Category Archives: General Tips

Dealing With Companies

The first thing to understand is that most companies in most industries have somewhere between zero and strong-negative incentive to help you fix their products. So they’re somewhere between actively hostile (Apple, Tesla) to merely grudging in their help.

In their defense, companies are besieged by waves of lazy, uninformed, self-righteous assholes who won’t RTFM and/or make unreasonable or fraudulent demands. And helping someone make a repair that later fails and gets them sued isn’t good business either.

This is why “first-line support” exists. CSRs and tech support folks are (under-) paid to get your query “resolved” as quickly as possible, where “resolved” means you go away, regardless of whether your problem is solved or not. Specifically, their job is to protect the engineers/experts/smart-people from having to talk to the hordes.

The truth is that those smart people are often perfectly willing to help, but only if you’re competent, respectful of their time, and not a jerk or a nutjob. Reaching such a person-who-can-help-you can be difficult, and it’s often down to luck. But you can greatly increase your chances of success if you:

  1. Do your research. Do not call in with a question that 10 minutes of Googling would answer, especially if the answer is available on the company’s site or in the manual. Doing so immediately identifies you as someone who does not deserve to talk to someone smart.
  2. Know every possible thing you can about the thing you’re trying to repair. Model numbers, serial numbers, date of manufacture, options, configurations. Sometimes you’ll find some other more popular model/configuration that’s similar but not what you have. Be prepared for the rep to assume you have the common thing, and to politely correct them.
  3. Use the knowledge from #1 and #2 to shock and awe whomever picks up the phone. You want them to be convinced within the first 30 seconds that you deserve to be connected to someone smart. What you’re going for is a deer-in-the-headlights moment of silence from them, followed by “Umm…let me connect you with [engineer/supervisor/expert/old-guy-who-knows-everything].” Note that saying you deserve to be connected to someone smart is the exact wrong thing to do. A person who would say that is probably wrong and definitely an asshole. You need to show them, with your knowledge and politeness.
  4. If and when you get connected to someone who knows their stuff, DO NOT waste their time and/or be a jerk. Every minute a competent person is talking to you is money out of their pocket, because it’s a minute they’re not getting their own work done. Get your specific, well-thought-out question out right away, tell them what you’ve done so far, then shut up and let them talk. Bonus if you can make your project sound cool or interesting (without lying).
  5. Often times a someone is willing to help but just comes up empty. Try to probe what they know. Is there a service manual, maybe for a different but similar device? Drawings? In one case I read off 4-5 company part numbers from a circuit board, and one of them matched a schematic in the rep’s database. He said “it just looks like a bunch of circuits and stuff” and assumed I wouldn’t be interested, but agreed to send it anyway. Score!

Troubleshooting Tips

Electronic/Circuit Board Tips

  • A flatbed scanner can help trace single-sided circuit boards. Scan the solder side, then flip the image in software and use the brightness/contrast controls to wash it out (i.e. lighten the image so you can write over it later). Print it, then you can draw the components onto the page.
  • If you find patent numbers on a device, try Googling them. Sometimes the theory of operation is explained in the patent.
  • A huge percentage of electronic problems are due to bad solder joints. Try reflowing joints.
  • A wooden chop stick is a great tool for gently pressing on components on a circuit board under power. Often bad solder joints are revealed this way and there’s little risk of electric shock at any reasonable voltage.

Mechanical Tips

  • A flatbed scanner is a great way to get the dimensions of flat surfaces like gasket surfaces. Scan a ruler alongside the part for scale.

Collecting Information From People

People Know Less Than They Think

It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so.

— commonly attributed to Mark Twain

When you’re diagnosing an intermittent problem you haven’t seen yourself, you rely on the observations of others. But people’s memories and technical skills vary greatly. A tricky situation is when someone who’s reasonably technical has already diagnosed the problem for you, but they’re wrong.

Device A is acting up. Joe replaces a switch and Device A works better again, at least for a while. The old switch tests good, but since replacing it fixed the problem, Joe concludes the switch was the problem. When the failure recurs, Joe replaces the switch again, and it gets better. “Man, that thing is sure going through switches,” Joe says as he tosses a second perfectly-good switch into the bin. What Joe doesn’t realize is that each time he replaced the switch, he had to remove a control panel, which jiggled all of the wires on the panel and temporarily reconnected a bad crimp joint on a quick-disconnect a foot away. But he’ll swear up and down that the switch was the problem. And thus begins the myth of the machine that eats switches.

Unscrewing the panel, moving the panel around, replacing the switch, and putting the whole thing back together made the problem go away — temporarily. All you know is that one of those things helped — and only temporarily. The old switch testing good, and the new switch “failing” soon after installation are red flags. To narrow it down further requires further detailed testing.

People Know More Than They Think

Tom and Ray Magliozzi of Car Talk fame were great at this: a caller’s car makes a noise. After the have-the-caller-make-the-noise-over-the-phone bit, they’d start asking questions. When does it happen? “It only happens when I go to my sister’s house.” It’s pretty unlikely the part making the noise knows it’s at her sister’s house, so the lazy troubleshooter ignores this information. But the smart troubleshooter, like Tom and Ray, asks more questions. What’s special about the trip to the sister’s house? Is it the only time the car gets driven for longer than 20 minutes? Does the sister live on a crappy road full of potholes? Or is there a really sharp uphill turn into the sister’s driveway that requires accelerating the car at full steering lock, revealing the real problem — a bad CV joint?

The Kernel of Truth

People are better at reporting observations than they are at explaining them. This is the basis of mythology: the volcano erupted because the gods are angry because you didn’t sacrifice enough goats. Just because we now know that volcanic activity isn’t appreciably influenced by killing livestock, doesn’t mean the volcano didn’t erupt.

In the case of the load manager, the firefighters driving the engines said that things got worse when they switched on more stuff (lights, sirens, etc.). They figured that the load manager must have been getting overloaded, so it started shedding loads. That’s not a crazy theory — after all, that’s what a load manager does. But the theory was wrong, and it led them down a very expensive path that did nothing to fix the problem.

When I examined things more closely, I found that a) the load manager has no measure of how much load is on its outputs, and b) it wasn’t actually trying to shed any loads. So I knew their explanation was wrong (also because the previous repairs hadn’t helped). However, this only disproved their explanation — not their original observations that turning on more switches made things worse.

It turns out that things did get worse when more loads were switched on — but not because of excessive loads. It was because turning on more control switches put more current through the single ground wire that served all of the low-current control switches on that panel, AND that wire had a marginal connection in the loom, AND the load manager input circuit was particularly sensitive to imperfectly-grounded control switches.