wh20 switch matrix help needed

[studley67]

while reasembling the uper playfield,with the power on,my son trapped switch 57 under said playfied.rather than remove playfield me brightspark said `i can free it`and inadvertingly shorted this switch.i have since got a manual,and it looks like the whole column of switches are out.how do i test the chips for this column?i have a logic probe,multi meter and oscillascope but not sure how to test or even if i need too.please help.damien

[pinmadd]

oh crap,hard lesson to learn, always have machine off when working on them, 

[MartyJ]

Hi Damien.

Not sure if you've seen the Pinrepair guides.  They are my first place of reading generally when I strike a problem.

Switch matrix's can be a little overwhelming at first but simple once you get your head around it.

I suggest having a couple of reads of this and see if that helps

http://www.pinrepair.com/wpc/index2.htm#switch

[MartyJ]

It looks like Mark has the ULN2803's if you need them
http://www.pinballspareparts.com.au/index.php?search%5Bterms%5D=ULN2803&search%5Bmode%5D=any

I think RTBB must be sold out for time being.

The LM339's are available from Jaycar if you need some too
http://www.jaycar.com.au/productView.asp?ID=ZL3339&keywords=LM339&form=KEYWORD

PCB repairs are not difficult, but if you havn't done one before (ie desoldering IC's) you need to take care as to not damage the board which can end up being $$...

If you're going to have a go yourself too - I would strongly urge to ALWAYS socket rather than solder the IC directly onto the board too.  Lately I've been leaning towards the strip sockets more but a standard socket will suffice.

[studley67]

thanx guys.after reading marvins it is pointing to the u20 chip.have just ordered one from mark.i am proficient in ic removal however this chip is socketed.too easy.thanks again damien

[MartyJ]

thanx guys.after reading marvins it is pointing to the u20 chip.have just ordered one from mark.i am proficient in ic removal however this chip is socketed.too easy.thanks again damien

Happy days.  If its already socketed makes it even easier!

[studley67]

i have even just purchased an anti-static wrist strap.so i get to try it out.i wanted to get the oscilloscope fired up,maybee i need to ask for lessons on pinball 101.lol.