No score display Williams Flash

[robm]

Hi,

Just picked this machine up yesterday, $40 from a garage sale - the lights worked but nothing else, got it home and looked at a few very helpful web pages, where one suggested pulling the CPU and driver boards apart and gently clean the connections.  Put them back together and it worked!!!  I had never seen inside a machine until yesterday and am looking forward to fixing a few lights and switches that aren't working.  But first i would like to get the score being displayed.

I did the diagnostic test on the coin door, and all digits on all displays work fine.

I carried out the CPU diagnostic and the two LEDs both flashed - in the manual it says this is either a CMOS RAM or PIA I Display Output failure. 

I looked at the diagram and pulled both these out of their holder, cleaned pins and put back in - no change.  I have made an assumption that replacing these might be the best way to go (the display output one seems to make sense?) - wondering if there are any suggestions/advice/other testing or places to get parts from.

I am comfortable enough doing basic multimeter testing and soldering but don't know all the electrical or pinball terminology/jargin yet.

Thanks in advance

Rob

[MartyJ]

$40 from a garage sale!  What a bargain.....

Not sure if you have seen these guides, but they are the 1st reference for any pin repair...

http://www.pinrepair.com/sys37/index.htm

For your display issue:

http://www.pinrepair.com/sys37/index3.htm#display

Re parts, depends on what you need.  There are a number of great online shops locally (in Aust) which carry most parts (pinballspareparts.com.au, RTBB.com.au just to name a few!)...

Good luck!

[Retropin]

So displays work in diagnostics but not with switch closures from the playfield?

[robm]

Yep, all the display digits work in diagnostics, but stay on 000000 throughout a game...

[robm]

Oops, just double checked - Player 1 display stays just 0 (ie first 5 blank) and the other 3 are 000000.

The credit and ball no display (4 digits) works fine.

[Retropin]

Ok we can ignore the missing digits for now, but we need to get scores running a display first - missing digits will be a different problem.

When you close a switch - do you have any sounds at all? Is anything registering on a switch closure?

[robm]

As mentioned i'm 1 day new to this stuff.. i assume you mean a switch closure by when the ball hits a target or runs over a button etc... if so, yes is the answer - a couple don't register but 90% make a noise every time they are hit.  There also seems to be a score type of system (series of recessed lights - see pic) just above the flippers, this increases as you play the game.

[MartyJ]

For the cost of a Flash manual, you've got a clean looking (free) machine there!  With the experts on this site you'll get it going in no time!

[Retropin]

Ok what happens is when a switch is closed, it comes into the driver board through connector 2J3. Signal goes through 1 of 2 buffer chips ( ic 15 &16), then into the PIA chip at IC11, up through the 40 pin interconnect and into MPU.

In diagnostics, the driver board is ignored as its the MPU itself that strobes all the digits.

Check IC 15 & 16. These are designed to protect the PIA. They are inverters, so if a high signal is coming in ( 4-5V) then a low is outputed.
Or if low in then high out etc,

any other readings and these chips are gone.

If one of these chips is bad then we have to test PIA also at IC11 - youll need to test this anyway, but always best to start with the simpler stuff first

[robm]

I'm following most of that, but am unsure of how to test the ic15 and 16 chips.

I put my multimeter on one side of the green resistor?? thing at the bottom of each chip (underlined in red) and got 4.93V on one side and 0.2 on the other of both.

Is this right or do i need to test the chip itself? and can i do that with just a multimeter?

Thanks very much for the help so far

[robm]

Since the last post i have read the guide at http://www.pinrepair.com/begin/index.htm#howdmm on how to test chips.

From what i understand put the red lead of mm on the GND pin of the chip and all the rest (except PWR) should read between 0.4 and 0.6V if i read the guide correctly...

After doing this, on both the IC15 and 16 i got a range of readings - most around 3V, some 4.8 and some 0.

Did i do this right and/or is the chip faulty?

Thanks

[Retropin]

Ok - the green thing is a capacitor, its there to smooth off any signals, youll get 0.2v or so on one side as this side goes to ground.

You need to test the chip itself and yes - can be done with a DMM. A logic probe makes this kind of testing much easier - well worth investing in.

On DC volts - lowest setting. Put the black lead on pin 8 - ground and then go round the chip with the red lead, pin by pin.
IC15;
Input pin 3 should be high, output pin 2 -low
7 high, 6 low
14 high, 15 low
9 high, 10 low

IC16;

3 high, 2 low
7 high, 6 low
14 high, 15 low
9 high, 10 low.

These are the switch inputs - make sure these work OK.

The switch outputs are IC17 & 18 - these are 7406, slightly different configuration, pin 7 is ground.
IC17
Pin 1 high, 2 low
5H, 6L
13H, 12L
9H, 8L

IC18

 same as IC17.

Let me know whjat you find, from this we can see if buffer chips are ok and if PIA is working OK

[Creech]

I cannot believe you picked that up for $40. I mean, I do believe you but I can't fathom how you got it that cheap. Were they totally clueless to what it's worth?

[robm]

Creech,

I've always been keen for one, as i thought they would be a good project - but never knew too much about them - i saw this advertised at a garage sale and went straight over.  We had to come back 1.5hrs later with the trailer and the lady said about 15 or 20 people ad wanted it since.  She and her husband were far from handy at fixing things and said they never used it...so good luck to me!!

[robm]

Retropin,

This has been great - thanks a million.

Testing IC15 (8 as GND)

3  3.64
2  1.63
7  3.59
6  3.56
14 1.55
15 4.2
9  4.26
10 4.23

IC 16  (using 1 as GND - 24 pin chip)

3  3.21
2  2.68
7  3.16
6  2.85
14 3.57
15 1.41
9 2.57
10 2.32

Some of these are as you suggested - others are not

IC17 - you mentioned pin 7 as GND, but using circuit diagram it says pin 12 is GND (again 24 pin chip)

Using pin 7 as GND

1  0.24
2  0.2
5  0.6
6  0.16
13 0.66
12 2.26
9  0.47
8  0.14

IC18 (Big PIA Display Output Chip - circuit diagram says 1 is GND?)

using 7 as GND

1  -0.03
2  2.57
5  2.37
6 0.00
13 0.33
12 0.34
9  0.00
8  0.00

I await your instruction.....