(Topic ID: 125333)

wpc fuse 115(switch matrix) issue

By cubie

4 years ago

Topic Stats

  • 13 posts
  • 6 Pinsiders participating
  • Latest reply 4 years ago by cubie
  • Topic is favorited by 2 Pinsiders


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SwMx U18-19-20.jpg

#1 4 years ago

hi, i'm new to pinside and pinball. i was adjusting a switch for a bumper with the machine on and blew a fuse on my fish tales. i get error code to check fuse 114 and 115. i replaced both and 115 blew again, but not 114, still says check both. i pulled my wpc power driver board and tested the diodes resistors and a few transistors as was my first thought but i didn't find any problems, 115 fuse is for switch matrix. does that sound like i blew a ic chip and 114 is lamp matrix. the lamps all light up and dance no issues. i need suggestions

#2 4 years ago

First thought is that you shorted coil voltage to the switch matrix and blew those chips, maybe just the column driver, so no switches would be showing up in the switch test mode.But I'm not sure why your fuse would be blowing. Does it blow if you disconnect the CPU board from the driver board? If so, something's up with your 12V power supply on the driver board. If not, something on the CPU board is drawing too much current.

#3 4 years ago

Yea sounds like you blew u19 on the cpu board.
we've all been there.
Check to see if its socketed already and replace it if it is.
if not your going to have to have it done or do it yourself.

#4 4 years ago

Sounds like you shorted 50 volts to the switch matrix and blew your U20 switch matrix chip on the CPU. A blown U20 can cause F115 to blow, which is most likely why the fuse continues to blow. Sometimes U14 will be damaged too, so keep that in mind if replacing U20 doesn't fully cure the problem. Be sure to put a chip socket in for U20. Your exact scenario was common enough that later CPU board versions came with that chip already socketed. Also why later games have an interlock switch to cut the 50 volts when the coin door is open.

#6 4 years ago

well the bumper switch was shorted to to the kick-out on the ball lock(low power solenoid) i will need to order various common ic chips and replace the chips with sockets.i'm having trouble locating a supplier for 11pin idc connector female, pinball life has 12 pin i can modify but they don't sell the 11 pin outside a kit, thank you everyone i will update after i try suggestions

#7 4 years ago

Just take the 12 pin IDC to a bench grinder or belt sander and carefully remove one space from it.

#8 4 years ago

can i use LM339A or LM339N in place of LM339

#9 4 years ago

Are you sure you want to replace the LM339 already, you could first cut the leg U20-10 away from 12Volt and see if the short goes away. If the short is away, you can perform test in testmenu T1.

SwMx U18-19-20.jpg

#10 4 years ago

i wanted to get all possible parts in the mail so i can have on my bench. that picture is a big help

#11 4 years ago
Quoted from cubie:

i wanted to get all possible parts

ah ok, I'm not sure but all LM339's work in this CPU-board and LM339N has the best specifications, but again, I'm not sure.

Quoted from cubie:

that picture is a big help

If you need more of that picture, have a look on pinwiki :

#12 4 years ago

To answer your question on the LM339, yes both 339A and 339N will work. Replacing U20 will likely take care of the fuse blowing and fix all your woes. It's the one that took the hit when the short occurred. Suggest you replace U20 first and not do them all just to do it. Beyond U20, U14 can also take damage in this short scenario, though not always. So before you mess with the LM339 row chips, I'd look at U20 first, then check U14 if there are still switch issues.

2 weeks later
#13 4 years ago

replacing U20 did fix the issue and as a bonus i rebuilt my bumpers (replaced wafer, spring and coil tubing) replaced a burnt header on my driver board and a molex connector with a idc so that's back to original. tomorrow i need to replace Q9 on my fliptronics board to fix my LF hold then i can play it. it's been down for about 3 1/2 months and was a great excuse to by some new toys like a soldering station ended up settling on a wtcpt. thx for the help everyone

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