(Topic ID: 269722)

Road Show WPC Resets


By Ghostcri

43 days ago



Topic Stats

  • 23 posts
  • 13 Pinsiders participating
  • Latest reply 29 days ago by ChrisHibler
  • Topic is favorited by 1 Pinsider

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#1 43 days ago

Hi guys, I've been running through the various steps in Pinwiki about fixing WPC reset issues and am at a point where I could replace BR2 and C5 but don't see a need. I've tested all of the bridge rectifiers and they are good.

Basically, I'm losing .2 volts from the driver board to the rom. I have a stable 5v on the driver board but on pin 32 of the game rom I only have 4.98V. I assume this is what is causing my resets? I have redone the header on the CPU board as well as the driver board and have also redone the 7 pin connector between the two. When I unplug the connector from the CPU and test the voltage directly at the 5V on pin 3 and 4 I get 5V on each.

Where on the CPU board am I losing the .2 volts before it gets to the rom? I guess the last thing I can try is replacing c31?

Thanks!

#2 43 days ago
Quoted from Ghostcri:

Where on the CPU board am I losing the .2 volts before it gets to the rom?

Weak trace on the CPU not letting current through ?

LTG : )

#3 43 days ago
Quoted from Ghostcri:

Hi guys, I've been running through the various steps in Pinwiki about fixing WPC reset issues and am at a point where I could replace BR2 and C5 but don't see a need. I've tested all of the bridge rectifiers and they are good.
Basically, I'm losing .2 volts from the driver board to the rom. I have a stable 5v on the driver board but on pin 32 of the game rom I only have 4.98V. I assume this is what is causing my resets? I have redone the header on the CPU board as well as the driver board and have also redone the 7 pin connector between the two. When I unplug the connector from the CPU and test the voltage directly at the 5V on pin 3 and 4 I get 5V on each.
Where on the CPU board am I losing the .2 volts before it gets to the rom? I guess the last thing I can try is replacing c31?
Thanks!

I'm not sure you're experience the same thing, but I had these "double-flipper" resets on my Road Show. Added a Kahr daughter board and boom. All fixed. Was like $39. https://www.kahr.us/daughterboard.html

#4 43 days ago

double and triple check your connectors. I believe there is a connector on the right side of the driver board where the power comes in. I had the IDC connections on that go bad, and it caused problems because the whole machine would lose its 5V. I finally discovered it when I had the Kahr board installed, and the sound reset, but the game was still running (MPU didn't lose its 5V). I had replaced all the caps, rectifiers, modded the board for higher 5V, etc. Came down to the simple IDC connectors that seemed good, but apparently were not. Just re-pin them if there are any questions about them...

Jeff

#5 43 days ago
Quoted from LTG:

Weak trace on the CPU not letting current through ?
LTG : )

Would it hurt to just run a jumper from J210 directly to pin 32?

I have the Kahr board and when I use it it actually makes the resets worse.

#6 43 days ago
Quoted from Ghostcri:

Would it hurt to just run a jumper from J210 directly to pin 32?

No.

LTG : )

#7 43 days ago

I had reset issues with my RS as well. Tried the Kahr daughter board and that worked for about 2 months before the problems came back. Sent my boards off to Chris Hibler, who replaced a bunch of the smaller caps (Br2 and c5 stuff had been replaced sometime before I got it), fixed a couple of bad thru holes, and installed new header pins. Meanwhile, I replaced the IDC connectors with Molex ones and got rid of the Z connector. Should be bulletproof for another 25 years!

#8 43 days ago

5.0 - 4.98 = 0.02, not 0.2. Is 0.02 volt drop really going to cause problems?

#9 43 days ago
Quoted from TheWiz:

5.0 - 4.98 = 0.02, not 0.2. Is 0.02 volt drop really going to cause problems?

You are right but I am unsure if this is enough of a drop to reset the game. Anyone with more advanced electrical knowledge able to say?
.02 is big difference from .20.

Looks like I need to go ahead and replace the 2 large caps and some other suggested components on the driver board and see where I'm at then.

#10 43 days ago

and get rid of that z-connector if it has one.

Quoted from Ghostcri:

You are right but I am unsure if this is enough of a drop to reset the game.
.02 is big difference from .20.
Looks like I need to go ahead and replace the 2 large caps and some other suggested components on the driver board and see where I'm at then.

#11 43 days ago
Quoted from rad:

and get rid of that z-connector if it has one.

No Z connector. J102 has also been changed out to a molex connector.

#12 43 days ago
Quoted from Ghostcri:

Would it hurt to just run a jumper from J210 directly to pin 32?
I have the Kahr board and when I use it it actually makes the resets worse.

What does the kahr board lights indicate?

#13 43 days ago
Quoted from TheWiz:

5.0 - 4.98 = 0.02, not 0.2. Is 0.02 volt drop really going to cause problems?

Yes, he is only seeing the drop not under any load, resets usually happen under load.

#14 43 days ago
Quoted from eyeamred2u:

What does the kahr board lights indicate?

I don't remember it having lights on it so it must be the older version. When I use the Kahr board it will boot up, reset when I hit the flipper buttons a few times then normally won't boot again.

#15 43 days ago
Quoted from eyeamred2u:

Yes, he is only seeing the drop not under any load, resets usually happen under load.

I suppose I should have my wife operate the flippers while I watch the meter and see what the 5v actually drops to.

