Quoting Malvineous from another thread :

Malvineous wrote:

I've seen some "programmable" MHz displays where you held the reset button down for a few seconds and the number on the display would rapidly increase to 999 and then wrap around to 000 so you could change the number displayed when the turbo was on or off without messing around with jumpers.

I wonder whether that's what the three lots of two pins are for? Power, turbo LED and reset switch?

And yeah, I'm guessing the dead battery has something to do with the numbers not appearing correctly / not being remembered by the chip.

Bought a new battery, still displaying the same thing. Any ideas? Looks like I might just hardwire it...

I had a couple cases with this many years ago. They were just set with jumpers. They had inputs from the turbo switch and when that sensed voltage it would just change to a different setting. The actual jumper settings varied based on the case - not really a standard. They did not actually detect the speed or anything. Not exactly sure what chip/cob is on there but presumably a fairly simple decoder. It's definitely not any kind of frequency counter. If you want to test it, use a multimeter with a diode tester that has enough voltage for LEDs (test it on a known working LED and make sure the LED lights up) and then test all of the segments.

This module has reverse polarity protection with those 2 diodes but your +5v is where 5v is marked and ground is on the outside. In your pic the vertical diode supplies the decoder's Vcc. Looks like the decoder drives the transistor to drive a common anode. Try the multimeter with the positive on the middle pin of the transistor and move the negative around the 7-seg pins.

Thanks to both of you - Turns out the programming was done by holding the reset button, but I only discovered that after I took apart (unsoldered) the battery connector and cleaned it thoroughly from corrosion and checked the leads with a multimeter, then replaced the battery.

Unfortunately the two pack of batteries I bought are supposed to put out 1.4V (hearing aid type, the large store that specializes in electronics did NOT have my cell, or one for my cyclometer which I bought batteries for in Daiso in Korea for $1 for 5) but when I take a multimeter to it, I see one at 0.5v and the other at 1.4v and dropping fast before my eyes and settling at about 0.7. Sayal Electronics, how much you've gone downhill... /rant

Jed118 wrote:

...Turns out the programming was done by holding the reset button, but I only discovered that...

Well, that was mentioned in the very first reply you got in the thread, namely these words :

Malvineous wrote:

...I've seen some "programmable" MHz displays where you held the reset button down for a few seconds...

But anyway, apart from suggesting you buy new glasses 🤣 , I find it odd that brand new batteries would be so below their advertised voltage.
Either you got an old batch from a few years back, or they are just simply VERY cheaply made to boot.

From the picture it seems that you should something much smaller than a CR2032, but without a ruler it's hard to determine. Or maybe if you still have the old corroded one you could measure it (diameter, thickness) to narrow down the possibilities. I don't see anything written on the board to indicate the correct type of battery and that is not nice.

I don't think I need glasses, but from the following post, that idea may warrant a closer look:

http://imgur.com/a/FMvQD

Not my best soldering, (it's 12:30 whaddayawant) but continuity checks out, and now I have a much more accessible option, so that in 2037 when this battery dies, I can don my +20 spectacles and replace a single AA cell instead of removing the video card to make way for the ZIP100 and hard disk arrangement (unplugging all sorts of cabling along the way) to come out and then piloting a tiny screwdriver in between a dim and confined area to get to the LED PCB, freeing it in order to replace a cell, and then putting it all back together again.

The reasoning for this contraption stems from the irritability I got when I called the electronics store (they're open when I'm working and out of my way when I'm not) they say that I must have somehow shorted the batteries... So instead of wasting time, I took a kitchen knife, cut out a single AA cell housing from a 4x1 setup (the other leads were badly corroded, out of the 386SX system in which I had replaced the onboard cell with a dime battery setup, soldered onto the board) and behold, a 5 min "free" fix, complete with accessibility and peace of mind.

And a standard cell I might add.

Now to transfer some saved Settlers 2 files from my P100 laptop onto this, and barricade myself in my computer room for hours of fun!