(Topic ID: 209289)

Metallica hammer magnet troubleshooting question (multimeter?)

By Fezmid

6 years ago


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  • Latest reply 1 year ago by cooked71
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#1 6 years ago

Looking for a little help troubleshooting this issue - more guidance on how to see if my theory is correct since I'm new to this hobby (how long am I allowed to say that for? ). This will be a little long, mostly to ensure I'm not missing any troubleshooting steps.

Anyway, a few weeks ago while playing my MET Premium, the hammer magnet engaged when it wasn't supposed to and held the ball for a long time without letting go. Before I had a chance to figure out what to do, the ball released and I thought all was well. After playing a few more games though, I realized that none of the magnets were working... Doing some troubleshooting, I found that the F7 fuse blew. I replaced it, tested the magnets, and all seemed well. Success! (except for not understanding the root cause of the issue - which I initially attributed to a software glitch of some sort).

I was playing again yesterday and realized that after I hit the coffin 5 times, the magnet wasn't energizing (couldn't hear the buzzing). To confirm this, I took the glass off and tested it -- nothing. The other two magnets (Sparky and coffin) both worked fine.

So I lifted the playfield, unplugged and reconnected the leads to the magnet board, tested again, and it seemed to work. I guess that worked to fix the strobing GI lights, so maybe that's what fixed this?

But after a couple more games, the hammer magnet stopped working yet again.

So I did some research and found this site: https://pinballsupernova.wordpress.com/2016/10/07/pinball-repair-fixing-metallica-lepremium-coffin-magnet/

Sounds like a broken wire could be my issue, BUT, I don't see any obvious issues with the wires (not that I'm an expert in spotting this....). So how would I test this to see where the issue is? I received a multimeter for Christmas, but have never used one before - I suspect that is what I'll be using, but some step by step instructions would be awesome. Or maybe this isn't the issue and it's something else I didn't know to look for?

Thanks for the help! The old saying I read last year before buying my first pin holds true: "If your pins aren't broken, you aren't playing them."

#2 6 years ago

since all you're looking for is a broken wire, put your multi-meter in continuity test mode (that's the mode that should give you an audible "beep" when you touch the two leads together

using the leads on the meter, test the ends points of the same length of wire. if the meter beeps, then you know that the wire is fine and you can move onto the next. if it doesn't beep, then you've identified where you have a break (and most likely just a bad connection where it's been terminated)

I can't remember if each magnet has its own magnet opto board, but that might be a place to start if the wires check out ok. if the board part no's are the same, you can temporarily swap to see if the problem moves with the board and if so, you've now identified that you have a bad board that will either need to be repaired or replaced

http://www.marcospecialties.com/pinball-parts/520-6801-00
marco's is currently out of stock, but I believe this is the board in question

#3 6 years ago

Thanks! I don't remember seeing more than one board, but I'll doubelcheck that as well, especially if I can't find a bad wire.

I'll try out the multimeter tonight (time permitting) and see what happens. Sounds easy, so fingers crossed!

#4 6 years ago
Quoted from Fezmid:

So how would I test this to see where the issue is

This magnet should measure 4.3 ohms with your meter on the ohms scale (see image below)

WARNING!!!! Do not disconnect this magnet!!! If you disconnect this magnet and your hammer magnet locks on you will dissipate over 10 watts of power through the 5 watt load resistor on you magnet board ... IMO this is a MAJOR design flaw as 10 watts of power is not high enough to blow your fuse but is more than enough power to start a fire (see images) Fortunately I was at home when the smoke started coming out, and promptly shut off the machine.

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#5 6 years ago
Quoted from j_m_:

since all you're looking for is a broken wire, put your multi-meter in continuity test mode (that's the mode that should give you an audible "beep" when you touch the two leads together
using the leads on the meter, test the ends points of the same length of wire. if the meter beeps, then you know that the wire is fine and you can move onto the next. if it doesn't beep, then you've identified where you have a break (and most likely just a bad connection where it's been terminated)
I can't remember if each magnet has its own magnet opto board, but that might be a place to start if the wires check out ok. if the board part no's are the same, you can temporarily swap to see if the problem moves with the board and if so, you've now identified that you have a bad board that will either need to be repaired or replaced
http://www.marcospecialties.com/pinball-parts/520-6801-00
marco's is currently out of stock, but I believe this is the board in question

I think MET only has a single magnet board - at least that's all I could find under the playfield.

