I know this is an old post but you don't know how much it helped me. I too recently purchased a Time Warp.
Of course the old "it works at the place you buy it but once you get it home it doesn't" came into play.
Once I turned the game on solenoids 1-8 would automatically lock on.
Thinking it was a connector and not the eight TIP120s I reseated the black connector. No joy.
After looking at Vid1900's blog on bulletproofing I looked at the 40 Pin connector and saw that just one of the connectors was broke.
Well I wanted to get this game ready for the Rocky Mountain Showdown 9 days away and didn't want to have to order new connectors so I just borrowed one bank of 8 connectors off of a driver board I recently purchased.
Sure enough she fired up and came to life.
Now all I'm having to do is troubleshoot a switching matrix problem.
Seems the top left and center pop bumpers will fire in test but will not fire when the switch is pressed.

Thanks Vid1900 for the bulletproofing blog.

Vid here is what I've troubleshot so far for switches 19 and 22.

-In test mode the switches aren't recognized/registering.
-All other switches on Row and Columns register in test mode.
-Tested Driver board, in Test Mode, with 2J3 and 2J2 disconnected, switches registered. (PinWiki Assist)
-Reseated 8P1/8J1 (Looking back this wouldn't have made a difference)
-Cleaned switches with business card, repositioned - still not registering

Next step is to check voltage at the switch while in Test Mode.
Don't know how a leaf switch could go bad but could the switch be bad?

I think I am getting close.
After looking at Vids Guide to Rebuilding Pop Bumper.

https://pinside.com/pinball/forum/topic/vids-guide-to-rebuilding-pop-bumpers

I found out the "scoring switch" wasn't registering because the "solenoid switch" wasn't registering.

-I put the game in switch test and this confirmed that the scoring switch was working correctly.

After looking at the "Special Switches", which are not part of the switch matrix(switch test), I crossed checked with PinWiki again.(see section 4.23.2)

"Confusingly, the CPU can also fire the 6 special switches from PIA lines for the diagnostic tests, but these PIA signals are never used during game play. If all these solenoids work during diagnostic tests, but not in game play it points to the switch inputs or the 7408s at IC6/7. It won't be the 7402s at IC8/9."

http://www.pinwiki.com/wiki/index.php?title=Williams_System_3_-_7#Controlled_Solenoids

So it looks like a logic issue at IC6 and IC7 because both solenoid switches are fed to each one separately.

Solenoid_Diagram.jpg

Still a little confused about my voltage reading of .1 to .2 volts at the solenoid switches.

barakandl I would try this but I don't have a logic probe and I don't know how I would use one.
Next on the list of things to learn. Thanks though.

Having a difficult time tracking down the 5+ volts for the solenoid trigger switch input to explain the .1 and .2 voltage readings.

Sometimes I over think things.
Thankfully I'm the kind of guy who has a rule of not wanting to do "major surgery" on a board unless I absolutely have to.

I found out that the switch connectors (2J13) on the driver board had cracked solder joints. So I resoldered them and this took care of both the switches on the pop bumpers.

Now it won't go into test mode from the diagnostic switch on the door.

I think this is the switch itself because I am reading 4.8 volts accross the switch.
Only problem is I can't short it get it into Test Mode.

Thanks Vid1900 and barakandl for the help.

Last update.
Cracked solder joints again.
Game is up and running once again thank you for the assist.