How to fix. - Page 1
Forum section: electronics / repair

author: Serge125
author_rank: Regular Contributor
timestamp: September 18, 2018, 06:25:17 pm
content: HI allI have played with electronics for a long time BUT I never learned to fix them (in a way depending what it is). I can fix broken wires, replace switches, desolder parts, do mods etc... but when it comes to troubleshot like a non working monitor well it's all?I would give ANYTHING to learn how to do this!!! I've checked on YouTube but 97% is all Hindu stuff and can't understand.I have an old Commodore 1084S-D monitor that isn't working BUT when plugged in I hear a faint high pitched squeal, the power on LED doesn't turn on and no video. Some told me to do a voltage test, HOW??? With power on or off? how do I do this?? I know that I need to "discharge" it first before I do any work. Any HELP on how to troubleshot would be WELCOMED!!!Thanks all for any info!!!SergePS; I have an NTCS monitor.

author: homebrew
author_rank: Frequent Contributor
timestamp: September 18, 2018, 06:49:39 pm
content: Hi Serge,welcome to the forum. Great, that you are interested in fixing stuff.However, a CRT-Monitor is DEFINITIVELY NOT a device to learn trouble shooting on ...There are lethal voltages all over the place and also true high voltage stuff. Capacitors might hold the charge even when not plugged in and, to make matters worse, often everything is literally crammed into the case which doesn't actually help troubleshooting a lot ...At least you would need an isolation transformer, a decent SAFE multimeter and probably some differential probes and a scope... and A LOT OF EXPERIENCE ...Anyway - A CRT Monitor? Just not worth the risk!

author: DaJMasta
author_rank: Super Contributor
timestamp: September 18, 2018, 07:05:34 pm
content: There should be a lot of information around about troubleshooting CRTs (and most operate similarly), so the info is out there, but as mentioned, it is not something to be doing a repair on unless you are familiar with the device and are very confident in your safety skills and your discipline to adhere to them.CRTs operate with very high voltages, usually many kilovolts, and because of the capacitance of the system, these charges can stick around in the chassis for days or more, depending on the design. For this reason, it is very difficult to troubleshoot them safely - there's plenty of material to show how they work, but until you are comfortable working with such voltages and have the precautions set in place to be safe doing so (which is developing habits, having the right equipment, and mentally checking basically everything you do), it can be VERY dangerous to troubleshoot.The charge present on the back of a CRT tube can instantly slag a decent sized screwdriver in some cases. Don't work on a CRT unless you know what you're doing and are setup to be safe about it.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: September 18, 2018, 08:50:26 pm
content: Welcome to the forum Serge. Unfortunately, repairing old CRTs is an art that is rapidly dying with the advent of the modern LCD monitors. One of the reasons that there weren't many who dabbled in that art is because of the inherent dangers of the high current/high voltage elements. I at one time wanted to learn how to troubleshoot and repair CRTs, but after watching (from a distance) a person who was very skilled at the art get zapped and his screwdriver vaporized, I decided to stay clear of such endeavors.Find a device that is more docile, like a stereo or an old digital clock to learn on, or a modern LCD monitor. If I could send you a video of what horror my eyes saw in that experience, I would gladly do so, but take my word to stay away from them unless you can find a mentor that is already very skilled at repairing such devices.Hope this helps...

author: DaJMasta
author_rank: Super Contributor
timestamp: September 18, 2018, 09:39:33 pm
content: As a potential alternative, because not many CRTs are being manufactured now, there are a number of LCD conversion kits and projects, so almost any kind of CRT drive signal is well understood and can be converted over to use on a more modern screen.

