There are electrolytic capacitors near where he was heating, and the capacitance of electrolytics can have a strong temperature dependence. He probably managed to heat one of the electrolytic capacitors, which happened to change its capacitance in the correct direction to make the circuit work.
Chances are the monitor would work reliably if all the electrolytic capacitors were replaced.
Edit:
I'm guessing the problem is C208. Section 10 of the LDO data sheet, linked in the article, talks about how stability is dependent on the output capacitor (C208). C208 has probably dried out, reducing its capacitance and making the LDO unstable. Heating was enough to make the circuit stable (for a while).
Further edit:
Predating my comment, "Gordonjcp" also called out C208.
In over 35 years of troubleshooting gear and systems, my experience is that 90% (no exaggeration) of problems are bad cables.
It seems even worse, these days, with high-speed serial cables, running on razor-thin margins, and often with embedded ICs.
That's why, when the IT geek comes to your desk, they just rip out all your cables, and replace them with new ones, out of the shrink-wrap. They'll toss out a hundred dollars' worth of perfectly good cables, because they know the deal. They could waste an hour, trying to troubleshoot a problem caused by an intermittent USB C cable.
But capacitors are definitely the second most common issue.
Also, here's a related article describing how a Chinese failure at industrial espionage created a worldwide capacitor problem: https://www.theguardian.com/technology/blog/2010/jun/29/dell...
Lo and behold, I saw three 1000uF caps that had leaked, one of which had a clear bulge on the top. So I ordered a bunch of replacements off Mouser, bought myself a soldering iron, and replaced all three. Worked like a charm!
I’ll never understand why even high-end equipment manufacturers wind up using crappy knockoff capacitors in their stuff. It seems like it’s just a failure waiting to happen. I guess they get to make good money on the support and service?
drop the operating temperature of a capacitor by 10°C and you extend the life by 10x. The inverse is also true.
Crappy caps will die more quickly than top of the line capacitors, but they'll all die eventually.
More examples: https://www.google.com/search?q=power+supply+blinking+light+...
https://en.wikipedia.org/wiki/Micro_Genius
There's a photo of us smiling at the counter of a department store, handing over money. We bought a couple of multi-game cartridges. 190-in-1 and 27-in-1 or something.
We tested it in a Hong Kong hotel room, and briefly played a few games. Then imagine our dismay when we eventually got back to Australia and the thing wouldn't reliably load a game. We were blowing on cartridges and all that.
One day, we gave it a shot up in our non-A/C, second-storey bedroom. It was a 40 deg C day, so absolutely cooking upstairs. The console worked! The games loaded! We got to play an assorted of games we'd been eagerly waiting on.
We eventually decided it must be the heat and on the next day I can remember us taking it in turns with a hairdryer trying to warm the console or cartridge to get a game to start while the other person played. It might let us play for several minutes and then fail. Unfortunately, this trick didn't last for long and then the console was surpassed and the games no longer kept our interest.
30 years later, I still have the useless boxed console in my garage and can't bear to throw it out.
For my kids, I'm not sure the Micro Genius era of games holds up to the sandbox style of say Goat Simulator or constant chaos of Fortnite. Bit of a shame. In hindsight, I should've walked them through a bit of history of gaming in sequence.
But you reminded me that we did take it to an electronics store for a quote to try and fix it, and I think the quote was more than we paid for it. Also a bit pointless with the pace new consoles were being released!
> A common issue with these types of components is that the quiescent current which ensures for the internal circuitry to work properly depends on the ambient temperature. If it’s too low and the regular doesn’t have enough supply current left the output appears to be dead.
Which honestly makes very little sense to me, and also reads a bit like a terminology tombola. A quick googling did not turn up more material on the idea that voltage regulators depend on the temperature like that, and it would be surprising (generally electronics performs better when cooled).
I would expect the problem to be due to a bad solder joint, which would explain why heating it helps since it might make the solder flow a little bit back into making connection (although hair dryer temperatures at 200°F/93°C) are too low to properly reflow solder). Or it might just make components and/or solder expand enough to make contact (which is kind of the same thing but different).
All real hardware experts, please explain. :)
I'm wondering if perhaps C206/C207/C208 in the LDO circuit that decouple the output might have gone a bit leaky and warming them up causes them to act more like capacitors and less like resistors to ground. If they're SMD multilayer ceramics that would be a pretty common failure.
https://en.wikipedia.org/wiki/Low-dropout_regulator
https://en.wikipedia.org/wiki/Low-dropout_regulator#Quiescen...
