Posts Tagged ‘repair’

Repairing the micro Cluster

May 3rd, 2008

Airglow Cluster

Last summer, with the help of a fellow graduate student, I retrieved some old computers from the dorms to build a small cluster.  Total cost: $100.  Five of the machines had Maxtor DiamondMax 8 40-gB drives in them.  All five failed over the past few months.  For $200, I could replace them with new drives.  But, first I called surplus and ended up with a smattering of used drives with capacities of 20 and 40 gB. Three hours later, we were up and running again.  I’m sure they’ll get plenty of use as the ISEA deadline closes in…

Bench Time: Airplane and a TS-930 repaired

April 23rd, 2008

Benchtime

As I lamented in the last post, I am surrounded by ailing gadgets in need of repair.  Last weekend, I tackled two of them.  The first was the airplane.  A gust of wind had destabilized the plane sending it crashing to the ground.  The front set of pegs where rubber bands attach the wing were sheared-off.  A trip to a craft store with Sarah yielded an “1/8-inch” dowel and a sack of miniature thread spools.  I reamed-out two of the spools and press-fit them to the dowel for a slick replacement (sorry, no photo).  I have not flown the plane again, yet.  However, the weather has changed favorably.  So, that should happen any day now.

My older TS-930S developed a PLL unlock error over time.  The error occurred when I changed bands or modes.  Fortunately, several months ago, the topic had been discussed on the TS-930/TS-940 reflector, although I was just getting around to thinking about it.  Clif Holland, KA5IPF, who has repaired Kenwood radios for many years, suggested that a common culprit is the 36.1-MHz heterodyne oscillator in the signal unit and prescribed a simple adjustment of L77.  It took a little while to adjust it to my satisfaction.  Indeed, I wasn’t even sure I’d made any improvement at all at first.  However, once the radio warms up, band and mode changes are seamless again!  This sure helped out for fast QSYs in the Michigan QSO Party.

On the topic of TS-930’s, I’m still having woes on SSB with the other radio.  I swiped (and promptly returned) a microphone from the TS-850S at W9YH to ensure that the problem wasn’t my Pro-Set.  It has to be something between the mic jack and the signal unit.  But, the mic jack is a real pain to get to.  Someday.

Repairs and junk…

April 13th, 2008

One of the curses of attempting (I say ‘attempting’ because I’m mostly a failure) to be a “sustainable consumer” of electronics and appliances is the inevitable repairs.  My venerable desktop PC of 8.5 years (known affectionately by it’s hostname “sakhalin”) is finally showing its age.  It has trouble finding the boot drive from time to time.  The “A radio” TS-930S doesn’t transmit on SSB anymore (this is a long-standing problem I have yet to diagnose), which is unfortunate because it has the roofing filter and Inrad SSB filters.  The power nozzle for our Hoover canister vacuum cleaner needs an agitator belt.  I need to find a local vacuum repair shop because none of the big stores carry the right size.  I think Sarah would be just as happy to replace it with an upright.  But, the canister still works!  I wrecked the airplane a couple of weeks ago when the weather was not quite nice enough to be flying it.  Fortunately, I have $3 worth of MacGuyver parts and epoxy that should be sufficient to make that repair.  The wind broke one of the wires on my open-wire 80-meter dipole.  (Finally, I reached the point of “if it stayed up last winter it’s not big enough.”  The proof is in the performance, too.)

I’ll probably get the airplane and the antenna fixed yet this afternoon.  The other problems are more long-standing.  The desktop PC isn’t really necessary, especially since Sarah will be getting a laptop with her new job.  So, I really probably could let it go.  I still have the Pentium 166 that I bummed off of Dad for a contesting computer.  It’s working great.  But, do I unload the newer, superior computer that’s flaky?  I have been tempted to dump the 166.  I should try a new hard drive in sakhalin.  Then there’s Sarah’s desktop…I can count on one hand the number of times it’s been turned on since we got married and I was the one using it!  I’m holding onto Alan’s PowerBook because it’s the only place I have Adobe CS2.  And, I have the ThinkPad “contesting laptop” that Ryan gave me when I got married…  I guess if I weren’t such a tightwad and Mac-addict, I wouldn’t have this problem!  No more junk!

We have five CRT’s in the house…two Dell 19″ Trinitrons on my desk, Sarah’s 17″ un-Trinitron Dell, my oscilloscope, and the TV.  I’m not planning to replace the ‘scope or the TV anytime soon.  So, I guess it’s the computers are the ones that will have to go…I just can’t let go of my junk…  And, I went out and bought a new camera…sigh.

R/C Flying

August 2nd, 2007

The demolition-derby-monster-truck-madness-motorcross-tractor-pull-with-a-few-animals that is our county fair ended over the weekend.  Since we’re travelling a little less now, too, I decided to fly the plane at the fairgrounds again last night.  This is the first flight since the catestrophic wreck mentioned in the last post.

I walked out the front door and there were kids playing in the street.  (When are there not kids playing in our street?)  “He’s bringin’ that out to fly it!” one of them exclaimed.  “Excuse me, are you gonna fly that plane right here in the street.”

“No, sorry, ” I said, “I’m going to the fairgrounds.”

“Awwww!” she said.  At least somebody told them where they can and can’t go…and they’re still young enough to listen.

No worries for me…I’m still not quite good enough to fly with an audience.

