{From a defunct Atari board}
This problem is not as common as the XL fault bearing the same symptoms. Some times this can be a simple black screen, while others you'll see random flashing images or colours.
Black Screen:
1] remove, clean (with Isopropyl Alcohol) and re-seat all cards and ICs. - if you can't get hold of Isopropyl Alcohol, then use compressed air.
2] swap out OS rom on 10k board
3] check the power connection is clean - no rust.
4] swap GTIA
Black Screen w/flashing Colours:
1] check for bent, twisted contacts - boards, ICs etc - the left cart port can fall victim to this
2] does inserting a cartridge "fix" the issue? - if so, the s201 switch may need repairing. this is the switch that tells the 800 the cart door is closed. this can be fixed by adding a small amount of solder on the switch contacts - underside of the board
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Progress, guys.
With the 'persuasion' of some carefully used pliers, I got the initial 10K ROM off and I found once this was removed... we were in business with the other RAM modules which came out with just a good old wriggle/pull on each end tab.
Here's the state of the contacts:
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ABOVE: If you look carefully, there's some muck across some of the contacts over on the far right...
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ABOVE: Thark-recommended contact cleaner soon brings the contacts back to a gleam - the cotton buds show you just how grimy and oxidised these contacts become
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ABOVE: Hoy em all out and clean one by one those grime-covered contacts - then peer in to the ROM/RAM slots and see if there's any dust n crap in there... again, use another cotton bud to scrape/clean out
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ABOVE: The source of many of these little black bits of dirt... the 800's ROM/RAM top cover has a foam insert which, after 37 years of ageing, has a tendency to disintegrate and shed its parts and pieces all over the shop - any of this gets in any sensitive areas 'down below' and you can bet you'll get some more black screens of death
Cheers, Brenski. I;ve just given it all another dab and clean with a damp cloth so just waiting for it all to air and dry before reassembly and re-testing.
Will update - as is my raison d'etre - later - STAY TUNED ATARI TEARDOWN FANS!
Last Edit: Jul 30, 2017 at 10:54am by 8bitbaz
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I'm afraid we're still at the same fault, guys - I have cleaned all the RAM/ROM slots and have sprayed the power input with your magic spray Thark, and although it tries to power up, we get a black screen then a crackling/distorted sound coming from the TV speaker and flashes of colour before power cuts out on the 800 / signal lost on TV, just after power-up.
I've tried pushing a couple of carts in and nothing happens other than...a black screen.
Clearly there are other issues here.
I've now detached the power (right hand side) board from the main unit and it's as below:
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ABOVE: Note - The two red LEDs don't light and the RF lead has now been completely removed
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ABOVE: Although electrical contact spray has been sprayed on the power input component, corrosion is still very evident. The 800 will try and power up - displays a black screen - then crackles and distorts and the screen begins flashing distorted colours and then powers down - signal lost on TV... CAPS gone? Thark'd find out...
Thark, mate, I know you've been real busy of late with Dom's fixes and I know you've plenty on at home at the moment, but if you could have a look - anytime in the near future - I'll send the power board to you as I'm thinking there's clearly some kind of power problem - eg. the two red LEDs at the bottom don't light and the machine just powers down after a few seconds...
Do you not need the rest of the machine? We'll save on postage if you don't but I'm wondering if you really need to test the rest of the kit out to see if it does actually all power up after you've checked out/repaired/recapped the power module?
Fellas - thanks for your help - especially Brenski - I will have another furtle with it later as I'm going to strip down the area under the ROM carts plastic bases and see if they have those little black bits all over - I'm certain they will have - maybe some other rogue bits in the wrong places?
It can't do any harm having one more thorough look and then it's over to Thark but NO RUSH, buddy - as ever - as and when - anytime will do!
CHEERS!
Last Edit: Jul 30, 2017 at 12:16pm by 8bitbaz
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I've stripped the bugger down to its barebones and I can find nothing wrong whatsoever in terms of ROMS not seated, custom chips not home properly or anything bent/making a bad contact/ leaking/shrinking/peeling outwardly - well, there's nothing obvious to the untrained eye.
I've had the plastic ROM fitments off and everything underneath looks fine, in fact it looks in great nick other than this continuous black screen followed by tearing flashes of colour streaks for about 5-6 seconds and then the display cuts out.
I've also tried running the 800 with JUST the 10k ROM inserted and do you know what you get? Just a plain yellowish screen with no colour flashes or static sounds...so that was different. Otherwise, if you try just inserting one bank of 16K RAM at a time, ie. from 1 up to 3... you get varying degrees of this black screen then colour flashing/tearing and static noise going on - it's worse when all 3 are in... god knows what that means? Sticking ROM carts in makes no difference - still the same screen corruptions/flashing colours.
