Looks like it might be sort of similar to this one: https://www.minuszerodegrees.net/led_speed_di … 0-%20SD-402.jpg

Can you post pictures of the front and back with the cable removed, and make a note of any markings on the transistor cases? Might be possible to work out the pinout from that.

snufkin wrote on 2024-04-09, 14:44:

Looks like it might be sort of similar to this one: https://www.minuszerodegrees.net/led_speed_di … 0-%20SD-402.jpg

Can you post pictures of the front and back with the cable removed, and make a note of any markings on the transistor cases? Might be possible to work out the pinout from that.

Here you go!

If you need any other images let me know 😀

Ok, so I can't see enough to be sure of the wiring, but my guess for the connections is in the picture below. GND and +5V go to the top row, M+ and M- go to the motherboard turbo LED header, then T+ and T- can go to a case LED turbo indicator.

The GND and +5V are based on the +5V pin going to pin 1 of the cable to the LED display and the GND pin going to each of the 'C' pins of the segment selectors, so those segments would be on all the time, not switched through the transistors. It looks like the middle row might be an input to two of the transistors, which I think would be one transistor to control selected LED segments and another to control a case LED, so I think that's the switch input from the motherboard. The bottom row looks like it might be an output from one of those transistors, so probably the output to an external LED.

There are several guesses in that, but that also fits with the pins 1-6 described in that instruction sheet I linked to before.

Before trying to plug anything in, you'll want to fix the jumpers for the segment selections (use those instructions as a guide). The top set in particular look wrong to me. I think the bottom set are ok and should switch from a 3 to a 7. Once that's fixed then try just connecting the +5V and GND and see if the display lights up. It's possible that using a bit of wire between the M- pin and either the +5 or GND pin then you might be able to test if the display changes.

So not certain about it, but best guess...

Also, there's a fair bit of silkscreen markings, so there might be some markings to be seen if you remove the 6 pin connector.

snufkin wrote on 2024-04-10, 16:04:

Ok, so I can't see enough to be sure of the wiring, but my guess for the connections is in the picture below. GND and +5V go to […]
Show full quote

Ok, so I can't see enough to be sure of the wiring, but my guess for the connections is in the picture below. GND and +5V go to the top row, M+ and M- go to the motherboard turbo LED header, then T+ and T- can go to a case LED turbo indicator.

The GND and +5V are based on the +5V pin going to pin 1 of the cable to the LED display and the GND pin going to each of the 'C' pins of the segment selectors, so those segments would be on all the time, not switched through the transistors. It looks like the middle row might be an input to two of the transistors, which I think would be one transistor to control selected LED segments and another to control a case LED, so I think that's the switch input from the motherboard. The bottom row looks like it might be an output from one of those transistors, so probably the output to an external LED.

There are several guesses in that, but that also fits with the pins 1-6 described in that instruction sheet I linked to before.

Before trying to plug anything in, you'll want to fix the jumpers for the segment selections (use those instructions as a guide). The top set in particular look wrong to me. I think the bottom set are ok and should switch from a 3 to a 7. Once that's fixed then try just connecting the +5V and GND and see if the display lights up. It's possible that using a bit of wire between the M- pin and either the +5 or GND pin then you might be able to test if the display changes.

So not certain about it, but best guess...

Also, there's a fair bit of silkscreen markings, so there might be some markings to be seen if you remove the 6 pin connector.

Thank you so much for all the info, it’s a great start. Really appreciate it. I forgot to mention it’s a 3 digit display so it can do up to 199. First digit can only be “1”. I should be able to figure out all the jumper positions. I’ve configured 2 of these displays in the past.

I’ll also probe around with a multimeter and see if I can confirm which pins are ground.

There's that separate T in the top right, which I'd guess is for the hundreds. Good luck with it.

snufkin wrote on 2024-04-10, 17:13:

There's that separate T in the top right, which I'd guess is for the hundreds. Good luck with it.

I've done some probing and found the following continuity between components. Same color = common continuity. Not sure if this helps?

I'd also like to point out that out of the 3 connections that plug into the LED PCB, two of them have 2 wires and one of them only has 1 wire. I've seen this before with another LED display. The single wire plugs into one of the 2 turbo light pins on the motherboard.

