Thursday, April 16, 2009

Another Day, Part 8

(GO TO BEGINNING)

Maybe I should have said, "Not that complicated to misdiagnose?" One of the two; while anticipating the Chief's wrath, I went back to put the cover over the Isolated Supplies board and looked directly above it to see a pair of fat filter capacitors, screw-terminal ones, with the screws, well, gee: a bit unscrewed. Hanging at angles, the lugs that should be held down are instead supported by the wires that connect to them and looking a little burned. It's not all that obvious if you're looking in from the outside but from less than a foot away, how did I miss it earlier? And how long has it been this way?

"Hey, Jon, I think I've found something -- hand me that Philips, willya?" Sure enough, the screws are wobbly-loose and for no good reason. We haven't changed out the components or the subassembly they're a part of since this PA was installed, five years ago. Whatever, those caps are across the heater supply and the connections should be tight.

So I proceed to torque them down and Jon and I button up the cabinet, set everything back to normal and power it up with no signal applied. Whoa! Heater voltage is way up there, much higher than it had been. A good sign but we had to shut down, open the back and change to a lower voltage range. Fine, twenty minutes of my life I didn't need anyway.

On the next go-round, things are looking up: voltage in the right range, though we still have to run it a little high to make the control logic happy, and the no-signal Phantasmajector current is So Fine. I trip the Buffer Amp breakers back on, applying signal, and start inching up the power control, 10 percent, 20, 30...all the way up full idle, 50 percent, with the other two PAs throttling back automagically to Almost Nil. It holds. It's happy. Phantasmajector collector current is right on the money. You know what this means? It means the Chief is probably not gonna put a lot of effort into his, "This could have been done a lot faster and more directly" lecture, is what; also we're now that much less likely to find ourselves as-good-as marooned between very distant here and even more distant there, the avoidance of which is what we in the starship biz like to think of as a Plus.

It's a funny feeling, a combination of relief, wonderment and the sincere awareness that this is something I should've caught weeks earlier.

But there's no time to bask in it; Jon looks at his watch and proclaims, "Hup! I should've been gone half an hour ago!" And he's gone in the time it takes to work the hatches. From the sounds of his egress, I'll find the outer hatch undogged.

I reduced the number 2 final back to nominal power and turned to number 3, which hadn't been getting near 100 percent. 80's the rated gotta-fix-it level; I pushed it to 50% with front-panel controls while the other two throttled back, then reached for the intercom handset and punched for Drive Control. "Gary...Oh, Eric? Get ready for a little glitch, I'm gonna drop the signal to two and one so I can run three up a bit more. Can you give me a fifty, no forty-percent duty cycle on the 'Drive waveform?"

"Okay, that's pre seven, isn't it? Yeah, there it is. Standing by."

"On my mark....mark," as I reached out and flipped the IPA breakers for 1 and then 2. Number 3 power came up but stopped at 75%. It felt as if the deck wavered ever so slightly underfoot and I heard Eric mutter, "...c'mon," then he spoke up, "Pre six. Fifty percent."

"Thanks, Eric, sorry 'bout that. Hold on just a sec--" I took the tweaker screwdriver from my pocket and turned up RF LIMIT adjustment on #3, watching the output rise past 80...90...95. "There. I'll turn it down and you can go back to normal once I get the other two back on, ready?" as the power fell low enough to get the other two finals online and Eric replied, "Whenever."

"Okay, on go: three, two, one, go." He must have hit the switch while I was flipping circuit breakers; there was hardly a glitch as we came back to three finals online and nominal idle signal to the CLASSIFIED. I took another couple of minutes getting the outputs balanced.

With all three stardrive PAs back to normal, I pull a set of readings (nice little vampire software looks at the remote control data and grabs it right into the utility portable), add notes on the problem and the solution and readings from the five meters that don't have telemetry outputs, the ones in the High Voltage section we read through a transparent window (heater voltage of course among 'em), enter that in TASKER, forward a copy to the Engineering redundant docserver, print it out (hard drives crash; active storage gets EMPed or bit-flipped by stray cosmic rays) and add it to the Maintenance Log clipboard. Might as well give the next tekkie -- or me, if I'm sleepy enough -- a head start. Plus there's still the Triennial Inspection. Never know exactly what logs and such they'll want to see.
#

Securing the drive compartment takes awhile. All the tools, books, materials and supplies have to go back in their clips or cubbies. I do a quick walk-through, including checking the side compartment where the RF driver for the aft octet of ion maneuvering engines resides and on back along the pressurized sections of the CLASSIFIED and their connections to the huge power dividers and waveguides that feed power to the 'Drive projector array. It all looks nominal and I've just time to take the official Engineering electric car crawling back down the service passageway and bop up to the Engineering Shop to sign out. The main room's empty. According to TASKER, Handsome Dave finished his day in the portside squirt-booster bay, initializing some new escape pods (coolness!) but bedarned if I know where the rest of the guys are off to. I hear a chair creak from the Chief's miniature office and walk back to the open hatch. He looks up from his monitor and almost smiles, "Nice catch on the Number Two HPA, Bobbi."

Yowza. Caught me off guard. "I don't know why I didn't find it sooner, Boss."

I hear footsteps and voices behind me and the Chief harrumphs, turning back to his paperwork with a louder, "See that you do in the future!" as Conan the Objectivist and his usual shift mate enter the shop, hauling some blamed bit of dusty, malfunctioning electronics.

Hmmmmm.

That's 8-on for me, a sweep through Drive Control to trade an inquiring look for a reassuring nod with Eric on my way out of the Tech Core and onto slidewalks, five miles back aft to my apartment.

Where I lay awake and wonder about the mystery Sheriff Mike told me to ignore. Who wanders into the hot stuff unaware? It's posted in five languages and simple cartoons, repeatedly, way before you're in any danger. And it's not something that could be done to the victim; she had to get there under her own power.

(TO BE CONTINUED)

4 comments:

Bruce B. said...

I'm now completely caught up on your "I work on a Starship" series. Consider me hooked. Educated as an EE in RF and microwave technology I understand alot of your tech jargon but never got to work with anything like a high-power broadcast transmitter. I encourage you to keep writing and wrap these stories into a novel for publication.

I'll be eagerly anticipating the next installment.

Turk Turon said...

Stayed up waaaaaay past my BT to read this latest episode. Always worth it!

wv: brawarn

[no s***!]

D.W. Drang said...

Hanging at angles, the lugs that should be held down are instead supported by the wires that connect to them and looking a little burned. It's not all that obvious if you're looking in from the outside but from less than a foot away, how did I miss it earlier? And how long has it been this way?

"Hey, Jon, I think I've found something -- hand me that Philips, willya?" Sure enough, the screws are wobbly-loose and for no good reason. We haven't changed out the components or the subassembly they're a part of since this PA was installed, five years ago. Whatever, those caps are across the heater supply and the connections should be tight.
You just answered your own question: It was something no one ever thought would happen, so it never got noted in any Periodic Maintenance chart. Seen it happen on much more mundane things than Stardrives. You know, trucks and radios and helicopters and CLASSIFIED.

WWV: sective. Of, or pertaining to, religious sects. (But not cults, which wold be sectic.)

Hank Morgan said...

Nice. Good catch, indeed. Hey, check your mail.