Fixing a dying monitor - Page 1
Forum section: electronics / repair

author: SeanB
author_rank: Super Contributor
timestamp: July 20, 2014, 02:41:04 pm
content: This monitor at work has been getting rather dim over the months, so eventually it stopped showing an image totally. So I opened it to see if it would be a quick fix, or if it would be an even quicker replacement with something else.

author: SeanB
author_rank: Super Contributor
timestamp: July 20, 2014, 02:48:35 pm
content: Traced it to the very obvious bulging capacitor. As I was not going to go buy a new one to fix this very old unit ( around 20 years old or more, I was not actually looking at date codes in it) I went and got down a dead colour CRT monitor that was kept just in case I needed spare parts. Pulled out the closest value capacitor that was rated higher in voltage, and of course as it would not fit I added some wire to fit it in. Wire was part of the internal loom from the monitor as well. Stuck down close by and it works again.Think the old cap was about to go into orbit soon.

author: Tinkerer
author_rank: Frequent Contributor
timestamp: July 20, 2014, 04:34:53 pm
content: Yea, nice to have some old parts laying around like that.The thing I am curious about though is why dont you just get a new monitor? LCDs are dirt cheap today and probably alot more energy efficient.(after looking it up, it would appear that LCDs use half the energy CRTs do and efficiency is increasing)

author: robimarko
author_rank: Regular Contributor
timestamp: July 20, 2014, 05:37:55 pm
content: Maybe because he cant afford them or just doesnt like lcds.Why wont he repair old crt with just replacing caps for few bucks

author: SeanB
author_rank: Super Contributor
timestamp: July 20, 2014, 06:39:26 pm
content: Fix was free aside from an hour of my time in between other things.Yes it is easier to replace, but as this has been around for a long time, a replacement would be $70 ( buy locally and take what is available) and would come out of my budget ( which is tight as it is anyway ), repair if possible is better. Zero cost on budget is a lot better.As well I was just looking to do it to keep up the experience. You do not often repair monitors these days to component level, you are like a car shop and simply are a panel swapper. This is easy enough to fix to component level.Only reason I actually used a camera is because Dave has the new sub forum, and I have a nice new Zest phone with a pretty decent camera on it, so I need to get a little more idea of the camera capacity and limitations. Around half the pics were blurred or otherwise unusable. I am kind of liking this phone, nice screen, semi decent battery life and it cost under $200 outright with a 1 year somewhat limited data plan thrown in. But a good web browser and quite usable. Media player as well is good. Has a pretty good FM radio in it as well, no RDS ( pity) but otherwise good.

author: miguelvp
author_rank: Super Contributor
timestamp: July 20, 2014, 07:19:04 pm
content: $70 seems a lot, but the power consumption difference of new LED backlight LCD will pay itself pretty quick.My 40" tv in the living room had an Energy Guide sticker showing yearly operating cost of $15 and 136KWh of yearly energy use.That's less than an old school 60 Watt lightbulb.

author: tautech
author_rank: Super Contributor
timestamp: July 20, 2014, 10:43:49 pm
content: QuoteThanksSeanBfor sharing theeasyfix.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 21, 2014, 02:01:47 am
content: What is it, regular TV? Boring VGA? Don't see anything nearly Trinitron level in there... chuck it in the dump!(After parting out of course.)FWIW, the most common things I've seen (on the few Trinitrons I've even fixed) are either dried up caps (they use electrolytics for all the video coupling caps, because it's cheap, but they inevitably dry out and the picture gets weak -- weaker than CRT age alone would account for), or cold solder joints (one in particular had a thick film module for the video finals, which was bolted to a heatsink on one side... and the PCB just flapping in the wind on the other -- needless to say, every single solder joint on that part was broken, it's amazing it still worked at all). The caps themselves seem to be good quality (even the good ones age), not poor choice or below spec as in the above example (so it would seem).Tim

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 21, 2014, 04:15:21 am
content: Must be pretty old to have a 60Hz transformer inside. All the monitors I have taken apart used switching PSUs.

author: SeanB
author_rank: Super Contributor
timestamp: July 21, 2014, 04:53:22 am
content: Plain video input, and a small screen, used as a camera monitor. It is old, likely 20 years plus, and this was a common monitor used with home computers when the only options were a TV set or a monochrome white or green or amber monitor. They all used a pretty much similar inside with an 11VAC transformer, a simple circuit and almost invariably a TDA1170 for driving the vertical stage ( changed many of those or the 100uF bootstrap cap) and a few other parts that rarely gave problems. This one probably has some resistors in the high voltage side that have drifted high, but I am not bothering to go hunt them down and change them. Worst case it gets tossed and I put the last spare one in, though the screen on that one is orange.

author: Rick Law
author_rank: Super Contributor
timestamp: July 21, 2014, 06:26:00 am
content: Quote from: robimarko on July 20, 2014, 05:37:55 pmI don't think everyone like the new wide screens. I much prefer the old 4:3 (1600x1200) over the 16:9 you typically find in the stores.

author: wagon
author_rank: Frequent Contributor
timestamp: July 21, 2014, 12:40:22 pm
content: Sometimes it's fun to fix something 'just because you can'....

author: SeanB
author_rank: Super Contributor
timestamp: July 21, 2014, 04:40:38 pm
content: Yes, nice to fix rather than toss.Plain 320 by 240 PAL monochrome video camera, so the picture looks very poor on anything other than a 4:3 display.

author: VK5RC
author_rank: Unknown
timestamp: July 23, 2014, 01:02:40 am
content: I support the fix if you can, not too expensive or too difficult. Too much stuff, that does the job, gets tossed (landfill etc) for the price of a capacitor.

author: Stonent
author_rank: Super Contributor
timestamp: July 23, 2014, 05:27:16 am
content: Quote from: SeanB on July 20, 2014, 02:48:35 pmZA Space Program!One small step for man, one giant leap for capacitor kind!

author: SeanB
author_rank: Super Contributor
timestamp: July 23, 2014, 06:49:05 pm
content: Quote from: Stonent on July 23, 2014, 05:27:16 amThanks, I have had those........ I put the first one in backwards, but it still worked. Not surprising as it was a 160V component and it has 20V across it. Did not even get warm, it was just to see if it was the only fault. Then I measured the voltages and decided that it was wrong, and looked for another that would be closer to 220uF than the 100uF I had initially tried. So used a 150uF 400V instead and the little wires. When putting it in I noticed the board markings were reversed on the screen print. Original was in the right way, just the screen print was wrong.