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Yet another problem with my LOTR!!

Bigbossfan

Bigbossfan

Active Member
Aug 22, 2013
491
97
28
Lincoln, NB
I posted on Pinside about this, but thought I'd engage the Rev community as well.

Last week was playing the LOTR and suddenly smoke started coming out by the bumper area. I immediately shut off the pin, lifted the playfield and saw that the coil for the bottom bumper was charred. Subsequently ordered a new one and sleeve. Just installed it minutes ago, flipped on the pin and within 30 seconds noticed a smell (like plastic melting) and shortly thereafter, smoke again. Same coil (new one at a cost of 30.00 here in good old Canada!) charred again.

So I'm suspecting that I also have to replace the transistor? Is this correct?? And if so, can someone tell me how I determine which transistor it is?? I've got a guy locally I can probably reach out to to do the job for me (way above my comfort level, Dave Astill, are you listening?? LOL), but need to know which transistor I have to order.

Thanks for any help folks!
 
brewmanager

brewmanager

Active Member
Nov 14, 2012
629
111
43
Scarborough, ON
Menace just left my place after replacing q16 for me on my LOTR.

I think they recommend you go with the 40 transistor now as the 10s are very prone to failure.
 
DRANO

DRANO

Super Member
Nov 15, 2012
2,827
519
113
Mississauga
Generally not a good idea to replace a bad coil with a good one without first addressing the cause.
Coils don't usually just fail on their own... and they can be pricey.

There are various resources you can look up on how to test transistors, but it's basically setting your DMM to diode setting then placing one lead on top while testing each leg one at a time. Can't remember which lead goes where... but when you do it right, I think the reading you're supposed to get on a regular TIP102 is about .4 to .6 for BW games.

Stern boards use MOSFET transistors. Not sure if the testing technique and ranges are the same, but you can quickly determine if the transistor is good simply by comparing readings from known good ones next to it.

Hopefully menace or someone else here with a bit more experience can chime in.... But yeah, don't go throwing in good parts until you've fixed it. Same way you never move a suspect board into another game to test it. You'll just end up damaging another game.
 
Bigbossfan

Bigbossfan

Active Member
Aug 22, 2013
491
97
28
Lincoln, NB
Thanks for the responses gents. I've got Dave coming over sometime this week hopefully to take a look and repair for me!
 
Menace

Menace

Well-Known Member
Staff member
Nov 14, 2012
2,440
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Santiago de Aurora
You've definitely got a shorted FET that will need replacing along with another new coil. Few things to note;

-When removing the old coil, make note of which wires go where in relation to the DIODE ON THE COIL, not the coil lugs. Coils themselves do not have a polarity but if the coil has a diode installed on it the diode does. (not all coils require a diode) Never assume the replacement coil has the diode installed or if it does that it's on in the same direction as the old coil!!! If you need to verify what wires go where you can always check a similar adjacent coil for general wire colours.
-When replacing a Stern FET such as the 22NE10L your options are to use the STP40NE10L or the IRL540N. (I prefer the latter) Make sure you DO NOT USE an IRF540N as a replacement!!! It is NOT a good substitute! (see my LOTR repair in the Menace files for explanation)
-As for testing, using DMM in diode setting use the red lead on the tab of the FET and black on the center lead should be dead short. The lead to the right of center when looking at the part from the front marking you should see .4 to .6ish, and you should see nothing (or open or OL) on the lead left of center. Anything other than that and the FET should be replaced. (this is not a hard and fast rule, but a general guideline as FETS and transistors can sometimes test OK when they are not)
-If re-using the original coil after replacing a FET or transistor, replace or at the very least test the diode on the coil before powering the game up. In order to test the diode correctly you must lift one leg of the diode off the coil. Then in diode setting on your DMM, you should see .4 to .6 across the diode one way and open (or OL) the other way. If you get anything else, replace the diode, especially if you get a constant "buzz" from your DMM in both directions. If you fail to check this and the diode is bad, you will destroy the new FET / transistor you just installed on power up / activation.

My only other piece of advice is if you are not comfortable doing PCB re-work, call someone that is. I have seen more damaged PCB's than I care to admit from people that thought they could handle a repair...

D
 
Bigbossfan

Bigbossfan

Active Member
Aug 22, 2013
491
97
28
Lincoln, NB
LOTR

Thanks Doug. Everything you wrote above is WAY OVER MY HEAD, and I wouldn't even dream of attempting any of this. Dave Astill is coming over (hopefully tomorrow, I miss playing me some LOTR!) and hopefully will be able to rectify the problem.
 
Bigbossfan

Bigbossfan

Active Member
Aug 22, 2013
491
97
28
Lincoln, NB
To add to this, and was thinking about this today.....probably coincidental, but you never know. LOTR was working fine. Then I installed one of those Pinnovaters headphone jacks. A few days later all this happened. Knowing as little as I do, I'm assuming this was just a coincidence as the headphone jack only was plugged into the audio slot on the board. Am I right in this assumption?

http://flipperfidelity.com/hardware/pin ... pac-5.html
 
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