author: james_s
author_rank: Super Contributor
timestamp: September 18, 2018, 10:35:09 pm
content: That monitor is definitely worth repairing, it's a good well known unit, very classic, it's worth a bit in good working order and there are not a lot of them left. I've enjoyed repairing CRT monitors for a long time and am sad to see them vanishing so quickly so whatever you do, don't throw it out.Now that said, I would not recommend this as a beginner project. I see some hyperbole in this thread but people are not wrong that CRT monitors can be hazardous to work on. There is the high voltage for the anode but even more dangerous is the "low" voltage B+ which is typically 120-180VDC with a big filter capacitor so that can really pack a punch. Be careful!Another thing you should know is that the horizontal deflection and high voltage circuit is a resonant tank, so everything has to be just right. If anything goes wrong it will tend to go bang and fry potentially hard to get parts.Now regarding the squeal and lack of power indicator, that suggests to me that the power supply is being overloaded. The first thing I would do is test the horizontal output transistor, this will be a large transistor on a heatsink near the flyback transformer. It is part of the resonant tank I mentioned previously and operates under rather high stress so it's a common failure. I would suggest you remove the HOT and then power it up and see if the power LED comes on. If the HOT is bad there are a number of things that can cause this. Sometimes they just fail for no apparent reason but a bad flyback transformer, bad capacitors or some problem with the drive waveform can also kill them.Do you know anyone with experience repairing CRT monitors? I learned by practicing with a friend who worked at a repair shop years ago, then I quickly surpassed him and have fixed hundreds of them. These days most of the CRT repairs I end up doing are for classic arcade games and some retro computers. No other display technology looks quite like a CRT, I'm happy to provide whatever help I can to keep them alive. Respect but don't fear them, stories of people vaporizing screwdrivers are either greatly exaggerated or involve the lower voltage B+ which is present in any modern switchmode power supply.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: September 19, 2018, 12:10:16 am
content: Quote from: james_s on September 18, 2018, 10:35:09 pmAlthough I don't have experience in troubleshooting CRT monitors, that is no reason to say that I am lying about my experience. I don't appreciate anyone saying that I am using hyperbole or exaggerating about what I observed.Your experiences with CRTs sounds extensive, however, I would never encourage a beginner to try this without having someone experienced like you to guide them. At the time that I observed this screwdriver vaporizing on the end, yes VAPORIZING, (that's hyperbole) I was a very experienced electrical/electronic tech at the time, just not with CRTs. I had worked with 480 VAC mains and had seen large copper cables vaporize, but I was well experienced with this and understood completely the risks. However, with a unit like a CRT that has various power supplies and large caps, I decided not to proceed with my CRT education/tutillage.As I said before, I hardly hear of anyone still repairing CRTs unless it is for a very special vintage unit. I have a vintage Osborne computer that has a tiny CRT monitor built in and for collectors this could be a very good opportunity to learn how to repair them or get them repaired. Perhaps you could do some videos on YT showing the downfalls of troubleshooting CRTs with an emphasis on safety. You could perhaps walk through the different modules and explain what each does as in a tutorial. Then go troubleshoot and repair various monitors to show your methodology. This would keep the art alive and perhaps save some of the vintage units that you like. I for one would watch them. Perhaps Serge would watch them too. I know that for someone like you that has accumulated all of this expertise and knowledge, that it is a shame for it to disappear.We as electrical/electronic professionals need to be wary of understating the dangers of devices and take into account whether the asker is a skilled and experienced troubleshooter or a beginner. I realize this forum is here to help, but sometimes helping is advising the OP to get a mentor with experience, for safety's sake. We should never advise a beginner to undertake troubleshooting a CRT without any experience. This is the prudent way in which to encourage, but emphasize the possibility of higher dangers. You did this as well, and I think it is the most prudent approach.Rock on James_S...

author: Cyberdragon
author_rank: Super Contributor
timestamp: September 19, 2018, 12:32:49 am
content: There are plenty of people repairing (larger) CRTs, namely all of the old TV collectors/restorers and as has been mentioned arcades. Those are worse than any little computer monitor, yet shango plugs them in with weeds and dirt in them and sticks his fingers in them (glad its him and not us). Computer monitors are just rather plain and not appealing unless they are the really old ones.Anything mains power can explode or electrocute you if you mess up though. You should probably start with battery operated (or power adapter) equipment (if working alone) before jumping straight to high voltage.

