TIP: When replacing capacitors in a video monitor...

I don't know your service experience, but you gave a simple example of why professional service people warn people who don't have the proper training and experience to give their service work out to qualified services to have their repairs done.

I know of cases where people have had injury from a terrible electric shock, of cases where people had fires, and who were injured from exploding parts that have not been correctly replaced.

But... For some reason many people think they can do the work themselves, thinking that they will save a few dollars.

Jerry G. ======

Thats exactly why it is of the utmost importance to wear safety googles and other protective gear when attemping such a dangerous task. I usually drink first. Rick

Gotta side with the amateurs on this one. I am by no means a tech. I have made mistakes while repairing things. You fix the mistake and move on. If you wanted a safe hobby, you would have taken up golf. Nothing safer than little white projectiles flying all over a field with drunk guys yelling fore. I think anyone whos been in this hobby for more than a year has probably had a decent shock before. Lord knows I have. But it doesn't affect me any. But it doesn't affect me any. The trick is to know when I a project is above your head and send it off if you cant handle it. If you don't think the hobby is dangerous, I know of someone who was moving a large game and if fell striking him on the head. He later developed neurological problems that was diagnosed as Lou Gerhigs disease. That is if I overheard everything correctly. Just about everything about these games can cause death. Whether its electrocution, fire, or being crushed by an HS-5 dynamo. But we do it cause we love it. And we try to better our skills by gradually taking on smaller projects until we are ready for larger ones. If you get right down to it, no tech was born a tech. They learned it somewhere whether its MIT, ITT or the TSHK(the school of hard knocks.) Just my 2cents.

Nah, practice makes perfect. Your going to have to try REALLY hard to kill your self with a monitor. FWIW, Matt's a veteran in this group and in the field. We all make mistakes...

Matt (a different one)

There's usually a big difference in size between a 50 and 250 working voltage one. And if replacing the lot it should have been obvious by the size difference between all the new ones?

I always change a part or two and did the next part. Sometimes test the unit after changing one or two parts, checking for problems caused by new part. I don't like pulling too many parts without checking work performed, it depends on job.

Thanks for sharing the story, Matt!

I won't tell you to spend gobs of money paying someone else to make the mistakes for you, since they're only human too. It is a wise man (person) who listens to someone's story and logs the wisdom in their own skull , then hears the little voice repeating that story in their ear at the right time.

Bob WC3P

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Heavily and without prejudice.

I disagree, that example can happen to ANYONE, professionals and amateurs alike. I wouldn't doubt it happens to professionals more often because of pure cockiness. An amateur is more likely to take necessary precautions and check the work over and over.

I for one, if I have the tools or equipment to do so will do anything myself rather than have a professional do it. (not without doing a little research first of course) Diagnosing a problem is a different story.

You are kidding right? And you are trying to offer advice?

First bit of advice to you: Replace ONE AT A TIME... Second bit of advice to you: Check, then double check that yuo have the right part, in the right way.

Indeed it was. Fortunately, the silk screening on the circuit board is what gave me the clue. After the fact it said that the original cap was physically much larger than the replacement I had installed. Sometimes newer drop-in replacment caps are smaller than the originals, but not by THAT much!

And thanks for the backup, everybody. Everybody makes mistakes, no matter how many years you've got under your belt. And electricity, like steam and the ocean, does not respect an idiot; it's waiting for you to make a mistake. You gotta have respect for it or it'll kill you.

So learn from the mistakes of others as well as your own and don't be shy about passing on what you've learned. It just might help someone else in the future.

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and

It would help if there was a standard, some mark + , some mark - and some mark with arrows consisting of a line of negative signs leading to the other side

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Hmmm, here's a little story-

After several attempted and failed warranty repairs on my cooker to fix the same fault, and all by different engineers, my son leant on the metalwork and got a shock. I did a quick test with a multimeter from chassis to a nearby earth point and, guess what- no earth.

I removed the small access panel on the back of the cooker where the mains feed enters, and discovered that the internal earth leads had been disconnected from ther terminal block and taped together. The mains lead had also had its earth disconnected from the block and had a small length of thin, solid core red wire taped to it which went nowhere.

One tech who came out said he'd 'done something to the wiring' to try and eliminate the fault (the clock and oven randomly go off) so it's likely he is responsible for this, but the worrying thing is that all the techs have signed the paperwork saying that the appliance had been tested for safety. The first rule of checking for electrical safety is surely checking the earth- it took me literally 5 seconds so why did they all miss this? The engineer who called today said it was disgraceful and he would be 'having a quiet word' with the engineer who did it, but I had to suppress the urge to point out that *he* was happy enough to sign it off as safe without checking it, pots and kettles spring to mind.

So, no offence, but qualified techs can and do not only screw up but are capable of potentially homicidal recklessness. Some individuals are competent, some are not, regardless of qualifications. I have no formal qualifications but I would *never* have done something like this, the importance of a good earth on metal kitchen appliances is blatantly obvious and cannot be overstated. Had I not have had an electronic background, the missing earth may well have gone unnoticed and the shock may have been dismissed as static. The consequences don't bear thinking about.

Morse

I've blown them up on purpose but can't recall having one explode on the bench.

Common sense dictates that you change one capaitor at a time. You should also verify polarity and value of the capacitor you're replacing and the new one too. Remember that monitor manufacturers sometimes have incorrectly marked the polarity on the chassis too (Hantarex I'm pointing directly at you).

I never remove ALL the caps at one time. I do it one at a time and verify voltage and polarity of the old cap first before installing the new one....sometimes the markings on the circuit board are wrong.

Anyone who's ever built a kit of any complexity can see the value of doing all the unsoldering and cleaning at once, followed by doing all the parts insertion and clipping at once, followed by doing all the soldering at once.

The problem Matt ran into was misreading a value on a cap .It can be made whether you do all the caps at once or one at a time. Matt took all the necessary precautions needed to avert any wrong installations of the caps by noting each caps place, value and polarity rather than rely on the circuit markings (to me, that shows some experience there) Though it is more time consuming and there is more chance of a mistake, I see no problem with removing all the caps at once so long as those steps are taken.

Thats my brother in laws attitude, and he gets screwed on everything. From basic house maintenance, working on cars, right down to paying someone to fix his computer problems.

He doesn't have to worry about fixing games because he can't afford them after paying everyone else.