions and I would hate to miss something because I was too dumb to see it. LOL!  I'm really new when it comes to the Atari line so it is all brand new to me. My electronic skills are all self-taught and watching YouTube videos (Adrian Black, ArticRetro, JanBeta, etc).

I took your advice and tried the River Raid cartridge and it comes up fine. I don't have a joystick at the moment (or any controller that will fit), but demo screen of the game works fine.

 

 

I also holding the mylar keyboard at different angles to see if that would make a difference (not touching anything else) but still black screen. Kheller spotted a partially broken pin on the mylar connector that could be giving me trouble as well. I read else where you can 'trim' back the mylar connector but I'm not sure that would fix my problem.

 

Also, I searched for any broken traces on the mylar with my eyes, but I haven't see anything that stands out as an issue. Of course, that isn't very scientific so I could have missed something.

 

Thanks!!

 

 

[_The Doctor__]

I hope you are taking e.s.d. precautions. static kills.

The 800XL was functioning, you took it apart and now it has black screen all the time? or just when you attach the keyboard?

I would fix any traces on the mylar that are too discolored or show cracks etc. Then once trimmed and dry, I would reassemble the keyboard making sure orientation/alignment is correct.

At the point I would try plugging it in, making sure to have a clean connector socket with no damage and that it is all lined up correctly during re install. That means compressed air in the socket and across the mother board as well.

Make sure you didn't blow the 4051's pokey or GTIA.

 

sure does sound like something is crossed or shorted if I understand what you have conveyed correctly.

Edited July 16, 2023 by _The Doctor__

[Beeblebrox]

Hi

in this image the mylar an some of it's conductive traces are resting on the pcb directly so powered on it's likely just shorting some components.

 

Just try the keyboard reassembled and screwed back into the upper casing. If it powers up with no black screen issues then you can assume it was just the bare mylar shorting it.

 

Best way to test a mylar is with a mixure of checking conductivity using a multimeter in continuity mode, fixing any issues of broken traces you find with conductive circuit paint, reassembling the keyboard, etc etc until you have fixed all the issues with the mylar. Or just buy a new mylar. 

 

I just wouldn't test the mylar live as you have been doing.

 

 

 

 

[+kheller2]

I'm not sure you can short out the mylar by resting it on the computer, it screws to a metal plate, so the outside better not have traces.

Check the physical socket on the motherboard to see if anything is stuck in there and shorting pins.  Make sure the mylar separator is positioned correctly as that does prevent shorts!

Pull the 4051s out with the keyboard plugged in and see if it boots, you won't have anything alphanumeric but the function keys should work.

[Beeblebrox]

13 minutes ago, kheller2 said:

I'm not sure you can short out the mylar by resting it on the computer, it screws to a metal plate, so the outside better not have traces.

Check the physical socket on the motherboard to see if anything is stuck in there and shorting pins.

Pull the 4051s out with the keyboard plugged in and see if it boots, you won't have anything alphanumeric but the function keys should work.

So the OP has confirmed the computer boots with the keyboard/mylar disconnected. It's when the bare mylar is plugged in that he gets the black screen when powered up. Remove the bare mylar and it works again.

 

If you look he is plugging the bare mylar into the 24 edge connector to test it and as the mylar is bare and the bottom edge of it wraps around, those traces at the bottom will be exposed and touching components on the pcb:

 

 

I don't have a keyboard mylar to hand to look but I think this is the case.

Edited July 16, 2023 by Beeblebrox

[bfollowell]

On 7/15/2023 at 6:13 PM, pentad2k said:

I am in the US (Indiana) and using NTSC as you can see now.

 

Not to interrupt your troubleshooting too much, but whereabouts in Indiana are you located? I know there are a couple of users near Indy but I've never met or heard of any in my neck of the woods down in the southwestern tri-state area. Just curious if you'd be close to Evansville.

 

Edited July 16, 2023 by bfollowell

[pentad2k]

Thank you all for the advice and suggestions,

 

I tried removing some chips from the motherboard that had been suggested. I removed the two 4051s and that did not make a difference. On the Lemon Commodore 64 forums they suggested I remove the 6502 chip and now I get a black screen every time I turn the computer on!  Boy, you can't trust those Commodore users...even after all these years!  KIDDING!  Just wanted to offer you all a laugh!  :-)

 

Recap: Bought 800XL at a garage sale. Computer boots to ready and runs carts. No keys worked except the function keys (restart, option, etc). Disassembled the keyboard, gently cleaned everything, now when they keyboard is plugged in I get a back screen. No keyboard plugged in and the computer boots to ready and also runs game carts.

 

First, I assure all of you that when I was attaching just the mylar it was not touching anything but my hand. In the photo it may look like it is touching the motherboard, but it wasn't. I did reassembly the keyboard, but continue to get a black screen.

 

Took your advice and reassembled the keyboard and plugged it back in, but still black screen.

 

Question: kheller2 spotted an issue with one of the lines on the mylar that plugs into the keyboard connector on the motherboard. A trace is partially missing from the end of the connector (See the photo below). Do you think that might cause the issues I'm experiencing?

 

Question 2: The top case has two wires. One attaches to the keyboard (it is yellow) and the other is gray-ish and connects to the motherboard. I did not attach these wires when I tried the keyboard assembled. Would that cause any issues? Does the yellow cable ground the keyboard assembly?

 

 

 

I actually haven't tried pulling the 4051s yet, but am going to try it this week.

 

Again, thank you all for you help!!

 

 

 

Quote

Not to interrupt your troubleshooting too much, but whereabouts in Indiana are you located? I know there are a couple of users near Indy but I've never met or heard of any in my neck of the woods down in the southwestern tri-state area. Just curious if you'd be close to Evansville.

