Help needed with Creech .. FIXED

[Homepin]

Mike , what is U20 and how much are they ?

U20 is a ULN2803 Darlington Driver IC and it is situated directly above the plugs on the MPU for the switch looms.

It is also directly in the line of fire for battery corrosion as well as being easily damaged by a minor hickup on the playfield.

Jaycar don't list them I'm afraid but they are available at most electronic wholesalers and the usual pin parts sellers - should only be a few dollars including a socket.

[goodolddays]

Mike , what is U20 and how much are they ?

U20 is a ULN2803 Darlington Driver IC and it is situated directly above the plugs on the MPU for the switch looms.

It is also directly in the line of fire for battery corrosion as well as being easily damaged by a minor hickup on the playfield.

Jaycar don't list them I'm afraid but they are available at most electronic wholesalers and the usual pin parts sellers - should only be a few dollars including a socket.

Thanks Mike . Since you last posed i did a bit of googling and realised thats what it was , but thanks for the location on the board .

I see that Mark C has them for $2.95 a pop (might as well grab a couple) .

In the meantime , with nothing to lose I swapped 207 to 206, 209 to 208 and game didn't pass self test (reporting error on switch 34) .
Swapped back and same thing so next step is to check if Opto's are getting power I think .
I'm giving up for today though as its giving me a headache

I still have in mind about U20 but the thing is there doesn't seem to be a whole row or column out from what I can tell so far. From googling if this chip is dead/faulty thats the typical symptom.
 My guess is the fault ss still related to the game being moved .
The last 3 EM's I've sold have all had probs at their new home when fired up for the 1st time .

Cheers
Dave

[goodolddays]

Just had another look and someone has already fitted remote battery pack and U20 is in a socket (probs replaced before) so easy enough to swap out 

[Steevsee]

Congrats on your first DMD machine.

You can check to see if the switch problem is on the PF or CPU by using a jumper lead to trigger the switch columns and rows directly at the connectors.

Clay's WPC guide covers how to do this pretty well.  (PM me If you don't have access to a copy of this guide)

[goodolddays]

PM sent re Clays guide Steevsie .

I cleaned the optos on switch 34 and switch 37 but boot up self test still fails with switch 34 fault.
I then turned off, unplugged row and column from CPU , turned back on and still self test fails with same error , but when i go into single switch test , only the 'always closed' switch is reporting closed , all others show open as I'd expect .

To recap, with the row and column plugged into the CPU its reporting all 3 through switches and the ramp up/down switch as being closed in the single switch test .

My conclusions at the moment are :-
1) U20 seems to be OK
2) I have something wrong on the playfield side
I am confused as to why self test fails with a switch error when row and column are unplugged though .

Anyone care to comment ? Suggestions ?

[Steevsee]

I think the switch error report stays active until the cpu senses that switch activate.

Also I think as well as the always closed switch, the opto switches should show up as closed and then change to open when they are activated (I.E oppsite to the normal microswitch)

[Steevsee]

Also check fuse F116 on the power driver board which protects the +12v to the opto transmitters.

[goodolddays]

I think the switch error report stays active until the cpu senses that switch activate.

Also I think as well as the always closed switch, the opto switches should show up as closed and then change to open when they are activated (I.E oppsite to the normal microswitch)

Ok Steve .. It makes sense that opto switches should read normally closed (DOH hadn't thought of that) .
I started a game and put the ball in the playground hole to activate switch but when I turned off /on the switch 34 error still comes up in self test .
Also I have realised that both poppers (switch 34 and 37) activate several times when you 1st start a game .. I had heard something but kept thinking it was the ball shooter .
So , at least whatever is wrong is consistent and related to opto switches it seems . Thanks to a reply from JPD (Jeff) on AA , I know understand that the second popper (or VUK) looks after both the snack bar hole and Tailight Park . When I put the ball in the hole there I saw it roll down to the VUK at switch 37 and sit there till ball search kicked in .

Even though I do have a problem with my new pin at least I am learning a lot about how it works.

Next thing I will try is reseating all connectors related to optos .  

[swinks]

Hi Dave

sent a PM as luke gave me a call and thinks he knows the problem

[goodolddays]

Hi Dave

sent a PM as luke gave me a call and thinks he knows the problem

Thanks Jady . Earlier today I found that there is no power to the Optos .
I had decided to contact Luke to see if would help me out . I wonder why he rang you and not me ??

Anyway, just called and left him a VM.

Fault is not that simple though , because there is no continuity in the harness between the plug he is talking about (connects to J118 on power driver board) and the plug connected to J1 on the Opto board (according to the manual there should be as this is where the Opto board gets its +12V and earth (pin 2 and 3 on the connector plugged into  J118) . That same plug (J118) has the piggyback connection for the 12V to the topper.

Before I checked the harness I checked related fuses (F115 and F116)

[goodolddays]

Fixed     

Had a chat to Luke (previous owner) and he talked me through to find a connector was unplugged (was NOT obvious to me )
The red connector in J118 in this pic .

[Steevsee]

Nice to hear it's fixed.

[swinks]

awesome - game on now..... 

cheers to Luke also for helping.