This statement seems to get the relationship between quiescent current and the operation of internal circuitry backwards.
Quiescent current doesn’t power the internal circuitry. Quiescent current is a measure of current consumed by the internal circuitry while it’s idle.
The temperature relationship exists because the circuitry consumes more power when it hot. But there isn’t some temperature dependent magically quiescent current provider that must work correctly for the rest of circuitry to operate. Just like there isn’t a “standby power provider” inside of a TV to allow it to remain in standby. The standby power is just a measure of the power consumed while in standby.
I still don't think it makes sense; it's not as if you have the heat the device to be hot enough to draw the quiescent current, it's the other way around. As the internal temperature rises, the efficiency of the components degrade, things start to "leak" more current and the quiescent current draw goes up.
On my first pass I was also a bit confused whether he is talking about the regulator's internal circuitry or something else: It's not obvious that LDO stands for low-dropout regulator, so at first it felt like he's misusing "quiescent current" to refer to some kind of "standby current" (comparable to an ATX power supply +5V Standby line) that the regulator has to supply to some other circuitry that then powers on the regulator to supply the rest of the device.
Did kind-of the same with my Philips TV a while back. Still going strong.
https://www.devroom.io/projects/repair-philips-42pfl6057h-12...
Or inside the IC a bad bonding between the chip and the package leads. Or IC package developed cracks and moisture creeps in.
Yeah, most probably it deformed into contact
Not a hardware expert either, but Wikipedia points at this TI doc[0] which claims ambient temperature is necessary for the quiescent current. There's no mechanism described there, though.
No it does not say that. It says ambient temperature is a factor contributing to quiescent current:
"The value of quiescent current is mostly determined by the series pass element, topologies, ambient temperature, etc."
In an LDO you normally want as little as possible quiescent current when idle. You certainly wouldn't design stand by operation to be dependent on temperature. If it turns out to be so with time, it's an aging problem.
That being said, I'm often struck by how often something can be fixed by just opening it up and looking at it, even if you know next to nothing about the internals.
Two examples, both car-related:
- I used to drive an old Ford Ranger, and one day it started running like crap. Horrible acceleration, engine running rough. I made an appointment with a mechanic, but the day before my appointment I thought "What the heck, I might as well look at it." I popped the hood and immediately noticed that the air filter housing was cracked in half. Patched it up with duct tape, and it was good as "new".
- One of my wheels started making a godawful constant squealing. I couldn't drive 10 yards without turning heads. I brought it into the mechanic, where they took the wheel off and promptly a pebble fell out of the brake calipers. Had I just jacked it up and taken the wheel off myself, I would have saved a trip to the mechanic.
Is this some kind of a trend that I'm not up to date with?
I was surprised to find out that my laptop fans started first getting noisy and then rattling after less than two years since purchase. I searched around and apparently the tight tolerances combined with low quality of the bearings eventually produce this effect.
This is especially audible if I let them heat up - it appears that thermal expansion is enough for the blades to get too close to the housing.
I ordered a set of new ones and appropriate tools, but I can't imagine doing this every two years. My previous laptop lasted around seven, after which both the battery and the power socket gave out.
It's called planned obsolescence and it's part of the factory-to-landfill pipeline. It's not exactly new.
Do we know how to make a long lasting laptop fan? Yes. Would nearly every consumer pay $0.25 more for a laptop with a longer lasting fan? Yes. Can you buy laptops with high quality fans? Yes, but seemingly only by dumb luck.
By the time you figure out that a product has a high failure part the company will no longer be manufacturing it and therefore reviews won't be relevant (granting relative immunity to bad reviews). And when every brand is doing it, there's no way for "free market" competition to sort it out. It's a race to the bottom. (3. 2. 1. Cue "The morality of protecting share holders eclipses the morality of ripping consumers off.")
I only buy used laptops now. The significant reduction in price is a reduction in risk. Also a used product has had "burn in" time to weed out the lemons. The engineer calculated xx% of fail-early laptops often aren't the ones being resold.
I'm bitter. I'm cynical. Despite being aware of my mind's ability to find patterns to confirm my biases... I'm really struggling to be excited about new products. I'm spent like nuclear fuel; I'm toxic. They say knowing is half the battle... not in psychology. Doesn't help me a damned bit.
