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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
Posted to rec.games.video.arcade.collecting,sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
Something I learned the hard way...
I was replacing a bunch of electrolytic capacitors in a video monitor. I removed the originals all at once, taking careful notes about each location, its reference designation, and the value and voltage of each capacitor. All the original caps went into a zip-lock bag. Then I got a fresh batch of new capacitors, tested each one first, and installed them in one go. I carefully checked off each capacitor on my list as I went. (Another tip: I colorize the top of each new electrolytic capacitor with a red magic marker so I can readily see if I've missed something later.) This was about 30 capacitors. It's very easy to put one in backwards, as you well know. I was very, very careful. I apply power, and... BOOM! One cap literally got blown completely out of the monitor! It sailed past my ear and landed about three feet away! It was a small one, a 10 uF, 50 volt job, but it learned how to fly that day. Well, poop. I quickly removed power and found the location of the fried capacitor. I checked my notes again. Something in my gut told me to re-double-check. I went back through the bag of original capacitors and checked off each cap's value and voltage rating. Now, here's the golden moment: I found my mistake. I had the right value of capacitance, and I'd installed it correctly. My mistake was the voltage rating. I had installed a 50-volt capacitor, which is what the original capacitor was rated for. But... The original capacitor had some white rubbery gunk on it; that had been applied on the circuit board at the factory to keep parts and wiring from moving around much. It's basically a rubberized version of hot glue. This white gunk had hardened all over one side of this cap, and it had masked something critical: one digit. That's all, just one digit. I removed the gunk. The original capacitor was rated for 250 volts, not 50! No wonder the replacement cap exploded. So, keep this in mind the next time you're replacing a bunch of capacitors or other electronic parts: make sure you can read ALL the numbers and letters on them!!! Matt J. McCullar |
#2
Posted to rec.games.video.arcade.collecting, sci.electronics.repair
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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. ====== On Dec 7, 9:45 pm, "Matt J. McCullar" wrote: Something I learned the hard way... I was replacing a bunch of electrolytic capacitors in a video monitor. I removed the originals all at once, taking careful notes about each location, its reference designation, and the value and voltage of each capacitor. All the original caps went into a zip-lock bag. Then I got a fresh batch of new capacitors, tested each one first, and installed them in one go. I carefully checked off each capacitor on my list as I went. (Another tip: I colorize the top of each new electrolytic capacitor with a red magic marker so I can readily see if I've missed something later.) This was about 30 capacitors. It's very easy to put one in backwards, as you well know. I was very, very careful. I apply power, and... BOOM! One cap literally got blown completely out of the monitor! It sailed past my ear and landed about three feet away! It was a small one, a 10 uF, 50 volt job, but it learned how to fly that day. Well, poop. I quickly removed power and found the location of the fried capacitor. I checked my notes again. Something in my gut told me to re-double-check. I went back through the bag of original capacitors and checked off each cap's value and voltage rating. Now, here's the golden moment: I found my mistake. I had the right value of capacitance, and I'd installed it correctly. My mistake was the voltage rating. I had installed a 50-volt capacitor, which is what the original capacitor was rated for. But... The original capacitor had some white rubbery gunk on it; that had been applied on the circuit board at the factory to keep parts and wiring from moving around much. It's basically a rubberized version of hot glue. This white gunk had hardened all over one side of this cap, and it had masked something critical: one digit. That's all, just one digit. I removed the gunk. The original capacitor was rated for 250 volts, not 50! No wonder the replacement cap exploded. So, keep this in mind the next time you're replacing a bunch of capacitors or other electronic parts: make sure you can read ALL the numbers and letters on them!!! Matt J. McCullar |
#3
Posted to rec.games.video.arcade.collecting, sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
On Dec 7, 9:28 pm, "Jerry G." wrote:
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. ====== On Dec 7, 9:45 pm, "Matt J. McCullar" wrote: Something I learned the hard way... I was replacing a bunch of electrolytic capacitors in a video monitor. I removed the originals all at once, taking careful notes about each location, its reference designation, and the value and voltage of each capacitor. All the original caps went into a zip-lock bag. Then I got a fresh batch of new capacitors, tested each one first, and installed them in one go. I carefully checked off each capacitor on my list as I went. (Another tip: I colorize the top of each new electrolytic capacitor with a red magic marker so I can readily see if I've missed something later.) This was about 30 capacitors. It's very easy to put one in backwards, as you well know. I was very, very careful. I apply power, and... BOOM! One cap literally got blown completely out of the monitor! It sailed past my ear and landed about three feet away! It was a small one, a 10 uF, 50 volt job, but it learned how to fly that day. Well, poop. I quickly removed power and found the location of the fried capacitor. I checked my notes again. Something in my gut told me to re-double-check. I went back through the bag of original capacitors and checked off each cap's value and voltage rating. Now, here's the golden moment: I found my mistake. I had the right value of capacitance, and I'd installed it correctly. My mistake was the voltage rating. I had installed a 50-volt capacitor, which is what the original capacitor was rated for. But... The original capacitor had some white rubbery gunk on it; that had been applied on the circuit board at the factory to keep parts and wiring from moving around much. It's basically a rubberized version of hot glue. This white gunk had hardened all over one side of this cap, and it had masked something critical: one digit. That's all, just one digit. I removed the gunk. The original capacitor was rated for 250 volts, not 50! No wonder the replacement cap exploded. So, keep this in mind the next time you're replacing a bunch of capacitors or other electronic parts: make sure you can read ALL the numbers and letters on them!!! Matt J. McCullar- Hide quoted text - - Show quoted text - 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 |
#4
Posted to rec.games.video.arcade.collecting,sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
In article
, "Jerry G." wrote: 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. ====== Professionals - in any profession - are injured and killed, too. Let the service tech who hasn't had an electrolytic capacitor explode, please stand up... being an amateur is no reason to leave things alone. |
#5
Posted to rec.games.video.arcade.collecting, sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
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. |
#6
Posted to rec.games.video.arcade.collecting, sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
On Dec 7, 8:28 pm, "Jerry G." wrote:
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. ====== On Dec 7, 9:45 pm, "Matt J. McCullar" wrote: Something I learned the hard way... I was replacing a bunch of electrolytic capacitors in a video monitor. I removed the originals all at once, taking careful notes about each location, its reference designation, and the value and voltage of each capacitor. All the original caps went into a zip-lock bag. Then I got a fresh batch of new capacitors, tested each one first, and installed them in one go. I carefully checked off each capacitor on my list as I went. (Another tip: I colorize the top of each new electrolytic capacitor with a red magic marker so I can readily see if I've missed something later.) This was about 30 capacitors. It's very easy to put one in backwards, as you well know. I was very, very careful. I apply power, and... BOOM! One cap literally got blown completely out of the monitor! It sailed past my ear and landed about three feet away! It was a small one, a 10 uF, 50 volt job, but it learned how to fly that day. Well, poop. I quickly removed power and found the location of the fried capacitor. I checked my notes again. Something in my gut told me to re-double-check. I went back through the bag of original capacitors and checked off each cap's value and voltage rating. Now, here's the golden moment: I found my mistake. I had the right value of capacitance, and I'd installed it correctly. My mistake was the voltage rating. I had installed a 50-volt capacitor, which is what the original capacitor was rated for. But... The original capacitor had some white rubbery gunk on it; that had been applied on the circuit board at the factory to keep parts and wiring from moving around much. It's basically a rubberized version of hot glue. This white gunk had hardened all over one side of this cap, and it had masked something critical: one digit. That's all, just one digit. I removed the gunk. The original capacitor was rated for 250 volts, not 50! No wonder the replacement cap exploded. So, keep this in mind the next time you're replacing a bunch of capacitors or other electronic parts: make sure you can read ALL the numbers and letters on them!!! Matt J. McCullar- Hide quoted text - - Show quoted text - 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) |
#7
Posted to rec.games.video.arcade.collecting,sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
In article ,
Matt J. McCullar wrote: The original capacitor was rated for 250 volts, not 50! No wonder the replacement cap exploded. So, keep this in mind the next time you're replacing a bunch of capacitors or other electronic parts: make sure you can read ALL the numbers and letters on them!!! 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? -- *Acupuncture is a jab well done* Dave Plowman London SW To e-mail, change noise into sound. |