This is hard for me to test since the magnet has been working again... I unplugged some of the molex connectors and used the continuity test mode and was getting consistent beeps, but but not sure how to test all of them - two black wires go right into the magnet assembly, for example, and I'm a little nervous to take it apart...

However I do think that the magnets aren't as strong as they used to be. While it's hard to tell with the hammer magnet, I have now seen on 2 or 3 occasions where the Sparky magnet doesn't catch the ball when activating multiball mode. Could be a coincidence I suppose, but I'm skeptical.

Quoted from Pin_Guy:

This magnet should measure 4.3 ohms with your meter on the ohms scale (see image below)
WARNING!!!! Do not disconnect this magnet!!! If you disconnect this magnet and your hammer magnet locks on you will dissipate over 10 watts of power through the 5 watt load resistor on you magnet board ... IMO this is a MAJOR design flaw as 10 watts of power is not high enough to blow your fuse but is more than enough power to start a fire (see images) Fortunately I was at home when the smoke started coming out, and promptly shut off the machine.

Ok, I guess I'm moving past continuity and learning about a new mode on the multimeter. How do I test this? Where do I touch? And do I leave the pin on? I'm not sure how to test this at all but want to learn. And I don't want to burn my machine down.

#6 6 years ago

the graveyard and sparky magnets should catch the ball [tight], almost like it's glued in place

I never understood why it wobbles like it does when it's on the hammer magnet, unless that outer ring interferes with the magnet somehow (in which case, stern should have probably used something like a phenolic material)

I would also check to see how much damage your magnet cores have (they might be candidates for replacements)

#7 6 years ago
Quoted from Fezmid:

This is hard for me to test since the magnet has been working again... I unplugged some of the molex connectors and used the continuity test mode and was getting consistent beeps, but but not sure how to test all of them - two black wires go right into the magnet assembly, for example, and I'm a little nervous to take it apart...

You are checking in the right spot...and there is no reason to take it apart as you can determine if it's good or not right at the connector.

A continuity test is great for checking point-to-point connections; that being said, I have no real world example of when I would ever use it. I know many people use it and rely on it for a troubleshooting aid and that's fine, I'm not trying to belittle anyone for using it as it's a fast easy way to check the continuity of many points; however, for testing a magnet, your entire magnet coil could melt into a solid block of copper and it would give you the exact same beep as a brand new coil ... how useful is that?

Quoted from Fezmid:

However I do think that the magnets aren't as strong as they used to be. While it's hard to tell with the hammer magnet, I have now seen on 2 or 3 occasions where the Sparky magnet doesn't catch the ball when activating multiball mode. Could be a coincidence I suppose, but I'm skeptical.

Being skeptical is a great attitude for a technician to have as you are questioning coincidences and trying to find a commonality between two events; Unfortunately, the only commonality here is that they both run off +50V as the magnet board is a premium/LE feature and is there for the coffin magnet exclusively. Both the graveyard and Sparky magnets are powered on by the PDB so I would have to assume this is an actual coincidence.

#8 6 years ago
Quoted from Pin_Guy:

You are checking in the right spot...and there is no reason to take it apart as you can determine if it's good or not right at the connector.
A continuity test is great for checking point-to-point connections; that being said, I have no real world example of when I would ever use it. I know many people use it and rely on it for a troubleshooting aid and that's fine, I'm not trying to belittle anyone for using it as it's a fast easy way to check the continuity of many points; however, for testing a magnet, your entire magnet coil could melt into a solid block of copper and it would give you the exact same beep as a brand new coil ... how useful is that?

Being skeptical is a great attitude for a technician to have as you are questioning coincidences and trying to find a commonality between two events; Unfortunately, the only commonality here is that they both run off +50V as the magnet board is a premium/LE feature and is there for the coffin magnet exclusively. Both the graveyard and Sparky magnets are powered on by the PDB so I would have to assume this is an actual coincidence.

