(Topic ID: 36098)

Lamp Matrix Problems

By jrawlinson_2000

11 years ago

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6 posts
4 Pinsiders participating
Latest reply 11 years ago by jrawlinson_2000
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Linked Games

Judge Dredd Bally, 1993

Hi All,

I have just purchased a Judge Dredd from eBay (UK).

Sadly it has an issue with more than 1 light coming on, as such I have undertake a load of research but so far have not been able to find the cause.

At the end of this post I will include the lamps that are affected, but first what I have tried;

In single lamp test;
Take for example lamp 64 it also lights 68 & 84.
Lamp 65 also lights 68 & 85
In both these cases if I take out 1 of the offending lamps the other offending one goes out.

Still in single lap test;
87 (Buy-in) is dead
88 (Start) is dead
38 (Super game) is dead
However they all come on when the game is flashing all the other lamps in attract mode.
I have found they are coming on with;
77 lights 87
78 lights 88 & 38

Next I took out my corc clips and wires, hooked up a lamp and in the back box disconnected the row and column power driver connectors, put the machine into single lamp test mode.
When testing say 64 which also lights 68 & 84, column 6 row 4 lit my test lamp, but nothing else did, i.e. moved to pin 8, then c8 r4, I also buzzed the other rows, nothing.
I ran this test for a fair few 'known' issues in all cases the lamp only lit up as it should.
Except oddly 88 (start) did not light up at all, I put the machine into all lamp test and still no joy, seeing as the other tests were ok I shall forget this for now.

I have visually checked the lamp PCBs and the individual sockets they all appear OK, diodes in place (except the start button), and no bent connectors.
Cables all look OK no pinches.

I should say the machine was a bit dirty, I have cleaned it up, on a fair bit of metal there was a whitish 'fur', maybe its from being near the sea?!?
The boards all look fine, in fact whilst the underside of the playfield was quite dirty the boards were remarkably clean, no burn, no acid.

Another couple of points;

I am now stuck, and looking for ideas on what to do next

What struck me as I typed the lamps below is the offending ones are always at the end of the row and/or column (sometimes both)!

Lamp issues (first is the lamp that should light, then any others this also light up;
14, 84
15, 85
16, 86
21, 28
22, 28
23, 28
24, 28 & 84
25, 85
26, 86
38 IS DEAD IN SINGLE LAMP TEST
42, 48
43, 48
44, 48 + 84
45, 85
46, 86
51, 58
52, 58
53, 58
54, 58 + 84
55, 58 + 85
56, 86
61, 68
62, 68
63, 68
64, 68 + 84
65, 68 + 85
66, 86
71, 81
72, 82
73, 83
74, 84
75, 85
76, 86
77, 87
78, 38 + 88

87 IS DEAD IN SINGLE LAMP TEST
88 IS DEAD IN SINGLE LAMP TEST

Thanks in advance for any help.

Kind regards

Julian

Column 8 and Row 8 are common to all these

I would start by checking diodes. One or more shorted diodes can cause most of these issues. If a diode isn't shorted to the socket then one may simply be bad. You may have to disconnect lamp wires to get to the bottom of this.

Unfortunately, I didn't understand your board test. If I follow it, you tested all 88 lights at the board but only one lit?

Markmon... I think it is the other way around.... Coming directly off of the board, everything worked correctly EXCEPT for 88 which is completely dead. (I think this is how I understand it....)

So 8/6 worked and 6/8 worked, but 8/8 did not? That is kind of weird... row 8 works with different columns and column 8 works with different rows, but they don't work together. (That would make me think board/chip error - again, provided those are the readings that you are getting right at the pins, not down the line somewhere.)

Personally, at this point (if I understand correctly) I would stop fooling around with anything under the playfield until you got your pins reading correctly. You could spend forever chasing down weird things.

Once the pins read correctly if you still have exactly the same problem I would spend a lot of time looking at that 88 lamp. It is the point where your problems converge. I would look closely at the diode, whether it was installed the correct direction, whether the wires are connected to the correct side and check to see if it is actually working.

Again though, get those pins reading correctly before anything else.

Quoted from lordnorth:
Markmon... I think it is the other way around.... Coming directly off of the board, everything worked correctly EXCEPT for 88 which is completely dead. (I think this is how I understand it....)
So 8/6 worked and 6/8 worked, but 8/8 did not? That is kind of weird... row 8 works with different columns and column 8 works with different rows, but they don't work together. (That would make me think board/chip error - again, provided those are the readings that you are getting right at the pins, not down the line somewhere.)
Personally, at this point (if I understand correctly) I would stop fooling around with anything under the playfield until you got your pins reading correctly. You could spend forever chasing down weird things.
Once the pins read correctly if you still have exactly the same problem I would spend a lot of time looking at that 88 lamp. It is the point where your problems converge. I would look closely at the diode, whether it was installed the correct direction, whether the wires are connected to the correct side and check to see if it is actually working.
Again though, get those pins reading correctly before anything else.

If this is what he meant then I agree. Start at the board. I'd like clarification though so we can properly advise.

We think its a driver board issue, as such changing this out over the weekend and will update all after that.

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