PhilCs blog / the latest things hes broken(fixed)

[Steve]

Don't forget the Indigo 2 Will be nice to see if you get it going

[PhilC]

Don't forget the Indigo 2 Will be nice to see if you get it going

Oh I've not forgotten that yet Steve, I've had to make room to get that beast of a machine onto the desk. Its next in line

[PhilC]

Whilst I was packing up at the Cyber Legends show @Steve graciously gave me an SGI Indigo 2 Impact with a power supply fault.

Steve had recapped the power supply and a few other bits but could not get the computer to work. So Initially I had a visual check of the power supply as I have no idea how it worked but found a few dry joints.

Next up was to plug it into the SGI and see what happens. And... press power button... Nothing. Not even a blip from the fans or less or anything.

So this power supply has some hefty power connections for powering up the computer but it also has a 2 pin wire going to the riser board that the expansion cards sit into. This two pin connector has no power present at all. Some I'm kind of presuming that this works similar to other power supplies that I've looked at. That there. is a small power supply sent to the power switch, which then makes a connection and tells the rest of the power supply to power up.

So once again the power supply will be in bits on my bench and we will see if we can work out why the start power isn't present. BTW, this PSU is a real pig to work on. It has two board fitted tightly opposite each other, meaning its not exactly easy to get out the case, let alone work on.

Pics to follow.

[rubber_jonnie]

Whilst I was packing up at the Cyber Legends show @Steve graciously gave me an SGI Indigo 2 Impact with a power supply fault.

Steve had recapped the power supply and a few other bits but could not get the computer to work. So Initially I had a visual check of the power supply as I have no idea how it worked but found a few dry joints.

Next up was to plug it into the SGI and see what happens. And... press power button... Nothing. Not even a blip from the fans or less or anything.

So this power supply has some hefty power connections for powering up the computer but it also has a 2 pin wire going to the riser board that the expansion cards sit into. This two pin connector has no power present at all. Some I'm kind of presuming that this works similar to other power supplies that I've looked at. That there. is a small power supply sent to the power switch, which then makes a connection and tells the rest of the power supply to power up.

So once again the power supply will be in bits on my bench and we will see if we can work out why the start power isn't present. BTW, this PSU is a real pig to work on. It has two board fitted tightly opposite each other, meaning its not exactly easy to get out the case, let alone work on.

Pics to follow.

Are there any schematics to be had?

That reminds me, I must try and have a look at my spare Octane at some point.

[PhilC]

@rubber_jonnie none that I’ve been able to locate so far but there is a page telling you what to expect on each psu pin and how to get it to start, so will just work through it step by step.

[rubber_jonnie]

@rubber_jonnie none that I’ve been able to locate so far but there is a page telling you what to expect on each psu pin and how to get it to start, so will just work through it step by step.

Thats a start at least.

[PhilC]

Slowly been working on a few of my projects in the free time I’ve had.

The ATX ST is up and running but has an interesting display issue which I’ll post about when I get a mo. It’s self inflicted as I used a few different value caps etc as they were what I had.

Secondly I’ve finally fixed the Vic-20. It turns out it needed a few new chips, so maybe had a PSU failure. In the end it needed three new ram chips, a 6522 and a kernel rom chip.

I obtained a multi rom chip from eBay which has helped me get the Vic up and running but I’ll get it replaced with the proper chip and keep the multi chip for diagnostic purposes.

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Great picture through this composite to VGA adaptor I’ve been using.

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[PhilC]

Just a very quick update.

I'll be doing a bit of retro work this weekend and whilst I'm at it may build a couple of ST536 Rev 5 boards. Please PM me to discuss.

[PhilC]

So I’ve been quite busy with anything but retro stuff lately but decided it was time for another purchase after I say one of these on eBay.

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I’d never owned a Sharp before but remember trying to win an MZ-80K by entering a competition in a magazine. I didn’t win obviously.

The MZ-700 is actually a really well built machine but actually quite a complex motherboard with quite a number of 74 series chips on it.

This one didn’t work when I got it and it took a couple of hours of Googling 74 series data sheets and trying to remove stubborn old faulty chips. In the end I've had to replace the screen ram and one of the logic chips on the address lines as it was no longer functioning.

Then press reset and….

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I don’t have any software for this at the moment, so can’t really set up the tape deck on it.

[stephen_usher]