Help with a CPU Speed display circuit Board

[whitewulfe]

Okay, I received a donor case from friends at a local computer store, and I'm wondering if one of the features on this case can be used... It's an older case (heh, it had a relay for power. ), but it's not the case I'm wondering about...

It's one of those CPU Speed display thingies, and it goes to 999... What I'm wondering is this... Is there anywhere I can find info on what all the jumpers do, or at least a way I can mod it to show something, like say CPU usage, or be able to "program" it somehow to show whatever I feel like showing?

Here's a pic of the back of the unit... Model number is T-298, if that makes a difference...

[streetster]

im guessing its preprogrammed to a specific number on the 7-segment displays with all those jumpers... what i recommend you do is find a 5v powersupply (or use like 3 AA batteries or something) connect up the 5V pin to + and the G pin to earth/negative, and then move the jumpers about to see what it acheives... unless im missing the point it should change which 'bars' on the display light up so with a bit of fiddling you can work out how to do some numbers any chance of a picture of it more square on (so you can see all the tracks on the pcb?)

[whitewulfe]

im guessing its preprogrammed to a specific number on the 7-segment displays with all those jumpers... what i recommend you do is find a 5v powersupply (or use like 3 AA batteries or something) connect up the 5V pin to + and the G pin to earth/negative, and then move the jumpers about to see what it acheives... unless im missing the point it should change which 'bars' on the display light up so with a bit of fiddling you can work out how to do some numbers any chance of a picture of it more square on (so you can see all the tracks on the pcb?)

Sure, why not... It shouldn't kill me... Darn lighting in the room will be a tad painful, but I'll do my best... Gimme a min or two, and I'll edit this post with such for ya...

(edit) Here's what I've been able to get, after playing around a fair bit with angles and such to actually get most of it... Model is actually T-298, my bad.

[streetster]

ok.. im guessing there are 3 numbers (cos you say it goes upto 999)
each number would be 1, 2 or 3.. with A->G as each 'bar' of the seven segment display (a picture of the front would confirm this for me)

here:



does it look like that?

im guessing its wired up like most 7-segments (just look at the a,b,c,d,e,f,g bits in the picture below.. im guessing its the same as yours):

[whitewulfe]

Yes, it's a triple seven segment LED, sorry for not saying such earlier



So then each jumper should control the on-off state for each bar... Question is of course this... Would the jumper being on cause the bar to be off, or on?

[streetster]

id guess that the jumpers bridge the gap between the 5+v and the ground through one of the leds so, connect a few up (just try all the 1a->1g ones first) and see what happens, its only 5v (which you can use the RED wire from a molex inside your computer (and black for ground.. the yellow one is +12v)) or just get some AA batteries (well 3 of them will give you 4.5v which will suffice) and see how you go

hope this helps buddy, would be useful if someone else could confirm what im saying tho hehe

[whitewulfe]

hope this helps buddy, would be useful if someone else could confirm what im saying tho hehe

You've been a tremendous help... Been years since I've played with seven segment LEDs (years being something like five, aka back in high school )...

Thanks greatly for the help, I'll give it a try when I get back from work today...

[streetster]

hey buddy, just wondering if you've made any progress with this thing?

[Zak33]

me too...but gonna move it to Hardware cos ys might get more info in the other Forum

[whitewulfe]

Ooops, I knew I forgot about a thread I'd posted. No real progress with it as it was set aside for several months due to working full time. I'll secure some extra wires and electrical tape to give her a try today, sorry for keeping you guys waiting for so long

[Kumagoro]

surely there needs to be decoder ic's for it to work all i see is a resistor and a 7 seg display. Are you sure thats all the electronics it came with?

[streetster]

if you look at the PCB all it is some jumpers which affect different segments of the 7-segment display, and a connection for 5v and 0v... thats it, it doesnt decode anything, simply lights up the 7-segment depending upon which jumpers are connected up

[Thorsson]

Yeah, this goes wayyyyy back. Some PC makers "hard-coded" just how fast your machine was. Don't think they'd even reached 3 figs at the time, just built in some "future-proofing".... . [Either original Pentiums or 486s I think.]

[Steve]

This is so much more fun that running CPUz.exe