Atari 800 repair and restoration - advice needed!

[TJ76]

Hi Everyone,

 

I recently sourced an Atari 800 from eBay, as I have wanted to own one for quite some time.  I started out with an 800XL as a kid when they were first around, and after revisiting Atari hardware in recent years, I felt it would be great to have one of the original Atari 8 bit machines in my collection.

 

Soaring prices have put me off previously, though the one I purchased recently was sold as faulty at a reduced price, so I thought it would be a great project to use some of my knowledge to hopefully preserve it.

 

So far however, I have made limited progress as I have no direct experience with an 800, and no spare chips to swap in to rule out damage to those.  I do have various 800XL and 600XLs however if there is any cross-device compatibility and worth trying changing any IC's across.

 

It would be great however if anyone here with better experience of faults on an 800 may be able to help me focus down on the issue from my description here:

 

The unit was provided with an incorrect power supply, which was for at Atari 1027 printer, part : CO 61605-34

It was rated at 8.5V , 4.2A AC

I am aware that this was connected previously by the seller to attempt to power the machine.

 

I've now sourced a 9.0V 2000mA AC supply which I believe is correct for the machine.

 

So far I have only been able to see either a black screen or distorted lines and bars.  If I adjust the potentiometer on the CPU card, I see different colours in the output.

 

I've cleaned the boards as best I can and from casual troubleshooting, I've found no obvious visible damage or dead traces anywhere, so I suspect component or chip failure somewhere.  

 

Any suggestions or comments would be greatly appreciated.

 

I have documented my amateur efforts to date on the following YouTube video as part of my otherwise game related Atari 8 bit channel should anyone has the time to take a look.  I'd love to be able to find something relatively simple and source appropriate components to replace / solder in to test any fault scenarios anyone may suggest. 

 

https://youtu.be/0Ml87cKWAg0?si=_AS33-leLgApkAUm  .

 

Video's a bit long, so If you want to skip to the screen outputs, they are from around 16:40

 

Thanks all, any help greatly appreciated.

 

Have a great day everyone!

 

TJ

 

[_The Doctor__]

AC supplies are not normally marked as milliamp ratings. Can you post pictures of the new supply markings?

It should have 9 VAC and 16 VA or similar on it. not 9V with just milliamp. so look for vac and va

Edited May 22 by _The Doctor__

[Beeblebrox]

@TJ76Where are you based?

 

Also - NTSC or PAL 800?

 

I'll have a look at your vid later (I've lots of experience fixing and upgrading the 800).

 

Re Power, did you get one of these, which is what I use:

 

Rock solid and cheap:

 

https://www.poweradaptorsuk.co.uk/2000ma-2a-9v-18va-acac-ac-output-mains-power-adaptor-162-p.asp

You also need this:

 

https://www.ebay.co.uk/itm/174950199535

 

 

 

Edited May 22 by Beeblebrox

[+Stephen]

Fortunately, the other power supply would not damage the machine, being that it was AC and only half a volt different.

[_The Doctor__]

It's an 800 so card swap game can be helpful if it's a memory issue. A good number of things are normally socketed for parts swapping. Check out a few 800 repair threads. Try a moderate to small thread as they normally are concise and successful. Only after reading and following the moderate and short threads would I suggest looking at a super long one, and those long ones I'd read last to first.

[TGB1718]

2 hours ago, TJ76 said:

It was rated at 8.5V , 4.2A AC

That would work fine

 

Looking at your video, that looks like Horizontal sync on the TV, not the 800, can you adjust that ?

 

Edited May 22 by TGB1718

[Beeblebrox]

One quick ting you can do sometimes  with the 400 and 800's is this. With the computer powered up with no carts in the cart bay, and a red poer light present, just press a few main keyboard keys. (Of course this pre-supposes no issues with the keyboard itself, which obviously can be an addition issue.

 

If the system is working, you are getting a red power light and the internal speaker is present and working - you should hear the internal speaker registering each key press. If you do, then at least for the most part it's likley the system is ok, or at least booted to the memo pad. If not, then you just troubleshoot some more.

