Popeye Saves the Earth
Bally, 1994working on a popeye and was working great until today
comes up with a ground short row 2 white-red r2 error
i have replaced the u18 chip (lm339) with a socket and no change
i have disconnected all the switch wires going to the cpu and still get the same error
no battery acid on the board either
any help would be great
With switch row connectors removed, using a logic probe or voltmeter measure the outputs of the LM339, U18 pins 1,2, 13 and 14. They should all be solid and match. A mismatch will indicate either the replacement LM339 is bad or the problem is with the circuitry between the connector and inputs to the LM339.
If all LM339 outputs are matching and the error remains, then the problem is likely U13, 74LS240.
heres is what i have done
the switch row connectors disconnected and checked the lm339 at u18 and checked pins 1 and 2 also 13 and 14
using a meter i get a buzz from 13 and 14 pins. i have changed the lm339 with a new one and same result
what else can i check??
Can we see a picture of the bottom half of the MPU? I would like to see if there is any battery alkaline damage.
Quoted from gameover1173:There is not a spot of acid on this board but I can take a pic of it
I hear that too often. Alkaline damage is not easy to spot sometimes. "Acid" is not the correct term, by the way.
Also, do you have any other WPC games you can swap the MPU with to verify that is the board at fault?
Very nice. No board damage. I'm happy to see that. Consider upgrading to either Lithium batteries or to NVRAM so no batteries are no longer required.
Have a look at this topic:
https://pinside.com/pinball/forum/topic/wpc-switch-matrix-issue-tz#post-3286100
It is a test for 'row3' but it's easy to translate this to 'row2' and find where signal goes wrong.
Row 2 -Start at J208/209-2 , D4-cathode , D4-anode , R53 (top) , U18-9 (input) , U18-14 (output) and finally U13-13 (input).
I have checked u13 like pinballmaniac40 had posted and everything checks out
The only odd thing I did see is when testing rows with a meter putting one lead on row 2 on the switch row connector (208/209) and the other lead on any of the caps above the connectors on the bottom lead of the cap they all read shorted. This is with the board out on bench
Also u19 is clean and good
Seems to me pin 2 is shorted to ground
I need to try and get a better picture of the schematic. Though, I bet zaza beats me to it, with his awesome illustrations.
Can you try and test the way zaza suggests?
Quoted from PinballManiac40:I need to try and get a better picture of the schematic.
Some pictures can be found in the PinWiki.
Quoted from gameover1173:I swapped u19 and u20 with no change
Both have nothing to do with row2.
It is possible a piece of solder connecting 2 traces in the area of J208/209/212.
Another possibility is a short in multiple components but less likely.
You can lift a leg from D4 and measure again. Check for a short in C4 as well.
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Almere