author: Serge125
author_rank: Regular Contributor
timestamp: September 19, 2018, 01:01:02 am
content: Quote from: homebrew on September 18, 2018, 06:49:39 pmHi and THANKS for your reply. Well for A CRT monitor? Just not worth the risk well in my case is worth the risk because it's a Commodore and I need this monitor for my Amiga 500 and it only syncs at 15khz for Amiga rgb so today's monitor doesn't do this so I really need this monitor. Right now I have it setup on a tv but it's NOT very clear compared to my monitor.THANKS!!! ;-)

author: james_s
author_rank: Super Contributor
timestamp: September 19, 2018, 07:12:03 am
content: The thing I see about CRT displays is that people always fret about the ~15-25kV anode voltage but that really isn't all that dangerous. Yes if you get bit by the HV it HURTS, been there, done that, but it's very unlikely to be lethal, it just can't deliver enough current. What it can do is make you yank your hand away and slice it open on something sharp, or the charge stored in the CRT can startle you and cause you to drop the thing on your foot. Now that's no reason to be careless but the HV is something to be respected, not feared.Now that said, there *is* a quite dangerous voltage in most of these monitors, and that's the B+ supply. It's "only" a couple hundred Volts max but in many it comes straight from the rectified mains and has a good sized bulk capacitor on it. The B+ can pack a punch, and definitely requires care. The thing is, modern LCD monitors have the same danger, virtually all switchmode power supplies have the same danger, and yet nobody seems to freak out about it because it's not "high voltage" but it as a far greater lethal potential than the HV in a CRT monitor.

author: helius
author_rank: Super Contributor
timestamp: September 19, 2018, 07:22:48 am
content: I agree with everything james_s has said. CRTs are not more dangerous than other mains-connected equipment. The idea that 30 kV at less than 10 pF can vaporize a screwdriver is just chinese whispers of long ago overheard and misunderstood safety information. Indeed, grounding the anode cap using a screwdriver is the recommended method to neutralize the charge present.

author: johnwa
author_rank: Frequent Contributor
timestamp: September 19, 2018, 07:25:00 am
content: For learning to fix things, I would recommend the extensive sci.electronics.repair FAQ:http://www.repairfaq.org/REPAIR/F_Repair.html. Although some of the material is a little dated now, the general principles are still applicable.

author: In Vacuo Veritas
author_rank: Frequent Contributor
timestamp: September 19, 2018, 12:57:19 pm
content: Try thishttp://personalpages.tds.net/%7Ercarlsen/cbm/monitors/1084s-d/

author: Rasz
author_rank: Super Contributor
timestamp: September 19, 2018, 01:33:00 pm
content: Quote from: Serge125 on September 18, 2018, 06:25:17 pmsounds like you lack basics, how old are you?thats 2-3 years of videos to learn from, subscribe to all, go to videos tab and start watching old ones:https://www.youtube.com/playlist?list=PL3C5D963B695411B6https://www.youtube.com/playlist?list=PLAD148FED92D96B00https://www.youtube.com/playlist?list=PLvOlSehNtuHtWlH0UOZNtOn-FlFCn1GYwhttps://www.youtube.com/playlist?list=PLvOlSehNtuHsc8y1buFPJZaD1kKzIxpWLhttps://www.youtube.com/user/TRXBench/videos?disable_polymer=1https://www.youtube.com/channel/UCPjp41qeXe1o_lp1US9TpWA/videos?disable_polymer=1https://www.youtube.com/user/mikeselectricstuff/videos?disable_polymer=1https://www.youtube.com/user/rossmanngroup/videos?disable_polymer=1https://www.youtube.com/user/Afrotechmods/videos?disable_polymer=1https://www.youtube.com/playlist?list=PLs4emDoNAn3HpsYxrAt-yOoN_7A0TU9nUhttps://www.youtube.com/channel/UCDbWmfrwmzn1ZsGgrYRUxoA/videoshttps://www.youtube.com/user/MrCarlsonsLab/videos?disable_polymer=1https://www.youtube.com/channel/UC39yMXOL0ubFxLWwF1RwelA/videos?disable_polymer=1https://www.youtube.com/channel/UCy0tKL1T7wFoYcxCe0xjN6Q/videos?disable_polymer=1https://www.youtube.com/user/w2aew/videos?disable_polymer=1https://www.youtube.com/user/Fake0Name/videos?disable_polymer=1https://www.youtube.com/user/msadaghd/videos?disable_polymer=1