 

It's something you can only do with the 400 and 800s which have internal speakers, but can save you loads of time looking for an issue when it turns out it a simple video cable and or TV/display hookup/config issue. 

 

When I get home I'll watch the video, but just thought I mention it.

[TJ76]

2 hours ago, _The Doctor__ said:

AC supplies are not normally marked as milliamp ratings. Can you post pictures of the new supply markings?

It should have 9 VAC and 16 VA or similar on it. not 9V with just milliamp. so look for vac and va

Thanks for replying - this is the new supply, sourced from here: 

https://www.ebay.co.uk/itm/296318902699

I also understand the 1050 supply is rated the same, and I have one of those and no different behaviour.

[TJ76]

3 hours ago, Beeblebrox said:

@TJ76Where are you based?

 

Also - NTSC or PAL 800?

 

I'll have a look at your vid later (I've lots of experience fixing and upgrading the 800).

 

Re Power, did you get one of these, which is what I use:

 

Rock solid and cheap:

 

https://www.poweradaptorsuk.co.uk/2000ma-2a-9v-18va-acac-ac-output-mains-power-adaptor-162-p.asp

You also need this:

 

https://www.ebay.co.uk/itm/174950199535

 

 

 

Thanks for your reply.  I'm based in Essex, UK.  The supply I bought doesn't show a VA rating.  I posted link and photo just now.  Hopefully what I bought is ok, and noting your link in case I go down the road of needing to source another..oh, and it's a PAL 800

Edited May 22 by TJ76

[TJ76]

1 hour ago, _The Doctor__ said:

It's an 800 so card swap game can be helpful if it's a memory issue. A good number of things are normally socketed for parts swapping. Check out a few 800 repair threads. Try a moderate to small thread as they normally are concise and successful. Only after reading and following the moderate and short threads would I suggest looking at a super long one, and those long ones I'd read last to first.

Thanks.  Yep, research is key I know, I'm not planning on giving up on this one.  I had already tried taking out the 16K ram cards and trying one at a time, and no difference there.  Unless they're all bad  Thinking though the problem may be elsewhere.  Reseated many ICs in case of bad contacts.  Just not had oportunity to swap any out yet with anything.

[TJ76]

59 minutes ago, TGB1718 said:

That would work fine

 

Looking at your video, that looks like Horizontal sync on the TV, not the 800, can you adjust that ?

 

One TV I was using simply doesn't often pickup the signal, and leaves a blue screen (it's default for no input).  What I show on video is via a USB video capture card that behaves fine with the same cabling using my Atari 800XL.  I'll check settings later to see if there is anything to clean things up, but suspect the problem is at source.

[Beeblebrox]

24 minutes ago, TJ76 said:

One TV I was using simply doesn't often pickup the signal, and leaves a blue screen (it's default for no input).  What I show on video is via a USB video capture card that behaves fine with the same cabling using my Atari 800XL.  I'll check settings later to see if there is anything to clean things up, but suspect the problem is at source.

It probably does have issues.

 

Happy to help. I am in the UK also. I love working with 800s. All socketed, great build quality. I have spare smaller logic chips I can give to you if needed. Can't really spare the custom Atari chips like the 40pin ones as aside from needing them, some are like gold dust. 

 

Some 40pin chips, like the pia, have a modern equivalent, which is handy. 

 

Like I say, will have a look later at the video. 

 

 

[TJ76]

1 minute ago, Beeblebrox said:

It probably does have issues.

 

Happy to help. I am in the UK also. I love working with 800s. All socketed, great build quality. I have spare smaller logic chips I can give to you if needed. Can't really spare the custom Atari chips like the 40pin ones as aside from needing them, some are like gold dust. 

 

Some 40pin chips, like the pia, have a modern equivalent, which is handy. 

 

Like I say, will have a look later at the video. 

 

 

Any further help like that would be incredibly kind, thank you.  I think my main issues are not having spares / knowing yet if any may be compatibly from XL machines, as have at least one sacrificial one if necessary.  No 800 specific spares here though.  I've just received a set of replacement capacitors, so wondering if worth going ahead with that.  On the one hand, guess nothing to lose, but not necesarily expecting that would instantly solve issues.  And if it did not, I guess I've changed something else with the problem, however a straightforward task, so not much that could go further wrong i guess.

