Help troubleshooting friend's dead 800xl

[iscariot]

Hi everybody.  I posted earlier about my neat 800xl.  Needless to say, a friend of mine bought one off craigslist untested and(surprise, surprise) it doesn't work.  The power clicks on, but nothing else.  Where should we begin to check?  He's planning on bringing it by this weekend to look.  I recall a video on youtube about bad memory but according to him he can't even get video.  Is it possible that someone hooked this into an ingot psu and if so, what should we do?

[+x=usr(1536)]

What are you connecting it to for video & audio output?

[iscariot]

15 minutes ago, x=usr(1536) said:

What are you connecting it to for video & audio output?

I am planning on plugging it in with my composite video and an older square LCD tv that takes composite.

[+x=usr(1536)]

Sanity check: nobody's trying to connect the output marked 'TV' straight to the composite input, are they?  If so, that won't work.  It needs to be connected to the antenna input of a TV that has an analogue tuner.  Many newer TVs have dropped analogue tuning and can only tune digital channels.

 

It's still not totally clear as to what you mean by the following:

 

1 hour ago, iscariot said:

The power clicks on, but nothing else.

Is the power LED on?

1 hour ago, iscariot said:

according to him he can't even get video

Hence my question: what is he using for video & audio input?  Based on what was written in the first post, there's not enough information to begin troubleshooting.

 

Don't go down the ingot PSU rabbit hole just yet.  I'm not saying it isn't a possibility, but for right now there are too many unknowns to be able to start pointing fingers at any potential causes.

[xrbrevin]

in case you are unaware, composite (and SVideo) requires use of the 5-pin DIN monitor port on the Atari

[Beeblebrox]

@iscariot 

 

So as @x=usr(1536) has mentioned earlier - initially knowing if the LED light comes on would really help? "Can't get video" needs more clarification for example, especially the exact setup and behaviour observed. 

 

If no power light comes on there could be various power related issues including:

 

• PSU not providing any juice in the first place, (ie failing or just not working)
• Bad power socket on the 800XL (rare in my experience)
• Power power switch on the 800XL (rare - they are pretty hardy swtiches)
• Other passive componetry involved causing the issue (eg bad capacitors)
• Bad LED (tbh unlikely)

 

One thing to check: 

 

If you friend is using a modern USB power cable (many available on the internet) - you need at least a 2amp plug for it to work. So a 5v 2a plug - if you use a 1a plug it just won't power up.

 

So this is what I mean:

 

 

They rarely come with a mains to USB plug so sometimes you grab the nearest one to hand thinking it'll work - often a mobile phone one. These won't work.

 

****

I agree with x=usr for now don't go down the road of thinking it has had a bad psu fry it at some point - not at least at this stage.

 

Also, depending on whether your friend has the video cable connected correctly and the TV set up right in the first place, do you have any indication when you switch on (whilst connected to the TV), that there is any change on screen - however subtle - when you flick the switch on?  If a black screen displays - does it "jump" a little, or are there lines running up and down a black screen for example. Or is it just a case of nothing at all?

 

Is the TV's volume turned up and can you hear anything when you power up  -a subtle pop sound, or anything else?  (Assuming of course you have the audio connected in the first place - especially with composite cables and S-video cables)

 

If there is an LED power light present and also any indication of a subtle change on the TV screen and or audio when it's powered on then you have a bit more of a clue.

Namely a black screen could be anything from bad RAM chips, and bad MMU chip, (latter related to the RAM), to a dead CPU chip. (All of these are very common in my experience for these vintage machines - I've had many 800XLs pass through my hands where I've had this. There - after RAM is replaced and/or the CPU it springs to life). 

 

We can help diagnose more then. 

 

Bear in mind it could be that you fix these issues and see others revealed  - as these machines can have multiple issues that only reveal themselves after you have fixed one. You then cross that bridge when you come to it.

 

I think if you are looking to troubleshoot it when he brings it over, the more you can get clarified in advance the more productive and successfull a diagnosis will be.

