So I'm supposed to be posting my repair adventures to this section but I have been slacking. Not due to lack of repairs, but more to do with the fact I keep forgetting to take pictures of said repairs along the way, and I feel posts without pics just plain suck! So I apologize to those following along for the lack of content. (it's not for lack of trying and I'm hoping 2014 I get better at this!)
Last night I had the pleasure of heading down to Scarberia to work on Brewmanagers LOTR. Exactly one month prior during his wife's birthday party / Christmas gathering the right flipper apparently got stuck and stopped working. Walt later confirmed the coil had for some reason locked on and destroyed itself, so he ordered up a replacement coil along with a couple of other new flipper parts. After successfully installing said parts the flipper failed to energize at all. Checking to make sure it wasn't something simple like a broken wire, at that point Walt knew it was time to send out the bat signal. With Christmas looming and all of the other repairs I've had on my plate as of late, scheduling this repair was proving tricky but I had a cancellation last night as did Walt so we jumped at the opportunity to resurrect the LOTR.
On arrival first thing was to pull the driver board. The main flippers on this game are controlled by Q15 and Q16, the latter being the one in question for this repair. Now, for those that don't already know... Stern Whitestar flippers are notorious for failing FET's. If you hold / cradle the ball for any length of time with any Whitestar (and maybe even SAM) games there is a very good chance the FET that controls that flipper will fail. It's a known issue and I have no idea why Stern never corrected it because they are well aware of it. Basically the FET they used for the flippers are underspec'd and destroy themselves when activated for too long. The OEM part# they have been using for high powered coils is 22NE10L. Not only is this part pretty much impossible to find these days, it's clearly not rated high enough for flipper coils. The suggested replacement is 40NE10L or an IRL540N. I prefer the IRL540N personally as it's easier to get and works great.
Quick PSA alert!!!
Please note, if shopping for an IRL540N, make sure you purchase the IRL540N and NOT the IRF540N. THESE ARE NOT THE SAME PARTS AND SHOULD NEVER EVER BE USED AS A REPLACEMENT FOR THIS APPLICATION!!! In laymen terms, the IRL version can be turned on and off with very low "logic level" voltages, which is what is required for this design. The IRF version requires slightly higher voltages to be able to turn it on and off reliably, and if used in this application what can happen is the FET will turn itself on and never turn off, ultimately locking the coil on and destroying it. (and potentially causing other PCB damage due to heat)
With the driver board out and a quick inspection I notice a couple of things right off the bat.
Not only has Q16 already been replaced by a previous owner (and unfortunately very poorly I might add as they managed to ruin ALL of the traces in the process), you can see they replaced the OEM part with the dreaded IRF540N!!!
That quickly answered Walt's question as to why this happened in the first place. I also noticed that a couple other FET's had been replaced as well (luckily all of the traces on these were still intact) and I'm guessing they were done by the same person as they too were also IRF540N! So I explained to Walt the best plan of action would be to replace the bad flipper FET at Q16 along with these other two IRF540N parts with the replacement STP40NE10L FET's that he had picked up from Starburst. The other flipper FET at Q15 was still the OEM 22NE10L and even though it was still working I also opted to pull it and replace it with the more robust STP40NE10L while I had the board out. (and ultimately save me another service call in the future)
Here are the two other IRF540N and the good OEM 22NE10L pulls, along with a quick after shot of the repair area.
With the PCB work all done I quickly went over the replacement coil that Walt had installed, and for good reason. First thing to check was wires installed on coil correctly. Even though the wires were installed to the same lug locations as the original coil that was removed, they were in fact backwards! Turns out the diode on the replacement coil was installed in the opposite direction to the original, which is not uncommon and why it's important to make note of where the wires are installed on the original coils in relation to the DIODE BAND and not the coil lugs.
The next thing to check after replacing a FET or transistor is the associated diode. This can be found on the coil itself or on the driver board if not on the coil. (every FET / transistor *MUST* have one so make sure you locate it) On a new coil there is no need to verify the diode is good, but where Walt had installed the new coil and powered the game on it needed to be checked. To do this one leg of the diode must be pulled from the coil as you cannot test a diode properly when connected to a coil. With your DMM in diode "buzz" test, you should see a .4 to .6 reading on your meter with the black lead on the banded side and red on the other side of the diode. Swap the leads around and you should get nothing. Sure enough the diode on this coil was completely shorted, so a quick diode replacement, re-attach the wires to their correct lugs, replace the 3A SB fuse under the PF and it was time to test.
