And the PSU went boom, and all the power went off...

[rubber_jonnie]

So I was doing one of my regular checks to see that stuff is working and put power into my Dolch L-PAC 486. One boom later and after resetting the ELCB, I found that a fuse had blown in the PSU.

This is not good as replacing the PSU in one of these things is tricky since they aren't exactly standard, so wondering if anyone has seen a fuse like this before:

IMG20240430132751.jpg

It's a 2.5A 250v fuse, and plugs into a small socket on the PCB and I've never seen anything like this before. Thoughts on a postcard please.

[exxos]

Bodge a wire ended fuse across it ?

[stephen_usher]

I've seen similar plug in fuses but they have a plastic cover over them, specifically the fuses on the serial ports and keyboard, but lower values obviously.

Something like this? https://uk.farnell.com/littelfuse/02730 ... dp/1596670

[rubber_jonnie]

Well, I think mine did have a plastic cover on it. Not so much now...

I did however find some of the right rating on ebay, a bit surprised. Though my worry now is why the first one popped...

Damn I hate PSUs.

[rubber_jonnie]

So, this Dolch PC is supposedly an expensive machine with top notch build quality, but then I see this:

IMG20240501100458-edit-20240501100711.jpg

Notice the glaring error?

Yep that's brown connected to N and blue connected to L.

Since both Live and Neutral are switched in this case then there is less chance of the machine becoming 'hot' but it's not a good idea and it really is making my OCD kick in.

[stephen_usher]

If there's no fuse in the power supply then the swapping of the wires doesn't make any difference in the end as it just makes the phase 180 degrees out as far as the equipment sees it.

However, as there is a fuse it must be on the live side, so swapping those over is a good idea.

[Badwolf]

So, this Dolch PC is supposedly an expensive machine with top notch build quality, but then I see this:

It's the bent over tabs that I like!

I plan to be installing an IEC socket later. I'm taking notes!

:lol:

BW

[rubber_jonnie]

If there's no fuse in the power supply then the swapping of the wires doesn't make any difference in the end as it just makes the phase 180 degrees out as far as the equipment sees it.

However, as there is a fuse it must be on the live side, so swapping those over is a good idea.

So what you said about the fuse needing to be on the live side made me wonder why they'd done it that way, and I had another look.

As originally, he power comes via the kettle connector to the switch and blue was wired as live and it then goes through an EMI filter to a plug that connects to the PSU. This is how said plug is wired:

IMG20240501155327.jpg

And next to the blue wire, is the fuse socket that connects directly to the blue wire before going off to the PSU. Clearly they had an issue with the plugs being wired incorrectly so they adapted by using the blue lead as live.

The EMI filter probably doesn't care how it's connected, it just has a 'Line' and a 'Load' side, so rather than swap the connectors in the plug so it was wired correctly, they just used blue for live and brown for neutral.

I bet they got a discount for the incorrectly wired harnesses.

I have corrected it now:

IMG20240501155517.jpg

Since my OCD wouldn't allow it and neither would my safety brain.

My biggest worry now is that the PSU has a fault, however if it does, there is nothing immediately obvious in terms of other exploded/burned out items, so I'll have to get the fuse sorted and see what it does.

[rubber_jonnie]

Well, having a search for a cable this morning, I heard a rattle inside the Dolch chassis.

I shook it until it fell out and it turned out to be the cover from exploded fuse:

IMG20240506111233.jpg

More recognisable now :)

Replacements still not arrived though 😒

[rubber_jonnie]

Well, the replacement fuse arrived and the PSU Didn't blow up again, but it didn't do anything at all...

:dizzy:

So that leaves me with a potentially dead custom PSU. I think I need to get hold of a 'normal' PSU to see if the machine actually still works. I did before I last put it away, so I am hopeful, but we'll see.

I suppose the PSU may need a load to work, but I am a little concerned about plugging it into a mainboard I may not be able to replace. I did connect a hard drive to try and add some load, but it didn't work.

EDIT: Change of plan, I've bought an ATX to AT adapter instead, since the AT PSUs are really expensive now apparently!