Have software ver.LF-6 here and can dim in test T.6

Does ZeroCrossing (120Hz USA /100Hz EU) signal arrive at U9 ? (reseat ribbon / push U9 in socket)

http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#LEDs_and_test_points_on_WPC-089_Power.2FDriver_Boards

Testpoint TP4

Yes correct, U9 on the CPU-Board and the ribbon cable between CPU- and PowerDriverBoard.

Without a oscilloscope / logic probe / frequency function on multimeter it would be difficult to tell if there is a ZC signal at CPU U9.
But you can measure continuity from testpoint TP4 (powerdriverboard) to U9-71 (CPU-board) with machine OFF and careful with needle in socket.

Voltage at TP4 is pulsing between 0 and 5 volt @ 100 or 120 HZ and I had about 0.4Volt average. Value could be different with another multimeter.

ZC.jpg

Now a scope would come handy to see if there is actual a 100/120 Hz signal.

Another continuity test than : )

With machine'OFF' and J101 connected.
On Powerdriverboard, measure continuity between anode D38 and anode D3.
Should be close to ZERO Ohm.

ZC 2.jpg

You're welcome !

00.8 means that both diodes are connected to transformer so that is perfect.

But this is as much as we can test now without frequency tester.
If you have a PLCC extractor tool and can work ESD-safe, you could pull ASIC U9 and check pins on socket and chip.

I can't tell 100 % either but I would expect that it can dim.
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I think that little board is to give an extra pulse to the coin switch input. There was something about coin settings and this way it was possible to give 1 credit for xx(?) dollarcent.

Could be a wire for coin cointer that was connected to the knocker-drive in the backbox.
If it is originated from the interface box (can't see in picture) , then be careful with it as it could be high voltage.

Final thought about GI, without the ribbon cable (CPU<->PDB) the GI should stay OFF (together with all ather lamp and coils).
If the GI is still ON without the ribbon cabel installed, there is an issue on the powerdriverboard.

Yeah, at this moment it is best to verify this signal, maybe you can borrow a multimeter with frequency function.

The test suggested in post #9 is to confirm that the diodes 38 and 3 are connected to the AC supply from transformer.
When Br.2 is replaced, the trace to the diodes can easily be damaged. But it still doesn't confirm that there is a ZC signal all the way to U9-71 on CPU board.

that's correct.
I don't see a Frequency function on your multimeters

I use a Metex M-4650 for this kind of frequencies. Very happy with this one
Metex M-4650.jpg

Could be a bad LM339 (U6) on the powerdriverboard.
Or socket of U9 lost contact with the chip. Did you push on the ASIC chip U9 ? (machine OFF)

What we know now for sure is that it is not a software (LX-5) issue, but more likely some bad connection.

What PinballManiac40 noted about leaking batteries could have caused this. The most right pin on J205 is for left coin input.

I've seen this a couple of times passing by on pinside

https://pinside.com/pinball/forum/topic/very-interesting-find-in-my-dirty-harry-dh
https://pinside.com/pinball/forum/topic/tech-roadshow-delayed-boot-up

I don't know exactly how it is wired and how it works but I would remove it. Always work on this powerbox with mains powercord unplugged !

that would be (if original colors are used)
Orn/Wht = Electronic coin acceptor enable
Gry/Yel = 12V unreg.
Black = 0V / GND
Brown dmd = +62V

----
About the left coin input switch, you can test it quite simple.
After you go into switch-test T.1 , unplug J205 and attach a wire from GND to J205-1. It should trigger Left coin.
J205-1.jpg

Glad to help you Sparky70 and nice to see that you understand the WPC-system better due to the pictures and explanations.
Once you are full into the WPC-system, you can answer most questions on the forum so that I can retire here

thank you RonaldRayGun

That is correct. With the machine 'OFF' and J101 connected, you can measure continuity to be sure that the traces from the diodes to the connector J101 and through the transformer are not interrupted in any kind of way.
It does not matter where to put the RED or BLACK probe on the red dots as shown in post #9. The multimeter should buzz when path is OK. When multimeter is set to resistance, it will show someting like 1 ohm.

The ZC signal itself can be measured with a multimeter (if it has a freqency function) or with an oscilloscope. In the UK it will read 100 Hz.

It means that the path from transformer to the 2 diodes is ok.
The same advice as mentioned earlier in this topic, you will need an oscilloscope or freq.meter for this.

Check also settings for GI in menu at A.1 25 'allow dim illumination'