Continuity across Driver Board Lamp Matrix

[James]

So probably a silly question, shouldn’t I get continuity across matching lamp matrix plugs 133 and 137 for example... getting a reading but no continuity which is baffling me but I suspect something to do with the the TIP102’s that drive the connection?

 

[Jay Walker]

On the Wpc driver board, J 133, 134 and 135 connect the Rows, while 136, 137 and 138 connect the columns, so I wouldn't expect direct continuity between a row connector and a column one. Each 'set' of pins for a particular line should have continuity, but not between different lines

 

[James]

Thanks @Jay Walker - I’ve got two rows out (pin 1 and 2) but am getting continuity from the plug to the lights (both lock lights are easily accessible from topside of playfield to driver board) - seems strange though that I’d have two failed TIP102’s on a game. Also - backbox GI is out, but all other GI working.

Will have the board out shortly to have a better look but strange.

 

[James]

What a mess...






So the previous owner has obviously had a pop at this - as the two resistors I assume are associated with Q89 are missing and the replaced tip102’s weren’t getting continuity across the centre pin to the pins on the board ... so I’ve added the jumpers to resolve that - not my finest work but does work - I’ll need to order those resistors in to sort that.

I was still not getting any joy though on those two rows (from pin one and two) - I will need to logic test the next chip up right?

 

[James]

Hi all - just answering the question in case anyone else is looking for this - resistors will be added they are missing above which actually feeds both Q89 and Q90 - which may be causing the issue...

I’ll also shotgun the entire thing and socket the 74LS74 and LM339

Resistors required are 1K and 2.2K