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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: maffoo on July 14, 2006, 02:11:06 PM
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Hi,
I've just got hold of a second-hand A1200, complete with hard disk, 030 accelerator (a Turbo 1230 Mk II, which I think is 50MHz) and 22MB RAM. It arrived on Wednesday and seemed to work fine, although I didn't do much with it. I basically just checked it was working, but I didn't have any way to get software onto it (my CF->PCMCIA adapter hadn't arrived.)
Yesterday my order (including the CF adapter) from Amigakit arrived. I replaced the 3.0 ROMs with 3.1 so I could install OS 3.5 and everything seems to boot OK, then the Amiga will suddenly reset itself for no apparent reason. I don't even have to be doing anything, it's happened while I'm playing games but today I've noticed that it will reset if left alone for a while.
I've noticed that the 030 gets very warm, I've taken the trapdoor cover off and raised the front of the computer slightly to try to improve cooling a bit but it's still not stable. Earlier on it reset itself twice in a short space of time, making it look more like a CPU overheating problem.
Is it likely to be the CPU getting too warm? Or is there anything else it could be?
Thanks :)
Matt
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Check the RAM on the accelerator by completely filling the RAM disk with data and then purging it (delete all the data)- if it crashes -could be faulty memory.
Could be the connection between the accelerator and expansion connector on the motherboard- try removing the accelerator and testing the Amiga with some software - does it crash then? Also caerfully clean the expansion connector.
Also check the accelerator for any corrosion (leaking batteries etc). Check any SIMMs are securely in their slots.
Check the motherboard is lying straight on the plastic base of the A1200 - there are grooves for it to rest in. A slightly bent motherboard can cause problems.
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Amigakit , its amazing how much you help us on these boards.
What a great company.
BTW I love my Compact Flash Adapter.
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What you describe there could just as well be power failure... what PSU do you use for the system?
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Brian wrote:
What you describe there could just as well be power failure... what PSU do you use for the system?
It's just the bog-standard A1200 PSU (which I suppose is a nit long in the tooth - maybe it's on it's way out?)
I've just taken out the accelerator and booted the computer to see if it still crashes, and sadly it did (after only 4 minutes :-( )
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Yup, sounds like the death of your PSU. That happened to me when I connected an accelerator and a hard drive. Can you test it with an a500 PSU (slightly more powerful) or borrow one to try ?
You can prove if its overheating by sitting it on an unfeasibly large household electric fan with the trapdoor off and see what happens then !
Oh, and have a :pint: , it always helps :crazy:
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Seems unlikely to be a power issue if it does it with just the A1200 and hard drive with no accelerator connected. Try disconnecting everything non-essential (including the hard drive) then boot to a Workbench floppy, and see if that hangs. If it does, then it may be that you have a problem with the Amiga itself. Perhaps Amigakit's suggestion of checking the positioning of the motherboard is the key? Also make sure none of the metal shielding is shorting any parts of the board.
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moto
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Motorollin, I disagree since when mine went, it damaged the PSU such that it would drop the power rails intermittantly. I stuck an oscilloscope on it at the time to try to work out why it kept crashing. Even with everything disconnected it still did the same.
Best bet and simplest too, is to try a different psu.
Anyway, have a :pint: :-)
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Thanks motorollin, I'm trying it now (just the monitor and power connected, nothing else. (I was hoping the hard drive wouldn't be a problem as I've swapped the one it came with for a CF card, which AFAIK needs less power.)
I had a quick check of the motherboard while I was taking the accelerator out and I couldn't see any problems there.
I was also wondering, if it works fine from the workbench floppy could it indicate a problem with SetPatch (maybe it doesn't like my A1200's motherboard revision or something, and makes it unstable?) If that's the case, I can always reinstall 3.0 and Ebay the 3.5 CD...
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Always check the A1200 for stability problems with a Workbench floppy disk rather than booting from HD.
Perform the RAM disk test (complete fill/purge) when booted from Workbench disk to check Chip RAM.
Ensure the Kickstart chips are inserted properly into their sockets and no pins are bent.
BTW: If you want us to check the motherboard, that isn't a problem.
Hope you get to the bottom of this.
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Homer wrote:
Motorollin, I disagree since when mine went, it damaged the PSU such that it would drop the power rails intermittantly.
Oh sorry, I thought you meant that the PSU was underpowered, which is why I was skeptical when it was occurring with just a HDD connected. I see your point about the flaking out completely.
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moto
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The bog standard A1200 PSU gives 23-25W where's the A500 gives 50W. The standard PSU for the A1200 isn't ment to take any upgrades except for HDD and PCMCIA memory. Usually sticking a turbo to it fries it eventually, add an external floppy or two surtanly takes it down sooner or later. I actually fried an A500 PSU with a A1200+3,5" HDD+2 external FDD and a B1230 so that too can be underpowered (had the exact same issues with random reboots every 5sec-10min... esp when the PSU gets warm it starts to fail more frequently than when it's cold).