Well there's a little more connectivity there since all the magnets are tied to F7... Maybe it's possible that when the hammer magnet malfunctioned and held the ball until the fuse blew that it somehow damaged the other cores? I'm not sure.

Good point on the continuity - although I was also using it for individual wires to make sure there wasn't a break I couldn't see, so that's good I guess.

Back to the problem at hand -- what do I touch to determine whether the ohms of the hammer magnet are 4.3? Is the machine on/off? And does the magnet have to be active or not? Thanks!

#9 6 years ago
Quoted from Fezmid:

Back to the problem at hand -- what do I touch to determine whether the ohms of the hammer magnet are 4.3? Is the machine on/off? And does the magnet have to be active or not? Thanks!

Turn the machine off, disconnect the wires to the magnet (2 black wires) connect your meter to the pins going to the magnet.

Quoted from Fezmid:

Maybe it's possible that when the hammer magnet malfunctioned and held the ball until the fuse blew that it somehow damaged the other cores?

not possible.

#10 6 years ago
Quoted from Pin_Guy:

This magnet should measure 4.3 ohms with your meter on the ohms scale (see image below)

So I did the test - and I think I did it properly. I set the multimeter to ohms, touched the leads to the connectors in the molex, and it beeped. Started at a high number and then kept going down. It made it down to 4.5, but would fluctuate between 4.5 and 5.0 or so. Attaching a picture of what I touched, along with the multimeter itself (to make sure it's set right since as I noted, I'm new ).

I then did the same test with the Sparky magnet. It also started high and dropped down, but it went between 4.4 and 4.7, never going above that.

I don't know what any of this tells me though....

Also some more data points -- the Hammer magnet was working fine again today. I had a great game (for me) going on, locked two balls in the coffin, and then hit it enough to lock it a third time -- but the magnet hum never started, so it wasn't activated... I came upstairs, ate dinner, and went back down after eating -- and the magnet was working again. Could it somehow be heat related? I played the game again and was able to get coffin multiball.

I like it better when things are just broken - so much easier to troubleshoot.

Now where do I go?

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#11 6 years ago
Quoted from Fezmid:

So I did the test - and I think I did it properly. I set the multimeter to ohms, touched the leads to the connectors in the molex, and it beeped. Started at a high number and then kept going down. It made it down to 4.5, but would fluctuate between 4.5 and 5.0 or so. Attaching a picture of what I touched, along with the multimeter itself (to make sure it's set right since as I noted, I'm new ).

Yep, you measured it correctly, and the magnet is fine. Intermittent issues like you are seeing are typically connection related and normally with the connector or header pins.

#12 6 years ago
Quoted from Pin_Guy:

Yep, you measured it correctly, and the magnet is fine. Intermittent issues like you are seeing are typically connection related and normally with the connector or header pins.

So I checked the continuity of the cable that connects the black wires to the magnet board, and that seemed fine.
I've checked the ohms and you said that looked fine, so I assume the connection from that molex to the magnet is probably ok? (I can't really see where the wires go to the magnet - I'm guessing I'd have to take the whole thing off).
The pins on the magnet board look ok -- they don't appear to be falling off or anything, at least...

Could there be an issue with the capacitor on the magnet board? Is there something else I should be looking at on the board? Or elsewhere?

#13 6 years ago
Quoted from Fezmid:

(I can't really see where the wires go to the magnet - I'm guessing I'd have to take the whole thing off).

No, there is no need to take it apart, as it already checked good, and the black wires you measures are part of the magnet, any connection to the magnet wire will be soldered and insulated.

#14 6 years ago

Another data point in my quest to solve this problem. The magnet worked fine today for a few games. Then it stopped activating. I turned the machine off and then turned it right back on, and it started working again... Doesn't that sound like it's less a connection issue and more an electronics issue? (ie: rebooting fixed it).

Maybe I should just buy another magnet board and see what that does... If nothing else, I'll have a spare part... :/

#15 6 years ago

I reached out to Stern tech support and explained what I was seeing and what I had done to troubleshoot. David Carver said it sounds like a problem with the magnet board itself and suggested I replace it. Now to find someone who has it in stock...