author: Serge125
author_rank: Regular Contributor
timestamp: September 19, 2018, 04:32:22 pm
content: Quote from: Rasz on September 19, 2018, 01:33:00 pmI'm 51 old. I know SOME basics like caps, resistors, diodes etc... but to repair or troubleshoot something I have just the very basic of stuff like I can check if fuse is ok and wiring and stuff but to trace down a problem on a circuit board that I can't do and would like to know how to do this. I do have basic tools for electronics, I have a somme analog and digital meters, soldering irons (dif wattage) and a very OLD oscilloscope. Oh I have more tools for electronics but I think that I've said the important ones. ;-)THANKS for the vids I'll check'em out!!!

author: Serge125
author_rank: Regular Contributor
timestamp: September 19, 2018, 04:56:06 pm
content: Quote from: johnwa on September 19, 2018, 07:25:00 amOk I red a few lines and this is ME HERE;Tall repair stories time:The IDE hard drive, given free, with two broken pins. Fixed with bits of bent paper clip soldered in place of the original connectors.The record player which wouldn't play at the right speed, and there wasn't enough adjustment in the pot. Fix: cover belt spindle in Araldite, leave to harden, machine down with scalpel.The VCR which wouldn't play. Roughened up drive tire with sandpaper, did same to spindles, worked a treat. Still working fine after 3 years.Another VCR, rejected by a repair shop as uneconomical to repair, and given back to my friend's aunt. Took it apart. found nothing wrong, cleaned it, reassembled. Still working fine (I have no idea what the "fault" the shop found was).A computer monitor with incorrect colour balance. Fixed by adjusting the guns at the back WITHOUT an insulated screwdriver (Hairy!). I didn't have one, so used a normal screwdriver taped with insulating tape to a (dry) 1 ft. wooden spoon. Oh, because of poor design, the CRT kept threatening to impact with the mainboard when I had the back off, so I had to hold it at the front with my other hand. Visions of 25,000 V going straight through my chest made it all a bit scary.First ever repair (this is true!): taught my mother how to wire up a household (e.g. at power meter) fuse because I'd watched my Dad do it (he's good at this sort of thing as well.Age? Five.A TV with a broken tuner, had been to a repair shop twice, they'd given up on it. Received it for free, found out the composite video in worked fine, so ran 20 ft. of cable to a spare video downstairs (there was no aerial in my room, see). Must fix that tuner sometime...A CDROM drive which couldn't read near the edge of some discs. Disassembled whole unit, (eventually) reassembled it, found out that I was the spring which holds the CD down. Fixed by plugging into computer, running a cdrom and wiggling the spring with my finger until I felt the least vibration. Still works fine, although I am replacing it soon with a faster unit.The dropped TV with a crack at the corner of the mainboard. Repaired all the cracks by patching with wire, TV nearly blew up in my face (hence, beware of CRTs). Thank goodness for the fuses... this little incident put me off repairing TVs for over a year. It was eventually chucked, a failure.So basically I'm a tinkerer, if they say that it can't be fixed chances are that I might fix it, this goes for electric appliances too!!

author: Serge125
author_rank: Regular Contributor
timestamp: September 19, 2018, 05:10:55 pm
content: Quote from: In Vacuo Veritas on September 19, 2018, 12:57:19 pmOH THANKS!!!! :-)

author: Serge125
author_rank: Regular Contributor
timestamp: September 19, 2018, 05:27:02 pm
content: Quote from: james_s on September 19, 2018, 07:12:03 amHi and thanks for your reply!! IF I discharge the flyback and that big "buffer" cap it should be ok to "play" in there without any worries to be electrocuted by all the small caps? B+ I have no idea what it is so.... Yep got lot to learn here!!!

