A Tender Tale

My boat sails stormy seas, battles oceans filled with tears.
At last my port's in view, now that I've discovered you.
Oh I'd give my life so lightly, for my gentle Lady,
Give it freely, and completely, to my Lady.
 ....Moody Blues

I had worked some long hours on something or other - I don't rememberwhat - but it was usual that when we did pull some long hours- we'd get the next day off. One such day I was home when thephone rang. "The" 28 volt power supply had crapped.We had several large test sets - and other equipment that used28 volts DC as the primary control and switching power. And withoutthat supply - nothing worked. I have mentioned that attimes I had wondered what manner of "nuts" were loosein the Navy hierarchy. This is one of the prime examples. Granted;with all of the equipment we had, plus an occasional feed to acouple of other shops, this supply had to be able to accommodatemany amps - like 100. Which is no small supply. So some loose-nutin the Navy decided to put a supply in there that could more thanhold the load. Now this was no ordinary supply - whoever got it- made sure they had any possible load covered! In theAft-Port corner of the Navigation repair shop was bolted this1000 pound jet-start power supply capable of some 5000 amps. Fedby the ship's three phase 440 volt main bus - this thing was nothingbut huge. You had to practically crawl inside to get to some parts.And because it was so old - and so - ah - strange - few peopleeven would try to work on it. The main transformer was huge -and had many windings. Six Primary and six secondary connectedin delta and wye configuration - to supply 12 phase power to theselenium rectifier stack. Yup Selenium. (If a selenium rectifierfails and shorts - the resulting smoke is quite toxic - And theseare HUGE). Back to the transformer - besides the six secondarywindings - (or should I say wound with them) were twelve saturationwindings - - they had this thing set up so that each winding endhad a bucking winding - so that the uneven voltage drops acrossthe selenium rectifiers could be compensated for. There were 12huge rheostats that controlled the bias to these "buck-windings."Once rectified, the DC was fed to two banks of capacitors - eachbank added up to about 500,000ufd at 50 volts - and each was fusedwith a 10Amp fuse(!). Since it was a day off - and we had beenon our way to the Anderson (Air Force Base) Commissary to shop- Sherry decided to "tag" along. Besides - I knew thatgetting into parts of that beast - her small frame could squeezeinto places I could barely stick my head. And she and I couldwork really fast together. So into the shop we zipped. Pullingthe covers revealed nothing unusual - hitting the start buttoncaused the main contactor to snap in - then the overload circuittripped - and the unit shut itself down. We found that both theCapacitor bank fuses had blown - replacing them helped - now itwould run about 10 seconds before blowing both fuses then shuttingdown. I started to go get a meter and a scope - I figured a fewresistance checks to start with. Sherry had moved around to theback side - and called out - "I got it" She poked herhand over the top and had what was left of a dead gecko (you'dcall it a garden lizard). "I need a soldering iron, dikes,needle nose - and about 2 inches of heat shrink." Seems thegecko had gotten into part of the bucking wiring / controls andhad somehow caused something to short -and cause a wire to burnin half. She always did have a knack for finding problems witha good visual inspection - I have a bad habit of grabbing metersand start probing... sometimes that isn't the best way... In afew minutes she had the wire repaired - and had found where thegecko had pushed another wire over and caused the original problem- she pulled that wire, applied heat shrink to it so it couldn'tshort anymore - and soldered it back. Two more fuses in the capacitorbank - and presto! up it came. Since it hadn't been touched sinceMare Island - we got a scope and ran through the rheostats - justto get it as smooth as possible. We were just about finished whena voice came from behind us... (we were both half in each sideof the beast - half the rheostats were on each side) - "Youguys about to get it?" "Yup - looking real good..."I answered. The voice was familiar - but I was concentrating onwhat I was doing - and didn't give it another thought. A few moreminutes and we put the covers back on; put the tools up - andwas fixing to head on up to Anderson. One of the chiefs came byand asked what we found - we told him - then he asked: "Whatdid the Captain want?" ohhHHhh ... That's who thatwas... "He just wanted to know if we were about done - why?""Just heard he had come through - he doesn't get up herevery often, must have heard we were down..."

There is a Navy axiom about ship's captians:
Captains may not be omnipresent - but their ears certainly are...

Chapter 5:

Table of Contents

© 1997 Common Cents Computers