Pink screen on 600XL

[Devalis]

I have a 600XL that I just recapped and added the monitor port to.  It was working and younger, inexperienced me decided it would be a good idea to replace the sockets on all the ICs.  After that, it died.  I just recently decided to get it going again so I carefully removed all the new sockets and checked for any bad traces.  I only found one and repaired it.  The machine still doesn't boot.  It will only show a pinkish/red screen.  I checked volage and all chips are getting around 4.8-4.9 volts.  The CPU and ANTIC are the only ones getting hot.  Where should I start?

[Nezgar]

Did you test swapping all the main IC's into a known good machine? To at least eliminate those as a possible fault, or that they have been damaged. Especially CPU, ANTIC as mentioned, and possibly OS ROM. See if the screen colour changes with OS ROM removed -- usually that results in a dark brown/red screen I think.

[Beeblebrox]

@Devalis  Just as a general suggestion could you upload a full pic of your board as well as the screen. Nearly always helps. Just want to see the colour.

 

If it is a red/brown colour in fact that can be a different indicator from pinkish/red. I've had a pink screen before which - if I recall was more to do with a failing Antic or GTIA chip. Whereas a dark red/brown screen can be a few things as eluded to earlier by others.

 

I've had bad CPU, PIA, ram and OS rom be the cause of the red/brown screen.

 

Check out my old post here: 

 

Edited February 23, 2023 by Beeblebrox

[Devalis]

I replaced the CPU and the ANTIC with no change.  With the adjustment dead center, it's a pink screen.  I was planning a ram upgrade, maybe I should proceed and see if it comes back to life?

[_The Doctor__]

https://8bithardware.wixsite.com/website/post/atari-8-bit-400-800-xl-xl-pictorial-fault-guide

 

there were other guides explaining other colors displayed during faults like yellow brown etc. but heck if I can find them today... sad how stuff disappears from the web. some even explained for pal vs NSC colors as the fault displayed slightly different colors on pal as opposed to ntsc for the exact same fault. Looks like we're losing stuff again.

 

Yellow/Brown started in the CTIA/GTIA and video buffer realm 4050 etc.

 

though after playing with the color potentiometer who knows what you now look at, if you remember what it was before it got moved.

Edited March 7, 2023 by _The Doctor__

[Beeblebrox]

@Devalis where are you based? As mentioned tweaking the colour pot could be skewing the colour seen.

 

Given you have done the mass socketing in he past can you remove all socketed chips and inspect your sockets, and give the board a good clean with the likes of a contact cleaner/detox/etc? 

 

As mentioned a full high resolution shot of both sides of the board might be a good idea, ideally with and also without the chips in place.

 

Someone might spot something, (bad solder point, etc).

 

Seems fairly obvious but have the correct chips definitely gone back in their original places? You'd be surprised the number of times  someone has accidentally put a 40pin chip in the wrong socket. (I've done it once or twice by accident in the past when I first started tinkering) 

[_The Doctor__]

orientation as well

[Beeblebrox]

Ha, great minds think alike. I was just coming back to edit my post to add the same comment!

 

Sometime in the last few month's I recall an 800 owner going round the houses troubleshooting where it transpired the route cause of the issues came down to a Pokey chip which had the printed writing upside down and the chip had understandably been inserted with the writing in the supposed correct orientation, overlooking the actual chip pin1 side indicator. (Easily done if you aren't familiar with these things. I've come across many 40pin custom Atari chips where writing is printed upside down.)

 

 

 

It was only picked up when images of the PCB were posted iirc. 

Edited March 7, 2023 by Beeblebrox

[Rybags]

GTIA often seems to powerup with COLBAK at $F0 (by the looks of it)

 

In the case it stays at that it can be sign of a CPU or OS fault.  Going beyond that of course it could also be PIA, MMU, memory select logic etc etc.

But if the colour changes after about .4 seconds it can be indication that the CPU and OS are probably OK and something else is causing the halt.

[Devalis]

Here are photos.  I haven't cleaned the bottom of the board yet.

[ClausB]

Did you have a reason to recap it? Ataris have proven to be damned durable machines, aside from a recent epidemic of unnecessary recapping.

[Beeblebrox]

I agree with ClausB, plus also the underside of the board needs a real cleanup as lots of solder bits and leftover residue from the socketing, any one of which could be causing many issues. 

 

 

[mimo]

I think all those solder joints need going over, some look to be hollow joints , possibly not making a connection. Then there is all the splatter and joints with irregular shapes that are for sure a potential for a short.
Then a really good clean up with some IPA
I've always been a fan of "if it ain't broke, don't fix it"
 

[Devalis]

It was an early learning experience for me definitely...Inam older and wiser now lol 

[Devalis]

So i cleaned the board with alcohol and I ran it through my ultrasonic.  I also touched up any questionable solder joints and there was no change.  The pink screen persists with or without a cart.

[_The Doctor__]

what's the deal with U4?

[Beeblebrox]

5 hours ago, _The Doctor__ said:

what's the deal with U4?

Looks like a 28pin socket used for the basic chip in the absence of having the correct 24pin socket, and 4x pins clipped to allow it to fit. Worth checking this isn't shorting anything in any way under those clipped pins to the left I guess. Good spot. 

[_The Doctor__]

U23 4051 chip socket looks solder splattered

capacitor below power switch looks like bad or corroded joint on right leg, re-flow

cap near color pot lower left looks strange, is it camera angle or bad?

transistor in same area but lower and slightly to the right center of color pot appear bent and twisted possibly able to touch upper resistor leg.

bank of caps below keyboard connector and above chelco silk screen has whisker of brush bristle, hair , or wire across upper left bank.

 

re-flow crystal leg if cruddy.

Edited March 15, 2023 by _The Doctor__

[Devalis]

The board has provisions for the larger socket.  Nothing was trimmed to make to make it work.

[_The Doctor__]

and pin 1 is in the pin 1 hole?

along with the list of other things?

 

I'd check chip config position jumper select right side slightly above chip

Edited March 15, 2023 by _The Doctor__

[Devalis]

The chip was shifted over to the right as it is now.

[Beeblebrox]

That's interesting. I've worked on many atari 600XL boards, mainly PAL but some NTSC. I don't recall ever seeing provision on the PCB for a 28pin socket for the basic chip location. It's usually just the the 24 pin vias for the 24pin basic chip socket. 

[+kheller2]

Early Chelco units have it.

[Beeblebrox]

23 minutes ago, kheller2 said:

Early Chelco units have it.

Ah, good to know. Were some of the early BASIC IC's 28 pin then?  I've only ever come across 24pin BASIC IC's IIRC

[+kheller2]

The original CHECLO 600XL and 800XL units were designed to hold either 24 or 28 pin onboard BASIC.  Eventually that feature was removed.

I have never seen a 28PIN chip, and I'm not sure there ever would be unless there are some prototype REV B BASIC's floating around.

Maybe it was a cary over the from the 1200XL design.