Ok, so you can see the usual T arrangement across the top and bottom. Using your colours then Yellow is the always lit position, Red is Turbo On and Purple is Turbo Off (on/off might be the other way around). The 150 ohm resistor in the top right (you've marked one side as brown) is probably for the hundreds LED, so it's likely that the centre pin for the hundreds is also up there. Check if the other side of the 150 ohm resistor connects to the second pin on the top row of pins.

So I'm pretty sure that the Yellow is Ground (I'd normally colour that black) and your blue is the +5V connection (normally red) that goes to the LED unit.

Pin 1 of transistors Q1 and Q2 (emitters) also connect to your yellow/ground. Pin 2 of Q1 (collector) should connect to your Red and pin 2 of Q2 to your purple. So when Q1 is conducting its collector will go to Ground and then any LEDs jumpered to the Red pins will turn on and when Q2 is conducting then LEDs jumpered to purple will turn on.

Too many traces are hidden under the connectors and components, so I can't see enough of what connects to the transistors and to the 8 pin resistor array in the top right. That makes it difficult to work out for sure the other 4 pins on the 6 pin connector block. One interesting thing is the pin you've marked red on the 6-pin connection, on the left-middle of the block. That will be connected to ground when Q1 is on, so is likely to be the T- output to a case LED, which is different to my previous guess. Check for the resistance between the middle-right pin and the top-right pin (5V) on the block. If it's a few hundred ohms then I'm now guessing that the middle-right pin is T+.

That leaves the pin from the motherboard. The bottom-right pin goes to one side of the 330 ohm resistor by Q1, and the other side of the resistor to the base of Q1. So it's possible that it controls the switching for Q1, turning any segments jumpered to Red on or off.

So my updated guess is:
G +5V
T- T+
NC M+

snufkin wrote on 2024-04-11, 11:43:

Ok, so you can see the usual T arrangement across the top and bottom. Using your colours then Yellow is the always lit position […]
Show full quote

Ok, so you can see the usual T arrangement across the top and bottom. Using your colours then Yellow is the always lit position, Red is Turbo On and Purple is Turbo Off (on/off might be the other way around). The 150 ohm resistor in the top right (you've marked one side as brown) is probably for the hundreds LED, so it's likely that the centre pin for the hundreds is also up there. Check if the other side of the 150 ohm resistor connects to the second pin on the top row of pins.

So I'm pretty sure that the Yellow is Ground (I'd normally colour that black) and your blue is the +5V connection (normally red) that goes to the LED unit.

Pin 1 of transistors Q1 and Q2 (emitters) also connect to your yellow/ground. Pin 2 of Q1 (collector) should connect to your Red and pin 2 of Q2 to your purple. So when Q1 is conducting its collector will go to Ground and then any LEDs jumpered to the Red pins will turn on and when Q2 is conducting then LEDs jumpered to purple will turn on.

Too many traces are hidden under the connectors and components, so I can't see enough of what connects to the transistors and to the 8 pin resistor array in the top right. That makes it difficult to work out for sure the other 4 pins on the 6 pin connector block. One interesting thing is the pin you've marked red on the 6-pin connection, on the left-middle of the block. That will be connected to ground when Q1 is on, so is likely to be the T- output to a case LED, which is different to my previous guess. Check for the resistance between the middle-right pin and the top-right pin (5V) on the block. If it's a few hundred ohms then I'm now guessing that the middle-right pin is T+.

That leaves the pin from the motherboard. The bottom-right pin goes to one side of the 330 ohm resistor by Q1, and the other side of the resistor to the base of Q1. So it's possible that it controls the switching for Q1, turning any segments jumpered to Red on or off.

So my updated guess is:
G +5V
T- T+
NC M+

snufkin I really appreciate you taking the time to help me. You prevented my LED from going up in smoke. Your first guess was 100% correct. Thank you!

5v G
M+ M-
T+ T-

The T+ is outputting 3v

Hey, cool. It'll be a bit of a bother, but could you take a couple of photos showing the connections so it's here as a reference. Also, it looks like I might have gotten the G/+5 the wrong way around as you've got it 5V G and I had it G 5V.

Still, glad it's working.