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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: mingle on November 19, 2008, 07:05:41 AM
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Hi,
Just picked up an old A2000HD with an ACD AdRAM 8MB board and a GVP Series II SCSI card and a couple of SCSI HDDs.
However, it doesn't seem to want to boot!
It goes through the screen colour-changes during the initial phase of the boot: dark grey -> light grey -> white, then the screen goes black (not blank) and nothing...
I've tried removing all the cards and still the same result.
Are there any jumpers on the motherboard I need to check/change? It's a rev 6.2 MB...
As ever; any help or comments greatly appreciated!
Cheers,
Mike.
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All the HD disks are placed? If so, try to keep only the boot one (normally the first on the chain).
Also check the PSU voltage levels, specially the +5V rail. It must be on the 4.95~5.05V range, and stable!
Less than 4.95V and some circuits don't work reliably. More than 5.05 will start to fry chips inside the computer. SCSI disks are specially sensitive to this.
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Given that you have removed all the cards, I guess what I am about to say should be applicable. When I first got my A500 it did the exact same thing, reseating all the chips solved it, have you tried that yet?
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Hi,
I haven't tried removing the chips, but I've pressed them down into their sockets.
The inside of this A2000 is pretty dusty though, so it may be worth removing the chips and giving it all a good clean.
Not sure how I go about removing the Agnus without a proper chip-puller though...?
Cheers,
Mike.
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WD40 the hell out of the motherboard, let it dry and take a good look at the battery area. Press those chips in hjard.
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WD40? Hmmm, wouldn't use WD40 myself, I prefer using compressed air followed by a good going over with Isopropyl alcohol and Q-tips. Some here prefer a distilled water bath followed by a good air drying, but I was always told never mix water and electricity, so I don't!
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It is well worth paying a couple of dollars for a chip puller rather than trying to lever it out.
Makes a nightmare job a doddle which is over in a couple of painless seconds.
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Never EVER spray WD-40 on anything electronic. It's conductive!! Good luck getting around everything to wipe it off anyway.
I think perhaps he meant to say 'contact cleaner'. High content of alcolhol in Rubbing alcohol is good too as most of it will dissipate. Even compressed air has moisture that leaks out with the spray. I've never understood why someone would use compressed air on anything. You're just blowing the dust to another part of the computer, your room or your lungs!
Use a vacuum and a paint brush to get dust out of a computer. At least that way, the miniscule dust from the exhaust is directed (again) somewhere else. lol
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save2600 wrote:
Never EVER spray WD-40 on anything electronic. It's conductive!! Good luck getting around everything to wipe it off anyway.
No, WD40 is a dielectric - an insulator. If it was conductive then the A2000 and A3000 I cleaned up yesterday would have burst into 2 balls of flames instead of powering up happily. :-)
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I've never heard anyone refer to WD-40 as being a dielectric. It's simply not true. Yes, petroleum based products are not the greatest electrical conductors, but they DO conduct some electricity, which is putting your components at risk of shorting out.
You are lucky your machines did NOT explode and burn yet! Besides being of flammable nature, WD40 will also collect and attract dust over time, degrading electrical integrity even further. Do this if you want to shorten the life span of your proprietary chips, etc.
Seriously, using WD-40 on electrical PCB's is terrible advise. Do some research. If you've had "luck" in the past, then that's all it is. Get as much of that stuff OFF your PCB's using alcohol as you can! This is from 30 years experience servicing electronics.
Note to self: never buy a computer from Darrin :-)
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LOL. OK, I'll take your word for it. For what it's worth, I cleaned the mobos up until they were sparkling afterwards BEFORE I powered them back up. :-)
Oh, and after multiple googling, it is DEFINATELY not a conductor - in fact it is a very good insulator. What it can do is attact dust if you don't clean it all off. It also disolves the heat paste used between CPUs and their fans/heat sinks! :-o
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Darrin wrote:
LOL. OK, I'll take your word for it. For what it's worth, I cleaned the mobos up until they were sparkling afterwards BEFORE I powered them back up. :-)
I doubt you got every last drop of WD40, that stuff gets into everything.
Oh, and after multiple googling, it is DEFINATELY not a conductor - in fact it is a very good insulator. What it can do is attact dust if you don't clean it all off.
Why bother using it at all if you have to clean off the cleaner? You don't need to wash away distilled water or Isopropyl alcohol, they simply evaporate leaving no residue at all.
It also disolves the heat paste used between CPUs and their fans/heat sinks! :-o
So does Isopropyl alcohol, but again you don't need to wash it away afterward.
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Darrin wrote:
LOL. OK, I'll take your word for it. For what it's worth, I cleaned the mobos up until they were sparkling afterwards BEFORE I powered them back up. :-)
Oh, and after multiple googling, it is DEFINATELY not a conductor - in fact it is a very good insulator. What it can do is attact dust if you don't clean it all off. It also disolves the heat paste used between CPUs and their fans/heat sinks! :-o
Research what WD-40 was developed for / first marketed for. You may be shocked.
Wikipedea quote;
"Typical uses of WD-40 in automotive repair include
* Driving moisture out of the high and low-tension electrical components of an internal combustion engine (e.g. cleaning and drying the inside of the ignition distributor cap) so that it will start, particularly on cold days"
This may be the root of why some people think it is conductive.
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* Driving moisture out of the high and low-tension electrical components of an internal combustion engine (e.g. cleaning and drying the inside of the ignition distributor cap) so that it will start, particularly on cold days"
This may be the root of why some people think it is conductive.
Yes, because it is mildly conductive and metal filings/shavings are likely to cling to it, it worked well for distributor points, etc. in automotive use as a quick "fix". But now that you bring up its use in an auto, think about those components you just mentioned. There's not really a great chance of there being a true short as there would be on something so populated/mini/precise as a printed circuit board.
We're also talking about a rugged 12volt system. Not the more fragile 5v and less found on mobo's.
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save2600 wrote:
Yes, because it is mildly conductive and metal filings/shavings are likely to cling to it, it worked well for distributor points, etc. in automotive use as a quick "fix". But now that you bring up its use in an auto, think about those components you just mentioned. There's not really a great chance of there being a true short as there would be on something so populated/mini/precise as a printed circuit board.
We're also talking about a rugged 12volt system. Not the more fragile 5v and less found on mobo's.
I can't find anything from a reputable source that says that it is even mildly conductive at those levels. In fact it is supposed to be non-conductive up to 5000v. I've personally used it on my pool pump where it was sprayed onto the active motor and contacts while it was running with no shorts, sparks, bangs or flames.
Now, you're right that the liquid could dislodge some metal filings and cause a short, but you could do that with compressed air too.
I think the main reason people think it conducts is because several of its rival products do.
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Okay - since we're obviously going to beat this thread to death and I've clearly got the time, I thought I'd set up a little experiment for you. I did not perform this experiment solely for myself as I've mentioned before, I know all too well the negative affects WD-40 has on electronics. If you're easily tricked by what you read, marketing, whatever, then no wonder this world is where it's at today! lol
Alright... here's what I did:
1) brought out a variable DC power supply and set it to exactly 5.14 volts. That would be typical of the logic voltage present in an older computer system such as our beloved Miggy's.
2) alligator<>jumper clipped the positive lead to my DMM set on mV.
3) alligator<>jumper clipped the negative lead to a plastic sandwich bag.
4) liberally sprayed the baggy down with the "dielectric" in question, while making sure it spread from the alligator clipped -5v throughout the middle of the bag.
5) using the other lead from my DMM, I poked about the bag and measured as high as 44mv down to 1.2mv depending how for away I got from the power lead and how much was sprayed near the lead.
I returned to the baggy after a half hour to measure voltages again. Interestingly, I measured even slightly higher readings this time!! A chemical reaction with the plastic?? OR is it attracting microscopic conductive particles, further enhancing its conductivity? There *has* been a lot of talk lately about plastics relating to brain tumours, cancer, etc. Maybe the truth is finally starting to leak out on some of this stuff, or more than likely, another company and group of people have an agenda with a product that they'd like to replace plastic with ;-)
Back to the topic at hand...
