Switch matrix prob

[MartyJ]

Cool, looking at it now, pretty straight-forward operation.

Which part of the diagram dont you get, when trying to trace the tracks?

IF you buzz the output pins of the LM339 (U16 pins 1,2,13,14) which goto the 74LS240 (U15a pins 8,6,4,2 respectively)
then you've proved that much.
Each of these 4 pins ALSO connect to a 10k resistor, and the other ends of those 4 resistors will (should) be all joined together which is the 5v pullup for them.

Confirm that LM339 pin 12 = GND (ground), and that pin 3 = 5v.
http://pdf1.alldatasheet.com/datasheet-pdf/view/3064/MOTOROLA/LM339.html

Inputs (-ve) to the LM339 are pins 4,6,8,10 and should be connected to 5v.
Inputs (+ve) to the LM339 are pins 7,5,11,9 and should wire to 1K resistors, the other ends of these 4 resistors should connect to diodes D14,13,12,11 respectively, to their 'Anode' ends.
At the join where the resistor connects to the Diode, there will ALSO be a 1.2K resistor connected too.
The other end of this 2nd lot of (1.2k) resistors connect to the 12v supply.

Buzz the diodes with a diode-check function on your meter too.

Assuming everything above checks out, you may have an external wiring error? a shorted/missing diode on your switch somewhere? or possibly lost a connection AFTER the output of your U20 chip.

There's a signal on the 'Direct Switches' connector named 'Enable', buit oi'd say that is ok if all the other direct switches are working?
Otherwise, replace Transistor Q1 (2N3904) and/or confirm U5f (74LS14) also works too.

I'll leave it here for now until you've eliminated all thse, then we'll dig deeper, as there's more chips that control U5f (enable signal).

Good Luck,
MM.

Firstly, Thanks MM for your help...I am more trying to get this working now not to beat me!

I was just having trouble working out what goes to where?  I've looked at ones where the tracks are drawn from each pin (numbered) to where it goes...I find this easier..

Outputs of LM339 U16 - :

pin 1 buzzs to 74LS240N U15 to pin 6 (you had 8?)
pin 2 buzzs to 74LS240N U15 to pin 8 (you had 6?)
pin 13 buzzs to 74LS240N U15 to pin 4
pin 14 buzzs to 74LS240N U15 to pin 2

Respective pins buzzs to R35 to 38

Inputs (-ve) to LM339 (U16) 4, 6, 8, 10 5v.

OK. I am guessing that these pins would share the power rail 5v in common.  If I buzz from U16 to U17 on pins 4, 8, 10 - it buzzs but NOT pin 6- which is where I was lacking voltage before..

Inputs (+ve) to LM339 (U16) 7, 5, 11, 9

pin 7 buzzs to R?? (this has broken pad)
pin 5 buzzs to R43
pin 11 buzzs to R45
pin 9 buzzs to R46

Diodes D14 to D21 test good.

Sooo...I need to jumper pin 7 to the right resistor and sort out power to pin 6.  Can the power for pin 6 be jumpered off pin 6 on U17?

pin 12 = ground (tested ok)   pin 3 = is this 5v or 12v.?



Pin 12 U16 - ground

[ajlaird]

Sooo...I need to jumper pin 7 to the right resistor and sort out power to pin 6.  Can the power for pin 6 be jumpered off pin 6 on U17?

Provided the pin 6 is meant to be permanently tied to +5V it can be jumpered from anywhere that has +5V permanently including pin 4 or 8 of the same device (assuming these too are permanently tied to +5v).

[MartyJ]

Sooo...I need to jumper pin 7 to the right resistor and sort out power to pin 6.  Can the power for pin 6 be jumpered off pin 6 on U17?

Provided the pin 6 is meant to be permanently tied to +5V it can be jumpered from anywhere that has +5V permanently including pin 4 or 8 of the same device (assuming these too are permanently tied to +5v).

I've jumpered it from pin 4 to 6, which ties the 5v to it.  Both U16 & U17 now buzz out identical and getting correct voltages to those pins.

Still no 12v on pin 3.

[MartyJ]

From that same RGP article (similar prob) their solution was to jumper 12v from pin 3 on U20 to pin 3 on U16 (which then carries to U17).

