A VGA monitor may be easier to repair than you think
cnx-software.com
cnx-software.com
Defective capacitors are a common plague in modern electronics, and the culprit is always the capacitor: the market is literally invaded by rubbish quality capacitors, and swapping a bad quality one with another bad quality one guarantees it will fail again one day, so buy only reputable parts from reputable vendors; avoid online purchases of branded parts from unknown resellers (pretty sure that 99.999% of Nichicon or ELNA capacitors sold by any Aliexpress, Ebay, Amazon, etc. sellers are relabeled fakes); pay them more but pay them once. A web/image search for "counterfeit capacitors" works better than 1000 words.
Anyway, when shopping for (hopefully genuine) electrolytic capacitors, respect also the temperature ratings. Capacitors mounted into a power supply are exposed to higher temperatures, so always choose the 105c degrees type. Capacitance is usually not critical; electrolytic capacitors accuracy can be worse than 20%, and that's not a problem because they're not required to be accurate for their job, so if you don't find the exact value, you can safely swap the part with one with slightly higher capacitance; same for the rated operating voltage which can be higher (not lower!). Low ESR rated ones are preferred; if you can, buy them instead of generic ones.
It is not necessary to use such capacitors on the primary side, i.e. when the large capacitor nearest to the mains input dies, just replace it with a normal electrolytic capacitor that matches or exceeds the original’s voltage rating and closely matches its capacity.
Actually, even a quality capacitor will fail eventually, just not as early as the fake ones. As you have mentioned about the heat, the capacitor will be exposed to it and will fail because of it.
The 9 years old range hood in my kitchen is already had the start capacitor replaced twice. Whoever designed this unit decided to place the circuitry right in a hot spot, making sure that the capacitor will be gently toasted to death in a couple of years.
A place I worked at had a bunch of 19" Optiquest LCD monitors which ALL eventually died from a single bad cap on the power supply board. I fixed every one of those monitors, think it cost less than $10 to order the caps from digikey.
Leakage (ie, when a capacitor exhibits resistive properties by conducting current also when fully charged) can be measured easily by using an analog tester or a digital one plus a few parts, while the ESR (equivalent series resistance) measurement would need a proper instrument called ESR meter. The ESR is an unwanted static series resistance the capacitor would exhibit no matter the frequency it works at, it increases with aging and it's independent from the capacitive reactance which it's related to the frequency. Therefore, the lower the ESR, the better quality or condition is the capacitor.
However, you can just ignore the 2nd sentence if repairing a device would require just a bunch of capacitors; quality ones aren't that pricey, and if you find a bulged one, it is often advised to replace all capacitors employed in the same stage anyway. Some in fact can degrade without showing any visible hints of their condition.
In another post here I mentioned fixing Optiquest monitors. The usual issue was you would press the power button and the power LED would flah for a second and... nothing. This is because the output cap of the switching supply would cease to filter the high speed square wave that goes through the transformer. So your DC power supply is now an AC square wave supply. Of course logic circuits don't like that so they will outright fail.
Sometimes there is enough capacitance via decoupling caps, ground planes on the PCB and local filter caps on the logic board so the initial power up works but once the load increases the ripple increases until it becomes AC again and everything goes haywire or shuts down.
If there aren't many, one can just replace all of them.
Regardless of what the safety standards say, you should always remove power, and short any capacitors with a screwdriver or freshly checked jumper lead, as bleeder resistors (and jumper leads) fail. LCD backlights with cold cathode fluorescents use quite a bit of voltage, so be careful, and good luck!
Can you give any advice on what good fume extractor for soldering does and if hobbyist that does repairs now and then should care?
I shocked myself almost immediately as I was doing basic examination. I hadn't even gotten to probing for shorts or broken connections. Thankfully, the shock wasn't bad, more startling than anything (I remember it being somewhat like brushing up against an electric fence). I was wearing a grounding strap on the arm of the hand where I got shocked. Not sure how much/if that helped any.
That was enough for me to determine I wasn't qualified to work on it. I reattached the case and lived with its flakiness for a few years longer until it was replaced with an LCD.
Not universally a good idea to do that, especially not in a power supply. Safe enough in some circumstances but not all. Better to buy a discharge probe or make one by soldering a 2200 ohm 5w resistor between a couple of insulated wires.
EDIT: made it less condescending.
I learned dealing with 600V monster filter capacitors in vacuum tube power supplies, they'll happily vaporize a screwdriver and knock you off your feet in the process.
A friend gave them away since their backlights would flicker making the monitor unusable for the first 10 or so minutes after they were turned on, after which they worked completely fine.
I have little to no knowledge of electronics, but did know how to use a soldering iron. As I recall, I watched a YouTube video and was confident that if the problem was just the capacitors, then I could manage to replace them.
