No User Serviceable Parts

The first thing I setup is the network and computers. Much to my sweetie's consternation, the dining room has been taken over by machines. She's been a good sport about it. She knows it's part of the deal. You take me, you get the computers too.

It was a little touch and go for a while. Soon after my computers and I moved in, the house lights started flickering. We'd be sitting in some room and suddenly there would be a brownout. The lights would flicker a few times and then everything would return to normal. For a while.

"It's not my fault," I'd protest. Computers don't eat that much power. Besides, I don't keep that many powered up. Just chinacat and glacis. And weiner is usually charging. Plus peavine has been running a lot lately. Also, there is the KVM and switches and stuff. But really, it's not enough electricity to brownout a house.

After a couple weeks of dreading the worst, she called an electrician. He rummaged through the service panel and rattled the incoming main. He couldn't find anything and I couldn't recreate the problem.

About this time the next door neighbor walked by. "I noticed the electrician's truck," he said. "Have you been having problems with flickering lights?"

This is becoming a nightmare. It's like a bad science fiction movie, where the mad scientist runs crazy experiments in his laboratory and blacks out the entire city.

Or, maybe it was a problem with city power. The electrician thought it could be. So, I called it in. They sent a truck that afternoon and returned later in the week to do more work. So I guess they found something to repair. In any case, there have been no brownouts since then.

This episode reminded me that there is still one piece missing in the computer setup: the UPS (uninterruptible power supply). I've got a nice unit, a Tripp Lite Omnismart 850. It served me well for many years. Unfortunately, I lost it in a storm. One of those nasty Texas storms took down the power. The unit kicked in and held long enough for me to get everything safely powered down, but ever since I've been unable to get it back online.

I wasn't too upset--at first. The unit was several years old and was well due for a battery replacement. What upset me is there was no way to do that. This is not a user serviceable design. There is no access panel. There is no way to get at the batteries short of disassembling the entire unit. I couldn't find anybody local who wanted to work on it. Best I could do is ship it off somewhere, and between parts, labor and freight it would cost so much I might as well just buy another unit.

The problem is further complicated by the nagging feeling there might be something more than dead batteries going on. The unit doesn't do a blasted thing when plugged into the wall. If the batteries were dead, I think I'd at least get some indicator on the front panel. I didn't want to invest a whole lot into it, only to find out it was going to have to be scrapped anyway.

So I figured I had nothing to lose. I'd crack it open and see if I could service it. I am a degreed electrical engineer, you know. I'm supposed to be able to do this kind of shit.

While I'm pretty good with electronics, I'm a mechanical klutz. I twisted and turned and yanked and pried, but couldn't get the unit open. Finally, I unscrewed the nuts on a back-panel D-shell connector, the circuit board slid loose and I had access to all the innards.

When I looked in I saw a cable had pulled loose from the circuit board. Rats! After all that I busted the thing taking it apart.

Oh, well, in for a penny. Maybe I could repair it. As I was getting ready to solder the cable back in, it scraped across the circuit board, touched the back of another component and a spark flew. "Oh shit! This thing is live."

I put a voltmeter across the three 6 volt lead acid batteries. It read 18.3 volts. The batteries were good. Real good! Even after sitting for a few months, they were holding a full charge.

If I can repair the busted wire I may be back in business without even a change of batteries. It will be tricky, though. My tools aren't ideal for this job. I need to solder a spade lug back onto the circuit board, and my soldering iron is better suited to soldering delicate 74LS04 ICs (don't ask).

While this all has been most frustrating, it's been really nice to hold a voltmeter and soldering iron again. For too long, the only tools I've worked with have been a keyboard and mouse.


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re: No User Serviceable Parts

Hex inverter. Low power Schottky.

DIP or small outline?


re: No User Serviceable Parts

Woo hoo! Today I bought myself a $10 solder sucker from Fry's, repaired the broken spade lug and the UPS appears to be back in operation.

In the immortal words of Homer Simpson: I'm so smart! S-M-R-T ... smart!

re: No User Serviceable Parts

In a tangential note: not long ago I heard some alarming claims that computing and the Internet consume as much as 20% of total energy generation in the US. I think it was in this unabashedly pro-nuke lecture.

Fortunately that statistic is not the last word on the subject. At least one major study find those claims grossly exaggerated -- although the Koomey study uses 1999 data and I don't easily find anything more recent.