author: In Vacuo Veritas
author_rank: Frequent Contributor
timestamp: September 19, 2018, 05:35:42 pm
content: Quote from: Serge125 on September 19, 2018, 05:10:55 pmSure. There are still user groups for Commodore and Amiga stuff. Where are you located? With a name like Serge... BC? Alberta?

author: james_s
author_rank: Super Contributor
timestamp: September 19, 2018, 08:43:33 pm
content: Quote from: johnwa on September 19, 2018, 07:25:00 amThat is indeed a wealth of information and Sam is a personal friend of mine. The information is a little old, but so is the technology in question, lots of useful repair info for CRT monitors in there.

author: tkamiya
author_rank: Super Contributor
timestamp: September 20, 2018, 12:21:56 am
content: Well....Really, CRT is not something you want to mess with. Being consumer goods, many manufacturers take all sorts of shortcuts. It may not vaporize an entire tip of screw drivers but it may leave a mark. It may not kill you but you'll feel it for quite sometime. I have a test lead with melted part, and memory of burn (from 500v no less) to prove that.Having said that, when people say measure voltage, they usually mean power supplies. At minimum, CRTs have anode, and heater. Logic and analog control has 5 volts and 12. Usually a few more for driving grid and deflection coils. I'd check all of them. Anode will require high voltage probes. If I have to place a wager, I'd say power supply is a good bet. You should at least do a visual check. Look for burned components, burned trace, bad soldering joints, etc. Look CLOSELY for discolored registers, bulged, leaking, or otherwise look funny capacitors.Since you are determined to try this, I won't try to stop you. Just be careful. Check and double check power and large capacitors before you touch anything. For safety, use screw driver and discharge everything. It's not that dangerous if you know what NOT to do. But everybody is careless one time or another.I have a friend who touched 3000 volts high current supply and lived to tell about it. Myself, I *almost* got myself few times. Good luck. By the way, people who tell you scary stories are really trying to help you, not discouraging you for any other purposes than to possibly help you save yourself from aggravations.I have a habbit of saying outloud, "POWER OFF", "Voltage checked" when I approach anywhere near oscilloscope's tube section. Then make a point to take my free hand, and hit small of my back. I really don't like pain.

author: Serge125
author_rank: Regular Contributor
timestamp: September 20, 2018, 12:48:59 am
content: Sure. There are still user groups for Commodore and Amiga stuff. Where are you located? With a name like Serge... BC? Alberta?NB!!

author: johnwa
author_rank: Frequent Contributor
timestamp: September 20, 2018, 07:58:07 am
content: Quote from: james_s on September 19, 2018, 08:43:33 pmYeah, it is quite comprehensive, most of what I know about servicing came from the FAQ, and reading the servicing column in "Electronics Australia". Perhaps you could pass on my thanks to Sam for his efforts next time you see him.

author: PaulAm
author_rank: Frequent Contributor
timestamp: September 20, 2018, 12:50:42 pm
content: Vaporizing a screwdriver on a mains I can see, in a crt HV circuit no. However, if the current runs through your heart it very well might kill you, so keep one hand in your pocket when poking around. Remember caps (and the crt) can hold a charge for a significant time so be careful even if you're setting up your instruments when the device is off.A significant hazard is that if you get zapped and your muscles spasm you might send your tool into the CRT which could implode sending glass everywhere. Wear safety glasses when working around exposed CRTs. This is not a huge risk, but your eyesight is worth the bother.Trouble shooting is a great example of the scientific method. Observe the behavior (and various measurements), then use your understanding of electronics to form a hypothesis of what is misbehaving to cause the observed behavior. Finally check the part to verify (or not) your hypothesis. If you were wrong, think some more and try again.You should have a plan and be methodical, generally starting with power supplies and then proceed step by step until the problem is found. When you get a lot of experience you may be able to go directly to the problem. Do not poke around haphazardly, that's just a waste of time. First figure out WHAT is not working, then figure out WHY. Simple.It gets interesting when you run into cases of bad engineering and you find the part was doomed to fail. Or they shaved costs and ran a part close to its limits rather than a more expensive part that wouldn't fail. You'll see that in consumer gear.Apropos of nothing other than the vaporized screwdriver story I once watched a tech attempt to put a shorting bar across the line side of a utility meter socket. I say attempt because it immediately vaporized in his face. This wasn't on purpose, he was confused about how to install them. Me? I was 20 feet away. He was unhurt but needed a change of pants. Stupidity does not impress me; I still do mains wiring.