I opened up the monitor, saw two or three capacitors which were clearly bulging and I used a soldering iron to get them off the board.
I went to an electronics shop expecting that someone there would be able to advise on replacements which would work. As I recall one or more of replacements they had available on hand had a different "number" on it, but they assured me it was a higher rating and wouldn't affect use, I don't know much about electronics, but this made sense to me so I trusted it.
I managed to re-solder them on and they then worked perfectly.
Fast forward to today, about 9 years later, and my brother is still using both the repaired monitors. They have DVI input, 1080p resolution and VESA mounts so are actually very decent unless things like >60Hz refresh rate, higher resolution or very good colour accuracy are important to you.
It's probably the amount of farad units the capacitor is rated for. You can often use a capacitor with higher farads as long as the voltage is the same and it can be even more reliable than the original part, the only trouble is sometimes they are physically larger or taller, so you have to be careful if you're working in tight spaces.
But in the past few years, retro tech has become sufficiently popular due to certain YouTube channels that a CRT TV or monitor in good working condition can now command a worthwhile price.
Same here. And I didn't think I was that old...
Really, it was more that we didn't have DVI outputs.
Its the smartest way to break the chicken-egg situation -- for many (I'd wager the majority) the advantage of a flat panel at first was more about space saving then picture quality.
The problem is, you can't add DVI to a VGA-only LCD monitor, and those things were everywhere.
This guide addresses the danger by saying you need to "wait for a while" without telling you what "a while" is (a minute? 5? an hour?) and how to spot the dangerous parts of the circuit board.
Having said all that, I think a general education on how devices like these can be fixed (safely!) is something a lot educational facilities should offer. Repairing basic and often even more advanced electronics requires little more than replacement parts, a soldering iron and some practice, but people are quick to throw something out when it stops working. The assumption seems to be that things are too complex to repair these days, but in all likelihood dead devices just had some protective circuitry do its job and fail before frying the mail circuits.
Note: do NOT do this with thin wires and large capacitors / arrays of capacitors, or you may get a hot copper shower.
Putting the leads over a capacitor, the multimeter will show the voltage and discharges the capacitor with a constant safe current. Beeps can be used to indicate when the capacitor is safe to handle or not.
That's all that I use. Don't hold the resistor in your hand though, depending on the size of the capacitor they can get quite hot. I usually use some pliers to hold the resistor.
If you take any capacitor and charge it, it'll take quite some time to discharge on its own.
The discharge is usually controlled by a resistor in parallel with the capacitor on the PCB. Removing the capacitor from the board disconnects it from the discharge resistor. So not much "modern electronics" going on here :-P
[edit] Ah I see this is called a bleed resistor, never mind
"Shawnee teenager is electrocuted while working on a computer":
https://www.kctv5.com/story/19767067/teen-electrocuted-while...
Same story as above as link not available:
https://www.dailymail.co.uk/news/article-2215200/Teenager-Sh...
And a warning:
"I just received an electric shock from an unplugged computer"
https://www.reddit.com/r/computers/comments/53cio2/i_just_re...
Then Google bought SageTV[0] and they stopped producing software/products. Meanwhile, I wanted another TV hooked up. Taking apart the device revealed capacitors that -- even though I had been unfamiliar with the issues -- were obviously bad -- one had leaked all over itself, others were bulging.
I hit up ebay, repaired that, and thought about the growing pile of unreliable/broken hardware in a room that I had been putting off salvaging. That weekend, I repaired about ten LCD monitors -- caps in the PSU all around, one old plasma TV, 5 ATX power supplies and two NetGear 1Gbps switches. EVERY single one had varying degrees of damage. All but one power supply was functional again.
[0] The product was a TiVo for PCs and was among the best. Google purchased them as an acqui-hire and -- I think -- used portions of the software in their STBs for Fiber. They later released the code open source.
Man I remember when that happened. I was happy for the SageTV devs but I knew that was the end of a great run. SageTV was our DVR for years... It was such a cool product!
Here are some links that might turn out useful.
http://www.elecrealm.com/down/class/
http://www.mattmillman.com/info/lcd/rovatools/
https://github.com/ghent360/RTD-2660-Programmer/
https://sites.google.com/site/lcd4hobby/home
https://www.codeforge.com/article/258602
> it was clear what the problem was with a swollen C812 capacitor.
> So no need to check anything with a multimeter or an oscilloscope, a visual inspection of the board could immediately detect the issue.
I'm looking at the picture. I'm not in electronics and I can assure you it's absolutely not clear to me that this is the capacitor I'm looking for. So what should it look like ? I understand these things sometimes burn or swell but is it always visible ? And if not, what should I do to detect it ?
