Re: TECH: WPC Driver Board Question...

On May 12, 10:25 pm, "Bob D." <bobdyk...@xxxxxxxxx> wrote:
Hey,

A silently stuck jet pop bumper fried a bunch of stuff (like 8 102s
and 1 36C) after my F105 blew today and so now I'm hoping that I can
test and replace the bad transistors on the board. So it's been a
rough day for me in pinball land.

Anyone else deal with this situation before? I started running
through testing individual 102s and 36s and lost quite a few 102s and
it seems I only lost the 36 associated with the Jet bumper. I also
used Marvin's quick test for 102s and found that several of them are
indeed "bad" as well.

Good news is all my LEDs on the board are on and all switches still
work as well as lamps. So I'm thinking if I simply replace the 102s
(this is in the solenoid section (low & high)) I will be okay?

I've ordered new 102s from competitive products and are awaiting their
arrival.

So overall, since I'm guessing the stuck on coil was caused by a bad
102/36, which in turn burnt a bunch more due to the constant completed
circuit being on, do you think I'll be good once I know all my
transistors are good? Should I pursue just buying a 100% used board
or maybe a new board?

Thoughts... experiences? I really need some encouragement on this.

Thanks!

I can't see so many TIP102's being burnt out from one popbumper being
stuck on. You are saying a constant completed circuit burned them all
up. But that isn't how it works, all they do is complete the ground in
the circuit to drive one solenoid. If one is locked on, then one or
more transistors in that one circuit fry, but that is only a TIP36C,
and TIP102, and a 2N4401, and after that you have IC problems, either
a 74XX or 74LSxxx and after that, a 6809 or 6821 in a worst case
scenario. But not multiple TIP102's, that is multiple "circuits"
frying. Are you sure you are testing them properly? Did any of them
cook badly enough to cause burn marks or burn the solder pads off? But
no matter, it's not nearly as bad as you think, certainly not bad
enough to consider buying a new board. Unless you have absolutely no
soldering skills at all, and even then you can get it fixed. But I
hope you ordered the predriver transistors as well, what are they,
4401's or 5401's? And it's very likely that you will need to replace a
74LS374 as well, so you had better get that and a socket. I recommend
you order this stuff from GPE, because Ed is usually the cheapest and
quickest, but get it from whoever you want. Also, there's no such
thing as a silent popbumper - when you turn the game on and it locks
on, unless you are completely unaware of what going on with your game
you should notice it. And if it's a WPC game it will give you an error
report. So there's no excuse there if you ignored that. But you need
to isolate the issue, replace any bad transistors, and if that doesn't
solve it work your way backward through the chain to the IC's that
drive them and replace them as well.
J.

.

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