author: james_s
author_rank: Super Contributor
timestamp: September 20, 2018, 03:49:16 pm
content: Quote from: johnwa on September 20, 2018, 07:58:07 amHe lives on the other side of the country from me but we've been corresponding via email pretty regularly for over 20 years now and I can let him know the next time we chat. His FAQ is one of the things that really got me started repairing things too and over the past decade I've been able to contribute back, particularly in the laser and X-ray sections.

author: In Vacuo Veritas
author_rank: Frequent Contributor
timestamp: September 20, 2018, 04:45:36 pm
content: Quote from: Serge125 on September 20, 2018, 12:48:59 amSure. There are still user groups for Commodore and Amiga stuff. Where are you located? With a name like Serge... BC? Alberta?NB!!OK that's a bit of a smaller place than Ontario but surely there are still some active user groups in your area? It doesn't need to be Commodore, maybe an Atari or vintage Apple group, they might have a person skilled in CRT repairs.

author: Serge125
author_rank: Regular Contributor
timestamp: September 21, 2018, 12:56:40 am
content: OK that's a bit of a smaller place than Ontario but surely there are still some active user groups in your area? It doesn't need to be Commodore, maybe an Atari or vintage Apple group, they might have a person skilled in CRT repairs.No groups where I live city too small for this so... this is why I'm here.

author: Serge125
author_rank: Regular Contributor
timestamp: September 21, 2018, 01:24:45 am
content: Quote from: PaulAm on September 20, 2018, 12:50:42 pmOh I go through all the process "figure out WHAT is not working, then figure out WHY" every time like for example; No power, ok may not be pluged in (dah), power cord could be broken inside, maybe a blown fuse inside and beyond the fuse is where I stop because I don't know what to do next. Yes I will look if there's any visual problems like burnt components, odd smell, deformed plastic, broken traces, cold solder joints etc... Beyond the fuse I have no idea on how to find shorts or to do trouble shooting. That is why I started to watch for some troubleshooting vids on youtube but mostly it's all hindu or too advance for me. I'd like to see a video that shows me step by step AFTER the fuse.My monitor I know that the LED in front doesn't light up BUT the fuse isn't broken so I know power supply IS working, there isn't any video on the front screen and at the neck of the tube there isn't any light in it. So there's power going in through the power supply and then I don't know what to do next. There is a very faint wining sound coming out of the speaker and even if the speakers aren't plugged in I hear that faint wining sound. Here's the sound file that I have recorded and been amplified to have a better sound.THANKS!!!

author: BrianHG
author_rank: Super Contributor
timestamp: September 21, 2018, 02:10:48 am
content: Quote from: Serge125 on September 19, 2018, 01:01:02 amGood for all Amiga RGB outputs. Also de-interlaces. Feed any flat panel VGA monitor, flicker free.RGB 15khz to VGA upsamplerRGB 15khz toHDMIupsamplerNoise Patch for the GBS-8220:

author: cdev
author_rank: Super Contributor
timestamp: September 21, 2018, 03:36:33 am
content: Fixing old style CRTs IS DANGEROUS and should not be done unless the CRT is something really special and unique. You should also have and follow the manufacturers service manual.Old CRTs are not so good for your eyes. Most of them are probably not long for this world. And they weigh a lot too and can cause a potentially dangerous implosion if you break one.

