M&W Microstat Micrometer

Another query for the hive mind.
Does anyone have a "Microstat" micrometer, or a manual for one please?
https://www.worthpoint.com/worthopedia/moore-wright-microstat-2000-163540887
This is the later version with the LCD, rather than LED screen and three buttons on the front.
I picked one up a while ago, and I'm struggling to work out how the on/off button is designed to operate.

This might sound odd for a simple switch; it's a sliding button, which also acts as a momentary press on the microswitch underneath, depending on its position.

I'm familiar with the LED Micro 2000 operation, and have a manual; it charges in the Off position, and works off the battery or charger in the On position, whilst a momentary press sets zero. (The microswitch only uses two contacts)
https://www.worthpoint.com/worthopedia/moore-wright-micro-2000-electronic-269343109

The LCD "Microstat" that I have only seems to charge in the On position, but the battery still discharges when Off. Someone has obviously been working inside it previously, and I wonder of they have done something odd.
The momentary press doesn't zero it, though the Z button does.

I do have contacts with "Digital Micrometers Ltd" in Sheffield, but I don't want to hassle them at this stage. They were most helpful when I had a query on my Micro 2000, but I'd rather not trouble them more than needed.

Cheers Bill

We used to use them a lot at work (some LED, but mostly LCD) - They were branded Cadar though.

I don't remember there being anything special about the on/off switch. It's a while ago, but I'm pretty sure that they charged whether off or on, and could work off the charger if the battery was flat. They often used to be plugged in to the charger 24/7 which tended to kill the batteries after a few years (you only found out if you tried to take one away to use elsewhere - which it sounds like what has happened to yours).

I replaced the batteries in a number of them - they are just a stack of NiCad coin cells inside the end cover; easy enough to change. (4.8V from memory, but don't trust that).

I *think* that the LCD ones may have had a serial interface and clicking on the thumb button sent the reading to whatever was plugged into the other end.

They were very rugged and dependable for such accurate instruments - and they held their accuracy extremely well, even in a shiftwork production environment.

Edited By Andy_G on 11/04/2022 18:22:42

Thanks Andy, it's not that the on/off switch is special; it's just a conventional microswitch, with the NO terminal cut off.
It seems to work differently on the LED versions, as opposed to the LCD ones though, which is why I posed the question.
On the LED one, it only charges with the switch "off" i.e. to the left.
This depresses the microswitch's NC contact, and seems to disconnect the measuring electronics/display, but allows charging. It's a 4.8v cell stack, and the micrometer can be used with a flat battery with the PSU, provided it's turned on of course, but the battery won't re-charge when the device is in use.
The LCD one only seems to charge its 3.6v battery with the switch on as far as I can tell, but the battery discharges even when the micrometer is switched off.

There is a warning in the LED manual, and also on the end of a different LCD model to mine, that the device should never be powered up without a battery fitted, as it can lead to the electronics being damaged.
My LCD one was demonstrated as working OK on ebay by being shown plugged in, but without a battery fitted, so I'm trying to suss out if it's caused a problem. (The battery, end cap and battery contacts were all missing, but I knew that when I bought it)

The LED one uses a 5v supply and the LCD one a 9v wall wart, but since they are old tech, the off-load voltage is a lot higher in both cases, which I guess is what might cause damage.
For the 9v one I've replaced it with a PSU from an old BT home hub, which is regulated (switch mode??) and supplies a stable 9v, regardless of load.

Also, yes, I'm guessing that the "C" button is for a serial digital output, as there is a 6 way connector as the charging port, though I only have a 2 pin plug for it.
This is part of the reason I'm trying to track down a manual.

My LED ones are M&W, the LCD is branded CADAR, but has a DigitalMicrometersltd sticker as well.

Cheers for the assistance
Bill

There's a thread or two on Vintage Radio Net about them if anyone's interested.
This is one of the longer ones.
https://www.vintage-radio.net/forum/showthread.php?t=91570

Bill

I have only just found this thread so hope this reply isn't too late.

On the LED M&W micro 2000's the on/off switch is the sliding switch on top. Yellow for the mm ones and red for the inch ones.

The Cadar LCD ones have a very similar design BUT the top sliding switch is a measurement hold switch, either just press it to hold the measurement or slide it forwards to hold the measurement.

to turn on press and hold the Z (left hand) button, once the micrometer is turned on a momentary press will zero the display. (provided the hold function isn't on)

The S button (right hand) changes between mm and inch.

The C button (middle) ???? it lights up a letter C at the bottom of the display but I can't remember what it's function is. I never used it.

Hope this helps.

Steve

Forgot to say that the Cadar ones turn off automatically after a period of being idle.

Thanks Steve, this explains much of my confusion.
I think I've been leaving the Cadar one in the lock/hold position, which might be preventing it turning of properly, and thus flattening the battery.
I'll nip back out to the workshop and put it back on charge.

Both imperial & metric LED ones seem to hold charge OK.

I think the C button probably related to the digital output, as it's a 6(?) way connector, though the only lead I have is a 2 pin charging one.

Bill

Bill,

That may well be your problem with the battery flattening. I last charged mine in February, it has been sat on a shelf out of use since then and has held it's charge. Provided your battery isn't duff yours should be the same.

My LED ones only hold their charge for a month or so.

Steve

I wonder if that may be down to battery technology?
The LED ones originally specified 4.8v NiCad, whereas the LCD ones are 3.6v Ni-MH
Digital Micrometers Ltd, now supply Ni-MH as replacements for both. 4.8v and 3.6v
https://digitalmicrometers.co.uk
Other sources may be available.
I think NiCad, as well as being harder to obtain due to the Cadmium, are also more internally leaky than the Ni-MH replacements.
Hopefully the replacements may also be more externally leakproof, though the issues may have been caused by overcharging NiCads; each of mine have needed the battery contacts repairing or replacing.

Bill

Playing with mine today I discovered that pressing the Z button twice quickly turns it off. I have always just left it to turn itself off though. Maybe I should have read the instruction manual 40 years ago! Or if I did I should have remembered it.