White Water Bigfoot Opto Board Matrix Short Circuit MYSTERY...

Quoted from mastercello:
What about the wiring from the board to the backbox?

As I have mentioned, this is part of the Switch Matrix wire loom, and when I disconnect the Molex connector from the socket on the Bigfoot Opto board, all the other switches in row 6, in the switch matrix, works flawlessly. Based on that, the fact that the same wires are daisy chained through all the other switches up to the backbox, the wire must be OK.

But could you please specify what you think could be wrong with the wiring, that could cause this problem...

#4 3 years ago

BUS

mastercello

Pinside+ Frequent

7y 47,950 187

Some kind of short or broken wire provoking the error in combination with the connected opto board.

#5 3 years ago

BOB

bobukcat

Pinside member

Interesting issue, could it be that when the closed optos (most optos are normally closed so I assume these are too) are in the matrix a shorted diode on some other switch is then allowing current flow through the row and hence the short? Does opening or changing the state of either opto make any difference to remove the short error? You could simulate that by leaving the board disconnected and using a diode / jumper to simulate them closing / opening?

#6 3 years ago

???

grumppy

Pinside member

Minneapolis, MN

5y 16,650 122

Are all of the closed switches in column 6 optos? If not you may want to check them out.

#7 3 years ago

???

grumppy

Pinside member

Minneapolis, MN

5y 16,650 122

Have you been triggering the left coin slot? it shows up in two of your pictures. If not try removing the coin door interface board see if there is something stuck behind it. maybe a loose or pinched coin door wire?

#8 3 years ago

PAW

AArhusC

Inactive member

Quoted from grumppy:
Are all of the closed switches in column 6 optos? If not you may want to check them out.

Yes, and they are alle working and switches when I test them (break the "beam")

Quoted from grumppy:
Have you been triggering the left coin slot? it shows up in two of your pictures. If not try removing the coin door interface board see if there is something stuck behind it. maybe a loose or pinched coin door wire?

No, I have not done anything to that, and it does not show as activated in the matrix.

Quoted from bobukcat:
Interesting issue, could it be that when the closed optos (most optos are normally closed so I assume these are too) are in the matrix a shorted diode on some other switch is then allowing current flow through the row and hence the short? Does opening or changing the state of either opto make any difference to remove the short error? You could simulate that by leaving the board disconnected and using a diode / jumper to simulate them closing / opening?

I have tried to follow your advice, and here is what I have found. If I try to interrupt the opto beams as below:

20210104_213336 (resized).jpg

The two shorted rows, row 6 and row 7, go away. The error disappear:

20210104_213340 (resized).jpg

And when i remove the paper obstructing the opto beam:

20210104_213351 (resized).jpg

The error reoccurs:

20210104_213356 (resized).jpg

We could be onto something here...But where to go from here, How to proceed? I have tested all the diodes in row 6 with my Fluke Multimeter, and all checks out fine. Any suggestions bobukcat , or any one else?

#9 3 years ago

PAW

AArhusC

Inactive member

I have found one other thing though...
On the picture below I can only measure ~6 volts at the point where the tip of the screw driver is.

20210104_221616 (resized).jpg

That is if I am measuring on the CPU board. At the red arrow:
(This is not my board, but just one I found online. I know it does not look to healthy, but I forgot to take a picture of my own)

ThisSpot (resized).png

At all the other junctions I measure ~12 volts. I do not know if this could cause the trouble I am experiencing with the optos, but I think not, as the rows above also has optos and they are not shorted, but I thought I would mention it. Either way, it is definitely something that I have to look into, because column 1 is not working properly. I will try to sort that out tomorrow
Could be U20 gone bad, or maybe a transistor, since the resistors measure fine a 1kOhm? any suggestions to why I only have ~6 Volts at the first pin? (I measure with J206/J207 and J212 unplugged)

#10 3 years ago

SDS

whthrs166

Pinside member

Arvada, CO

10y 93,050 4,526 12

You could also have a 7 opto board issue.

#11 3 years ago

BOB

bobukcat

Pinside member

OP
Quoted from AArhusC:
I have found one other thing though...
On the picture below I can only measure ~6 volts at the point where the tip of the screw driver is.
[quoted image]
That is if I am measuring on the CPU board. At the red arrow:
(This is not my board, but just one I found online. I know it does not look to healthy, but I forgot to take a picture of my own)
[quoted image]
At all the other junctions I measure ~12 volts. I do not know if this could cause the trouble I am experiencing with the optos, but I think not, as the rows above also has optos and they are not shorted, but I thought I would mention it. Either way, it is definitely something that I have to look into, because column 1 is not working properly. I will try to sort that out tomorrow
Could be U20 gone bad, or maybe a transistor, since the resistors measure fine a 1kOhm? any suggestions to why I only have ~6 Volts at the first pin? (I measure with J206/J207 and J212 unplugged)

Can't really be a transistor causing this if you have the cables off the connector, has to be related to U20, R67 or C11. I'd suspect it's U20 as those are pretty common failure points.