 

So my advice would be that if you are able to get your friend to confirm in advance of him bringing it up to you:

 

• All the above questions.

 

Also.......

 

• What exactly has he used to connect to the TV?

 

for example has he tried this (a DIN to composite video/audio cable):

or a DIN to S-video  -where for a stock 800XL using such a cable will only hae a greyscale black and white image

(there is a well known easy mod inside the machine you can do to restore this (don't worry about that now)):

 

 

or the old school RF lead to the TV's old RF in/aerial connector (requires the TV to be tuned in of course as mentioned by X=usr above.

 

 

The other consideration (if a power led is confirmed as coming on and the TV is hooked up correctly),  is simply that the video cable used is itself faulty. I have had this before where I spent ages thinking it was the machine and it was the @~$**! cable to blame!  Not common though in my experience.

 

Anyways - more clarity is key here.  

 

When you do get the machine and open it up - depending on previous owners you may or may not find it has the metal shielding plates in place. Once removed (if present) you can access the PCB. Hopefully it is a Hong Kong made 800XL  - which means all of the chip will be socketed.  You can quickly check if it is by asking your friend to look for the sticker on the underside of the machine. It will typically state Taiwan more often than not, but occasionally it will say Hong Kong. Fingers crossed it is the latter - will make it a whole lot easier to fix if it is.

 

 

Edited June 14, 2022 by Beeblebrox

[iscariot]

We're going to revisit it this weekend.  I don't recall if the light was on or not and you're correct I don't have enough info yet.

[machf]

11 hours ago, Beeblebrox said:

 

 

If you friend is using a modern USB power cable (many available on the internet) - you need at least a 2amp plug for it to work. So a 5v 2a plug - if you use a 1a plug it just won't power up.

 

So this is what I mean:

 

 

They rarely come with a mains to USB plug so sometimes you grab the nearest one to hand thinking it'll work - often a mobile phone one. These won't work.

 

 

Interesting, just yesterday I was wondering if anything like that already existed, given that the latest surge suppressors I've bought come with 2 USB ports each... still, a USB port wouldn't work for Atari disk drives, though, as those use 9VAC.

[iscariot]

Good to know--I'll check.  I wouldn't have thought of that.

[Beeblebrox]

@machf  This has been my personal experience. I use the USB power leads all the time over here in the UK for all my 800XLs, 600XL and XE A8s. I tried before to power my 800XLs on a 1a usb plug and didn't clock why they didn't power up. Then as soon as I grabbed at least a 2a one - no issues.

 

I use the same 9vAC Atari PSU to power my 1050 drives, my Atari 1200XL and my Atari 800s.

 

 

[Beeblebrox]

1 hour ago, iscariot said:

We're going to revisit it this weekend.  I don't recall if the light was on or not and you're correct I don't have enough info yet.

@iscariot  Cool. My advice is to document everything and also take pics as you do anything. Has saved me time and a lot of headaches to have notes and especially a visual record/reference to refer back to.

 

Also regarding the internal metal shielding - once removed I personally always leave them off for the XL and XE A8s. IMHO these days they aren't required and they are a pain to constantly remove and install. 

Edited June 14, 2022 by Beeblebrox

[machf]

29 minutes ago, Beeblebrox said:

@machf  This has been my personal experience. I use the USB power leads all the time over here in the UK for all my 800XLs, 600XL and XE A8s. I tried before to power my 800XLs on a 1a usb plug and didn't clock why they didn't power up. Then as soon as I grabbed at least a 2a one - no issues.

Thanks, I'll look for those next time.

 

30 minutes ago, Beeblebrox said:

I use the same 9vAC Atari PSU to power my 1050 drives, my Atari 1200XL and my Atari 800s.

Uh huh, that means one AC socket for each one...

 

27 minutes ago, Beeblebrox said:

Also regarding the internal metal shielding - once removed I personally always leave them off for the XL and XE A8s. IMHO these days they aren't required and they are a pain to constantly remove and install. 

