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Sadly I'm down to UAE at the moment, and play around with AROS, while hoping to see the Natami in this lifetime - this is because my main dev system, the towered A4000 with the Delfina is down.


An Adventure with A4k SIMMs

At one time I tried to get a replacement, but due to its SIMM clips broken off, it was in no better shape than my original mobo, and it ended up being sent back. Both worked in the desktop case, with a small epoxy plate holding down those SIMMs, but neither mobo worked in the ElBox tower, where the Zorro plate should be able to do the same job. Then again, even the power LED remains silent, or dark, so I came to the conclusion that the only part that could cause this problem had to be the PSU. The drives don't initialise either, so it seems very likely. But I'm a programmer, dammit, not an engineer...

A4k tower mobo assembled
A4000 with SIMM hack

When the A4000 arrived in the parcel, I tried to boot it, but it refused to do so. Then I took the lid off and saw this. The pressure from the SIMMs must have bent the epoxy plate upwards and pressing it back down restored it, though if it could loosen itself in transport, the same can happen from the constant vibration of the drives and fans over time.

big SIMMs with Zorro plate

So then I tried to transfer that "new" mobo to my tower. It had bigger SIMMs than mine and the Zorro plate pressed them down the same way the epoxy plate did. Only the CHIP RAM SIMM had to have some additional treatment - a pencil eraser came in handy. There was also a perspex ruler inserted just underneath the Zorro plate to keep the SIMMs from shorting. New uses for old office consumables. Sadly I did not manage to get it to work at all.

my original mobo in the Desktop

I also had the bright idea to test my old mobo in the desktop case, to see if it worked. A couple of years ago I had tried to fix it with hot glue, and at that time it did not want to work so I had to abandon the idea. This time however, now in the desktop case, only the CHIP RAM SIMM needed to be pressed down, and it actually booted up!

In actual fact, the epoxy plate doesn't even touch the three SIMMS in the middle, only the CHIP and the last FAST RAM SIMMs are pressed down by it, though the latter is as solid as the three others.

my own mobo with smaller SIMMs

So back to the tower and this is how the hack looks like under the Zorro plate. At first I put a couple of pencil erasers on top of the SIMMs with a piece of perspex on top, then came the Zorro plate on top of that, which ended up getting bent.

the mobo bends from pressure
SIMMs prepared for assembly

Since the above trick exerted too much pressure on the centre of the Zorro plate, I had to come up with this different solution. Here the perspex is directly on top of the SIMMs and the two erasers closer to the edges of the Zorro plate and its fixing points, so that won't bend now. At the same time, the perspex plate does bend, exactly the same way the epoxy plate did in the desktop. Theoretically sound...

But it still doesn't work, with the power LED remaining off, so now I am convinced that the fault must lie elsewhere in the tower. There aren't many possibilities, and as the power connector seems okay, only the PSU remains.

Isn't it strange how such a simple little thing like SIMM clips can cause such a lot of fuss?






Update on 20. Sept. 2017

About a year ago, AmigaOne sent me an adapter - a similar device used to cost ~$100 at Software Hut, then I couldn't find any at all for years, so this came as a nice surprise. It allows me to use a PC PSU in this machine, but sadly not even the power LED would come on. Obviously the poor A4k had been boxed-up and idle for quite a number of years, but then I remembered the old rumour about the delivery trucks at C= driving quickly over speed-bumps to re-seat all the chips on the mobos. Not having a truck, I just opened up the lid and applied contact cleaner in the places I thought might need it. This restored power, but still no boot. So my next task is to do this treatment to the IDE and SCSI connectors too, and maybe go over all the expansion cards as well.

A4k tower mobo assembled

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