S+ Door Optics Bypass

[Neonkiss]

I have made up a door optic bypass switch as indicated in previous post and it works.
However I got to thinking and why does it work? (I know this gets into dangerous territory)
I found and attached a schematic of the door LED and the machine side Photo Transistor.

The door LED has two wires (green and Purple w/black) The green is machine ground and is J/P170-1 in the attached schematic and meets up with the ground for the Photo Transistor J/P 171-2 (green w/blue)

J/P 170-2 (Purple w/black) is supplying 5VDC to illuminate the LED. That is it's sole purpose.
The Photo Transistor is the optical switch that is N/O and closes when aligned with the inferred beam of  LED.

Why can't I just switch the 9VDC J/P 171-1 to ground? Wouldn't this be the same as the Photo Transistor closing when it finds the light beam?

I know it doesn't work, because I tried it.
What does work is when you switch J/P 170-2 (5VDC Purple w/black) to the J/P 171-1 (9VDC Red)
Somehow this just doesn't make sense to me.

[Jim]

if you look at the same book page 38  it shows the relationship to the output circuits.  this is part of there security for the door.  just like you couldn't just ground the output to get it to work. its a pulsed output. that's why the door test shows a digital signal changing from one to zero, (high to a low). 

that.s why the door optic bypass will work. you are simply putting the digital signal directly to the input of the resistor pack #4 and into the rest of the circuitry. bypassing the physical elements of the door optics.   


Jim     

[Neonkiss]

Jim, Thanks.
I guess I'm more analog and don't quite grasp the digital stuff completely.
I do understand that the resistor pack is looking for the correct pulse signal. I just don't see how that pulse signal is generated through the optics, unless the Photo Transistor is passing along that pulse in whatever milliseconds the led is flashing? .....

WOW it just clicked for me.  That's exactly what it's doing.
K+ Jim I'm starting to think digital.

[poppo]

FWIW, for a door optics bypass, I simply mounted the the optics on the reel shelf. I can open the door whenever I want, and it thinks it's closed. If I need an open door situation, I simply stick that piece of plastic in between them. Simple, and keeps everything 'standard' (i.e. signals).

[erbs]

Poppo that is the best way to bypass those PIA door switches that I have seen yet.  Karma to you 

[Neonkiss]

FWIW, for a door optics bypass, I simply mounted the the optics on the reel shelf. I can open the door whenever I want, and it thinks it's closed. If I need an open door situation, I simply stick that piece of plastic in between them. Simple, and keeps everything 'standard' (i.e. signals).

I agree with your method. As this way you are only still transmitting the pulse signal. With the hardwired system you are applying the 5VDC from the led to the 9VDC to the photo transistor. That I would imagine would be sending 14Vdc back to the I/C where it's only expected to be the original 9VDC? almost a 50% overload.

Has anyone experienced failure with long term use of the hardwired bypass?
I was originally looking for some type of Cherry switch solution to avoid service calls.

[poppo]

Has anyone experienced failure with long term use of the hardwired bypass?

There have been reports of some SP chips that don't do some things properly with a hardware bypass. I think Bunker will have more info on that.

[Jim]

the nice thing about digital electronics is its either on(high), off (low)  or its broke.

Q-26 is fed with a digital pulse train from U23, that causes Q-26 to turn on and off at that rate. that on/off is transferred to the collector of Q-26 which causes the LED to pulse on/off.

that pulsing is detected by the photo transistor and is passed on to the rest of the circuitry.  so yes, you are getting digital  

while I was typing this I saw the other two posts,  shouldn't make any difference,  hardwired or going through the optics, basically you are grounding a 5volt signal through a pull up resistor,  likewise you are grounding the +vb through the pull up resistors.  doesn't hurt anything, if you were using TTL perhaps, but they're using CMOS chips. which means they can operate at a higher voltage,>5vdc.   so either way it shouldn't put any strain on any of the components.  
In fourteen years working on S+ machines I have never had to bypass the optics,  when they went bad I replaced them, and NEVER had any problems.  

Jim

[poppo]

 
In fourteen years working on S+ machines I have never had to bypass the optics,  when they went bad I replaced them, and NEVER had any problems.  

I think the two issues that mostly come into play regarding bypasses are:

1. Someone has a problem that might be the door optics, and they don't have a spare set (and thus are told how to make a bypass).
2. Those who want to be able to have a running machine while the door is open. One example might be accidentally hitting cash out without enough coins in the hopper. Makes it easy to keep tossing them from the tray back into the hopper. I do other stange mods, so I often need the door open and the machine running while working on them.   It really came in handy when working on the SAS stuff (homebrew RS232 converters).

[Neonkiss]

In fourteen years working on S+ machines I have never had to bypass the optics,  when they went bad I replaced them, and NEVER had any problems.   

Jim

Jim do you have a part number for the 5VDC LED and the 10VDC Photo Transistor?
I seem to have a few that are bad and if I can just replace the components that would be best.

[stayouttadabunker]

I'm going to call this picture my Cherry Switch Optics...lol
This is the way I've hooked up mine for years without any problems.
I could of left on the real receiver optic unit on the cabinet location there below the switch
but I needed it for a live floor machine...
This is a great set up for home use as there is never any problem with door latch alignments as well.
All you need is that little plate on the door latch that pushes the plunger on the cherry switch.

The S+ "Cherry Switch Optics" basically just runs two wires under the reel shelf back
to the other door emitter optic Molex and two to the cabinet receiver optic Molex.

Attached to this post is a photo I just took with the 3rd reel removed so you can see the set up better.
Below is a photo of the latch plate too.
I still have the unused/ UN-plugged door emitter optic there for some reason...
guess I didn't need it for anything...lol

Click on any photo to enlarge for better detail...>>>

[Jim]

Robert,

I will have to do some research,  have never just replaced the component itself,  have always replaced the entire piece.

 Jim 

[stayouttadabunker]

I made my own door optics out of a set of coin-in optics once.
I also made them from components bought at a Radio Shack store too.

I'd have to check around and see if I can get the part numbers...

[Buzz]

I think there is more than a few reasons to by pass the optics. First and fore most to me is when you get one of those cabinet' that is enough out of square that it takes two men and a boy to get the door closed. That and a sledge hammer to get the door latch completely down for the optics to see each other.  That's when I do the bypass, only have to have the door latched a little bit.