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Old 03-22-2011, 07:40 PM   #1
TheGoose
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Default White screen of sadness

Hardware know it all-s, I summon your knowledge.

I have a an A1000 that goes through a power up like so:


1 Switch on, power LED does the typical fast blinks an A1000 does
2 Goes to a grey screen for a moment
3 Followed by a solid white screen and nothing after. (this is the sad part)

I know this indicate a CPU failure but, I have tried two CPUs and I question that they are both bad. It could be possible. One was in a known, um, incident wiring up a 1Meg insider board and the other 68K is from an 11.50 cent ebay 'win' and judging by the abuse to the case (steak knife mod anyone?) could be DOA.

So, what else could I check, swap out? What else might cause the white screen of sadness?



Also note, with the keyboard, I can reboot the machine, no problem.
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Last edited by TheGoose; 03-23-2011 at 07:42 AM..
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Old 03-22-2011, 08:57 PM   #2
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Default Re: White screen of sadness

Quote:
Originally Posted by TheGoose View Post
Hardware know it all-s, I summon your knowledge.

I have a an A1000 that goes through a power up like so:


1 Switch on, power LED does the typical fast blinks an A1000 does
2 Goes to a grey screen for a moment
3 Followed by a solid white screen and nothing after. (this is the sad part)

I know this indicate a CPU failure but, I have tried two CPUs and I question that they are both bad. It could be possible. One was in a known, um, incident wiring up a 1Meg insider board and the other 68K is from an 11.50 cent ebay 'win' and judging by the abuse to the case (stake knife mod anyone?) could be DOA.

So, what else could I check, swap out? What else might cause the white screen of sadness?



Also note, with the keyboard, I can reboot the machine, no problem.
First remove the "stake" (steak) knife!

Seriously, instead of a dead CPU, it is probably a bad motherboard trace, or a short circuit. Have you checked for any obviously burned traces on both sides of the motherboard?
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Old 03-23-2011, 07:49 AM   #3
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Default Re: White screen of sadness

LOL, well it was like stabbed with a 'stake' ? Hmm, good point, I have studied the top side, nothing jumps out at me. I guess I can look at the back side tonight.

If I decide to get a 68K from ebay, I assume a 8Mhz Mac 68K would be just fine?
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Old 03-23-2011, 08:04 AM   #4
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Default Re: White screen of sadness

If your going to look at your backside it's best to use a mirror or get a doctor to do it for you...

Nah... seriously though... way back about 87 my old A1000 developed the same fault (ie: blank white screen at boot up) at that time I didn't know a lot about it and took it back to the shop where I bought it...

It cost me nearly 150 quid to get it repaired (as it was just out of guarantee) but the guy who fixed it at the time told me it was the CPU that was dead and he had to replace it. I don't know to be honest if he was telling the truth as I never checked and was just happy it was working again...

I know you've said you have tried two CPUs but you never know they could both be faulty. Also I would check out all the socketed chips first and connectors as you never know something may have worked loose and just require re-seating before you go spending any more cash on it...
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Old 03-23-2011, 09:16 AM   #5
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Default Re: White screen of sadness

check the power supply first. Try swapping the boot roms if u have a known good set. Look for bad ram also(may have some chips that are hot but not always).
If you havent reseated every socketed chip,do so now and check for any pins bent under or making bad contact. I've seen them with the slightest corrosion on pins that dont make good contact in the sockets.

the boot colors give you a general idea,but some times other related parts can cause the color and be decieving.


mike



Quote:
Originally Posted by TheGoose View Post
Hardware know it all-s, I summon your knowledge.

I have a an A1000 that goes through a power up like so:


1 Switch on, power LED does the typical fast blinks an A1000 does
2 Goes to a grey screen for a moment
3 Followed by a solid white screen and nothing after. (this is the sad part)

I know this indicate a CPU failure but, I have tried two CPUs and I question that they are both bad. It could be possible. One was in a known, um, incident wiring up a 1Meg insider board and the other 68K is from an 11.50 cent ebay 'win' and judging by the abuse to the case (steak knife mod anyone?) could be DOA.

So, what else could I check, swap out? What else might cause the white screen of sadness?



Also note, with the keyboard, I can reboot the machine, no problem.
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Old 03-23-2011, 09:24 AM   #6
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Default Re: White screen of sadness

Did you try it without the CPU?! Might give you a different kind of white.
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Old 03-23-2011, 10:50 AM   #7
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Default Re: White screen of sadness

Is there any blinking on the Keyboard LED after the white screen appears? I've had similar problems which were fixed by doing the PLA Ground Modification on PAL Chips J , K , L, N, P & Q on the Daughterboard and connection the wire to the Ground plane between the 68000 and the Expansion connector.
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Old 03-23-2011, 06:26 PM   #8
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Default Re: White screen of sadness

Found a scratch / gouge on the current one (my old one)
Looks like a squirrel with steak knife broken in...

@tone, I did that actually, it only showed a black kind of white.

@ sahf, no extra blinking, I looked for that.



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Old 03-24-2011, 03:14 AM   #9
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Default Re: White screen of sadness

It looks to me like here (where I've spent hours slavishly highlighting) the traces are all pushed to the right, connecting to the adjacent traces.

You do have a multimeter, right? Time to check those traces.

To be honest, though, if it just suddenly stopped working it's unlikely to be the fault. Scratches on the board don't happen by themselves, so if you didn't do it to break it, then it was like that when it was working...
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Old 03-24-2011, 03:32 AM   #10
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Default Re: White screen of sadness

I have at least one spare 68000 around here. If you wind up wanting a replacement, PM me before you go to eBay.
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Old 03-24-2011, 04:04 AM   #11
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Default Re: White screen of sadness

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I have at least one spare 68000 around here. If you wind up wanting a replacement, PM me before you go to eBay.
To be honest, I'd say it's very unlikely to be the CPU.
Even though the chances of both CPUs being dead is reasonable, the chances of both of them being dead with exactly the same symptoms is very unlikely.
Best thing to do is to try both CPUs in a known good machine such as an A500.
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Old 03-24-2011, 05:21 AM   #12
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Default Re: White screen of sadness

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Originally Posted by spirantho View Post
To be honest, I'd say it's very unlikely to be the CPU.
Even though the chances of both CPUs being dead is reasonable, the chances of both of them being dead with exactly the same symptoms is very unlikely.
Best thing to do is to try both CPUs in a known good machine such as an A500.
i believe all dead CPUs would have same symptoms.
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Old 03-24-2011, 05:29 AM   #13
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Default Re: White screen of sadness

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i believe all dead CPUs would have same symptoms.
Of all the CPU's I've seen that've died, they rarely die in the same way because they rarely die 'outright'. They just start malfunctioning.

For instance, I have a Commodore +4 with a malfunctioning MOS 8501 (+4 owners will know these probably have a design fault as they die VERY often). The way it doesn't work is that it adds occasional amounts to line numbers. BASIC seems to work, but the line numbers are all wrong.

In the same way, a 68000 can die by losing an address line or tieing one line to another, which can end up with all sorts of weird results... but rarely with just a white screen like this. Especially as the machine responds to the C+A+A sequence.

The progression from grey screen to white screen implies it's starting the boot sequence and then failing before the kickstart loader. That requires at least a partially functioning CPU, as far as I know.
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Old 03-24-2011, 10:41 AM   #14
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Default Re: White screen of sadness

Thanks you guys, I agree, after another night with the flash light and magnifier; I think the CPUs are ok.

I think something is blown up else where - the daughter board perhaps..

Also, I switch chips around to the 11.50 board, it now it will do the exact same thing, white screen. And it has no scratches. So, gotta be a short or some bit blown...
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