I realized quickly that I’d hooked the controls up backwards during the repair.  Fortunately, I was not yet “three mistakes high” and landed relatively easily.  I reconnected the controls and had a pleasant evening of flying.  I even managed some half-decent landings.

Flying takes a light touch.  It’s a lot like driving a car in that a little correction can go a long way.  What a great project!

The airplane

June 1st, 2007

My officemate Scott has a knack for winning things, either in competition or at random. Several months ago he said, “Hey, I won a radio controlled airplane last night.” I responded with enthusiasm and suggested he let me know when he was going to fly it. About a month ago, he said, “Remember that airplane I won? It doesn’t work. I think it’s somewhere in the radio. If you want to try to fix it, I’ll give it to you.” Duh. Of course, I’ll try to fix a potentially a free toy. After assuring me that he didn’t want the plane back if I got it working, I accepted it.

The plane showed up on my desk about a week and a half ago (just before our trip to Acapulco and Mexico City…which may or may not get blogtime). It’s a FlyZone Red Hawk, definitely not high-end, but free and good for a beginner such as myself. I retrieved the plane on Monday since it would be tough to carry on my bike. On Tuesday, I set about tracking down the trouble. Bingo! There were three cold solder joints on the transmitter board. I bought 8 AA batteries from ECE Stores (Eveready inudstrial alkalines for $2.64…the best deal on batteries in Champaign-Urbana) and the plane was ready to fly.

I took the plane to the fairgrounds, which are about a 5-minute walk from our duplex, hoping that the neighborhood kids wouldn’t see me. The elderly asian man who lives at the end of the street took interest in it and we chatted; but, he didn’t follow me. Whew. I set the plane on the harness track, did the preflight check, and revved the motor. The plane lifted off the track magestically and veered straight into the wooden fence, despite my best efforts to control it. That didn’t take long. Welcome to the world of the R/C pilot.

You see, this wasn’t entirely unexpected for me. When Seth (my brother) and I were just barely teenagers, we were fascinated by R/C airplanes. Seth finally managed to convince Dad to buy (I don’t know whose money was actually involved) one…a nice trainer with a 0.40 nitro engine and all of the accessories. The sage advice from experienced R/C pilots was: you will crash it…at least a few times. Dad got cold feet and sold it. We were somewhat devastated. Good move.

I collected the plane from the grass in front of the fence. Ah, nothing wrong…my lucky day. I set the plane back out on the ground and started the motor again. Ugh. Something doesn’t sound right. The motor had broken away from its mount. It was attached using the fine-pitch screws like those used to attach motherboards to PC cases. They were stripped-out. I replaced them with small sheet metal screws when I got home. This was much sturdier. It was too dark to fly again by the time I got the plane working again.

The next day (Wednesday), I took the plane out again. I tried taking off from the ground again. But, the plane kept getting stuck in the gravel. Must have gotten lucky the first day. Some neighborhood kids where skateboarding on the paved access paths in the fairgrounds. “There’s too much gravel down there. Why don’t you fly it up here on the pavement?” they called. “There are more trees, cars, and power lines, up there, I responded.” They lost interest in my feeble efforts after a few minutes. Kids are just like adults, a lot of them are all talk and no commitment. Good riddance.

It occurred to me that perhaps rather than practicing take-off and landing, which is what I wanted to do, I should actually follow the instructions, which suggested hand-launching for the first few flights. Holy cow, the instructions were right. Perhaps I should read them more often. I was rewarded with about 30 minutes or so of good flights and a few soft crash landings in the 3-ft deep grass before the battery died. I did actually kinda manage a real landing on the track, too. Rock on.

I charged the battery overnight and couldn’t wait to fly again. I managed a couple of good short flights that ended up in the tall grass. But, I really wanted to try landing on the track. While bringing the plane parallel to the track in preparation for descent, the wing brushed a tree and the plane careened to the ground. Only the landing gear appeared to be damaged. I bent them back into shape with my Leatherman Tool. I set the plane back on the track and did a preflight check. Everything appeared to be working OK. So, I decided to fly again. The plane felt a little sloppy this time. I couldn’t turn right and had trouble climbing and diving. I tried to bring it back over the track; but, it headed off to the northeast (toward a large herd of airplane-eating trees.) I cut the engine and started it into a dive, thinking that the plane was already over the trees. Fortunately, I saw it come down 50 feet in front of the trees…whew! Unfortunately, it sustained some pretty severe damage, some of which I’m still discovering.

I repaired the broken V-tail with some epoxy and packing tape, plus part of a K8GU QSL card. It appears that the servos are no longer attached to the airframe. That’s tonight’s project…although, I should probably do something with Sarah.

The moral of the story is this: R/C airplanes are not cheap, even if they’re free. Just like the saying goes, “Linux is only free if your time is worthless.” It’s a heck of a lot of fun, though. I’m afraid I might get sucked into another expensive hobby!

The blog…

April 7th, 2007

It never seems that I have time to update the site as completely as I would like. Part of that is in no small part due to the fact that I have to edit lots of HTML using vi. Some sort of CMS (content-management system) was in order. I’ve decided to go with the blog format because it’s a little like a research notebook. I can keep my thoughts somewhat orderly and don’t have to make massive entries as I work on things.

This is my philosphy on the blog: it’s a way for me to organize my thoughts in a public setting.

Enjoy…