Jump to content
Due to a large amount of spamers, accounts will now have to be approved by the Admins so please be patient. ×
  • 0
IGNORED

Shorted Matrix Row That Won't Unshort.


Autosteve

Question

One of those, it will probably be this but no, well it's more than likely this but no, well I'll change this piece because there isn't much else to change but no. I'm now to the point of what the fuk is causing this?.

 

Here's the rundown. It's a Judge Dredd coming up with "Gnd Short Row 2".

 

I take out all the matrix cables, problem still there so it's a board issue.

 

Changed U18 and put in a socket. Problem still there.

 

Probed all pins on the chip to there destinations on the board for continuity, all checked fine.

 

Checked all associated resistors and caps, all checked out fine.

 

Changed U13 and put a socket in. problem sill there.

 

Checked continuity between J208/209 pin 2 to D4, fine, checked between R53 to U18 pin 9, fine, checked U18 pin 14 to R 29, fine. R29 to U13 pin 13, fine. Checked Gnd and +5v on U 18, fine. Checked U13 D6 to U12 and D14 D6, fine.

 

Checked R 29 5volt, fine. Checked 12v to U 18 pin 3 fine. Checked 12v R54, fine.

 

Changed R54, 53 and R29 even though they were all within specs. Changed C4.

 

Well that is what I am up to and still have "Gnd Short Row 2" coming up. What have I missed?. I was going to pull the ASIC but I figure if the problem was on D6 (pin 27) or Switch Row (pin 48) on the ASIC, there will be more than just one row not working correctly.

 

I'm open to suggestions on this one. Not much I pull the pin on but this one is getting there. I am simply running out of parts to check or change.

Link to comment
Share on other sites

23 answers to this question

Recommended Posts

  • 0
One of those, it will probably be this but no, well it's more than likely this but no, well I'll change this piece because there isn't much else to change but no. I'm now to the point of what the fuk is causing this?.

 

Here's the rundown. It's a Judge Dredd coming up with "Gnd Short Row 2".

 

I take out all the matrix cables, problem still there so it's a board issue.

 

Changed U18 and put in a socket. Problem still there.

 

Probed all pins on the chip to there destinations on the board for continuity, all checked fine.

 

Checked all associated resistors and caps, all checked out fine.

 

Changed U13 and put a socket in. problem sill there.

 

Checked continuity between J208/209 pin 2 to D4, fine, checked between R53 to U18 pin 9, fine, checked U18 pin 14 to R 29, fine. R29 to U13 pin 13, fine. Checked Gnd and +5v on U 18, fine. Checked U13 D6 to U12 and D14 D6, fine.

 

Checked R 29 5volt, fine. Checked 12v to U 18 pin 3 fine. Checked 12v R54, fine.

 

Changed R54, 53 and R29 even though they were all within specs. Changed C4.

 

Well that is what I am up to and still have "Gnd Short Row 2" coming up. What have I missed?. I was going to pull the ASIC but I figure if the problem was on D6 (pin 27) or Switch Row (pin 48) on the ASIC, there will be more than just one row not working correctly.

 

I'm open to suggestions on this one. Not much I pull the pin on but this one is getting there. I am simply running out of parts to check or change.

 

 

 

So you haven't checked U20 and U14?

Link to comment
Share on other sites

  • 0
So you haven't checked U20 and U14?

 

No because it is a Switch Row 2 ground short and I wouldn't have thought U20 or U14 would affect the row as both these chips seem to be only Column related but I may be wrong.

 

This is the diagram I use for repairing WPC MPUs. It's a '89' board but pretty close.

 

http://pinwiki.com/wiki/images/6/6d/WPC89_CPU_compnt-side_ZAZ_FEB2017-10.jpg

 

You can use this diagram and see exactly what I have checked so far.

Link to comment
Share on other sites

  • 0
You think U20 as well?

U20 is a Darlington array I.C and is responsible for the switch matrix control. I would replace U20 first as it's a $2 chip & it should be socketed as they regularly fail. This chip has a history of failing partially on rows, columns or a single x,y position without affecting other matrix functions.

Link to comment
Share on other sites

  • 0
U20 is a Darlington array I.C and is responsible for the switch matrix control. I would replace U20 first as it's a $2 chip & should be socketed. This chip has a history of failing partially on rows without affecting other matrix functions.

 

Arr OK. I've changed a fair few U20 ULN2803 in the past but they have always been to fix switch Column problems. This is actually the first switch Row shorted to ground problem I have had and couldn't see how U20 would effect a whole Row to become shorted.

Link to comment
Share on other sites

  • 0
Arr OK. I've changed a fair few U20 ULN2803 in the past but they have always been to fix switch Column problems. This is actually the first switch Row shorted to ground problem I have had and couldn't see how U20 would effect a whole Row to become shorted.

 

There is another on the Power Driver PCB U19. I'm not sure if it's related but also worth a check.

Link to comment
Share on other sites

  • 0
Does the power driver board have a relay on it for the flippers? If so perhaps the optocouplers are worth a check? Interesting reading about it here: http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Cabinet_Flipper_Switch_Detection_Problem_Diagnosis_for_Pre-FlipTronics_Games

 

No relay on the driver board. Ive had to change blown optocouplers before on boards like T2. No lane change was the symptom I spotted with opto problems. This machine's symptoms were, other than it booting up with the warning "Ground Short Row 2", was because the machine is Judge Dredd, no way to launch the ball at the start of each ball because one of the Row switches effected is the ball launcher switch. Other than that, the machine did still play.

Link to comment
Share on other sites

  • 0
So still no closer to an answer as to what's wrong?

 

I gave up and sent the board to Ken. I have already lost bad on this repair, sinking to many unpaid hours into it so the best solution was send it to someone that has a test bench. I have done most of the playfield repairs already and the customer wants the machine back so rather than throw more unpaid hours into the board, send it to the master.

 

I have another two machines lined up so I just started on them till the board comes back.

Link to comment
Share on other sites

  • 0
I gave up and sent the board to Ken. I have already lost bad on this repair, sinking to many unpaid hours into it so the best solution was send it to someone that has a test bench. I have done most of the playfield repairs already and the customer wants the machine back so rather than throw more unpaid hours into the board, send it to the master.

 

I have another two machines lined up so I just started on them till the board comes back.

 

I totally agree, It's hard when you don't have a test bench. :)

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...