#12 3 years ago

BOB

bobukcat

Pinside member

OP
Quoted from AArhusC:
Yes, and they are alle working and switches when I test them (break the "beam")

No, I have not done anything to that, and it does not show as activated in the matrix.

I have tried to follow your advice, and here is what I have found. If I try to interrupt the opto beams as below:
[quoted image]
The two shorted rows, row 6 and row 7, go away. The error disappear:
[quoted image]
And when i remove the paper obstructing the opto beam:
[quoted image]
The error reoccurs:
[quoted image]
We could be onto something here...But where to go from here, How to proceed? I have tested all the diodes in row 6 with my Fluke Multimeter, and all checks out fine. Any suggestions bobukcat , or any one else?

Although I'm sorry you're having this issue these are my favorite kind of threads on Pinside because I get a chance to try to help and almost always end up learning something along the way. Whenever I work on the switch matrix (other than something super simple) I want to isolate it to the board or the playfield. I know you kind of did this but what I would do is pull all the cables going to the matrix off the board then simulate those two optos being closed and in that state simulate every other switch in the rows and column to see if the problem presents itself when one of those is also closed.

Quoted from whthrs166:
You could also have a 7 opto board issue.

Might want to start here and disconnect the 7 opto board too see if the problem goes away as this would be a quick thing to do.

#13 3 years ago

PAW

AArhusC

Inactive member

Quoted from bobukcat:
Quoted from whthrs166:
You could also have a 7 opto board issue.

Might want to start here and disconnect the 7 opto board too see if the problem goes away as this would be a quick thing to do.

I have tried to disconnect the 7 opto board, but it makes no difference whatsoever. I am still a bit stuck.

But for now I have decided to get the other 6 volts issues on the CPU board solved, and then I will get back to the optos. I do not think that this is related to the Bigfoot opto trouble that I am experiencing, but I do not like to have 2 problems at the same time, if they do interfere.
I have just ordered the components for the CPU board, and I hope to have them before the weekend.

I will get back to you with an update, once I have the CPU issue sorted.

#14 3 years ago

CKR

Classe

Pinside apprentice

Göteborg

3y 24,650 98 16

I don't know if you did this, but the first thing I do when we have this type of switch matrix problems, is to isolate if the problem is on one of the boards in the backbox or out in the cabinet.
Start the game.
Go in to Tests->Switch Edges.
Disconnect all the cables at the bottom of the CPU-board (J206/J207, J208/J209, J205 and J212.).
Short-circuit a switch with problem. Eg. pin 1 on connector J207 to pin 1 on J209 with a short cable, and switch 11 shall then get affected in the test.
If no switch register, more than one switch register or the incorrect switch registers, then the problem is not in the cabinet.

#15 3 years ago

PAW

AArhusC

Inactive member

I am happy to report that the mystery is solved. As planned I received the parts for the CPU-Board to fix the missing 12 volt. After changing U20 the issue is gone...!...I must admit this came as a total surprise to me, as I had no idea that the two things could be related, as the 12 volts that was missing was in column 1, but never the less, it works now, and I am quite happy of cause...

Quoted from Classe:
I don't know if you did this, but the first thing I do when we have this type of switch matrix problems, is to isolate if the problem is on one of the boards in the backbox or out in the cabinet.

Yes, that is also what I always do. That was how I found the issue with the missing 12 volts, but as previously mentioned, I did not think that is was related to my opto problem.

Quoted from bobukcat:
Although I'm sorry you're having this issue these are my favorite kind of threads on Pinside because I get a chance to try to help and almost always end up learning something along the way.

I know what you mean. When you are in the middle of it, it is just frustration but afterwards it is another experience, and some knowledge to carry on for the next project...It is never the things that went totally according to the plan that you talk about afterwards. They are soon forgotten. It is the trouble that gives the knowledge, even though it can be ever so annoying when it is ongoing.

Now the machine is working, and now I have learned that the waterfall bulbs on top of the backbox is a special kind, not the #555´s used every where else. I will have to order some #194´s...

Thanks for your help and support...

#16 3 years ago

BOB

bobukcat

Pinside member