author: james_s
author_rank: Super Contributor
timestamp: September 21, 2018, 03:55:47 am
content: Oh come on now, quit with the hyperbole. We used CRTs for decades without people dying left and right. You'd really have to try in order to make one implode without completely removing it from the monitor and smashing it with a hammer or dropping it on concrete. I've been repairing CRT displays for ~25 years and after working on hundreds of them I have yet to ever seriously injure myself. I was poking around inside old TVs by the time I was 12, several years before I finally learned to actually fix them. They are not appreciably more dangerous to work on than any other equipment that has a mains connected switching power supply. Use a little common sense and you will be fine.Yes you can easily drive a flat panel LCD from a vintage computer but it looks like shit. A CRT monitor has a really unique look and on a retro machine anything else just looks wrong. It's like a 1930s-40s classic car with an automatic transmission, it's possible to do and people do it but it's stupid.

author: PaulAm
author_rank: Frequent Contributor
timestamp: September 21, 2018, 12:51:31 pm
content: QuoteNo, you don't know the power supply is working, only that powermightbe going into it. Have you measured the AC line going into the actual power supply? What are the output voltages? What is the ripple on the output rails? If you can answer those questions, only then can you say the power supply is working, then you can start looking at the next piece of the puzzle.If you see a problem there, what type of power supply is it? Linear or switching? That makes a big difference in how you troubleshoot.You're assuming the power supply is working without verifying that, which is a mistake. The LED not lighting up is a clue that the power supply may have a fault (it might also be a shorted cap on the power rails somewhere) but you won't know unless you actually measure it.A shorted cap somewhere may pull the power supply voltage down enough so some of the circuitry doesn't work, but not draw enough current to blow the fuse.If you don't have a schematic, it gets tougher. Look for fixed output regulator chips which will tell you what the voltage should be. The filter cap voltage rating will give you a clue as well. Look for parts which get very hot which may indicate a short. Linear regulators may run hot, so you need to have an idea about what's going on.

author: james_s
author_rank: Super Contributor
timestamp: September 21, 2018, 03:40:04 pm
content: The schematic and some related service information was already posted in this thread.http://personalpages.tds.net/~rcarlsen/cbm/monitors/1084s-d/It uses a switching power supply based on the STK73410, datasheet for that is online.The very first thing I'd check is the horizontal output transistor, that is a fairly common failure and if it is shorted it will cause the monitor to be dead. The HOT is Q202 in this monitor.

author: Bashstreet
author_rank: Frequent Contributor
timestamp: September 21, 2018, 04:54:46 pm
content: Yeah just remember be careful it is best not mess with CRT's unless you know what your doing and how to take precautions.Stay safe and good luck !

author: Serge125
author_rank: Regular Contributor
timestamp: September 21, 2018, 06:37:02 pm
content: Quote from: james_s on September 21, 2018, 03:40:04 pmOk how do I do this check??? Do I need to discharge the flyback and that big cap?? Do I have to remove it from the board or leave it there. Like I said I NEVER DID ANY ONBORD CIRCUT TESTING, so do some very good explaining on how to do this.THANKS for any help!!

author: Serge125
author_rank: Regular Contributor
timestamp: September 21, 2018, 11:35:52 pm
content: Quote from: BrianHG on September 21, 2018, 02:10:48 amTHANKS checking it out just in case things doesn't work out!!!

author: james_s
author_rank: Super Contributor
timestamp: September 22, 2018, 05:01:52 am
content: Quote from: Serge125 on September 21, 2018, 06:37:02 pmYou really should learn the basics and practice troubleshooting low voltage stuff before you poke around inside any mains powered gear. At the bare minimum you should be proficient at testing transistors and diodes with a multimeter.No need to remove anything from the monitor, just shut it off and wait a few minutes and the CRT will discharge itself through the focus divider. The bulk filter capacitor usually will discharge itself but in some monitors a fault condition can prevent it from discharging, so best to measure the voltage with a multimeter.