If I remember correctly, D19 should be off, D20 blinking and D21 solid. It sounds like your game may not be blanking.

Did anything happen before this started?

With the game off, try reseating all the ribbon cables. Always a good place to start. Here is a reference that could help:

http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Power-On_LEDs_and_Sound_Tones_.28Bongs.29

Good luck.

Dan

Hmmm..... re check all the connections in the back box again?

check the batteries and holder ?

Check the voltage test points on the power driver board in the head.

See if any are low or missing.

The 50 volt not under load can be higher.

LTG : )

Did you replace the board with a different board?

I had that problem when I swaped my Funhouse CPU board with my White Water board, even though I swaped the ASIC, Game Rom, and U4. I'm trouble shooting a switch problem but unrelated to yours. Granted my Funhouse might be pooched now but I'll find out later.

I found this bit of info online, Look at pin 3 of U21 there starts the blanking signal coming from the ASIC; if it is "low" there then you have a problem in the amplifier chips U21 or U5. You can follow the signal through both chips easily using the schematic. If it is already "High" at U21 Pin 3 then the signal coming from the ASIC is bad, again change the ASIC or 6809 (U4). If that doesn't help, look for a pro to send that board too because you'll just spin your wheels. This is all assuming your power is where and what it should be. I didn't have power issues, I put the old board in and it booted just fine. Just missing a switch column.

You have your work cut out for you, should see my help wanted post on here. I'm getting a logic probe this week. I have no choice!

Let's put the horse in front of the cart here. Might be jumping ahead. I'm reading up on the blanking circuit now. The voltage is ok at TP6(my whitewater boots and is 72V at TP6).

Not sure if there was a failure with one of your coils or not but first thing I'd isolate the CPU from all other boards. Pull all the ribbon cables including the switch cables. The only one to leave is J210 because that's your 5V supply. Power up and watch for blinks. D19 Should come on for a bit then off, if D20 blinks 1, 2 or 3 blinks it's telling you a fault code. If there is a problem with all cables detached note the D20 blinks, tells you if U6, U8 or U9 are bad as your suspecting possible U6 so that's a single blink.

You mentioned humming in the game, the 15,000 ufd caps might very well be weak on the driver board if the sound is coming from that area.

The bong means nothing in relation to the CPU. The bong simply indicates that the sound board has booted, it has its own processor, RAM, and ROMs.

If the CPU still isn't booting with everything but power disconnected, you've definitely got a CPU issue. Sending it out for proper repair would be my recommendation.

--
Rob Anthony
Pinball Classics
http://LockWhenLit.com
Quality Board Work - In Home Service
314-766-4587

There is a guy selling a U6 chip on ebay in Indiana. johnwartjr is the user name. I agree though with Borygard, Clive at Coin-Op Caulron is reliable and post a price of 78.00 to repair but they'll quote you first. Can pull your hair out trouble shooting this and get nickel and dimed on parts and shipping. But for 150$ get your 4000+ dollar machine working again. While that board is away consider replaceing caps on the driver board in the mean time.

http://webpages.charter.net/coinopcauldron/brepairs.html

That's me. This doesn't sound like a ROM problem.

I would strongly recommend against just replacing caps for the heck of it. Most driver board problems are NOT cap related, even though internet folklore has advised to replace bridges and caps for years in various sites and forums. You can do a lot of damage changing the caps if you don't know what you are doing!