Tuesday, May 11, 2010

Back in the shop - Pandora's Box Part 2

We left off with a cleaned, rebuilt, and nicely lit pop bumper.  The problem was, it was locked on.  I've got a couple of months of experience and reading under my belt now, so I know that I probably have a bad transister.

I know now, that to test your transistors quickly, you put one lead of your Digital Multimeter on ground, then test continuity to the metal tabs of the transistors.  I do this and I find Q17 has continuity!  Here's my culprit!

I feel really clever and smart, so I unplug the corresponding connector to the board and turn the machine back on, fully expecting the pop bumper to be silent.  If there's no connector, there's no short, and there's an unlocked pop bumper.

I turned on the power and "WHAM!!" it locks down.  I found that inside the front cover of my F-14 manual is a list of all of the solenoids and their corresponding transistor.

Q17 is labeled as "Flash Lamps".  Wait, so what number is the pop bumper?  (I've heard Jet Bumper and Pop Bumper, in the manual it's "Jet").  Q69?

Yep.  That one buzzes out also.  I checked all of my transistors and found that I had 4 of them out.  Jet Bumper, Flash Lamps, Left and Right Slingshot bumpers.  What I don't understand is why aren't the slingshot bumpers locked on?  I really wasn't looking at them, maybe they were.

*Sigh*

I guess I have a lot more work to do than I though.

The pinrepair guide recommends replacing the pre-driver transistors as well as the main transistor.  After removing the board from the back box, I cut them all out and started on replacing them.



There isn't much else to say about this.  I cleaned up my flux, replaced the board, and everything worked great!

I have no idea why, but the slingshots are stronger now.  I have no explanation for that and no one on RGP did either.  I could be imagining it.  One person said that maybe just the act of taking off the connectors and plugging them back in made a better connection so the slingshot bumpers worked better.  I'm picking that reason because the alternative is admitting that I'm nuts.

I did OK soldering on the board with my 15w Radio Shack soldering iron.  But for this job I used my nice new Weller soldering station ($99) and it made a big difference.  The end result was the same, but I was much more confident that I would not lift the traces because the Weller has temperature controls.  Also, the soldering pencil was much more comfortable to hold and the tip was made for soldering on boards.  The old 15w jobber has a general purpose tip which means it does everything OK but nothing great.

I'm down to fixing my lit beacons, putting the new toppers on them, then moving everything to the nicer cabinet.  I'll clean each part as I move it.  After that is done, I'll have a fully functioning F-14 Tomcat which I will put in my basement.

Then the F-14 project will go on a break while I work on the Jungle Lord.  I'll start a new sub-blog for that machine.  Once the Jungle Lord is done, I'll start back on the F-14 to Remove the playfield, remove all of the mylar, re-set the inserts, and then clearcoating!

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