Make sure that diode is good and on correctly. I'm guessing that your gonna have a board problem though. To determine this disconnect the switch connectors on the CPU board. If the errors still appears the problem is on the board, if not it will be on the playfield. Once thats done we'll be able to figure out which way ya need to go.

"Is it possible a broken diode can take out a whole row?"

-yes

"The Shadow Knows !!!" hehehe

Was it the Sanctum Wall, bugray? I'm pretty sure you can find a replacement from Marco's for $25.

http://www.marcospecialties.com/product.asp?ic=03%2D9210

The one in my Shadow had to be adjusted from below the playfield. Luckily it wasn't broken. It wasn't adjusted correctly, and was neither in the down or up position, but rather halfway up. I might end up ordering a replacement wall from Marco's eventually.

Hmmm... I think I had those problems after shopping out my Shadow...The targets needs to be in the up position when the game boots up, otherwise the game gets confused. Try that and see if it helps.

You can remove a diode at one end and a coil will still work without it. It's mostly a reverse voltage surge protection thing. So if you want to try it you can. A bad/hurt diode will cause a coil to not work when attached. Just don't run the machine without the diode except for troubleshooting in the short term.

To add a little more info coils are essentially electromagnets creating an electromagnetic field. As they shut down the field tends to reverse polarity in a much less powerful way. The diode blocks this minor reversal from happening across the coil. Without the diode blocking this damage will eventually happen to the components driving it.

if something shorted and blew that diode - it will take everything down - happened on my taxi, two new diodes on the flipper coil and it was all back up and working.

Based on what you've done so far I think you blew a chip or chips on the CPU board as a result of that diode breaking off. Clay's guide had the procedure for determing this. It's quite a bit of reading but you can get the testing procedure there. I think the most likely culprit is U20, but it could have gone back further.

If you add a diode to a DC coil just make sure to put it in the proper direction. The banded end goes to the negative (-) side. Usually a 1N4004 diode will work in most pinball applications.

There is also a method for checking the transistors and pre drive transistors - I think clay mentions it but basically you quickly ground the row to determine if you have blown those items - I would first fix your diode then get working on the board testing.

Yes it is possible for a diode to take out a whole row.

I had a similar problem on my nba fastbreak with all the switches in a row out. First definately unplug the connector from the board and "buzz meter it back to all the switches in that row from the plugs for the ground wire( grn-?) and the power (white-?).

If it is all good go to the pinball repair site (switches not working)and use a diode and a jumper to manually test the switches at the driver board, like fusion says.
And buzz out each switch to check if the diode is ok (fwd/rev)- (activated -non activated)
Step by step instructions in the online repair guide.

I thought it was U18-U19 as well but it was a combo of diodes, loose connections and a U20 problem as a switch was shorted to a coil. That is pretty much the only way the chip at U20 or U18-U19 will fail, and as long as your machine was fused correctly U18 should be ok. U18-U19 are run through U20 so if its good they should be too.

And if nothing was shorted to a coil or lamp matrix it is one of these issues or a combo
Wiring/connectors -loose broken
diode-broken or non working
transistor or predriver-shorted or non functioning

Because of your row grnd short error.. it is more than likely a shorted transistor controlling that row. To be sure do the diode test. in the switch matrix test. you can also unplug the connector to that row while the machine is on in the switch matrix test.
This will also let you know if its in the wiring or the driver board.
(follow online repair guide, to do this)
Or a diode/power lead is touching something under the playfield shorting that row to ground.

Go with the Williams pinball repair tips step by step for each issue you have. Just take your time and as long as you go through each step it should be fixed in no time.

Great to hear bugray! Looks like you figured this one out before the holiday. Now, to see if you can get it working (error free) in order to play your Shadow during the holiday break.

glass off is a great way to practice shots. I set up the same shot over and over

I have only done that on the BF because I didn't understand the Two Face Coins description in the manual. Wasn't written very well.

I do take the glass off to practice a shot over and over though.

Topless machines are naughty but let you see and play with their bits ... hehe

I was just playing Shadow again the other day. I should have been moving on and cleaning up my other machine playfields, but got sucked in like a tractor beam by the game. I can't really explain it. Only a regular Shadow player can explain the addictiviness of the game. Almost got to the final battle without using a buy-in on a 3 ball game.