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WH20 cpu controlled lamps

Spandangler

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Hi Gang

So as not to derail the led ocd thread.

I thought I had some ghosting issues but having changed the offending bulbs to incandescent, the problem remains.

As you can see in these vids, my insert raft 6 is always illuminated during gameplay

As is V in RIVER although that is an LED.

The bottom lock light is on when no locks are lit

Also the extra ball insert is faintly lit. Wet Willies also does the same sometimes!!

Any ideas why????

During attract and at the start if a game before anything is hit, they are off.
 

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Ok, let’s have a peep at this. As the Sarge says most of your issues are on the same row. Row 3.
The lamp matrix tells us that the transistor for that row is Q88. If I remember correctly WPC games also have a pre-driver transistor and a diode in that circuit.
Before you check those though I would check the diodes to each of the lamps on that row. I would also check that the bulbs are all actual 555’s.
If all that is good then start looking at transistors and diodes on the boards.

4AA03104-A1A8-46E8-8FDE-7C6FEC93D7CE.jpeg
 

I’m noticing all kinds of lamps now which are not on row 3.
Am I correct in thinking diodes have to be tested out of circuit?
I haven’t done this yet as I can’t be bothered to clip all of those diodes if I can help it.
Hopefully the vid paints a thousand words.
 

I’m noticing all kinds of lamps now which are not on row 3.
Am I correct in thinking diodes have to be tested out of circuit?
I haven’t done this yet as I can’t be bothered to clip all of those diodes if I can help it.
Hopefully the vid paints a thousand words.
Yes diodes need testing with one leg unsoldered. Looks like you have current leakage somewhere.
The CPU board doesn’t have (or had) battery corrosion does it ?
 
Hi, Gaz,

Have you tried the "Single Lamps" test, where only one selected lamp (strictly speaking one 'node' of the lamp matrix - there may be more than one actual bulb used on some games) should be flashing at any one time? Going through this test for each lamp in turn, in conjunction with the matrix chart, may help to narrow down the condition(s) where the problem(s) occurs.
 
This is getting confusing now.
So I put some LEDS in and now different lamps are illuminating which were never before!!

I also removed my CPU board and tried it in my mates WH20. The issues did not transfer across to his, so I think we can rule that out.

The case continues...
 
Put it in all lamp test. Disconnect the row connector. Reconnect just one row at the end of the connector. Note which lamps Flash. Move the connector to the next pin but the same socket on the connector. The same group of lamps should Flash. Repeat for all the pins. If one pin causes the group to act differently than normal the fault is in the board on the circuit driving that pin.

Repeat for column connector.
 
Cool thanks Andy. I presume from your wonderful advice that by doing so I don’t risk putting a different voltage through a pin that way and blowing anything up??
 
This is getting confusing now.
So I put some LEDS in and now different lamps are illuminating which were never before!!

I also removed my CPU board and tried it in my mates WH20. The issues did not transfer across to his, so I think we can rule that out.

The case continues...
I would put all incandescents in the inserts until you solve the problem.
 
Hi guys
I haven’t tried Andy’s advice yet regarding the connector but here’s a vid of the symptoms in single lamp test.
Sorry. It’s a dead boring vid!!

 
Thanks dude

This kind of supports my suspicion that I need to replace Q88. Based on nothing other than a hunch!!

It’s not testing short but nor was the guys on the pinside thread.
If your soldering skills are fine I would replace it.
 
Put it in all lamp test. Disconnect the row connector. Reconnect just one row at the end of the connector. Note which lamps Flash. Move the connector to the next pin but the same socket on the connector. The same group of lamps should Flash. Repeat for all the pins. If one pin causes the group to act differently than normal the fault is in the board on the circuit driving that pin.

Repeat for column connector.

Ok Andy. Done that. It behaved impeccably.

So it seems they behave themselves when initially illuminated. As soon as another bulb is illuminated it goes haywire.

So I’m now thinking a diode somewhere.

Any ideas to save me checking and potentially changing 64 of them :confused::eek::(:tut:
 

  • Testing a Lamp Diode.
    In order to test a lamp diode, use the DMM set to diode test. Put the black test lead on the banded side of the diode. A reading of .4 to .6 volts should be indicated. Reverse the leads and put the red lead on the banded side of the diode. A null reading should be shown. Any other reading and this lamp's 1N4004 diode should be replaced. The light bulb doesn't need to be removed, nor does the diode need to be desoldered to perform this test. Also test the diode soldered to the circuit boards that hold the 555 lamps in the same manner (but remove the connector and the 555 lamp before testing).

Taken from the good old.

http://techniek.flipperwinkel.nl/wpc/index3.htm
 
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