Hi,

Well I am am getting a little better at this problem solving thing; however I am stuck. I have determined that switches 41 through 46 are not registering. They are all gapped correctly. Given it is an entire row in the switch matrix I believe they are all interconnected. This is where I am stuck.

Please keep in mind I am an Economics major and a sales rep so I am having to learn the electronics from scratch. I do have a multimeter etc. Any advice is helpful.

Drew

Quoted from Jester

Hi,

Well I am am getting a little better at this problem solving thing; however I am stuck. I have determined that switches 41 through 46 are not registering. They are all gapped correctly. Given it is an entire row in the switch matrix I believe they are all interconnected. This is where I am stuck.

Please keep in mind I am an Economics major and a sales rep so I am having to learn the electronics from scratch. I do have a multimeter etc. Any advice is helpful.

Drew

If no single switch works in that row, confirm that you have continuity from the first switch in the daisy chain to the connector (ruling out broken wire).  If it's not a wire issue, use your DMM (diode test) and test the transistor for that row.  Consult your manual to find the driving transistor for row 4.  If you have no idea what I'm talking about, find a local pinhead to give you a hand.  Better that than to do potential damage to your board.  

Quoted from Jester

Any advice is helpful.

RUN! RUN LIKE THE WIND AND DON"T LOOK BACK!

jk. I would think that you need to trace the GRN-BLU wire that runs from the switches back to the 2J2-3 and check for a break. Something wrong closer to the driver board if they're all gone. Maybe need to repin?  

THx for the advice,

I believe that I have found a crushed wire. I ill fix and see what happens.

There is no transistors for for the switch matrix on WMS SYS3-7, there is just a buffer chip. Check for continuity from the switches back to the connector at the driver board. If you have continuity, pull the driver board and check for cold solder joints on the header of the board. SYS3-7 Driver boards are *HORRIBLE* for cold solder joints, especially on the headers. If everything is good back to there, you're probably going to have to change the 7406 that drives that column (I believe it's IC18 ).

Well I am still working on it but have to leave for a holiday. Wanted to get it working before I left but no luck. Thx for the info. I have determined I have continuity to the board so now I am looking into that.

Quoted from Grauwulf

(I believe it's IC18 ).

The schematics say IC17. Change them both!

I stand corrected, I was just going from memory.  I don't advocate changing components just to change them though, especially chips, it's way too easy to lift a trace if you're not careful.

The problem is definately at the board.

I followed pin repair:
Now disconnect the driver board connectors at 2J2 (columns) and 2J3 (rows) at the upper right. These are the connectors for the playfield switches. Both connectors are at the upper right of the driver board. Use an aligator test wire and run it from 2J2 pin 1 (col1) and touch the other end of the wire to 2J3 pin 1 (row1). Should see one switch number come on the score display. Then tough the next pin on 2J3. After eight pins on 2J3 are tested (all should report one switch closure on the score display), move the jumper to the next pin on 2J2 (col2) and repeat. Do this for all pin combination (it only takes a couple minutes). If a single pin jump gives more than one switch closure or no switch closure, there is a driver board board.

The Col. 6 Grn-Blu 2J2-3 shows no activity when testing. All other switches operate correctly.

Since the playfield wires are diconeected it must be at the board. (Please correct me if I am wrong.)
I tested continuity between the 2J2-3 pin connector and the first resistor. There is continuity so a cold solder joint here is out.
I have tested each chip below and all check out??? WTF I am out of things to de and everything testing fine??????
The row chips (4049 at IC15/IC16) and column chips (7406 at IC17/IC1 can be easily checked with the power off using a DMM set to diode test.

With the power off, remove the two switch connectors J2 and J3 from the driver board (two upper right connectors.) Put the red DMM lead on ground, probe each of the switch matrix chip legs with black DMM lead. The chip legs should show .4 to .6 volts on the meter (except for 4049 pins 7,14 and 7406 pins 1,7,12,14). Usually when one of these chips goes bad, the meter will show a near short like .2 or less, or some value higher than .8 volts. It's generally pretty obvious, and it happens a lot on these driver boards. Particularly problematic are the two 7406 colum driver chips at IC17/IC18.

Beyond the row and column chips is the switch matrix PIA at IC11 (6821).

Any more ideas?

I have determined that Pin 6 is not pulsing. pinrepair.com says it is 7406 or PIA. I think both check out when I use my DMM. Should I replace the 7406 anyway and see what happens?

This can be diagnosed further using a logic probe. Remove connector 2J2 (switch columns). With the game on and in switch matrix test mode or even just attract mode, put the logic probe on each pin of connector 2J2. The logic probe should be pulsing for each pin. This is the driver board scanning the switch matrix columns. If a pin is high or low and not pulsing, then the associated 7406 chip or PIA is probably the problem.

You can try re-soldering the pins for the 7406, it could be a cold solder joint, otherwise just cut the 7406 off, install a socket and put a new chip in.

New Issue!

So thanx for all the help on the switch issue. I have installed a new socket and chip and the problem is resolved. I now have found out that the bell no longer rings when hitting a million or getting an extra ball.

Any ideas?

Thx

Drew