[TJ76]

51 minutes ago, Beeblebrox said:

One quick ting you can do sometimes  with the 400 and 800's is this. With the computer powered up with no carts in the cart bay, and a red poer light present, just press a few main keyboard keys. (Of course this pre-supposes no issues with the keyboard itself, which obviously can be an addition issue.

 

If the system is working, you are getting a red power light and the internal speaker is present and working - you should hear the internal speaker registering each key press. If you do, then at least for the most part it's likley the system is ok, or at least booted to the memo pad. If not, then you just troubleshoot some more.

 

It's something you can only do with the 400 and 800s which have internal speakers, but can save you loads of time looking for an issue when it turns out it a simple video cable and or TV/display hookup/config issue. 

 

When I get home I'll watch the video, but just thought I mention it.

Missed this above bit earlier - tried with speak reconencted and no sound i'm afraid

 

[Beeblebrox]

27 minutes ago, TJ76 said:

Missed this above bit earlier - tried with speak reconencted and no sound i'm afraid

 

Sure. Worth trying. So a deep issue or set of issues.as I say, the machine being socketed is a real bonus for troubleshooting further.:)

[Beeblebrox]

37 minutes ago, TJ76 said:

Any further help like that would be incredibly kind, thank you.  I think my main issues are not having spares / knowing yet if any may be compatibly from XL machines, as have at least one sacrificial one if necessary.  No 800 specific spares here though.  I've just received a set of replacement capacitors, so wondering if worth going ahead with that.  On the one hand, guess nothing to lose, but not necesarily expecting that would instantly solve issues.  And if it did not, I guess I've changed something else with the problem, however a straightforward task, so not much that could go further wrong i guess.

I have spares and happy to help. Will get it sorted.

[TJ76]

I've now verified the Sally and Antic are both ok, by booting with them successfully in an 800XL.  Also tried the GTIA from the 800XL in the 800 and received same result.  ICs swapped in confirmed ok in 800XL before and after trying them in the 800.

 

I guess that's some major things ruled out.

 

<Edit> And the Pokey also proves to be good.

Edited May 22 by TJ76

[_The Doctor__]

Check the frequencies, 4050, and transistors in the video paths

[TJ76]

12 hours ago, _The Doctor__ said:

Check the frequencies, 4050, and transistors in the video paths

Thanks for the tips.  Had a few minutes this morning, so removed and cross checked the 4050 with the doner 800XL and it's ok + swapped back one didn't change anything on the 800.

 

In terms of checking frequencies, I don't have an oscilascope, and my multimeter doesn't handle frequency, so may have to come back to that suggestion if problem not found elsewhere.

 

My current theory is that something on the ROM board could be bad, after seeing a YT vid where someone had a similar issues resolved by swapping with a good card.  I've found an inexpensive replacement ROM board, which is listed as tested, so have ordered and will likely try that next when it arrives if nothing else worth checking within my ability at the moment.

 

Thanks again.

 

TJ

[spookt]

I see you’re using a cable from the monitor jack. Did it come with the unit? It might be worth checking the wiring is correct. 

[Beeblebrox]

1 hour ago, spookt said:

I see you’re using a cable from the monitor jack. Did it come with the unit? It might be worth checking the wiring is correct. 

I think, because the op has listened to the internal speaker and is fairly confident it is functional, but no keypress sounds are coming from it whilst powered on, there is a deeper issue. 

 

One thing to also suggest @TJ76 is to confirm whether the light is coming on at all. Remember that the cart bay door needs to be closed for it to power up, and also if the bay door swtcih is out of action, it won't power up. Apologo6 of you've already mentioned this. 

 

One other quick thing you can to is open up the encased os Rom and ram boards and make sure you press all the chips into their sockets. They can rise out of them over the years and also sockets and legs can oxidise. 

