bally supersonic/no controlled lamps

[studley67]

hi all, i have replaced all sockets and pia's and i still do not have any controlled lamps.looking at the schematic i am now thinking the culprit may be u20 MC14502B .can anyone confirm this?if so is there an equivalent for this ic.

[mildflame]

look up:
CD4502BE, I think that might be one

[Retropin]

http://www.jaycar.com.au/productView.asp?ID=ZC4502&keywords=4502&form=KEYWORD

[studley67]

thanks 

[studley67]

but will it fix my problem controlled lamps?

[Retropin]

...Possibly.

Cant remember whats on a Bally lamp cct ( this is where Clay came in REALLY handy!), but im guessing that the PIA is decoded by the 4052 multiplexer, this signal i would have thought would go through some kind of buffer chip.. say a 7407 or similar. Normally though there are more than 1 7XXX buffer. If this is the case... and all lamps are off then id look at the PIA and 4052.... if only 1 7xxx buffer then test this first.
Or just gun shot it.. replace both series chips and never be the wiser as to which it was

[studley67]

i have a 4052 chip ,so i will try this first.not sure how to go about testing it.i have replaced the pia and socket.thanks gavin

[Mr Pinbologist]

I'm slighty confused here, you mentioned earlier it was a MC14502 you suspect is the problem... is it a 4502 or a 4052 chip you're replacing?? coz they are NOT the same 

a 4052 is a dual 4 input multiplexer, and a 4502 is a HEX inverter!! definitely not interchangeable!!

[studley67]

sorry typo,i have the hex inverter

[Retropin]

That was me causing the confusion getting carried away without checking first.... so long as you know what im on about studley you should be OK, cos buggered if i do

[studley67]

getting late,i will have a fresh look at it in the morning.i would have thought someone would have come accross this fault before.

[Mr Pinbologist]

sorry typo,i have the hex inverter

Oh ok.. that thought crossed my mind that it may have been a typo after i posted 

[studley67]

replaced 4502,still no lamps.now thinking an address line is broken.i do not know the history of this machine,but the lamps have never worked.so much for "fully working" !*!ozpinball

[Marty Machine]

This fault might not be on the MPU board itself, it could be on the Lamp Driver board instead.

MM.

[studley67]

i have tried another woking ld board.but it could be in the wiring.but  it dosnt look hacked