Power up the machine, start a game.... and LOTR lives again! Needless to say, Walt was a very happy camper and glad I was able to help him out.
D
Last night I had the pleasure of heading down to Scarberia to work on Brewmanagers LOTR. Exactly one month prior during his wife's birthday party / Christmas gathering the right flipper apparently got stuck and stopped working. Walt later confirmed the coil had for some reason locked on and destroyed itself, so he ordered up a replacement coil along with a couple of other new flipper parts. After successfully installing said parts the flipper failed to energize at all. Checking to make sure it wasn't something simple like a broken wire, at that point Walt knew it was time to send out the bat signal. With Christmas looming and all of the other repairs I've had on my plate as of late, scheduling this repair was proving tricky but I had a cancellation last night as did Walt so we jumped at the opportunity to resurrect the LOTR.
On arrival first thing was to pull the driver board. The main flippers on this game are controlled by Q15 and Q16, the latter being the one in question for this repair. Now, for those that don't already know... Stern Whitestar flippers are notorious for failing FET's. If you hold / cradle the ball for any length of time with any Whitestar (and maybe even SAM) games there is a very good chance the FET that controls that flipper will fail. It's a known issue and I have no idea why Stern never corrected it because they are well aware of it. Basically the FET they used for the flippers are underspec'd and destroy themselves when activated for too long. The OEM part# they have been using for high powered coils is 22NE10L. Not only is this part pretty much impossible to find these days, it's clearly not rated high enough for flipper coils. The suggested replacement is 40NE10L or an IRL540N. I prefer the IRL540N personally as it's easier to get and works great.
Quick PSA alert!!!
Please note, if shopping for an IRL540N, make sure you purchase the IRL540N and NOT the IRF540N. THESE ARE NOT THE SAME PARTS AND SHOULD NEVER EVER BE USED AS A REPLACEMENT FOR THIS APPLICATION!!! In laymen terms, the IRL version can be turned on and off with very low "logic level" voltages, which is what is required for this design. The IRF version requires slightly higher voltages to be able to turn it on and off reliably, and if used in this application what can happen is the FET will turn itself on and never turn off, ultimately locking the coil on and destroying it. (and potentially causing other PCB damage due to heat)
With the driver board out and a quick inspection I notice a couple of things right off the bat.
Not only has Q16 already been replaced by a previous owner (and unfortunately very poorly I might add as they managed to ruin ALL of the traces in the process), you can see they replaced the OEM part with the dreaded IRF540N!!!
That quickly answered Walt's question as to why this happened in the first place. I also noticed that a couple other FET's had been replaced as well (luckily all of the traces on these were still intact) and I'm guessing they were done by the same person as they too were also IRF540N! So I explained to Walt the best plan of action would be to replace the bad flipper FET at Q16 along with these other two IRF540N parts with the replacement STP40NE10L FET's that he had picked up from Starburst. The other flipper FET at Q15 was still the OEM 22NE10L and even though it was still working I also opted to pull it and replace it with the more robust STP40NE10L while I had the board out. (and ultimately save me another service call in the future)
Here are the two other IRF540N and the good OEM 22NE10L pulls, along with a quick after shot of the repair area.
With the PCB work all done I quickly went over the replacement coil that Walt had installed, and for good reason. First thing to check was wires installed on coil correctly. Even though the wires were installed to the same lug locations as the original coil that was removed, they were in fact backwards! Turns out the diode on the replacement coil was installed in the opposite direction to the original, which is not uncommon and why it's important to make note of where the wires are installed on the original coils in relation to the DIODE BAND and not the coil lugs.
The next thing to check after replacing a FET or transistor is the associated diode. This can be found on the coil itself or on the driver board if not on the coil. (every FET / transistor *MUST* have one so make sure you locate it) On a new coil there is no need to verify the diode is good, but where Walt had installed the new coil and powered the game on it needed to be checked. To do this one leg of the diode must be pulled from the coil as you cannot test a diode properly when connected to a coil. With your DMM in diode "buzz" test, you should see a .4 to .6 reading on your meter with the black lead on the banded side and red on the other side of the diode. Swap the leads around and you should get nothing. Sure enough the diode on this coil was completely shorted, so a quick diode replacement, re-attach the wires to their correct lugs, replace the 3A SB fuse under the PF and it was time to test.
Power up the machine, start a game.... and LOTR lives again! Needless to say, Walt was a very happy camper and glad I was able to help him out.
D
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