Altai HM-103S Refurb

[rubber_jonnie]

As you all know, I try to fix things in general, not just computers, as I'm in it for the fun of the fix :)

I found this Altai HM-103S during our house move last year, buried in a pile of things I'd used back in the days when I was doing my own car maintenance, amongst a pile of tools like dwell angle meters and other tuning kit from Gunstons I'd bought back in the 80's

PXL_20221201_151958174.jpg

As it goes, the meter even pre-dated my car tampering days and I'd had it probably from my mid-teens, and IIRC, it was bought from the Tandy near Liverpool Central Station many years ago. So, it has some nostalgic value for me, so I thought it'd make a nice quick little repair/refurb project.

Sadly, it had an ancient set of batteries installed, which played havoc with the battery connectors, but has fortunately missed the main PCB and meter. I have some 30G brass sheet on the way to make replacement items from, and I'll replace all the wires that were attached and have corroded.

Here it is in bits:

PXL_20221201_151903203.jpg

It's relatively uncomplicated, and should live again with a bit of TLC, and though it'll never replace my digital meters, I think it'll scratch a nostalgic itch to get it functioning again.

First things first, a damn good clean with IPA, then I can reassemble the front switch with some lubricant, as the years have not been kind to what's in there!!

[rubber_jonnie]

Bit of silicone grease into the switch and it turns just lovely again:

PXL_20221201_160710761.jpg

And the contact side of the PCB used for selecting the mode cleaned up fine :)

However, during reassembly I noticed that one of the pins for the 'Ohms Zero' pot was barely soldered in, and given the poor zeroing capability and the behaviour if you press on the pot knob, this might explain a few things:

PXL_20221202_092919916.jpg

So, I'll fix that and now the little bit of corrosion is sorted in the power end of the board, I've just got to wait for the brass sheet to come so I can re-do the battery contacts.

It's quite shocking how poorly it's made, but given the age of the item and the fact that I still have the box and manual I'm surprised it made it this far.

Just wondering though, do any of you on here collect test equipment and if so, what?

[stephen_usher]

It was probably made down to a price rather than up to a quality. :-)

I'm sure there are test equipment collectors out there. I would imagine though that it would be more oscilloscopes and those bigger items rather than multimeters.

[rubber_jonnie]

It was probably made down to a price rather than up to a quality. :-)

Oh, 100% for sure. The case isn't too bad, robust and quite nice injection moulding with decent labels, but it does hide a multitude (Multimeter???) of sins and it's clear where the money was spent.

I'm sure there are test equipment collectors out there. I would imagine though that it would be more oscilloscopes and those bigger items rather than multimeters.

Yeah, you're probably right there, and large stuff I just don't have room for. Perhaps I can start something new with multimeter collecting, will look into it. It's either that or handheld computers from the 80's like my Sharp PC-1211 or Casio FX-720P.

[rubber_jonnie]

My brass sheet for the replacement battery contacts arrived yesterday, but as I was busy, I only got round to looking at it today.

So first I made some blanks, I needed two, based on the basic shape of the old disintegrating ones:

PXL_20221204_123037393.jpg

And tested them in position:

PXL_20221204_123758295.jpg

Then it was a matter of a bit of final shaping and soldering on the replacement wires:

PXL_20221204_124345380.jpg

And a test fit of batteries plus final test of the meter:

PXL_20221204_124826241.jpg

And we're done, as Hugh Jeffreys would say:

PXL_20221204_125058489~2.jpg

It's been a fun little side project for a bit of nostalgia, though I doubt I'd trust it for any real work :)