I learnt a lot about computing hardware and software on that Pentium box: 166 MMX (overclocked to 200MHz), 16MB RAM (later 64MB), running Debian and my resurrected 15” LG CRT. Oh, and a 56kbps modem.
Just throw the whole thing away (preferably in the garden waste bin for that extra good feeling) and buy a new one. /s
Unfortunately Capacitor is an area that is easiest to cut cost and has no immediate effect on the devices function and are hard to spot. Part of the reason why I switch over to Mac ~20 years ago. I dont want to spend time looking at every capacitor on a motherboard or to gather enough information on all these details. That was before the time when Capacitor marketing on motherboard was a thing.
That is a thing? What do they advocate, the fine smell of rotten eggs when they die?
Good capacitors do exist, but they're getting less common with time; actually you're more likely to find good electrolytic caps in a 30 years old radio than in a 5 years old one. Today some manufacturers are cutting corners everywhere and parts quality tanked.
One day it turned and stayed off, sent it to some local shop for repair, and the tech told me that he added another light control circuit and, my brightness had to be adjusted via an external control. He also said that two ICs damaged, and he cannot source any.
I got pissed, found the parts, removed the other abomination and changed the damaged parts myself.
The monitor came back alive for 30 seconds and then died again.
It had no leaky caps, no visible damage, nothing on the board.
Had to trash it.
So, YMMV.
The tech probably figured out that this was happening but was unable or unwilling to isolate the issue.
I suspect. It was just a run of the mill repair shop. If he had found it, it would have warned me when I told him about my future intentions.
Being 'technical' I'd still suggest evaluating things before engaging to them.
Some repairs aren't worth it. this is per-basis calculation based on your capabilities, experience and time.
So the important word is... MAY be easier... maybe it won't be easier than you think ;)
I was surprised by how simple and spacious the boards in these displays are, easy for an oaf like me to replace components on. Just find where the magic smoke came from and order a replacement part for pennies.
In short, get in there are see what happens. Sometimes you will destroy something, but right now it is landfill material so you didn't lose anything. sometimes it is an easy fix.
The article says it was clear that the cap was "swollen" but how do I know what a swollen cap looks like?
And what if it's broken but not swollen?
I'm not sure it can be broken without being swollen, or at least that's not a frequent failure mode.
Having repaired a few displays just like that, I can say it's really easy provided you are able to open the display and solder on a basic level, which anyone can learn in an afternoon.
On the other hand, not all display will be that easily repaired. Sometimes, you cannot easily identify any swollen capacitors, or there is a burn mark somewhere else, or something else that you cannot identify (and thus order a replacement for). In those cases, unfortunately it generally doesn't make sense to bring it to a shop to be repaired by pros.
Think of SmartTV, microwaves, or every kind of consumer electronics in general.
I used to go along this line of thinking, and had a "dumb" TV for a long time. I would spend hundreds of hours trying to get a PC/xbmc/kodi setup with a remote control to be comfortable, but always required a keyboard and mouse next to the TV. In the end it was a waste of time and I wasn't enjoying my TV as an entertainment device.
When I finish work, I want to sit down and just have everything work. I don't want to have to keep getting up and pressing buttons and messing around to get a myriad of supplemental devices of varying quality to work. I just want one single device, on the wall, with a remote.
And don't get me started on weird bugs that i can't even fix myself. Stuff like my dad's TV randomly outputting 1-2 seconds of audio of the last selected sender /while being turned off/. Audio only, with the screen turned off. Just a few moments. Nightmare fuel when its dark and you are sleeping in the same room.
Regarding data collection, who cares? Just get a pi hole if you really care about that.
Also you are describing a fault that can occur with a dumb tv.
EDIT: okay. I found this https://external-preview.redd.it/DcKcaASCdFkfM-eK5pOiu6DIOZb...
I have a samsung TV and I do not see this. Perhaps this is a region thing. I've lived in The Netherlands and the UK and not experienced this.
Tens years ago I argued with a previous boss that it didn't matter how cheap the monitor was, he shouldn't force anyone to use a VGA monitor and hurt their eyes when DVI was available and only slight more expensive.
That being said, if you need a VGA monitor, perhaps for some retro computing or a system that only supports VGA for some reason, it's better and cheaper to just fix it, if possible.
I have considered digital inputs (DVI, HDMI or DP) mandatory for any monitor I have purchased for myself since 2010 and when people ask me for advice on monitors I advise the same.
AFAIK, nearly all modern servers only have VGA, serial, network, and a couple of USB ports, so it's much more common than you think. Of course, most of the time you'll be configuring them through the dedicated management network interface, so the VGA and serial outputs are mostly a fallback.