I suddenly have a new problem with the switched lamps on my WH20 (machine has been fine for many years and this started happening today).

If a switched lamp of row X is on, the associated light (the one in the same column) of row 1 is also on. I am assuming that this means that the Red-Brown line (row 1's wire) is shorted to high somewhere. I have examined the likely playfield lamps, but have not found anything suspicious.

Is there some convenient way to determine if it is a playfield issue or a board issue? Or some trick to try to narrow down the likely culprit?

I do have a couple of simple mods, but I tried disconnecting them and that didn't help (and none of them are connected to that line anyway).

Well, that seems to have fixed it. Thank you very much!

Strangely, it also seemed to have caused a factory reset to occur when I turned it back on. I wouldn't have thought that removing/re-installing the cable would cause this.

I will have to observe to see if the problem recurs, but for now it seems to be working correctly.

Thanks again.

Well, it seems like I actually have multiple problems now.

I saw the same switched lamp issue appear again (and then it went away again), so obviously something loose is touching something somewhere.
Also, I have all of the mid-playfield general illumination not working (maybe it's related, but maybe not).

Finally, I got another factory reset this morning, for no obvious reason. I do have one of those remote battery connections to keep the batteries off of the CPU board. It's possible that there is a flaky connection there, but I haven't looked into that yet.

Is there a fuse that would affect only the middle section of the general illumination? Any ideas about how to go about finding the issue(s) would be appreciated.

Well, I found the cause of the factory resets at least. I removed the remote battery adapter and saw that one of the battery clip pads is broken.

It had a small amount of acid damage a long time ago (which is what prompted me to get the adapter), I guess it finally gave out. So what's the best place to get a CPU board repaired nowadays?

I suspect that my lighting issues are a separate matter, which I guess I will leave until I have a fixed CPU board.

I had Chris Hibler fix my battery holder issue, and he installed NVRAM so that is all good. The problem with the general illumination was just a fuse, and it is working fine now as well.

However, I still have my problem with the switched lamps.

If a switched lamp of column X is on, then the light of row 1 in the same column is also on.

For example, the "shoot again" light (row 1,column 1) will be on if the kickback (row 2, column 1) is lit (and will flash in time with it). The "shoot again" light will also be on if any other light in column 1 is on (though for some of these, the shoot again will be much dimmer than normal - but still on).

I am assuming that this means that the Red-Brown line (row 1's wire) is shorted to high somewhere. I have examined the likely playfield lamps using that line, but have not found anything suspicious.

Is there some convenient way to determine if it is a playfield issue or a board issue? Or some trick to try to narrow down the likely culprit?

This problem seems to come and go a bit (though usually it is "on"), as if something is loose and making an intermittent connection. I have tried re-seating the J113 connector on the driver board (several times), but that never seems to have any effect. I strongly suspect it is a playfield issue, but don't know how to track it down any further.

Any insight would be appreciated.

So of course, now that I'm trying to track it down, it's stopped happening again...sigh.

I have no doubt that it will re-appear shortly.

Would a bad diode be intermittent like that? I thought that when they went "bad", they stayed "bad".

Still working to track this down...

If I put 5V across the Kickback lamp (with the machine off and the lamp connectors J133 and J137 disconnected from the power board), it will also light up the Shoot Again lamp. This pretty much indicates that there is a short somewhere in the playfield lamp wiring (and not a board problem).

I don't know if this is a clue or not, but Shoot Again will also light (at varying amounts of brightness) if I put 5V across any other lamp on its column EXCEPT for the left inland lamp.

Voltage on the left outlane lamp will light Shoot Again, but voltage on the left inlane lamp will not - even though they both are in the same column as the Shoot Again. I'm not sure how to interpret these results.

Any insight would be appreciated. Thanks.

Yes, it's a socket with diode. And it only lights in one direction.

I don't believe it is really a problem directly with the Shoot Again lamp (that's only the most obvious symptom).
As I explained in post #12 above, it's really a problem with lamp row 1.

Well, here is where it gets a bit interesting...

If I use my meter's continuity test, it never signals. However, if I measure the resistance I get some unexpected results that I don't really know how to interpret.

The resistance between red-brown and red-yellow, red-violet, red-grey are 1.0.
The resistance between red-brown and red-black, red-green, red-blue, red-orange are all about 0.3.

Interestingly this lack of resistance seems to only occur in one direction - if I invert the probes on my meter, the resistance shows as 1.0.
These lines without 1.0 resistance seem to correspond with the incorrect lights.

Does this indicate a bad diode somewhere? If so, is there some trick to tracking down which one?

Thanks for the help.

Well, I have a bit more useful info now...

I tested the diodes that I could access, and they seemed fine.
One of the diodes in question (on the red-brown line) is for the "Whirlpool 1 bulb". The whirlpool bulbs are on a small round PCB and surround the whirlpool "drain".

Getting to the diodes on that board will require a fair bit of disassembly and is kind of a pain, so before I tackled that, I pulled the connector to that PCB, and re-tested. With the connector off, the problem with extraneous lights went away. AHA!

Furthermore, if I test the pins on the PCB header, I can see that the pins 1 and 3 (for the red-brown and red-black lines) have non-zero resistance (about .615) between them - in one direction only. All other pin combinations on that header have no continuity between them.

So I presume that my next step will be to disassemble that whole thing and test the diodes on that board directly. I will try to get to that tomorrow evening.

I do know that at least one (maybe two) of the bulbs in the whirlpool had burnt out, and I just hadn't gotten around to replacing them (mainly because I was too lazy to take that whole thing apart). Could a simple dead bulb cause some sort of short there? Those are the only bulb(s) that are not working.

Thanks everyone for all the help...

I was finally able to locate (and fix) the problem.

Underneath the PCB holding the "ring" of whirlpool lights, there is a metal bracket/plate that supports the subway ramp.

That plate was apparently rubbing up against the PCB (probably for quite some time), and eventually it broke (and shorted) a trace on the board. The bulb that was out on the board was not a burned out bulb, but a broken trace.

I suspect that there was supposed to be a standoff on the screw that holds the ramp/bracket in place to prevent it from touching the board, but mine had no
such standoff - now it does.

So I patched the broken trace, and then covered the plate in electrical tape (in addition to adding the standoff) to be certain such a thing can not recur.

Everything is all well and good now. Thanks to everyone who provided info or made suggestions.