Hi All,

I recently purchased 2 new stern opto trough boards from a dealer – in separate transactions – one a transmitter, the other the receiver.

After much troubleshooting, I am convinced there is a board error – or also wondering do they have very fine tolerances in the sensitivity of the LEDs? The attached is my testing – hopefully its not too complicated!

I have 2 machines to test in – Grand Prix and LOTR – all combinations of all boards test the same in both machines – so I know its not a wiring, machine or plug issue.

I have 3 sets (transmitter nad receiver) of boards
A – what I purchased from a dealer
B – out of LOTR originally (not working well)
C – out of GP – works fine in both machines

Given that each board has 2 LEDS, the attached diagram shows where I tested each transmitter board against each receiver board, as well as checking each LED for a switch opening (ie: I did this without the board mounted so I could line up LED1 of receiver against LED2 of transmitter and vice versa.

The main takeaway is that receiver board C works with all transmitters, however receiver board A (new board) only works on LED 1 of transmitter board A (also new). So I suspect that transmitter board A is a problem, however I can’t work out why receiver board A does not work at all with transmitter board C (yet it works on LED1 of transmitter board A). Both LEDs are bright red on transmitter boards A and C. I am certain there are no loose connections and I reflowed solder on boards and ensured everything is correct. So this is why I wonder if different batches of leds do not work well, and wonder if the two boards I got new were from different batches? Or is there some other testing i can do?

Or is the only solution to get another new set - i have sent a message to the dealer, and am awaiting hhis reply, but thought i'd try the brains trust as well!
20210805_132400 (resized).jpg

520-5173-00 transmitter
520-5174-00 reciever

Well i started swapping LEDs around, as i also have a 3rd (B) set of boards that were largely not working.

I had the A transmitter board that only 1 LED on that would work with the B receiver. So then used the B transmitter and nothing would work there with the B receiver, but the C (fully working) transmitter would work with 1 LED of the B reciever. So i pulled that working reciver LED from the B board, put it in the LED 2 position of A board (that worked fine with C transmitter, but not A transmitter), and now both A boards work! Confused...cause i am!

Anyway, its working, but still doesn't make a lot of sense to me

Yeah i know, and they glow all the time on all 3 transmitter boards, yet get recognised by one receiver board completely, another only LED 1 on receiver, and another only LED 2 on receiver. But then if i pair a different transmitter board (with glowing LEDs), 2 of the receivers only partially work, and the 3rd works completely. No pattern at all!