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A VGA monitor may be easier to repair than you think

cnx-software.com

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Re: A VGA monitor may be easier to repair than you think

#51

Post by janci »

barbegal wrote: post #18
jeroenhd wrote: post #9

I'm always wary if these guides. If you know what you're doing then yes, replacing a capacitor is a quick fix to give your hardware a new lease on life, but you can get seriously injured or even killed if you mishandled the open power supplies these devices often contain. 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 s…

IEC 60335 and IEC 62368 state that the voltage across the capacitors must be below 34 V in 1 second after the input power is removed. Modern electronics are remarkably safe and I have never heard of anyone being shocked by power supply capacitors in the last decade. Of course cheap electronics sometimes aren't standards compliant and bleed resistors can conceivably fail hence the advice to wait a bit longer if you wa…

Probably this is only about exposed terminals? Like touching the power plug will not shock you, but poking at the internals could.

Re: A VGA monitor may be easier to repair than you think

#52

Post by _fizz_buzz_ »

nathan_f77 wrote: post #22
barbegal wrote: post #18

Earlier quoted context omitted.

IEC 60335 and IEC 62368 state that the voltage across the capacitors must be below 34 V in 1 second after the input power is removed. Modern electronics are remarkably safe and I have never heard of anyone being shocked by power supply capacitors in the last decade. Of course cheap electronics sometimes aren't standards compliant and bleed resistors can conceivably fail hence the advice to wait a bit longer if you wa…

I'm working on a project where I may need to open and repair an old device that probably contains some high-voltage capacitors. Would it be relatively safe to do this if I was wearing rubber gloves + shoes, and used a multimeter to check for voltages, and a large resistor to discharge any capacitors? What kind of bleed resistor is typically used, e.g. for old TVs?

> a multimeter to check for voltages, and a large resistor to discharge any capacitors

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.

Re: A VGA monitor may be easier to repair than you think

#53

Post by tyingq »

sysadmindotfail wrote: post #43
zbuf wrote: post #23

I feel old; I came here for a guide to repair a "VGA monitor" and instead got a flat panel.

I am old. I did not even open the link until you mentioned it was an LCD. I was thinking: "Why would you repair a CRT?"

Comes up fairly often as a nostalgia thing for old Macs, Kaypros, Compaqs, arcade games, and so on.

Re: A VGA monitor may be easier to repair than you think

#54

Post by HPsquared »

mrweasel wrote: post #15
glugc wrote: post #2

Opening Amazon and buying a new one is even easier and you end up with a more modern and therefore better product.

I don't completely disagree. VGA should have been removed from monitors 10 years ago. Some companies still buy new monitors and hook them up via VGA. That should be prohibited by labour laws. The image quality wasn't good enough to be used for an entire work day in 2010 and it certainly isn't acceptable today. Tens years ago I argued with a previous boss that it didn't matter how cheap the monitor was, he shouldn't f…

I think with VGA, being analog, the image quality depends on the specific hardware. I've used monitors on 1080p 60Hz using VGA cable and it's been fine. On the other hand, I've also had poor image quality (ghosting) at the same resolution with a different cable and monitor. So it is possible to have decent quality on VGA, but not guaranteed.

Re: A VGA monitor may be easier to repair than you think

#55

Post by _fizz_buzz_ »

Waterluvian wrote: post #21
barbegal wrote: post #18

Earlier quoted context omitted.

IEC 60335 and IEC 62368 state that the voltage across the capacitors must be below 34 V in 1 second after the input power is removed. Modern electronics are remarkably safe and I have never heard of anyone being shocked by power supply capacitors in the last decade. Of course cheap electronics sometimes aren't standards compliant and bleed resistors can conceivably fail hence the advice to wait a bit longer if you wa…

What do bleed resistors drain towards if the ground wire has been unplugged by unplugging the monitor?

You should never discharge towards the ground wire. The resistor is simply across the two poles of the capacitor.

Re: A VGA monitor may be easier to repair than you think

#57

Post by mikewarot »

Since the title specified a resolution, I assumed a VGA CRT with a DB15 connector. (Not an MDA, CGA or EGA) I was all set to warn you kids about the dangers of CRTs, high voltage, Xrays, and of course the implosion if you break the neck of the tube... and instead got bad capacitors on LCD displays.

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!

Re: A VGA monitor may be easier to repair than you think

#58

Post by hulitu »

barbegal wrote: post #18
jeroenhd wrote: post #9

I'm always wary if these guides. If you know what you're doing then yes, replacing a capacitor is a quick fix to give your hardware a new lease on life, but you can get seriously injured or even killed if you mishandled the open power supplies these devices often contain. 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 s…

IEC 60335 and IEC 62368 state that the voltage across the capacitors must be below 34 V in 1 second after the input power is removed. Modern electronics are remarkably safe and I have never heard of anyone being shocked by power supply capacitors in the last decade. Of course cheap electronics sometimes aren't standards compliant and bleed resistors can conceivably fail hence the advice to wait a bit longer if you wa…

IEC states what should happen. I strongly suggest making sure that the capacitors are discharged before working on any circuit.

Re: A VGA monitor may be easier to repair than you think

#59

Post by jve »

mikewarot wrote: post #57

Since the title specified a resolution, I assumed a VGA CRT with a DB15 connector. (Not an MDA, CGA or EGA) I was all set to warn you kids about the dangers of CRTs, high voltage, Xrays, and of course the implosion if you break the neck of the tube... and instead got bad capacitors on LCD displays. Regardless of what the safety standards say, you should always remove power, and short any capacitors with a screwdriver…

Thanks. I appreciate when someone gives safety advices as they come in handy when starting to tinker electronics. When repairing dishwasher I had to disconnect a huge capacitor... well it looked like it. Knowing what you just wrote about capacitors, it gave me shrugs and I was VERY careful handling that piece of thing.

Can you give any advice on what good fume extractor for soldering does and if hobbyist that does repairs now and then should care?

Re: A VGA monitor may be easier to repair than you think

#60

Post by cesarb »

mrweasel wrote: post #15
glugc wrote: post #2

Opening Amazon and buying a new one is even easier and you end up with a more modern and therefore better product.

I don't completely disagree. VGA should have been removed from monitors 10 years ago. Some companies still buy new monitors and hook them up via VGA. That should be prohibited by labour laws. The image quality wasn't good enough to be used for an entire work day in 2010 and it certainly isn't acceptable today. Tens years ago I argued with a previous boss that it didn't matter how cheap the monitor was, he shouldn't f…

> or a system that only supports VGA for some reason

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.

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