Today's sponsor is Better Help. I should just stop now.
I've felt this so many times that I gave it a name: "the falling physicist problem".
A physicist falling without a parachute from the very top of the troposphere knows, that his terminal velocity is around 50m/s and was reached via gravity pulling him towards the ground.
Nevertheless he's going to go splat the same way anyone else would, because sometimes knowing is just not enough.
Are you willing to pay for it though?
As others have noted, it's in fact probably bad capacitors, which is a really common issue for electronics of that era. I also encountered that several times, it's a quick fix if you know how to solder new ones, and you can find such capacitors for cheap (like 1$ cheap last time I had to look, though finding that price for a single one is hard, and much less when bought in bulk).
It wasnt, the explanation in the blog is nonsense. 10 years is a good lifespan for capacitors working in hot environment, and that is what failed. Electrolytic Capacitors are perishable, they age even when not used.
>I ordered a set of new ones and appropriate tools, but I can't imagine doing this every two years. My previous laptop lasted around seven, after which both the battery and the power socket gave out.
then use better quality replacement mechanical part. People arent surprised when servicing cars, why different expectations with modern electronics?
But not that perishable. I have some old electronics, along with fully analog devices (guitar effects) and they, along with their power supplies(which get hot) still work.
> People arent surprised when servicing cars, why different expectations with modern electronics?
Because they have orders of magnitude less moving parts - if any.at all. Is it unreasonable to expect something that has one moving part to not fail after two years?
Actually, I wouldn't want a car exhibiting mechanical problems after such a short period.
Good luck !
There are a lot of similar 10 year old reports on the net. E.g.: https://www.badcaps.net/forum/showthread.php?t=24494&highlig...
1$ - Blowing a hairdryer at the monitor
9,999$ - Knowing where to point the hair dryer...
I would have no idea where to start to find that fix, or even where to find the schematics!
https://en-academic.com/dic.nsf/enwiki/2011837#Problems
https://semiaccurate.com/2009/08/21/nvidia-finally-understan...
>On July 2, 2009, the date being ironically a year after the notorious 8-K that publicly kicked off bumpgate, the company put up a job listing for a “DIRECTOR OF PACKAGE TECHNOLOGY”.
https://notebooks.com/2008/10/10/apple-to-replace-faulty-nvi...
It took longer and longer to turn on. Some guy on YouTube used this hair dryer trick. So I did just that, blow the air inside the TV from below through the panels, and like magic it works again. Life hack!
Curious why it works though
Not to be a worry wart, but a long time ago we got a batch of monitors with a defective board. A capacitor overheated, melted some sort of glue on an adjacent component, which in turn dripped on a power supply component, shorted out and started a fire.
A couple of days later, it happened again… and we ended up getting all hands on deck to find those monitors.
Also good to think of alternative fixes like this when it's difficult to source replacement components.
Also another Radeon card was identical as a more powerful one, except that two pins (maybe wrong word) were not connected. I drew the connection using a pencil directly on the board and it worked as well, saving around 100 Euros.
It's over a decade ago, so details may be slightly wrong. But still interesting how low tech solutions worked on such complicated machinery.
That being said, you don’t want to use that oven for food purposes anymore. Lots of toxic chemicals will off-gas in the reflow process.
ETA this reminds me of the Xbox 360 “red ring of death” fiasco. One DIY repair technique was to wrap the entire Xbox in towels blocking all the ventilation. The theory was the resulting overheating would reflow the failing BGA solder joints. I don’t know if this really worked or was anecdotal but it was one I remember seeing a lot.
Just run the oven at full heat for an hour and you are fine - the same process that off-gassed the chemicals in the first place, will also deplete them from the oven when you run it later. (Keep the vent on, or ventilate the kitchen.)
I got bored after a month repeating the same thing every day and sold it unrepaired.
https://badcaps.net/forum/showpost.php?p=1002389&postcount=7
If OP had a broken trace in there, then heat might have fixed it. Then again, OP's reasoning is probably better as I am not a hardware guy.
He may have added solder to fix the trace, but he didn’t melt the trace itself.
Context: https://www.reddit.com/r/mildlyinteresting/comments/gho3s4/m...
After 30 minutes or so, another part of the board has fried, so I just replaced the monitor, quite sadly.
Got it running again, and I managed another ~year out of it, before my then-two-year old daughter poured a pint of milk into the keyboard.