Hi bfellowell!  I'm in Fort Wayne, nice to meet a fellow Hoosier!  :-) I wish I was closer, I don't know anyone that has an Atari near me.

 

 

 

 

 

[Beeblebrox]

16 minutes ago, pentad2k said:

Question 2: The top case has two wires. One attaches to the keyboard (it is yellow) and the other is gray-ish and connects to the motherboard. I did not attach these wires when I tried the keyboard assembled. Would that cause any issues? Does the yellow cable ground the keyboard assembly?

There will be one small rigid exposed wire that grounds the metal on the cart bay doors to the metal on the casing. Then a coated 28 guage wire that in turn grounds the keyboard via the cart bay metal. However I've not seen two long wires before. Can the take a full shot and upload it. The grounding (connecting or not connected) shouldn't cause the system to not boot. I wonder if you had an unusual mod/setup here?

 

More pics

[_The Doctor__]

still sounds like there is a short happening when the ribbon is inserted into the keyboard connector, please clean and blow it out as well as the mb like I suggested. Make sure the led in the keyboard is good and not shorting out either.

[pentad2k]

 

I have attached some photos below that I hope will explain the two wires attached to the metal cartridge door. The non-yellow wire attaches to the motherboard and the yellow wire was attached to one of the keyboard screws holding it to the case. I have circled the screw hole in black.

 

Also, those two wires are soldered to a metal piece that is held down by two screws that hold the side of the cartridge door to the top case.  You can see it in photo 20230718-190300.jpg. This is how I found it when I hoped the case, but I have not idea if it came from the factory like this.

 

I also took some close ups so you could see the rest of the motherboard.

 

One of my kids used the last of Deoxit (and didn't tell me) so I ordered some from Amazon and it will be here Thursday so I can give the keyboard connector a good clean and air dry.

 

Question: I have a circuit pen that use can use to fix window defrosters. I used it to fix a broken trace on my youngest son's remote control toy car. It was mylar like and I drew over the trace and it worked!  Do you think I could use that to fill in the missing end of the trace on the mylar keyboard.

 

 

Thanks!

 

 

 

 

[_The Doctor__]

These are areas of interest that need closer /better pictures-

the the keyboard connector slot and pins too please!

The mylar itself needs to be folded with the traces facing inward and the separation sheet in between, (do no over tighten), is the LED good? is it orientated correctly?

test the LED or leave it out/ disconnected if you do not know which way it belongs or can't test it properly

[+kheller2]

The wires to the cart doors are normal for some units.

If you pulled the 4051s and plugged the mylar in and still had a black screen, that can narrow down the problem to function/reset keys.

You can cut the mylar end off a bit close to the missing trace and it should still work.  Some people just cut enough off for it to start working again.  But you will eventually run out of ribbon.

[Beeblebrox]

Just a quick thought. Do you think that there is a potential problem with the mylar where  - when connected up - the RESET circuit is permanently engaged? It's just a thought. Might explain why the black screen occurs when the mylar is plugged in. For some reason reset is on all the time.

 

The 4 x tested scenerios are:

 

No keyboard present - powers up ok

bare mylar (unassembled keyboard - so no other keyboard parts present) plugged in - black screen

Fully assembled keyboard plugged in  - aforementioned ground wires not connected - black screen

Fully assembled keyboard plugge in - aforementioned ground wires are connectioned - black screen

 

I wonder if - (as they are cheap) it's worth replacing the 4051's anyway. I've done this several times recently on 800's to fix dead keyboards.

 

Edited July 19, 2023 by Beeblebrox

[+scorpio_ny]

Did the power LED ever come on your 800XL? The reason I ask was just taking another look at your original photos and it looks an electrical short had occurred on mylar due to the discoloration on some of the lines of the conductors. If you look to the line closest to the connection of the LED, it especially pronounced. There may be a short there due the LED not aligning properly.

[pentad2k]

I finally got my deoxit order from amazon and some time to do more testing:

 

Note: The keyboard is reassembled, but not screwed into the top case nor is it attached to the yellow wire that attaches to the cart doors.

 

I sprayed deoxit on the keyboard connector, the mylar ribbon connector and cleaned them both (the mylar connector was quite dirty). However, even after cleaning I still get a black screen when I plug the keyboard in. The red light on the keyboard does light up, but none of the keys does anything. Even the system reset/restart key doesn't reset the computer.

 

If I remove the keyboard, the computer boots to ready or loads a game if I have a cart plugged in.

 

I then pulled the 4051s but still got a black screen. I tried the function keys, but nothing happened. If I remove the keyboard the computer boots to ready or a game cart if plugged in.

 

I replaced the 4051s.

 

Question: I thought about disassembling the keyboard back down to the mylar so I could do a continuity test to see if one or more keys is stuck on. Do you think that would work?

 

Here are close ups of the areas the Doctor wanted. I apologize, but my phone doesn't have the best camera.

 

Thanks for all the help!!!

 

 

 

[cbelcher]

On 7/17/2023 at 1:43 PM, pentad2k said:

 

Hi bfellowell!  I'm in Fort Wayne, nice to meet a fellow Hoosier!  🙂 I wish I was closer, I don't know anyone that has an Atari near me.

 

Hey!

 

You're welcome to come down to the Indy Vintage Computer Club meeting which occurs monthly and you can get help there.

https://www.facebook.com/groups/IndyVCC

 

Check in with me if you think you can go and I can let you know if I am going and will bring some stuff to help you troubleshoot.

 

Chris