@Hans

Just the backup battery again

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The numerous "deaths" of my A1 - It's still going.

Not necessarily in chronological order. On each occasion my heart was in my mouth - was my A1 dead? The club A1 was called into service on a number of occasions to test whether suspect boards or CPUs were still working.

1. mother board soon after purchase. That was serious - replaced under warranty but the replacement together with my G4 CPU was destroyed in transit by the Australian Post Office. After 15 months without I accepted a replacement with a G3 CPU. By this time OS4 began to appear so I escaped perhaps being locked into linux.

2. Three failed PSUs. In each case they failed during switch-on at the wall when the PSU switch was also on. Two of these were the rather upmarket Thermaltake PSUs, chosen on recommendation of other users for their voltage stabilisation and quietness, one was replaced under warranty. I did not bother to seek a further Thermaltake replacement. In seeking another I returned one that would not stabilise with low power drain. I now have an AcBel Power 440 rated at about 384 watts, peak 440 watts. It can survive switch-on at the wall when it's own switch is on although, having been 3 times burned, I do not use the wall switch in this circumstance but sometimes it has happened.

3. Two battery replacements but I did not fear for my machine on these occasions.

Creeping failure and precautionary measures

4. NVRAM contact failure - not suspecting this I blamed everything else but chiefly the seating of the sound card. Everytime I reseated the card the machine worked again until one day it refused. I really thought my machine dead for two or three months until corrosion of the NVRAM contacts was suggested. With some help from a paperclip withdrawing tool and isopropyl alcohol, usually disguised as CD, tape, or video head cleaner, my A1 resumed operation. Word of this led to restoration of some other machines. Note: not only corrosion but unfiltered power line noise and thermal variation can cause contact failures. On former 386/486 boards I had to press in all chips during the hottest month of every year to restore function. Line noise produces pitting corrosion of component legs and contacts.

5. CPU Fans. The original becoming noisy I replaced it with a Zalman, quiet and effective. Fan noise can also develop with dust accumulation, the Zalman vanes can aquire a solid carpet of dust. Side note for A4000 owners: turbulence caused by that crude stamped metal grill over which the fan is seated in the PSU doubles the noise and wear of the fan and halves the cooling. Remove it for longer life and better performance.

6. Tired hard drive - accumulation of read errors during booting or loading of large programs eventually became intolerable and confused diagnosis. Replacement of the hard drive removed this irritation and fear of imminent failure.

Noel

@NoelFuller

Woah! Now replacing the capacitors on a classic Amiga no longer seem like a chore!

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Amiga A1200, 3.1 ROMs, Blizzard 1230 MKIV 64MB & FPU, 4GB DoM SSD, Workbench 3.1

@Deniil715

Hope you can revive yours. I still have to check the PSU to see if mine still works.

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PowerBook 5.2 MorphOS 3.15
PowerBook 5.8 MorphOS 3.15
Amiga 1200 BPPC/BVision AOS4.1 FE

@all

Back in business, but barely and unstably it seems...

Well, the PSU was dead. Tried starting it standa-alone but it barely blinked, or rather janked its fan, just like a dead PSU does. (I've had a few..)

I have now put back my old, more noisier, PSU but the wierd thing was that the machine has shutdown again! Several times, during boot or a few minutes after boot. I clocked down the CPU to 800MHz and lowered Vcore one step and it is basically ice-cold now - but it still shut down, twice!!

Now it runs though, for hours with this same PSU. It's so wierd.

@Apple_hammer

Quote:

C based PSUs have the kind of "emergency shutdown" feature that you've described? It probably does have some kind of output protection, but whether this includes an emergency shutdown when too much current is demanded, I don't know. I'd be more inclined to believe that the PSU is dead, to be honest. I'll certainly be hoping that's the case for you, an

I think some PSUs have either have an auto-fuse or a protection circuit preventing them from breaking when they are overloaded or shorted, but most don't, they just break or have a one-time fuse that burns. The current, noisy one, seems to be protected though since it has survived at least 10 sudden shutdowns while two other PSUs died at the first same kind of shutdown.

It is also interesting to note that the shutdown has never happend during power-up, only while running and often while doing something heavy, especially using the Altivec.

I have a couple of theories:

1. The CPU voltage regulator is broken or the DIP switch controlling it is glitchy causing it to spontaneously raising the voltage by a volt or something causing a power surge that blows the PSU. There is no evidence though, such as bulky capacitors or anything looking fried, and the computer works.

2. There is an almost short-circuit somewhere (tiny metal debre or whatever) causing spontaneous overload and shutdown. No evidence for this either.

3. Glitch in the power switch causing it to simply think I pushed the power-button. But this wouldn't explain the PSUs breaking.

4. Overload of some specific power line, such as the 5VSB line for some reason. With one broken output the whole PSU would refuse to power up.

All lines except the 5VSB seems to be slightly over their rated voltage.
I could test this last theory by simply gradually overloading each line by a few amperes and see if anyone is on the border. I'm pretty sure it wouldn't be the 12V line though since I'm not using the 12V CPU connector.

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- Don't get fooled by my avatar, I'm not like that (anymore, mostly... maybe only sometimes)
> Amiga Classic and OS4 developer for OnyxSoft.

@Deniil715

Glad to see it was the PSU and not the A1! Phew!

But the shutdown is strange. My A500 used to reset--due to faulty PSU. My A1 will freeze. And loose input devices. Now your machine shuts down! Certainly a mix there!

I wonder if you get shutdown instead of a freeze. Just a thought. Maybe not.

Another thing, could the PSU have damaged the A1 power circuitry when it died?

Last edited by Hypex on 06-Apr-2010 at 04:04 PM.

@Deniil715

You might contact Kurt Grach (Kgrach here at AmigaWorld) of Revanche llc. He repairs AOnes. He has mine right now, it was behaving somewhat similar to yours.

-BCP
Indianapolis, IND. USA

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- BCP
AmigaOne X1000 & Amiga 4000

Amiga Response Crew Users Group
Indianapolis, IN USA

@Deniil715

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