To make sure I wasn't doing anything wrong (this test could not be any simpler), I snagged another new plastic baggy without WD-40 and proceeded to measure... hold on to your hat here... NOTHING! Nada. Zip. Zilch. τίποτα. Niets. Rien. Nichts. Niente. 何も. ничего.
The reason why you may have had good luck in the past douching your boards down with WD-40 is the simple fact that the traces etched into the PCB are covered by silkscreen. It's the chips and components that are more at risk of having something conductive stick to the excess of the WD-40 (which doesn't seem to be evaporating any time soon on my baggy I might add).
...hopefully this will be the end of the thread :-)
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save2600 wrote:
Okay - since we're obviously going to beat this thread to death and I've clearly got the time, I thought I'd set up a little experiment for you. I did not perform this experiment solely for myself as I've mentioned before, I know all too well the negative affects WD-40 has on electronics. If you're easily tricked by what you read, marketing, whatever, then no wonder this world is where it's at today! lol
Alright... here's what I did:
1) brought out a variable DC power supply and set it to exactly 5.14 volts. That would be typical of the logic voltage present in an older computer system such as our beloved Miggy's.
2) alligator<>jumper clipped the positive lead to my DMM set on mV.
3) alligator<>jumper clipped the negative lead to a plastic sandwich bag.
4) liberally sprayed the baggy down with the "dielectric" in question, while making sure it spread from the alligator clipped -5v throughout the middle of the bag.
5) using the other lead from my DMM, I poked about the bag and measured as high as 44mv down to 1.2mv depending how for away I got from the power lead and how much was sprayed near the lead.
I returned to the baggy after a half hour to measure voltages again. Interestingly, I measured even slightly higher readings this time!! A chemical reaction with the plastic?? OR is it attracting microscopic conductive particles, further enhancing its conductivity? There *has* been a lot of talk lately about plastics relating to brain tumours, cancer, etc. Maybe the truth is finally starting to leak out on some of this stuff, or more than likely, another company and group of people have an agenda with a product that they'd like to replace plastic with ;-)
Back to the topic at hand...
To make sure I wasn't doing anything wrong (this test could not be any simpler), I snagged another new plastic baggy without WD-40 and proceeded to measure... hold on to your hat here... NOTHING! Nada. Zip. Zilch. τίποτα. Niets. Rien. Nichts. Niente. 何も. ничего.
The reason why you may have had good luck in the past douching your boards down with WD-40 is the simple fact that the traces etched into the PCB are covered by silkscreen. It's the chips and components that are more at risk of having something conductive stick to the excess of the WD-40 (which doesn't seem to be evaporating any time soon on my baggy I might add).
...hopefully this will be the end of the thread :-)
Are you sure?
:-D
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@save2600
did you measure it without wd40? BTW, 44mV doesn't seem very high to me..
Why didn't you simply measure the resistivity, in MOhms or similar?
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Yeah, we're good :-)
Just stop using WD-40 on your Amiga's already! lol
Your auto, fine. Door hinges, fine.
BTW: if you want to try a good cheap alternative to cleaning contacts and PCB's... I've found Brake Parts cleaner to do the trick! lol Just hope you don't have weak nasal constitutions for a few days after spraying ;-)
Course, I would never use brake parts cleaner on any of MY machines. lol
I do know a very successful electronics repair guy that actually places his PCB's in the dishwasher, being sure to fully dry the things of course. Sometimes, he may even just throw the boards out on the lawn, hose 'em down and let 'em bake in the sun to dry out. He's never reported a single problem with that method and we're talking about arcade/pinball boards...
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@ orange:
Yes - I did measure it without WD-40. Please re-read the results.
And I didn't measure resistance because I wanted to prove that WD-40 conducts electricity - not just add resistance. Doesn't matter if a measurement in mV is low. Introducing foreign power to any circuit or IC is not usually good. Think static electricity.
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OK, just one small note IIRC, you cannot possibly 'add resistance' by adding new (passive) components.. you can only decrease it that way (like adding more paths for river).