I have a fully functional third-gen iMac (the "jelly bean") that needed its inner bezel replaced. Sourcing a non-broken bezel was one big job, but even after I did, finding someone with the knowledge and skill to repair it safely was a task. I wasn't willing to do the repair myself, it's just too dangerous for an amateur. These machines are supposed to have components that automatically discharge the screen after they're removed from wall power, but on a 20+ year old machine, no way to know whether that was working. You have to touch the screen and fasten it to the inner bezel, so repairing it without proper discharge was a non-starter.
I called around to various TV repair shops and was generally told they couldn't do it, or that it'd be prohibitively expensive. Finally, an electronics surplus store in my area referred me to a gentleman of the old-school AV hippy variety who knew how to repair all sorts of old equipment. He was able to construct a tool to ground the machine while working on it and we did the repair successfully together. It was an adventure!
Everyone in the comments keeps saying "if you don't know what you're doing, go find someone that does, skip the work, dont touch it", etc etc.
i'm here to say that that kind of behavior doesn't foster self improvement and learning.
here's what I suggest : learn about the job, learn about the hazards, take the precautions, get the equipment, don't let your guard down, and then do the work by-the-book.
you'll learn something in the process, both about the thing itself and the concept of maintaining a 'safety culture' around work that requires it. You won't get hurt, because you're going to follow the right safety precautions and work procedures.
Now, if you want to throw your hands up and just say "i'm not willing to put the hours in to ... " , then by all means, don't take the risk -- have it done. If you're in this for the pursuit of knowledge/skill/craft/gratifications then just pursue it as you would anything that is potentially dangerous and take the right steps.
You wouldn't tell someone to stay off a motorcycle, it's an enjoyable past-time -- you would remind them to follow safe driving procedure and to wear protective equipment.
I‘m generally with you here. I also like to learn and do stuff on my own. But there is a catch to some things when self thought. One can read and watch videos for hours and still miss a crucial detail that only a master in the field could teach you. I have high respect when it comes to high voltage, high/low temperatures or any machine work with fast spinning items. One should build up knowledge and confidence in a slow pace when no instructor is present.
For repairing your laptop sure, but there are huge risks with very low margins for error for safety in terms of dealing with high voltage electricity. If you want to do this safely you need to take the relevant electrical classes/certifications to know how, it’s not something a beginner can jump into without assistance. Sure if you fuck up a laptop repair it’s not a huge deal but this will fucking kill you if you’re not careful. Sure you can learn how to ride a motor cycle but you still need a license to do so and pass classes first, and most people deem the risks, efforts, and costs too high to be worth it.
As the author says CRTs are dangerous. Even when they're off they can still carry insanely high voltages. The flyback transformer is one of the more dangerous components of them.
I'm great at electronics repair and I tend to avoid them. Luckily these days that's easy :)
If you don't know what you're doing, you shouldn't attempt it. Just get a more technical friend to do it.
If you do know what you're doing you probably wouldn't need this guide in the first place :)
I've never worked inside a CRT (but may need to soon) and am not great at electronics repair, but I'm a little surprised you describe yourself as having a lot of skill but still tend to avoid them. From my understanding, it's straightforward to reliably discharge them and make them safe to work on. Do you think it's easier to get this wrong than I've understood or do you just feel uneasy about it in general? Just curious!
Ah, electronics hobbyists these days... I repaired my first TV at 16yo, it was a Nordmende B&W set with a resistor directly on the output of the flyback transformer. That resistor was broken which led to a nice corona discharge lighting up the inside of the set, looking at it was like looking at the set of a 30's Frankenstein movie. This set me up for a 'career' of repairing televisions and (later) monitors while at university where I came across all sorts of interesting light/sound/smoke effects from those 35kV flyback transformers with cascade circuits (called 'tripplers' since they were used to raise the output voltage) on large-tube sets.
I never got zapped which is a good thing since yes, that can be unpleasant and - depending on when and where it happens - dangerous. Discharge those tubes and cascades before you fiddle with them, use a screwdriver connected to a ground wire which is connected to the metal tube frame. If you want to do it 'professionally' you'll want to put a HT resistor in that wire, otherwise just zap the thing by sticking the screwdriver under the plastic cap on the high tension connector at the tube.
