Wms 400 backplane 24c04 problem - no boot up & no error messages

So i'm working on a bunch of Williams model 40x machines.
I was warned when i bought them that they, "weren't easy
fixes, this is the stuff that was deemed too much work
for us to get going." hehehe. Man i like stuff like this.
yea i know, i'm sick. but hey, ya gotta have a hobby right?

anyway, when i got all these games i took all the boards
out, and tested each one in a working game. marked the
boards as "ok" or otherwise. Also took all the DBVs and
updated them and tested them. And put all the power supplies
in a pile and modified their cabling so a computer ATX
could be plugged in. Also tested all the reels and all the
coin comparitors. I'm still working on the hoppers (a lot
of dollar hoppers that i need to convert.)

So i have this big pile of tested parts, and all these
"shell" games. So i put all the parts needed in one of the
game, and test it with "Power 7s" firmware (this is good
test software as it's only 4 chips, easy to put in and take
out of a board for testing purposes. I can change it to
a more desirable game after i get it working. And add
dotmation if i so deem it necessary.)

But the game does not work. I get the standard williams
"bong" at boot up, but then a "zer-ring" error tone. No code on
the red LEDs on the front door either. Nothing. That kind of
sucks because there's no direction because there's no error
statement or error code.

I should mention that the red LEDs on the front door
are checked upon bootup. They have a serial connection
to the backplane. So the game knows if the red LEDs
are missing or bad. Since i had no display there,
i removed the LED board and tested it in another game
to make sure it worked. These are rarely bad, but figured
what the heck. It tested fine.

So what's left to be "bad"? Well not much! Just the
backplane board (or the wiring harness, which
upon inspection was fine).

So i removed the backplane and really the only component
on this board is a single resistor and a 24c04 serial EPROM
8 pin chip. So i cut the chip off, desoldered the legs, and
used a HIGH QUALITY commercial desoldering tool to clean
out the chip holes. (That is an important point, because this
board is a 4 layer board! That means it does not desolder
easily. New solder has to be added, and then desoldered
from both sides of the board using a GOOD desoldering tool.)

Installed a 8 pin socket, and a new 24c04 serial EPROM
chip. And bam, game now works!

So bottom line is these chips do fail. And when they do, there's
really no indication that the serial EPROM is the problem. I thought
i would post this for future readers.