I was just cleaning the rust off a 130XE's RF shielding earlier and was wondering if it was worth the trouble... I had taken it off and bagged it when I got it several years ago and just yesterday decided to try to clean it before reinstalling it (since I had just cleaned the 130XE).

[iscariot]

OK well I just texted buddy.  He says the light isn't even coming on.

[iscariot]

Oh, and he's using a 4.5a USB power brick

[+x=usr(1536)]

Step 1: verify that the PSU is actually outputting a steady 5V at the connector to the XL.

 

Don't trust it because it works with an unrelated device; that device may not care if the power it's getting is out of spec, but the XL may very well.

 

Step 2: Connect it to a display device and see what's happening

 

One of the most useful troubleshooting mantras I've learned is 'ASAP' - Always Start At Power.  I'm embarrassed to admit just how recently I learned the acronym, given that it was the general principle I'd (usually) been working with for years.  However, it does hold true.

[iscariot]

Will do.  He's going to bring it by this weekend for us to poke around with again.  I've got one of the original power bricks which I know works(see my other post) and I'll try to plug that in too.

Edited June 15, 2022 by iscariot

[+DrVenkman]

11 hours ago, iscariot said:

Will do.  He's going to bring it by this weekend for us to poke around with again.  I've got one of the original power bricks which I know works(see my other post) and I'll try to plug that in too.

If his original power brick is an Ingot, that would explain the current problems. If so, there’s likely dead IC’s inside. Cut off the DIN pigtail, throw away the brick and solder the DIN cable to the outputs of a modern 5V DC PSU.

 

[iscariot]

That's what I'm afraid of.  We've set aside some time this weekend to test with my PSU.  It's one of the really, really big black ones in the picture with that "For use on atari 600xl atari 800xl"

 

If it is cooked, what needs to be replaced?

[+DrVenkman]

5 minutes ago, iscariot said:

That's what I'm afraid of.  We've set aside some time this weekend to test with my PSU.  It's one of the really, really big black ones in the picture with that "For use on atari 600xl atari 800xl"

 

If it is cooked, what needs to be replaced?

Those are the best models to have, honestly. They are big with lots of interior volume for ventilation. When they fail, they are not generally known to fail "hot" (high voltage) and destroy your computer, unlike the Ingot (which I've marked with the circle-slash. If that big XL-styled brick is dead, you can open it and replace the 7805 regulator inside and it should be perfectly fine.

[iscariot]

1 minute ago, DrVenkman said:

If that big XL-styled brick is dead, you can open it and replace the 7805 regulator inside and it should be perfectly fine.

IDK what he's got.  I probably should have actually paid attention to that.

[iscariot]

Ok.  Plugged into a known good PSU.  Nothing.  The switch looks good, I see 5v on the center pin.  Where do we check next?

[Beeblebrox]

@iscariot  OK I'd check the power socket din. Make sure it isn't loose, and that the solder points on the pcb look good and not dry, cracked, etc. When you push the plug in is there any play? You can reflow the solder for the 5 solder points if in doubt. I had an 800XL last year with this issue. That is where I'd go next if you aren't getting the led light. 

[+DrVenkman]

11 minutes ago, iscariot said:

Where do we check next?

Download a copy of SAM'S COMPUTERFACTS and start working through the troubleshooting checklists methodically. 

[iscariot]

Yeah plug looks good.  Not getting 5v to the CPU.  The inductor by te switch was broken loose.  Fixed it.  Now we get only b/w and no color on composite.  What to check next?

[Beeblebrox]

@iscariot  so just for the record is the machine working with led and with a ready prompt but just in black and white/grayscale on screen? If so try turning the colour pot dial. From memory component number r38. See if you get any colour as it is turned.

 

Also for the record if you were using an s-video cable it will be in black and white/grayscale as the chroma line isn't hooked up by default. This is easily done. But park that for the moment. Try the colour pot first. 

 

There is another possibility - that one of the transistors in the video circuit is faulty, but park that thought too for now. 

 

Colour pot first IMHO. 

 

Post an image if you like. 

Edited June 18, 2022 by Beeblebrox