It's not the transformer that's dangerous, it's the capacitor usually attached to it that's the problem. As transformers are passive components and do not store energy, they will not work without any power attached. The capacitor - if charged - will discharge through that transformer. NOW the transformer becomes dangerous, as usually the capacitor is at the low side for input, and your output voltage is multiplied a hell of a lot.
We do have the mantra in the styropyro discord "Do not the MOT" (Microwave Oven Transformer) but we all know it's harmless without power on it.
I've always wondered why modern multimeters don't have a "discharge" option.
I.e., you select the discharge mode, put the probes on a capacitor, and watch the voltage go down, while an internal current limiter makes sure that it happens at a safe rate.
Yeah, this webpage really should have a big prominent warning label at the top.
The flyback transformer can fucking kill you, and anyone who needs this webpage or is interested in the instructions (ie someone not working professionally in electronics repair and aware of such hazards) is less likely to know that.
That 'snap' is the arc and the voltage = zero until it gets going again - repeat.
This is common on old monitors as dust builds up and often a fix can be done by a careful cleaning plus application of 'corona dope' along spark paths. Turn it on in a dark room and watch/listen for the spark. Dope that path and alternate paths and dry with hair dryer.
Test.
There are universal repair flybacks - select what seems to fit. Usually the existing controller will serve - computer monitors are far smaller than most TV's of that era. Hardest thing is finding new old stock. To save the nation new flybacks can be wound - complex but doable. Hardest problem is adapting the space and circuit. The flyback can be wired point to point with hookup wire. Only the HV wire needs to be HV wire. Then you can zip tie the flyback in whatever space and dress the HV with respect.
> The focus knobs should be tuned so that the screen image is sharp. I don’t really have a good set of steps for this, so just play around with them until the monitor is as sharp as can be.
This explains my methodology for a lot of things in life
I haven't tried focusing a CRT with two focus knobs (horizontal and vertical?), but from my general experience with focusing a CRT oscilloscope and tuning VGA signal sharpness on CRT and LCD, one good way to focus is to create three B&W images of vertical stripes, horizontal stripes, and a checkerboard. When showing the vertical stripe image, tune horizontal focus until as much of the screen as possible is in-focus. Then repeat with the horizontal stripe image and vertical focus, then double-check on a checkerboard and regular desktop usage.
Thanks for sharing! I had a brand new one of these displays in 1999 when they first came out and it developed the same problem a year later. The replacement from MacMall’s warranty company (which was graphite instead of blue) also eventually developed the issue too. Good to know there’s a solution if I ever decide to fix it.
The 21” version was supposed to be solid but I have never seen anyone with one or seen it for sale. The price tag was probably too steep compared to the faulty 17” one. Sad to hear that the graphite model was just as bad though.
Lots of detail and explanations. P.S. I'm not affiliated with anything, I just genuinely think this is one of the best (educational) channels out there on this.
This desoldering component technique video is well worth your time. Of all the basic electronics skills, doing this has always been challenging, particularly on older equipment where the copper traces will tend to peel up.
Having that happen is not the end of the world because a simple bodge wire is not hard to do in most cases.
But, there are times when a failure like that can really matter!
A flyback with the high voltages can be one of those times when you just want a clean replacement.
This guy shows you how to use wire to desolder many component pins at one time.
From what I understand of this, the danger comes from charge stored in large capacitors. So what is the longest that these capacitors can hold a significant charge if the crt is left disconnected from mains power? Hours/days/weeks? Is simply waiting long enough a reliable way to render a crt safe to work on?
(Irrespective of the answer to this, there is no chance at all that I would ever mess with crt circuitry. But I am curious.)
I used to bench repair on broadcast monitors. Typically, the flyback circuits have bleeder resistors and they discharge in several seconds. But you can never trust them. They can stay charged for weeks if the capacitor is good. An old capacitor damaged by heat will still hold a charge for hours. I always shorted them before replacing.
If the discharge circuit is not present/functional, it can be months[1], even if the capacitor was discharged at one point.
When working with high voltage/power equipment, its best practice to keep the capacitors shorted while you are working to keep dielectric absorption from “recharging” the capacitor to 1-15% of its rated voltage.
Maybe I was super lucky or somehow immune.. but as a Kid I got zapped by flyback transformers quite a bit of times.. (5 or 6 times?) It hurts,and it leaves a burn point where it touched.. but did not killed me.
Eventually I learned to ground the whole thing with a cooper cable and a resistor.
We had a bunch of these monitors back in the day, don’t remember any of them dying early. I was always afraid of taking apart CRTs thanks to those transformers in them. People used to overclock monitors back in the day to increase the refresh frequency.
I love this kind hardcore repair hacking to keep hardware going. There is no logical reason to spend time on this, yet someone did. Big respect to the author, you are inspiring!
> To fix a quarter-century-old monitor that was nothing special when it was new.
> Why? I mean, I wouldn't bother fixing the thing anyway, but hiring somebody is going to cost you more than a much better brand new monitor.
There are folks out there who spend their time fixing unexceptional cars such as old Ford Orions, Austin Metros, VW Golf Mk 3's (poverty spec) and so on. In their day these were the most boring of the mundane mass market motors you could buy.
But it's about capturing and snapshotting a point in time. Sure this particular monitor was probably crap, but combined with a same period Mac it's a time capsule.
You might think it's a waste of time, for others it's a hobby/past time. And it's one less thing in the landfill.
Collecting and repairing vintage computer electronics as a hobby is comparable to lego or embroidering, except for this one specific example where it will easily Fking kill you. People might not expect mellow past time to have such dangerous traps.
The sad reality of externality-removed capitalism is why would you do that? In our disposable economy, a new monitor can be had for cheap. Repairing things is for the poor or nerdy. which I resemble the latter pay. Incentivizing fixing things, rather than buying a new shiny flashy thing is not a thing that we do well. Oh well. Hopefully room temperature superconductors and solar and batteries can lead is to a place of victory for the environment in place of coal.
A new monitor can be had for cheap, yes. But a new CRT monitor cannot be had for cheap. If you have reason to prefer a CRT, repairing a monitor you have is probably the least cost option towards getting a working CRT.
Many people don't have reason to prefer a CRT, and that's fine too. Lots of non-CRT options out there to use.
Even with the externalities accounted for, if you must use a monitor, it might be better to buy a new one than repair the old one.
The replacement parts have a footprint, and a newer monitor might use so much less power in operation that it’s more efficient to make and use it than to continue to use the older CRT.
I really wish there were an easy way to work out if this was where the ‘efficiency crossover happens in X years of use’ point was. For example, I have a perfectly usable Thunderbolt 1 [edit: Thunderbolt 1 dock] that meets my needs. But it uses 5-10W of power more than a new Thunderbolt 3 or 4 one would. Should I continue to use it or switch to a newer one?
ivraatiems|2 years ago
I called around to various TV repair shops and was generally told they couldn't do it, or that it'd be prohibitively expensive. Finally, an electronics surplus store in my area referred me to a gentleman of the old-school AV hippy variety who knew how to repair all sorts of old equipment. He was able to construct a tool to ground the machine while working on it and we did the repair successfully together. It was an adventure!
winrid|2 years ago
mvandermeulen|2 years ago
Excellent anecdote and love to hear that these people still exist
zxexz|2 years ago
serf|2 years ago
i'm here to say that that kind of behavior doesn't foster self improvement and learning.
here's what I suggest : learn about the job, learn about the hazards, take the precautions, get the equipment, don't let your guard down, and then do the work by-the-book.
you'll learn something in the process, both about the thing itself and the concept of maintaining a 'safety culture' around work that requires it. You won't get hurt, because you're going to follow the right safety precautions and work procedures.
Now, if you want to throw your hands up and just say "i'm not willing to put the hours in to ... " , then by all means, don't take the risk -- have it done. If you're in this for the pursuit of knowledge/skill/craft/gratifications then just pursue it as you would anything that is potentially dangerous and take the right steps.
You wouldn't tell someone to stay off a motorcycle, it's an enjoyable past-time -- you would remind them to follow safe driving procedure and to wear protective equipment.
bombcar|2 years ago
The trick is, that professionals often need to know how to do something just barely safely so that they can do it fast and efficiently.
But a hobbyist doesn't need to do it fast, so you can do it very safely.
In this example, learn how to ground out the equipment, do so, and then leave it for weeks, etc.
larusso|2 years ago
mjan22640|2 years ago
Shawnj2|2 years ago
userbinator|2 years ago
wkat4242|2 years ago
As the author says CRTs are dangerous. Even when they're off they can still carry insanely high voltages. The flyback transformer is one of the more dangerous components of them.
