2/15/2017 – Weekend of Suck

Yeah, everybody likes to send out blogs that say how great things are going, and how everything is peachy fine.  Well, last weekend was not that way for me.  Everything that could have gone wrong, did go wrong, and now I’m further back than where I started.

So the big plan was to switch over the power supplies from the four PC power supplies to a single cheap 24V switched mode power supply from China.  The previous week leading up to the weekend, I had soldered everything up, set up all the connectors so I could plug things in, and I was all set to go starting on Friday night.

I plug in the 24V supply, unplug everything else, and start testing.  Flippers work perfectly.  Drop target doesn’t reset, but that is expected because I haven’t changed the timings on the pulses.  Kickout hole, same thing.  Everything is looking great…but here is where things go south.

I think to myself…hey, I have a 36V power supply sitting here.  Why not toss that in and see what happens.  Instead of slowly building things up from a known base, and actually having the machine run on the original 24V that the machine used, I decided that I would add 50% more voltage and with ohms law, yes, 50% more current.  I switch to that power supply hit the flippers a couple of times, and then, all of a sudden, one of the flippers locks on.  Ahhhhhhh.  I pull the power quickly.

OK, guess I will simply desolder that MOSFET and put a new one in.  I “guess” at which MOSFET that I need to replace, and guess incorrectly.  That means I just spent an hour replacing a MOSFET that didn’t need to be replaced, and the board still doesn’t work because there is still one MOSFET that needs to be replaced.  Why didn’t I bother to pull out a schematic?  (Yeah, I knew that it was one of two MOSFETs on that side of the connector, but damn it, I guessed the wrong one!)

After that second failure, I was just mad at myself, mad at pinball, just simply in a bad mood and I couldn’t work on pinball for the rest of the weekend.  I just needed to take a small break from it.

Here is the thing that really irks me.  I knew that throwing 36V through the flippers caused too much current for the MOSFET.  I knew that from when I first brought up the playfield, assumed it was 43V, and only later looked at the manual and found out that it originally ran at 24V.  If I would have simply taken a step back, and thought about what I was doing and not rushed into it, I would have been OK, and could have saved myself a couple hours from replacing the parts.  That’s what angered me the most.  That I just didn’t take the time.  I rushed a decision, and now I am paying for it with extra work.  It teaches me for being a dope.

Luckily there was a ton of snow this weekend, so I could cool off by going out and building a large igloo in the back yard.  Come to think of it, I’m still angry at myself.

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2 responses to “2/15/2017 – Weekend of Suck

  1. I am guilty of the same thing in just about everything I do… just hoping I don’t electrocute myself too badly. =) BTW, are there particular power supplies you recommend for use with your boards? I think I recall you mentioning “eBay power supplies” in one of your old posts.

  2. It’s tough to give a link because ebay listings really change frequently. Most people that I know about are using a 48V power supply that produces slightly less than 10A. That should work for most of the pinball parts that people might have scavenged from late 80s on up machines. Always check the resistance of the flipper coils, those are the guys that are going to draw the most current. I usually choose a seller from Hong Kong/China because by the time that I actually hook it up, a couple months have normally passed. (They tend to be cheapest). If needed faster, make sure it is filtered on US sellers (at least for me), but that will cost slightly more. There is a new power filter board that I did which I just sent to the Mezels. It basically adds some big caps after the power supply to reduce surge current on the power supply (which can sometimes cause a false short circuit trip). I just haven’t had time to write that board up yet.

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