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#16 6 years ago
Quoted from Fezmid:

I reached out to Stern tech support and explained what I was seeing and what I had done to troubleshoot. David Carver said it sounds like a problem with the magnet board itself and suggested I replace it. Now to find someone who has it in stock...

exactly! I never understood why stern doesn't provide a store site for the common replacement parts for games that are still being produced (or at the very least, provide enough stock for the resellers like marco to keep them available for their customers.

I believe that these have been sold out for a couple of months everywhere

#17 6 years ago
Quoted from j_m_:

I believe that these have been sold out for a couple of months everywhere

Well this is a scary as it shows just how high of a failure item this board is, and it also explains why I haven't received my warranty repair board from Stern yet.

#18 6 years ago

After scouring the Internet, I found that Pinball Spare Parts in Australia had one magnet board left - only place on the Internet I could find that still had one in stock - so I ordered it. Like Pin_Guy noted, it's a little worrisome that it's hard to find a part for a game that's still in production.... But after spending as much as I did on the premium, I figured it was worth paying a few extra bucks to get one.

Hopefully the board is really the problem...

I'll keep everyone posted.

#19 6 years ago

Stern sent me a new one for free.
It's a common problem.

3 months later
#20 6 years ago

Fezmid Did replacing the board fix your issue?? I've just conducted the same tests as you did, and same results, continuity in the wire is fine and the magnet reads at 4.5 ohms. Too give a little background, this happened to me before, I contacted Stern and they sent out a replacement board. Seemed to work maybe for a month, and now back to the same issue. Fuse blows once I turn on the pin.

Any other suggestions folks?

#21 6 years ago

Yeah, replacing the board fixed the issue -- although occasionally the magnet stops trying to detect (no humming) in the middle of the game, so that sucks.. Doesn't happen often though. I have another board from Stern that Chaz said would probably fix the intermittent issue, but I haven't swapped it out with the one I paid for because it works 99% of the time... Keeping the Stern one as a backup for now.

2 weeks later
#22 6 years ago

To follow on my issue, I've hunted high and low for a fix...couldn't find one so apologies in advance if I missed a fix.

Chas graciously shipped me another board which I've just installed, and the problem persists.

Problem: Dreaded F7 fuse blows once I turn on the pin.

Trouble-Shooting Completed: checked the ohms at the coffin magnet (reads 4.5) and checked the continuity in the wire going from the coffin magnet to the magnet PCB. Checks out fine.

Any ideas?

#23 6 years ago

Well...must be Gremlins. Just got home from work, decided to take a look at the fuses. Put in another new fuse, working like a charm. Only thing I can figure is the new fuse I put in yesterday may have been burnt already. Guess maybe a good idea to test them before putting in. Weird!!

#24 6 years ago

I'm still looking for a fix. My magnet never seems to detect ball during gameplay. 4.8ohms and good continuity at the magnet.

2 years later
#25 3 years ago

I'm having the same issue on mine. Replaced the magnet board. Fuses check good. Getting the proper ohms when I check the magnet. I can even hear the high pitch buzz of the magnet activating. Started getting a check switch 63 after I took out the coffin magnet assembly to inspect it. Ball just wont get grabbed by the magnet...

#26 3 years ago

Connectors are often overlooked

#27 3 years ago
Quoted from mizzou:

I'm having the same issue on mine. Replaced the magnet board. Fuses check good. Getting the proper ohms when I check the magnet. I can even hear the high pitch buzz of the magnet activating. Started getting a check switch 63 after I took out the coffin magnet assembly to inspect it. Ball just wont get grabbed by the magnet...

Does it catch on a slow rollover? Try it with the glass off.

#28 3 years ago
Quoted from WH20_Buzz:

Connectors are often overlooked

I checked, but I'll take another look

#29 3 years ago
Quoted from Fezmid:

Does it catch on a slow rollover? Try it with the glass off.

Yep, tried...its just not sensing the ball at all..

2 years later
#30 1 year ago

Just to resurrect this, anyone had any better resolutions to the hammer magnet issues? I’ve got the latest (rev d) magnet board on my METLE, and it rarely catches unless it’s going super slow directly over the magnet. I’ve replaced the magnet connector to the magnet board, but haven’t touched the other connectors to the magnet board (except re-seated them). I can hear the humming when the magnet is activated but still won’t catch reliably at all. Any ideas?

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