Another Opto question

[Spandangler]

Hi guys
as part of my wh20 shop out I've shotgunned all of the optos. However the optos at disaster drop entrance aren't working.

When you plug them in, they show up on the switch test matrix. However when you block them they don't register. When you unplug them they make the noise you get when a switch is activated in test mode and the switch disappears from the matrix as if open.

Have I got a dud sender/ receiver or is there something else I should be looking at

Cheers all
Gaz

 

[stoptap]

Hi guys
as part of my wh20 shop out I've shotgunned all of the optos. However the optos at disaster drop entrance aren't working.

When you plug them in, they show up on the switch test matrix. However when you block them they don't register. When you unplug them they make the noise you get when a switch is activated in test mode and the switch disappears from the matrix as if open.

Have I got a dud sender/ receiver or is there something else I should be looking at

Cheers all
Gaz

Take them off and check them manually. You can shine a torch (not an LED torch) into the receiver and it should register. As for the transmitter, if you have an old phone camera (or digital camera) they can see the infra red light so you should see it glowing quite brightly. I've just diagnosed an opto problem using this method. When I looked at the transmitter through an old iPhone camera it was working but wasn't very bright compared to other optos. I put a new transmitter in and bingo.

You can check if the camera you are using is suitable by pointing your TV remote at it and pressing a button.

 

[Spandangler]

Great thanks Andrew. I'll try that tomorrow. I'd swear it was registering when I first did it then it stopped. Using a dmm, I've got power at the opto boards so guessing it's a dud opto.

Is the clear opto the sender and black the receiver?

 

[stoptap]

Great thanks Andrew. I'll try that tomorrow. I'd swear it was registering when I first did it then it stopped. Using a dmm, I've got power at the opto boards so guessing it's a dud opto.

Is the clear opto the sender and black the receiver?

Yes the clear is the transmitter.

If they check out ok it could also be the corresponding LM339 chip. I've had all sorts of problems down the years due to those little buggers.

 

[Spandangler]

Cool, thanks to @myPinballs ive got a slack handful of those chips. Is it 1 chip per opto pair? All other optos appear fine.

 

[stoptap]

Cool, thanks to @myPinballs ive got a slack handful of those chips. Is it 1 chip per opto pair? All other optos appear fine.

No they usually control a couple but they may just do one on occasion. Trace the wires back from the optos and see if they go to an opto board. If you are lucky your Fish Tales may have the same board so you could check it that way.

 

[Spandangler]

Ok. Sitrep

I'll start by saying when I put it in switch test yesterday it was registering the disaster drop optos. They stopped working after a short time. I was doubting myself yesterday but the same happened tonight so I'm quite sure now.

Tonight I swapped a known working mini opto board with the suspected faulty one. I put it In switch test and bingo, it's working. So I assume it was a faulty reciever and replace the opto on the board for a new one. I test this as well and it's working fine. I then leave the machine powered on for a good hour or so whilst I tinker around. Then out of curiosity, I do another switch test. And nothing!! It's not working again. Interestingly the switch isn't showing on the matrix this time. Yesterday it was visible on the matrix and made the beep noise
When I disconnected it, this time nothing. Using a dmm I check voltages and compare them with working optos.
Here are my findings.

Working receiver:

Orange: 0.50
Grey: 0.50

Working sender:

Grey: -1.30
Black: -1.50

Faulty receiver:

Orange: -1.50
Grey: 0.50

Faulty sender

Grey: 0.50
Black: -1.50


Hopefully this will make sense to someone. Does this sound like a Lm339 chip fault or still an opto fault?

Starting to do my nut now.

 

[stoptap]

Did you replace the transmitter or receiver ?
I don't think I have ever had to change a receiver.

 

[Spandangler]

I replaced the receiver. To be fair though both were brand new and it worked after I changed it for a while.
What's suspicious is the voltages at the boards.

 

[stoptap]

At this stage you may as well change the transmitter. At least then you know you have a new opto transmitter and receiver installed. You can then start to think about the LM339 of it still isn't right.

 

[pinballmania]

Sounds like the receiver might be reversed.

 

[Spandangler]

Could it be a gazza rewrire specialty??