[Marty Machine]

Outputs of LM339 U16 - :

pin 1 buzzs to 74LS240N U15 to pin 6 (you had 8?)
pin 2 buzzs to 74LS240N U15 to pin 8 (you had 6?)
pin 13 buzzs to 74LS240N U15 to pin 4
pin 14 buzzs to 74LS240N U15 to pin 2

I re-checked the schematic, it's DEFINATELY what i said, but what you found might highlight an error in the manual (wouldn't be the 1st time) or a late board-design change.
Either way, looks like all 4 outs are going into the '240 as you found....it'll still work.

Inputs (-ve) to LM339 (U16) 4, 6, 8, 10 5v.
OK. I am guessing that these pins would share the power rail 5v in common.  If I buzz from U16 to U17 on pins 4, 8, 10 - it buzzs but NOT pin 6- which is where I was lacking voltage before..

Alrighty, you definately need to take pin6 to +5v.
Yes, you can wire onto pin6 of U17, although you could use a shorter link by joining onto pins 4,8 or 10 on U16.
 

Inputs (+ve) to LM339 (U16) 7, 5, 11, 9
pin 7 buzzs to R?? (this has broken pad)
pin 5 buzzs to R43
pin 11 buzzs to R45
pin 9 buzzs to R46

The schematic shows pin7 is on R43, but no doubt the manual/typo has upset things, i'm assuming it's really R44 ;-)
As long as pin7 joins to that Resistor, and the other end of that resistor is joined onto D13?/D14?(typo) it will be ok.

pin 12 = ground (tested ok)   pin 3 = is this 5v or 12v.?

Pin 3 is looks to be +12v according to schematic.
There's bit of a screwup in the drawing, showing +5v connected to pin12(GND) up top...

Anyway, as long as there are volts on pin 3 (5v or 12v) the chip will work.

Hope this helps.....gettin' there ;-)
MM.

[Marty Machine]

So there's NOTHING on pin3 ?????
If that's the case, YES, grab Volts from another pin and jumper it across as u said....

Before going further, just confirm which voltage is on pin 3 of the other 339's (is it 5v or 12v).
Just be sure you're about to put the right volts on U16 pin 3.

MM.

[Marty Machine]

From that same RGP article (similar prob) their solution was to jumper 12v from pin 3 on U20 to pin 3 on U16 (which then carries to U17).

U20 pin 3 is "Column DATA", don't use this!!!!

MM.

[Marty Machine]

U18 & U19 are also LM339's, measure there volts to confirm what you should put onto U16/17.

[MartyJ]

OK MM,

It looks like I'm not getting 12v to the board.  I tested pin 3 on U20.  Same readings as U16 & U17....

Pin 3 on U18 & U19 are reading 12.1v!

Sooooo

I will have to check that pin 3 on U20 should be getting 12v also...Maybe there is a break in the 12v before U20?

[MartyJ]

OK yes, Pin 3??   

Pin 10 is +12.

Tested again, so pin 10 (U20) good 12v same as U18 & U19.  They all buzz out together so must share the same rail.

Jumpered PIN10 U20 to pin 3 U16.

All good.

Just letting run for a while to ensure no phantoms and will test all playfield switches again.

I suspect the cleaning and movement in / out may have caused issues where the batt damage had been.  I am still going to put a Rottendog board in.  I think this will be a better option for the long term.

Thanks MM,   

PS.  Even after you explained everything I cannot read that schematic.  I will keep trying though..

[Marty Machine]

Pin 10 is +12.
Tested again, so pin 10 (U20) good 12v same as U18 & U19.  They all buzz out together so must share the same rail.
Jumpered PIN10 U20 to pin 3 U16.

Yep
Yep
and Yep.
(and NEVER use U20 pin3 hehehe).

PS.  Even after you explained everything I cannot read that schematic.  I will keep trying though..

No probs, i'll come over someday and give u scematic tutoring.

MM.

[MartyJ]

OK,

Tested in gameplay, no more phantom direct switches.

Direct switches all working, no aparent issues.

So as far as the cause?  NFI.  BUT big thanks to MM for his help decyphering the schematics.

I will slowly stock pile parts (Greg, expect more orders) and the rebuild will more than likely take place in a couple of months... (playfield+cabinet)

 

[Marty Machine]

Cool Stuff 

Glad it's all sorted.

No doubt the battery acid has done some damage that you can't even see no matter how much you clean & scrape, must have eaten a track somewhere, albeit a hairline acid etch....

Keep them coming, ready for the next schematic decode 
MM.