As you have removed the hardware that made the computer start failing and it still does fail I say the PSU have had it. Suggestion to you, try an A500 PSU and if that works then get hold of an old PC AT PSU and use the powercord from the defective original PSU to create a super PSU. :)
(Just a heads up here, a 200+W PSU is super but now power loss in the powercable to the computer might get to be a problem if you upgrade wildly and you might have to supply the motherboard with a second powercables form the PSU.)
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Yup, I think that was the most normal death for an A1200 psu. Intermittant power rails ! I tried slaving in a pc psu and it worked perfectly :-)
Still does ten years later ! Its sat next to me as I write :-D
Anyway, thats why I suggest trying another Amiga psu since its just so easy to do ! Good luck :pint:
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Thanks for the advice. I've tried filling and purging the RAM, it seems to work when it's just Chip RAM but when I had the 16MB SIMM in it caused a crash. However with the CF card attached the machine crashed even when it was booted from floppy, so maybe the SIMM's power requirements just pushed the PSU over the edge. I've also double-checked that the ROMs are seated properly, that doesn't seem to be a problem.
I'm going to try to get hold of an A500 PSU (there are some on Ebay, I've e-mailed the seller to confirm if they're 50W or 25W.) I was considering upgrading to a D-Box tower eventually, so once I've confirmed that the PSU is the problem I might get it towerised so it will have 350W to work with :-D
PS. Amigakit, I noticed that you have Amiga PSUs on your site, are they 50W? If so I might be placing another order with you!
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Might be worth mentioning where you live to see if you can borrow one for fault finding :-) Much cheaper than buying one !
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Homer wrote:
Might be worth mentioning where you live to see if you can borrow one for fault finding :-) Much cheaper than buying one !
Good idea :-) I live in Leicester (England.) Any help would be greatly appreciated!
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Thanks for the advice everyone, I've got hold of an A500 PSU and the A1200's run for over an hour without crashing, so I think it was the PSU.
Just out of interest, is the A1200 PSU any use (eg. can it be fixed?) Or should I just chop the power connector off in case I ever want to adapt an AT PSU and throw the rest away?
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If it carries on working well, it would be worth thinking in the long term about a higher power psu, especially if you wish to expand it more (as explained in other responses - the A500 psu will slowly overload and may eventually die the same way as the weaker A1200 psu). You will find that different hard drives can take very different amounts of current, so the simplest change will throw you over the overcurrent edge again !
I don't know if anybody would be interested in the main body of your A1200 psu, I also chopped the lead off mine before it went in the bin ! (Take note of the pin outs which if I remember correctly are shown on the case).
Could be worth looking around for a PC AT PSU which you would probably find in your friends and family's throw away pc's !!!
Good luck :pint:
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Only use of it would be if it has the connectordiagram on the buttom showing what lines go where.
For repairing I don't think so. Depending on what kind of PSU it is you might be able to use the casing with a different lowprofile PSU from some other stuff and mix em together to get a propper looking Amiga PSU again. Unfortunatly every A1200 PSU I've seen have been soldered in the plastic (not screwed together) and the inner electronics of that have been covered with plastic making a solid square lump of none servicable electronics.
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Nice idea Brian, I didn't think of changing the internals ! Didn't matter to me as I was thinking of putting mine in a tower case at the time, which simply meant I tried the new AT psu and it all worked correctly :-D
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Homer wrote:
the A500 psu will slowly overload and may eventually die the same way as the weaker A1200 psu
Sorry if this is a stupid question, but how likely is it that the A500 PSU will overload? I had a look at Epia Center's Power Simulator (http://www.epiacenter.com/powersim/powersim_v2/epiasimulator_v2.htm) to get an idea of the power reqirements of 2 CF cards (one in place of the HDD and one in the PCMCIA slot) and it looks to be around 1W for the pair. The comp.sys.68k FAQs (http://www.faqs.org/faqs/motorola/68k-chips-faq/index.html) say the 030 should take 2.6W, so say 10W for the whole card. Assuming the A1200 itself needs all the power from its original 25W PSU, this brings the total to 36W, which should be well within the A500 PSU's specs (it says 60W on the bottom.)
(I expect the figures I've quoted for the Amiga and accelerator are way out - hopefully I've over- rather than under-estimated the power requirements!)
I'm considering putting the computer in a tower eventually so hopefully the PSU won't be an issue, I'm just wondering if it will definitely overload. (I suspect it will die of old age eventually, hopefully not in the near future :-) )
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Just to second the comment here about Amigakit, i've been very impresed with their prices, website, range, and service to the Amiga community. I'm in the process of coming back to Amiga-land and you can be sure all my upgrades will be coming from Amigakit. You're such a force for good in the Amiga world!
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Mafoo: Absolutely ! Just remember that these standard psu's were not designed for long term overcurrents due to unexpected extra devices being fitted to greatly expanded machines. This includes using an A500 psu on an a1200. It is still a short term fix for an ongoing problem. Plan early and minimise your data loss !
Good luck :pint: