New Monitor - which gamut?

docholliday_sc001 wrote in post #19109494
I'm lucky that I'm also an electronics engineer...old school one that still actually fixes boards instead of modern day board-swapping/firmware-updating type. I usually open up my monitors when I first get them and look for troublesome components and swap for better parts.

It sounds like you will be fine with sRGB gamut monitors: if you don't already know that you need aRGB because clients/printers have shown the need, then you don't need it! Just get/borrow a calibrator and calibrate what you do get.

The Lenovo monitors are really nice for the price. I've got them deployed at various locations and have no complaints about performance, longevity, or color gamut.

I could replace all the electrolytics. If I turn the brightness up it runs for a while then cuts out. Leave it off for a few minutes or dim it, and it stays up. So I was thinking overheating, but yeah it could be a power issue - or maybe a crowbar or foldback protection cutting in?
It comes on dim and gets brighter as it warms up which is about 10 minutes. Sometimes by the end of the day colours and brightness is even/better/much better, then it cuts out.
The flickering tones/brightness is fairly new. It's had a warm corner and a grubby look to the screen, for a while.
There's little useful info in the manual - only that there's an "adapter board" on the AC input, and an inverter board, and a main board.

Are there any other likely components you'd look to replace?

Chris-R wrote in post #19109686
I could replace all the electrolytics. If I turn the brightness up it runs for a while then cuts out. Leave it off for a few minutes or dim it, and it stays up. So I was thinking overheating, but yeah it could be a power issue - or maybe a crowbar or foldback protection cutting in?
It comes on dim and gets brighter as it warms up which is about 10 minutes. Sometimes by the end of the day colours and brightness is even/better/much better, then it cuts out.
The flickering tones/brightness is fairly new. It's had a warm corner and a grubby look to the screen, for a while.
There's little useful info in the manual - only that there's an "adapter board" on the AC input, and an inverter board, and a main board.

I went through the usual scenarios of trying to part boards & components into others when my Dell U2412M monitor
was flaky, but it ultimately turned out to be a losing effort, as not even the connectors matched up.
Manufacturing revisions rendered components inexchangeable between date-code versions.

I could replace cylinder-type electrolytics as well, but not holding a degree in circuit design,
I couldn't identify the SMT devices on the logic boards.

Chris-R wrote in post #19109686
I could replace all the electrolytics. If I turn the brightness up it runs for a while then cuts out. Leave it off for a few minutes or dim it, and it stays up. So I was thinking overheating, but yeah it could be a power issue - or maybe a crowbar or foldback protection cutting in?
It comes on dim and gets brighter as it warms up which is about 10 minutes. Sometimes by the end of the day colours and brightness is even/better/much better, then it cuts out.
The flickering tones/brightness is fairly new. It's had a warm corner and a grubby look to the screen, for a while.
There's little useful info in the manual - only that there's an "adapter board" on the AC input, and an inverter board, and a main board.

Are there any other likely components you'd look to replace?

There's more to it than just "bad caps" as you see all over the internet. A cap can read just fine in capacitance, but could have drifted out of ESR, impedance, or other specs. That's why one can't just "replace" a bad 1000uf, 25v with another and expect to fix something. Some people do and are lucky it works, but thats just luck or the cap they replaced just happened to be in the same range. Each manufacturer has piles of caps that are the same value, but have different specs and purposes.

It could also be one of the semis (FET, bipolars) drifting out of tolerance as well. Getting hammered by fluctuations or heat can cause silicon to leak and make the device slower to react or leak current in the off state.

There's also the safety caps that have exceeded their useful life and prematurely shut down the circuit.

Without proper diagnostic equipment, like a scope to view the feedback loop or ESR tester to check components, you'd be shooting in the dark to diagnose the issue. I've always heard that a blown up, burned out board is easier to fix than intermittent issues...at the the magic smoke lets you know where to start!

SkedAddled wrote in post #19109673
I suppose there's truth to this, though I seem to have been fortunate in my endeavors so far.
My few prints to a PRO-100 printer have gone from Photoshop to print extremely well,
onto Canon Paper, looking very much like what I see on the displays, if even exactly as expected.
Perhaps I've been very lucky in this regard - ?

The only noticeable discrepancy is with the software I use to print to disks.
I have to brighten every image in that software(Acoustica CD/DVD Labeler Pro)
by 15 to 30 points so that it's not too darkly printed to a disk.
I figure it's either the medium being printed to, or the software's handling of images,
which is the reason for requiring adjustments for print.

Yes, you've been lucky that your monitor settings just happen to fall around where you'd be calibrated and that you are using a Canon printer with Canon paper, so a generic output profile has already been created for you by the manufacturer. Also that most of your printing has been within the gamut that your monitor and/or printer can show.

Your disk printing software probably isn't profiled at all and probably doesn't handle profiling, so it doesn't even try to color match the image you sent. My disk printer has a full profile created: pattern printed on a test blank of one type of media, then read in and calibrated with an i1Pro. Even if the image sent isn't photographic in nature, printing can still be way off, like sending a blue colored background to the print and it comes out a completely different tone (purplish usually).

That profiling completes the workflow, so that the colors I see during capture are translated into the sensor/camera output correctly for import. Then, those values are adjusted to show the proper values on my calibrated screen by that profile. Because of the calibration, any changes I make are WYSIWYG because the profile in all my editors match a standard and my monitor(s) is now a known norm. Finally, the output profiles, whether to the disk printer, my WF printer, a press, or lab, adjusts the values I send to match their ink/paper combo. I have even shoved random materials like plywood, cardboard, and handmade papers into my WF printer and have the colors decently accurate - as long as I profile the material/ink combo first.

When my client hands me a bundle of yarn or bottle of product that's a certain color, I can guarantee that it'll look exactly like that on my screen, on the web, for a brochure, as a postcard, billboard, CMYK web press, or simple disc printed. Some bright reds and deep blues are notorious for being off during capture and without calibration are impossible to get right through output. Most colors when near the saturation point, are also hard to control in output because they'll fall out of the gamut the devices are capable of handling. You'll get anything from splotchy color on screen to completely whacked colors on prints.

Again, if you think that you don't need to calibrate your system and what you see is acceptable, then good for you! You've saved money and time. Maybe your work and it's output doesn't require it, the audience doesn't notice, or your work just happens to be narrow enough of a gamut that it just hasn't come up yet. But then don't expect it to work forever either, as you'll eventually run into something that does matter/gets noticed and you'll be wondering what to do...don't get mad when it becomes a real headache because you've been shooting in the dark and hitting the target by sheer luck!

docholliday_sc001 wrote in post #19109762
There's more to it than just "bad caps" as you see all over the internet. A cap can read just fine in capacitance, but could have drifted out of ESR, impedance, or other specs. That's why one can't just "replace" a bad 1000uf, 25v with another and expect to fix something. Some people do and are lucky it works, but thats just luck or the cap they replaced just happened to be in the same range. Each manufacturer has piles of caps that are the same value, but have different specs and purposes.

It could also be one of the semis (FET, bipolars) drifting out of tolerance as well. Getting hammered by fluctuations or heat can cause silicon to leak and make the device slower to react or leak current in the off state.

There's also the safety caps that have exceeded their useful life and prematurely shut down the circuit.

Without proper diagnostic equipment, like a scope to view the feedback loop or ESR tester to check components, you'd be shooting in the dark to diagnose the issue. I've always heard that a blown up, burned out board is easier to fix than intermittent issues...at the the magic smoke lets you know where to start!

I could test ESR from iirc 20Hz to 1MHz or apply a scope to 1GHz or a FLIR 285, though I'm not versed in SMPS characteristics. About 90% of the time faults like this has, are caused by cheap electrolytics and they're easy to change, as you say, for better ones. An old monitor like this one, and no circuit diagram, isn't worth much time though.

Chris-R wrote in post #19110270
I could test ESR from iirc 20Hz to 1MHz or apply a scope to 1GHz or a FLIR 285, though I'm not versed in SMPS characteristics. About 90% of the time faults like this has, are caused by cheap electrolytics and they're easy to change, as you say, for better ones. An old monitor like this one, and no circuit diagram, isn't worth much time though.

Yeah, the old monitors are usually not worth fixing, as it can be something as simple as the backlight tubes carboning up and drawing excessive current. And a lot of those monitors didn't have schematics available, even the manufacturer doesn't. They were usually multiple revisions or designs with the first 1000 units produced by X manufacturer, the next 1000 by Y manufacturer, etc. But, sometimes they are a quick fix.

I'd start by looking up the specs on the caps, both large value electrolytics and ceramic safety caps. Then check their ESR, value, and watch the charge time. I usually discharge them with a resistor, then short the leads out. Then, apply a capacitance meter and watch how fast they reach the rated value. If they're slow, they need changed just as bad as if they are out of spec (remember, there's a tolerance value too). I usually use nothing other than Nichicons as they are the most reliable. If I see a Rubycon, UCC, or NCC cap, they're usually the ones that fail (or those definite no-name ones). Panasonic, Elna, and Vishay also make decent quality caps.

After that, I'd check the leakage of the FETs and any other heatsinked semiconductor. Those will usually drift first since they run hot. Look up the specs online and be sure they are in that range.

Most other components on power supplies are usually go-no-go, such as transformers and resistors. If they die, they usually open up completely or let out magic smoke.

The other thing I suggest if that monitor was from around 2004-2012: go over the solder joints with a microscope. Or, better yet, replace all the lead-free solder with leaded 63/37 solder. I've fixed sooo many things that looked great until under high magnification showed stress cracks in solder joints!