LOTR magnet issues...

[Pharoah007]

So I had some time today to remove the PCB and replace the Q6 IRL540N FET.

I also swapped in a new diode just to be safe as they are $0.02

BOOM! I have a working magnet!!! Thanks so much for the tech support everyone.

I have the removed Q6 FET (it was a IRL540N as well) And I am wondering if anyone can tell me how to test it. This way I can post some pics of the test of a BAD IRL540N FET so future people using this post to troubleshoot their LOTR magnet circuit can use this thread for reference.

thanks again all.
Z.

 

[Pharoah007]

SO......

Now that my LOTR is working, I decided to try to fix my original board. ( I swapped a new Q6 into a replacement PCB to fix my game )

Whoever did some work on this PCB in the past butchered it, there are jumpers everywhere...

I have a question, I need someone to confirm what log on the IRL540n FET . the holes in the PCB for the Q6 IRL540n FET are DESTROYED, so I have to jumper them.

Is this the GROUND pin/connection of the Q6 IRL540n FET?
(Top in this pic)

(far right in this pic)

I have it jumped to ground right now, but want to be sure before I plug it in and blow something up.

 

[Menace]

Yes, that leg of the FET is tied to ground. Jumpers are not always hacks, sometimes they are a necessary evil, but looking at those limited pics I would say the "tech" that worked on that PCB should practice some more...

D

 

[Pharoah007]

Yes, that leg of the FET is tied to ground. Jumpers are not always hacks, sometimes they are a necessary evil, but looking at those limited pics I would say the "tech" that worked on that PCB should practice some more...

D

Cool beans, thanks.

I jumped the connection in question to the ground point near one of the mounting screws.

Will try to get it in tonight to test.

 

[Menace]

An easier jumper for that would have been to the ground pin of the next FET closest to the one you're fixing. This way you keep the jumper as small as possible. Something to keep in mind for next time.

D

 

[Pharoah007]

An easier jumper for that would have been to the ground pin of the next FET closest to the one you're fixing. This way you keep the jumper as small as possible. Something to keep in mind for next time.

D

Roger, makes sense.

Should be no problem with the point I used, correct? A ground is a ground right?

thanks again for all the help...everyone

 

[retroactive85]

Hello everyone, thanks for helping out Pharoah007 because I'm sure it'll be helpful for me as well. I have a LOTR with similar symptoms. When I power the game on, the magnet locks on until the fuse blows.

For what it's worth, this happened after an interesting scenario while playing. I was in Destroy the Ring(2 ball mode) and had the first ball captured in the ring. I hit the second ball in the ring, but both balls ended up sticking in the ring and staying there, not ending the mode. I was having a good game so I decided to see if ball searches would clear the balls instead of tilting trying to get them loose or taking the glass off. After a few ball searches the balls did not clear so I shook them loose and tilted I believe(can't quite remember the sequence), or I might have taken the glass off and pushed them through. Anyways, immediately following this, my ring fuse was blown and ring was not working obviously.

I first replaced the fuse with a 5A fast blow fuse and got a loud hum when I powered up for a half a second(same kind of sound the game makes when magnet is activated). Then I replaced the fuse with a 5A slow blow and there was still a loud hum when I powered up, assuming this was the magnet activated. The hum lasted approximately 15 seconds and then stopped and the fuse was blown.

The game is HUO with low plays, should a transistor go bad in such a low use unmodified game? Can I test the transistor while the driver board is still in the game? Thanks for helping a repair noob!

 

[Menace]

Yep, the FET that controls the magnet is shorted and needs to be replaced.

D

 

[retroactive85]

Thanks! Noob question, can I test the transistor from the front side with the board still mounted in the game?

In this scenario is there any reason to suspect that the diode that Pharoah007 mentioned went bad?

 

[Menace]

With the way Stern is designed it will be VERY difficult to near impossible to test that FET with the PCB still installed in the game. The associated diode may or may not be bad, but where you're going to have to replace the FET you should replace the diode at the same time. It's just cheap insurance.

D

 

[retroactive85]

Gotcha, thanks. I will count on removing the driver board to test. I found this video as a quick demo on testing Whitestar transistors.

A buddy is saying that Stern boards are harder to work on because they're surface mount technology. By looking at Pharoah's pics above it looks like the components go through the board. Can someone confirm which style PCB the Stern whitestar driver board is?

 

[brad808]

They are through hole

 

[Menace]

Yep. the whitestar drivers are T/H. The MPU/Sound is mixed technology.

D

 

[retroactive85]

Thanks for your replies. I'm curious, what causes transistors to go bad? I see in this thread where an improperly installed diode can cause it. Is there any chance that the odd scenario I noted would cause a transistor to fail - where the magnet was activated for 3 minutes at a time during Destroy the Ring? Do transistors just fail on their own?

I have the transistor on order, and I'm pulling the driver board this evening to test Q6. I'll update with the results.

 

[Menace]

Transistors can fail if operated for too long of a period under certain conditions, so it is possible the scenario you listed caused it. But they have been known to just fail for no reason as well. Same with diodes, they can and do fail and when that happens it can take out the associated transistor once triggered.

Don't forget the 1n4004 diode to go with the transistor replacement!

D

 

[retroactive85]

Just wanted to check back in - I replaced the transistor with a new IRL540N, fired the game up, and all seems to work as it should! Thanks for the help!

That marks my first board repair, as previously I only replaced a WPC driver board when it was having some issues. It's nice to build some confidence with working on PCB's.

 

[Menace]

Great success! Glad we were able to help, and you got your feet wet with some PCB repair.

D