The more and more I think about this, the more and more it must be the caps, fella.
I am willing to stake my fame as a loading error, I mean a syntax terror, that it's one or more of the following areas:
1) CAPS (No.1 suspect from what you've told me about other old gear flaking out when their natural life is 'up')
2) That corroded power input socket area (you have to twist the 1050's power jack around a bit until the power 'takes' in the 800s socket / recess)
3) ANTIC up the spout.
As I've no spares, no experience and definitely no more time (I've other fish to cook...I mean geese to fry!), it's pointless me soldiering/soldering on BUT I have learnt a lot about the physical layout of the 800 and I have now got a lot more experience in checking/fault-finding/going through the process of elimination - it's just a shame that this job is definitely beyond me and needs to be tackled by someone with that next level of expertise in testing faulty electronic boards and replacing dud old kit.
Let me know when it's best to send the power unit up to you, Thark, fella - I can send tomorrow but...
NO RUSH, mate!
Last Edit: Jul 30, 2017 at 4:09pm by 8bitbaz
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Just the power board, bud, but you know that now as you have it and ALREADY you've been beavering away at it at one helluva pace.
THANK YOU SO MUCH, Thark.
A couple of pics to follow, guys, but they're gonna be small / lo-res as our system of sending/receiving images from phone to phone is such that my morse operated apparatus isn't exactly equipped to do the job very well...
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ABOVE: I'm gonna invite Thark to provide the commentary BEFORE ^^^^^ AFTER ^^^^^
but apparently there's some evil stuff ganning on round about
C98... Someone's had their jacket ripped (in a fight?!)
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ABOVE: Old caps removed One super shiny like new power input connector - goodbye corrosion.
which are all defunct
Thark's next down to his Dundee branch of Maplins (I think he might have called it something else but nothing to do with Muppets, honest...) to raid them of the rest of their spare components.
Very grateful to you, fella - he's had a stack of Dom's work on just lately and I told him to go steady with this - anytime will do - no time like the present, eh, mate?
You're a STAR - very grateful indeed.
Fingers Xd for a more positive update, fellas, when it all returns to the Bazza biome in the near future and re-connects with the rest of the 800 unit...
WATCH THIS SPACE!
Last Edit: Aug 2, 2017 at 6:08pm by 8bitbaz
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the first photo was from an 800xl with an example of a cap needing replaced.
yeah im away to maplonks today see if they have the 2 axial 2200uf caps. no doubt they wont, so prob gunna be ebay.
i found a few cracked joints , one was at the channel select switch, the others were at the old caps.
also there is a little click switch whuch had very bad corrosion on the contacts which no doubt would of caused problems, im not sure of the layout of the 800 but its probably a switch that tells the computer the lid is closed.
the regs are probably ok but for the sake of pennies i will just replace them.
will keep you informed and now im off back to my own dimension to make a coffee and sort the kids out. the sound of thier wailing and arguing at this time in the morning is a transphasic experience.
have a good one y'all! going to see if spongebobs on tv.
--Thark
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Latest upload from the Thark showing - 2 axials done and recapping complete.... neat, fella!
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Next up, Brenski wants a good dekko at the various socketed chips so we can try and pinpoint ref numbers on ANTIC/CTIA/GTIA etc to try and get a good match IF we still run into gremlins in this department, when the power board returns home to 'Ull.
Photos to follow, folks.
Last Edit: Aug 4, 2017 at 9:19am by 8bitbaz
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Right, lads.
Here we go - latest pics of the 800 mobo and riser card at the rear.
I hope the chips in question and ref numbers can be read off and visible nice and clear...
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ABOVE: The 'riser' card / daughterboard at the rear of my 800 - If I'm reading this right from another reference elsewhere, from L to R there's...
C014889 PAL GTIA
C014887 PAL ANTIC
C014806 6502
Guys - this looks like the REAL DEAL and not that stated below 1st time
[Edited this...the 6502, ANTIC and CTIA in that order].
Can someone else please confirm? My source -
NB - how their chip alignment is different to mine showing different version/release.
This should tell us: www.jsobola.atari8.info/derelit/400_800sm.pdf
Sheesh.... page 103 of said manual (screen grab below) matches the wikipedia image (above) - but again it's not the same chip positions as on my riser card. These refer to A301, A302, A303 whereas mine show C302, C303, C304.
We need someone who's "been here" before!
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Any road, we'll get there no rush - must dash - pic of my motherboard as below...
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Cheers, guys.
I'll be back in a few hours... gotta see a man about: 3 cats, 2 greenhouses and... a dog.
Last Edit: Aug 4, 2017 at 12:39pm by 8bitbaz
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Not old. Vintage. :)
Black Screen Problems: Atari 800
Discussion about Atari 800 display issues
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