Needing more than a spark test?

[homebrewed]

I'm a little peeved at the moment. The laptop I've been using for my lab (which includes the XRF/Teensy stuff) died yesterday. At least, it didn't boot up when I pressed the power button . It doesn't even perform the POST sequence -- the fan spins up for a moment and then it shuts down. This vintage of laptop (a Dell Inspiron 6430) is supposed to display some trouble codes on the LEDs but that doesn't seem to be happening, either.

I've gone through all the recovery procedures I found on the internet, which basically amount to removing the battery, holding the power button down for 30-60 seconds, then re-installing the battery. No luck. Some have suggested powering up the computer without the battery, which apparently can get confused about its charge state: but when I tried it, the computer didn't do ANYTHING, just acted like an expensive paperweight.

I bought the laptop as a refurb and up to now it's worked great. Fortunately I've been doing regular backups so I should be able to recover fairly quickly. Since the laptop doesn't get far enough to display any error messages regarding the SSD I think it's likely that the SSD is OK so one option would be to extract it and stuff it into another computer, or use a USB adapter to convert it into an external drive.

I opened the computer up and found that the battery for the BIOS backup is dead as a doornail. I ordered a replacement, on the theory that it's a relatively cheap item and will try that but am not optimistic it will fix the problem. The battery is a CR2032 with tabs spot-welded on it, and some vendors think that makes it worth $23. Crazy. Fortunately Capitalism works, but, even so, it cost almost $5 for the stupid thing.

 

[homebrewed]

Well it wasn't as bad as I had thought. The problem actually wasn't the computer at all, it was a circuit breaker that opened for some reason -- combined with an old computer battery that isn't holding its charge very well. The breaker actually caused more grief than just the computer -- a friend brought over an old record turntable for me to look at and it appeared to be dead; and the same breaker affected some outlets in our kitchen so one of our kitchen appliances looked like it was a goner, too. The breaker interrupted normal activities for almost an entire day..

I need one of those plug-in outlet testers!

 

[rabler]

Well it wasn't as bad as I had thought. The problem actually wasn't the computer at all, it was a circuit breaker that opened for some reason -- combined with an old computer battery that isn't holding its charge very well. The breaker actually caused more grief than just the computer -- a friend brought over an old record turntable for me to look at and it appeared to be dead; and the same breaker affected some outlets in our kitchen so one of our kitchen appliances looked like it was a goner, too. The breaker interrupted normal activities for almost an entire day..

I need one of those plug-in outlet testers!

Those are the things I kick myself for not realizing immediately , sometimes knowing too much gets us sidetracked from the basics …

 

[WobblyHand]

Those are the things I kick myself for not realizing immediately , sometimes knowing too much gets us sidetracked from the basics …

I find that one of these units is very handy to have around. Great for now only checking if the outlet is alive, but if it was wired ok. It's not fool proof, but its a great quick check. A correctly wired outlet will light the top two lights.

 

[homebrewed]

Those are the things I kick myself for not realizing immediately , sometimes knowing too much gets us sidetracked from the basics …

Yeah, been there far too many times. I recall one failure analysis project where I traced the problem from one pin all the way through the IC to another pin. It was a laser driver IC and it turned out that the detector diode in the laser package was over-driving the feedback circuit, causing it to latch up. It was a design problem -- poorly designed amplifier circuits can switch from negative gain to positive gain if their input is over-driven: so they latch up. Apparently the design wasn't tested thoroughly enough before it was released for sale.

If i'd done a better job of checking all the device pins I would have gotten there MUCH sooner. But on the other hand, my finding motivated the designer to improve his design.

 

[graham-xrf]

I was always in a design build situation where I would (have to be) sidetracked, not even by the basics, but also by the details - and their fictitious speculated consequences. I had to chase down and debunk even quite outlandish and unlikely scenarios, which included "don't waste money and time investigating it. It's all actually working"! This when I knew it should not be, given the anomaly I knew was in there, because I had put it there when testing.

Finding a catastrophic software error (that could injure people) in servo software that was in "two wrongs can make a right" physical wiring error situation involving a reversed polarity position sensor made me cautious, perhaps unreasonably so. It was no problem for that build. It was the next one, correctly wired, that would madly move half a ton at maximum power. This is a analogous situation to Mark's laser detector.

This burdens me. It slows me down. I find it hard to shake the need to check everything to bonkers. It's a personality flaw reinforced by the military aviation standards I started out in! Perhaps the only solace is that the late Richard Feynman also had it, but he was really smart, and could see further and faster than the rest of us.

If you want to test your trust response, go ahead and submit your code to GPT-4, and ask for it to be given back to you as a "no loose ends" perfect listing, fully debugged, and maybe in C++ when you started with Python!

 

[rabler]

I was always in a design build situation where I would (have to be) sidetracked, not even by the basics, but also by the details - and their fictitious speculated consequences. I had to chase down and debunk even quite outlandish and unlikely scenarios, which included "don't waste money and time investigating it. It's all actually working"! This when I knew it should not be, given the anomaly I knew was in there, because I had put it there when testing.

I tend to be at the opposite end of the spectrum, chasing side projects and other , new projects and getting distracted, so things never really get wrapped up, just another increment. But it keeps me entertained and I do have a few working tools/machines/gadgets

 

[homebrewed]

FYI, for anyone wanting to build a PMT HV supply from the ground up -- at least in the US -- electronic goldmine has some high voltage transformers that are claimed to output KV-level voltages with just a 3VAC input. Not too expensive, in the $5 range.

 

[homebrewed]

BTW I just noticed that the thread is now up to 200 pages.

I find that one of these units is very handy to have around. Great for now only checking if the outlet is alive, but if it was wired ok. It's not fool proof, but its a great quick check. A correctly wired outlet will light the top two lights.
View attachment 443395View attachment 443396

I now own something similar! For about $9 it's a nice addition to my tool collection. The one I got also can test GCFI outlets. Press the button to see if it kicks out or not.

A fact about GCFI outlets (most likely fully understood by folks on this forum). They're designed to also protect outlets downstream in a situation (like a kitchen) where you need a number of protected outlets. It's important to make sure you connect the incoming line to the INPUT side of the GCFI. If you inadvertently swap the connections, the downstream outlets aren't energized -- ever. We had some (bad) renters who replaced a GCFI and weren't smart enough to figure that out. So naturally the connections were wrong. They complained about the dead outlets and it took us awhile to figure out what was going on. Things went downhill so we weren't able to go in to troubleshoot things until they were evicted.

 

[homebrewed]

The CCFL driver boards I ordered from ebay have arrived. It turns out that this particular version is fairly sophisticated, because it automatically shuts off if there isn't a CCFL lamp connected to it. I found some information on the web that provides information on how to bypass that (for troubleshooting purposes). The document clearly wasn't written by a native english speaker/writer but using that info I was able to get the driver to stay on.

I made a 1000:1 divider using a string of ten 10-megohm resistors and a 100K resistor so I can safely examine the output on my scope. The peak voltage output is a bit more than 2KV. I can drop the peak down to a little over 1KV by reducing the supply voltage, but the circuit stops working when I reduce the input voltage much below that point. I'm thinking that placing a small load on the output will drop the peak voltage. To reduce power dissipation I'll try a small high voltage capacitor.....when I get some. The high voltage capacitors I have on hand are too high in value.