BOP service menu switches dead

0

#1 3 years ago

OP

TIM

MT45

Pinball Loft

Lenoir City, TN

11y 110K 2,371 38 10

Looking for someone with some system 11 expertise ...

Not a single button on the service buttons inside the coin door are working

What I know:
I have 12 volts at the switch
All wires appear solid and connected

What I have done:
Shorted pin #9 on J205 to ground and to no effect
Replaced U16 with a new LM339 to no effect
Reflowed solder joints on U15 to no effect

Given that shorting the "enter button" pin to ground (on the CPU board) did nothing tells me that this is a board issue right?
Is replacing U15 the next logical step?

If it helps, I've noticed the call out "thank you" popping up in mid game randomly, and I'm pretty sure that's a coin up call out

You can see in the image that U16 needed to be replaced anyway (look under the battery holder in image 1) with the amount of corrosion that existed on the legs

IMG_9394 (resized).jpg

IMG_9396 (resized).jpg
IMG_9397 (resized).jpg

0

#2 3 years ago

JAM

Jmckune

Pinside member

5y 80,850 1,894 7

I see corrosion at what looks like U20. And yes. In WPC games when it comes to acid damage, the service buttons are usually taken out first. That battery pack also needs swapped ASAP

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#3 3 years ago

JAM

Jmckune

Pinside member

5y 80,850 1,894 7

Delete

0

#4 3 years ago

OP

TIM

MT45

Pinball Loft

Lenoir City, TN

11y 110K 2,371 38 10

Quoted from Jmckune:
I see corrosion at what looks like U20. And yes. In WPC games when it comes to acid damage, the service buttons are usually taken out first. That battery pack also needs swapped ASAP

Thanks so much for the quick response. So you agree I should replace U15?
Battery pack is already moved remote so I'm good there

Good eye on the U20

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#5 3 years ago

FNG

DumbAss

Pinside+ Frequent

9y 109K 2,976

I hope that your picture is a "before" and not "after". That's U16. It's directly involved in detection of the direct switches.

wpc-89_cpu.jpg

I don't see any evidence of alkaline corrosion on U20. U20 is the column drive for the switch matrix. If you can't enter diagnostics you can't test the switch matrix.

This image (courtesy of zaza) will help you understand the purpose of each IC. See https://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Further_MPU_Circuitry_Diagnosis for the image.

I would take and post a picture of the current state so better conclusions can be drawn.

0

#6 3 years ago

OP

TIM

MT45

Pinball Loft

Lenoir City, TN

11y 110K 2,371 38 10

Quoted from DumbAss:
hope that your picture is a "before" and not "after". That's U16

Thanks in advance for any help ... the first pic was U16 "before"
Second picture was after I used my Hako to desolder and replace U16

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2

#7 3 years ago

OP

TIM

MT45

Pinball Loft

Lenoir City, TN

11y 110K 2,371 38 10

Quoted from DumbAss:
This image (courtesy of zaza) will help you understand the purpose of each IC. See https://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Further_MPU_Circuitry_Diagnosis for the image.

By the way, I read the entire page and this is one of the most complete troubleshooting pages for the service menu switches I have ever seen!
Thanks for sharing it!

0

#8 3 years ago

FNG

DumbAss

Pinside+ Frequent

9y 109K 2,976

It looks like you have mild alkaline damage on at least pins 2 and 3 of U15.

It also looks like you have mild alkaline damage on the resistors R35-R38. It's hard to tell. It's not in focus.

Finally ... it looks like the solder has not flowed in the through hole of the U16 IC that you replaced and that you might have pulled a pad on the component side of the board. Solder should flow into the through hole and completely surround the leg of the IC. It often doesn't flow when you've pulled the through hole (often done during removal of the original IC).

You need to test continuity between the requisite points of U16. Consult the schematic for details. Please be aware that the Williams WPC-89 CPU schematic does have errors in the switch part of the schematic. I cannot remember exactly what the errors are but they do exist in the schematic. I believe the WPC-89S schematic corrects these or failing that you could consult the WPC-95 schematic. This part of the circuit did not change between any of the WPC revisions.

0

#9 3 years ago

OP

TIM

MT45

Pinball Loft

Lenoir City, TN

11y 110K 2,371 38 10

Quoted from DumbAss:
It looks like you have mild alkaline damage on at least pins 2 and 3 of U15.
It also looks like you have mild alkaline damage on the resistors R35-R38. It's hard to tell. It's not in focus.
Finally ... it looks like the solder has not flowed in the through hole of the U16 IC that you replaced and that you might have pulled a pad on the component side of the board. Solder should flow into the through hole and completely surround the leg of the IC. It often doesn't flow when you've pulled the through hole (often done during removal of the original IC).
You need to test continuity between the requisite points of U16. Consult the schematic for details. Please be aware that the Williams WPC-89 CPU schematic does have errors in the switch part of the schematic. I cannot remember exactly what the errors are but they do exist in the schematic. I believe the WPC-89S schematic corrects these or failing that you could consult the WPC-95 schematic. This part of the circuit did not change between any of the WPC revisions.

Thanks and I'll walk through each point:
R35-38 - yes, but checked resistance and continuity for each so I think I'm good there (but easy to replace if I should)
Yes on the solder not flowing but because of the delicate traces I was super careful in using my Hako to de-solder - very brief hits, suck the solder, then cut legs in back, then touch again to pull chip. Then very careful about heating the legs up too much when adding solder back. Not sure if just not enough or indeed the pads were pulled but ...
I also checked continuity through the entire circuit for each leg of U16 and was good (but I will try to get solder to flow through again)
Barring that working I can jumper as needed but if getting continuity out of each leg to the appropriate spot on the board - I'm good, right?
Thanks for heads up on schematic - I saw that the J205 wire arrangement and key was wrong ... I'll grab a copy of a WPC89-S
Lastly, I've got a U15 chip on order so I might wait for that to arrive, pull and replace and go from there

0

#10 3 years ago

FNG

DumbAss

Pinside+ Frequent

9y 109K 2,976

OP
Quoted from MT45:
Barring that working I can jumper as needed but if getting continuity out of each leg to the appropriate spot on the board - I'm good, right?

Correct. If there are correct connections between the requisite points the board is electrically correct. That's all that matters for function.

OP
Quoted from MT45:
Lastly, I've got a U15 chip on order so I might wait for that to arrive, pull and replace and go from there

If you are worried about damaging pads and traces then cut the individual legs of the IC as close as possible to the body of the IC and remove the body. Then individually remove each leg before finally cleaning out the holes. This is easier than trying to pull the entire IC as a single entity. It does mean that you're sacrificing the original IC but if you plan to replace then that's a worthy trade off.

0

#11 3 years ago

OP

TIM

MT45

Pinball Loft

Lenoir City, TN

11y 110K 2,371 38 10

Quoted from DumbAss:
Correct. If there are correct connections between the requisite points the board is electrically correct. That's all that matters for function.

If you are worried about damaging pads and traces then cut the individual legs of the IC as close as possible to the body of the IC and remove the body. Then individually remove each leg before finally cleaning out the holes. This is easier than trying to pull the entire IC as a single entity. It does mean that you're sacrificing the original IC but if you plan to replace then that's a worthy trade off.

Love this idea - will use on U15

By MT45

3 years ago

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