#16 43 days ago
Quoted from eyeamred2u:

Yes, he is only seeing the drop not under any load, resets usually happen under load.

This is where having a good meter with a min/max voltage recall comes in really handy.

#17 43 days ago

The WPC games will reset if the voltage goes below +4,7 VDC. But when you measure in attract mode without any heavy load (No coils that fires.), Pinrepair says at least +4,92 VDC at TP2, but even if you have a higher voltage than that it's no guarantee that you won't get a reset.

The first thing we do when we have a WPC reset is to press in the cables in the following IDC-connectors: J101, J102, J112, J114, J116, J117, J118, J210 and the cables at the Z-connector (DM, IJ, STTNG & TZ).
(WPC-95: J101, J127, J128, J129, J138, J139, J140, J141, J210.)
Se photo below of the tool we use. We bought it at Pinball Center in Germany.

If pressing in the cables doesn't help, then we change BR2 and C5, and after that the problem is normally gone.

Williams probably had their reason to change from bridge rectifiers on the WPC-89 games to diodes on the WPC-95 games, and in my opinion there are much less reset problems with the WPC-95 games.
The bridge rectifier can test good, even if the component is over stressed and the capacitors will dry out over time, so I would recommend you to change those components, if pressing cables in the connectors doesn't help.

image_97829_1_600x600 (resized).jpg
#18 43 days ago

The WPC95s finally hit on something for bridge rectifiers.

I did the math several years ago and found out that four independent 6A4 diodes (even though they have a lower max current rating) will run cooler than a GBPC3504W with all four diodes within one package.

Comparing 4 amp loads (typical fuse into bridge circuit for WPC95)
GBPC3504W type bridge as used on WPC. Each diode has forward voltage drop (VF) = 1V. Power for one conducting diode = (4A x 1V) = 4 watts.
Considering the bridge with four internal diodes - always two diodes conducting simultaneously so 2 x 4 watts = 8 watts total.
Due to how a bridge works - always two of four are conducting so this bridge rectifier is *always* dissipating 8 watts.
Thermal resistance = about 11.5C/W with typical bridge type heatsink.
Temperature rise at full 4 amp load = (8W x 11.5 C/W) = 92C temp rise. Add 25C ambient so bridge is operating at 117C (HOT!).

6A4/P600 type diode as used on WPC95, four comprising a bridge circuit. VF = 1V. Power for one conducting diode = (4A x 1V) = 4 watts.
All four diodes are separate so temp of one has no real affect on other diodes temps.
And each diode is on or conducting only 50% of the time so the average power dissipation over time = 2 watts.
Thermal resistance = 20C/W for this type diode with no heatsinking.
Temperature rise at full 4 amp load = (2W x 20C/W) = 40C temp rise. Add 25C ambient so each diode is operating at 65C (not cool but far from that 117C).

In addition to better thermal characteristics, four of these diodes costs much less than a GBPC type bridge rectifier.
So it is fairly easy to see why Williams went to four x 6A4/P600 type diodes with their WPC95 boards. Down side is they take up more board space.
The bad thing I see is that some of the bridges are fused at 6.3 amps (solenoid secondary) which just barely exceeds the current limits of these diodes. A 10A4/P1000 type diode would have been a better choice for these.

#19 42 days ago
Quoted from Classe:

Williams probably had their reason to change from bridge rectifiers on the WPC-89 games to diodes on the WPC-95 games

Quoted from G-P-E:

these diodes costs much less than a GBPC type bridge rectifier

Cost is the primary consideration in all manufacturing decisions. You can engineer a widget that would last forever, but if it costs more to produce than a widget that will wear out after 5 years, guess which one is going into production.

#20 41 days ago

ghostcri, .02VDC drop isn't enough to cause any problem at all.
Have you repinned J101 and J114 on the power/driver board?
Have you repinned J210 on the MPU board?
Can the reset be tied to an event going on in the game?
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact ... for board repairs
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#21 40 days ago
Quoted from ChrisHibler:

ghostcri, .02VDC drop isn't enough to cause any problem at all.
Have you repinned J101 and J114 on the power/driver board?
Have you repinned J210 on the MPU board?
Can the reset be tied to an event going on in the game?
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact ... for board repairs
http://www.PinWiki.com - The Place to go for Pinball Repair Info

Chris - Yes, all of those connectors have been redone. The issue only happens when hitting both flipper buttons at once. I had checked both coils for good solder connections as well as tested all of their diodes; everything was good. I went as far as to replacing both coils with new ones but the issue still persists. I do still need to check the upper left flipper, though.

#22 40 days ago
Quoted from Ghostcri:

Chris - Yes, all of those connectors have been redone. The issue only happens when hitting both flipper buttons at once. I had checked both coils for good solder connections as well as tested all of their diodes; everything was good. I went as far as to replacing both coils with new ones but the issue still persists. I do still need to check the upper left flipper, though.

Check to be sure your power cord in the back of the game has not came out of its socket a bit. You'll have to remove the plate to reseat the connection. I had this with a Cactus Canyon I worked on until it finally decided not to boot up at all.

1 week later
#23 29 days ago

If you still have your DW or JD, swap the power/driver board with one of those games. Let’s see if we can further isolate.

Chris Hibler - CARGPB #31
Http://chrishiblerpinball.com/contact
http://www.PinWiki.com/ - The new place for pinball repair info

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