 

Again, I suspect deeper issues, but the amount of 800s and 400s I've got working buy doing this is surprisingly high.:)

 

[TJ76]

On 5/23/2024 at 4:09 PM, Beeblebrox said:

I think, because the op has listened to the internal speaker and is fairly confident it is functional, but no keypress sounds are coming from it whilst powered on, there is a deeper issue. 

 

One thing to also suggest @TJ76 is to confirm whether the light is coming on at all. Remember that the cart bay door needs to be closed for it to power up, and also if the bay door swtcih is out of action, it won't power up. Apologo6 of you've already mentioned this. 

 

One other quick thing you can to is open up the encased os Rom and ram boards and make sure you press all the chips into their sockets. They can rise out of them over the years and also sockets and legs can oxidise. 

 

Again, I suspect deeper issues, but the amount of 800s and 400s I've got working buy doing this is surprisingly high.:)

 

Hi.  Re the power with cartridge bay door closed, I'm confident this is not root issue as have power light on Atari coming on and flicker on screen output as I power on.  It does seem that switch was damaged and corroded.  I was originally holding it down with blue-tac with the case off, though admit later i have had to solder a small wire between the contacts to force it on all the time.  Not sure if this will be a temp or perm solution as the switch it pretty corroded and not working that well even with case on now.

 

Re the rom and ram boards, I have removed all chips and reseated, and cleaned legs and sockets using cotton buds and isopropanol.  With everything returned, the situation remains the same.

 

I have a few days to wait for rom board i've ordered, so hoping switch that out may give me some luck.

 

 

[TJ76]

I just wanted to stop by and share that I was able to complete repairs of this Atari 800 to a point where it boots successfully, and after further efforts, now seems to be consistently working and stable. 

 

I've gone into considerable depth my 3rd video about this on my Youtube channel, which besides wanting to own one of these lovely machines, creating this content was a large part of my motivation for embarking on this crusade to source and fix an 800 at a more reasonable price than working machines are currently going on ebay.  

 

If video's a bit long, feel free to skip through, or I'll put a few lines on what happened further down, to avoid spoiling the surprises in the video!

 

Thanks again for the engagement / tips and offers of assistance from this post.  Always great to know a healthy Atari community lives on here and beyond!

 

 

 

 

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Turns out i'm an idiot.  At some point I replaced the CD4050 the wrong way around, which really didn't help further troubleshooting.

 

 

Once that resolved, seemed the original 10K rom was indeed bad, so at around £15 , the replacement I sourced was a good call, as that changed behaviour a little.

 

After a little messing about swapping in different pokeys, I got the machine to boot with only one of them, which was odd at the time, since all pokeys I was using worked in 800XLs

 

Eventually tracked issue to a dodgy socket, which I replaced, however made a bit of a meal of it if i'm honest, as could do with better tools (and skill?).

 

With the socket out, I had to do some basic repairs on about 3 damaged traces, two persueded to connect and resoldered back in with continuity verified.

 

One was beyond repair, so had to jump with some wire.

 

Once socket replaced, and I worked out how to put it back together properly, being the only 800 I've worked on, everything finished up working and stable.

 

When I have more time, I'll re-test the other two Pokeys I was using, and investigate one of the 800xl's that at some point I seem to have caused a fault with while using parts from it as doners for the 800.  I thought everything was put back as was, however perhaps not, and guess can't rule out socket damage on the XL either.  As have more than one of those, should be trivial to narrow down once I have time

 

That's all folks!!

 

 

Edited July 3 by TJ76
hit a key and posted before finishing

[TJ76]

@Beeblebrox , just spotted your Incognito guide and started paging through as may look to do that in the future.  Only spent a minute and already going to help me find where i forgot to replace some of the screws inside holding boards in properly

 

Looks like great work!

 

 

[Beeblebrox]

1 hour ago, TJ76 said:

@Beeblebrox , just spotted your Incognito guide and started paging through as may look to do that in the future.  Only spent a minute and already going to help me find where i forgot to replace some of the screws inside holding boards in properly

 

Looks like great work!

 

 

No worries. Watch FJCs vids as well.

 

I've done the incognito many times.  Best upgrade for the 800 IMHO.