I'm great at electronics repair and I tend to avoid them. Luckily these days that's easy :)
If you don't know what you're doing, you shouldn't attempt it. Just get a more technical friend to do it.
If you do know what you're doing you probably wouldn't need this guide in the first place :)
glhaynes|2 years ago
the_third_wave|2 years ago
I never got zapped which is a good thing since yes, that can be unpleasant and - depending on when and where it happens - dangerous. Discharge those tubes and cascades before you fiddle with them, use a screwdriver connected to a ground wire which is connected to the metal tube frame. If you want to do it 'professionally' you'll want to put a HT resistor in that wire, otherwise just zap the thing by sticking the screwdriver under the plastic cap on the high tension connector at the tube.
lightedman|2 years ago
We do have the mantra in the styropyro discord "Do not the MOT" (Microwave Oven Transformer) but we all know it's harmless without power on it.
amelius|2 years ago
I.e., you select the discharge mode, put the probes on a capacitor, and watch the voltage go down, while an internal current limiter makes sure that it happens at a safe rate.
sneak|2 years ago
The flyback transformer can fucking kill you, and anyone who needs this webpage or is interested in the instructions (ie someone not working professionally in electronics repair and aware of such hazards) is less likely to know that.
aurizon|2 years ago
Scoundreller|2 years ago
This explains my methodology for a lot of things in life
nyanpasu64|2 years ago
dougg3|2 years ago
I think Apple should have recalled these.
riveducha|2 years ago
unfocused|2 years ago
Lots of detail and explanations. P.S. I'm not affiliated with anything, I just genuinely think this is one of the best (educational) channels out there on this.
ddingus|2 years ago
This desoldering component technique video is well worth your time. Of all the basic electronics skills, doing this has always been challenging, particularly on older equipment where the copper traces will tend to peel up.
Having that happen is not the end of the world because a simple bodge wire is not hard to do in most cases.
But, there are times when a failure like that can really matter!
A flyback with the high voltages can be one of those times when you just want a clean replacement.
This guy shows you how to use wire to desolder many component pins at one time.
andyjohnson0|2 years ago
(Irrespective of the answer to this, there is no chance at all that I would ever mess with crt circuitry. But I am curious.)
kmbfjr|2 years ago
ComputerGuru|2 years ago
extrapickles|2 years ago
When working with high voltage/power equipment, its best practice to keep the capacitors shorted while you are working to keep dielectric absorption from “recharging” the capacitor to 1-15% of its rated voltage.
[1]: https://academic-accelerator.com/encyclopedia/dielectric-abs...
clueless123|2 years ago
Eventually I learned to ground the whole thing with a cooper cable and a resistor.
vondur|2 years ago
mhb|2 years ago
metadat|2 years ago
watersb|2 years ago
I still remember that One Monitor, flyback transformer I could hear from my office cube, in another wing, one floor down.
Hizonner|2 years ago
Hire a professional.
To fix a quarter-century-old monitor that was nothing special when it was new.
Why? I mean, I wouldn't bother fixing the thing anyway, but hiring somebody is going to cost you more than a much better brand new monitor.
teh_klev|2 years ago
> Why? I mean, I wouldn't bother fixing the thing anyway, but hiring somebody is going to cost you more than a much better brand new monitor.
There are folks out there who spend their time fixing unexceptional cars such as old Ford Orions, Austin Metros, VW Golf Mk 3's (poverty spec) and so on. In their day these were the most boring of the mundane mass market motors you could buy.
But it's about capturing and snapshotting a point in time. Sure this particular monitor was probably crap, but combined with a same period Mac it's a time capsule.
You might think it's a waste of time, for others it's a hobby/past time. And it's one less thing in the landfill.
rasz|2 years ago
userbinator|2 years ago
veave|2 years ago
fragmede|2 years ago
toast0|2 years ago
Many people don't have reason to prefer a CRT, and that's fine too. Lots of non-CRT options out there to use.
jrmg|2 years ago
The replacement parts have a footprint, and a newer monitor might use so much less power in operation that it’s more efficient to make and use it than to continue to use the older CRT.
I really wish there were an easy way to work out if this was where the ‘efficiency crossover happens in X years of use’ point was. For example, I have a perfectly usable Thunderbolt 1 [edit: Thunderbolt 1 dock] that meets my needs. But it uses 5-10W of power more than a new Thunderbolt 3 or 4 one would. Should I continue to use it or switch to a newer one?