#8
Posted to rec.games.video.arcade.collecting, sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
On Dec 7, 9:45 pm, "Matt J. McCullar" wrote:
Something I learned the hard way... I was replacing a bunch of electrolytic capacitors in a video monitor. I removed the originals all at once, taking careful notes about each location, its reference designation, and the value and voltage of each capacitor. All the original caps went into a zip-lock bag. Then I got a fresh batch of new capacitors, tested each one first, and installed them in one go. I carefully checked off each capacitor on my list as I went. (Another tip: I colorize the top of each new electrolytic capacitor with a red magic marker so I can readily see if I've missed something later.) This was about 30 capacitors. It's very easy to put one in backwards, as you well know. I was very, very careful. I apply power, and... BOOM! One cap literally got blown completely out of the monitor! It sailed past my ear and landed about three feet away! It was a small one, a 10 uF, 50 volt job, but it learned how to fly that day. Well, poop. I quickly removed power and found the location of the fried capacitor. I checked my notes again. Something in my gut told me to re-double-check. I went back through the bag of original capacitors and checked off each cap's value and voltage rating. Now, here's the golden moment: I found my mistake. I had the right value of capacitance, and I'd installed it correctly. My mistake was the voltage rating. I had installed a 50-volt capacitor, which is what the original capacitor was rated for. But... The original capacitor had some white rubbery gunk on it; that had been applied on the circuit board at the factory to keep parts and wiring from moving around much. It's basically a rubberized version of hot glue. This white gunk had hardened all over one side of this cap, and it had masked something critical: one digit. That's all, just one digit. I removed the gunk. The original capacitor was rated for 250 volts, not 50! No wonder the replacement cap exploded. So, keep this in mind the next time you're replacing a bunch of capacitors or other electronic parts: make sure you can read ALL the numbers and letters on them!!! Matt J. McCullar 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. |
#9
Posted to rec.games.video.arcade.collecting, sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
On Dec 7, 9:45 pm, "Matt J. McCullar" wrote:
Something I learned the hard way... I was replacing a bunch of electrolytic capacitors in a video monitor. I removed the originals all at once, taking careful notes about each location, its reference designation, and the value and voltage of each capacitor. All the original caps went into a zip-lock bag. Then I got a fresh batch of new capacitors, tested each one first, and installed them in one go. I carefully checked off each capacitor on my list as I went. (Another tip: I colorize the top of each new electrolytic capacitor with a red magic marker so I can readily see if I've missed something later.) This was about 30 capacitors. It's very easy to put one in backwards, as you well know. I was very, very careful. I apply power, and... BOOM! One cap literally got blown completely out of the monitor! It sailed past my ear and landed about three feet away! It was a small one, a 10 uF, 50 volt job, but it learned how to fly that day. Well, poop. I quickly removed power and found the location of the fried capacitor. I checked my notes again. Something in my gut told me to re-double-check. I went back through the bag of original capacitors and checked off each cap's value and voltage rating. Now, here's the golden moment: I found my mistake. I had the right value of capacitance, and I'd installed it correctly. My mistake was the voltage rating. I had installed a 50-volt capacitor, which is what the original capacitor was rated for. But... The original capacitor had some white rubbery gunk on it; that had been applied on the circuit board at the factory to keep parts and wiring from moving around much. It's basically a rubberized version of hot glue. This white gunk had hardened all over one side of this cap, and it had masked something critical: one digit. That's all, just one digit. I removed the gunk. The original capacitor was rated for 250 volts, not 50! No wonder the replacement cap exploded. So, keep this in mind the next time you're replacing a bunch of capacitors or other electronic parts: make sure you can read ALL the numbers and letters on them!!! Matt J. McCullar 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 |
#10
Posted to rec.games.video.arcade.collecting, sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
On Dec 7, 10:57 pm, wrote:
On Dec 7, 9:28 pm, "Jerry G." wrote: 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. ====== On Dec 7, 9:45 pm, "Matt J. McCullar" wrote: Something I learned the hard way... I was replacing a bunch of electrolytic capacitors in a video monitor. I removed the originals all at once, taking careful notes about each location, its reference designation, and the value and voltage of each capacitor. All the original caps went into a zip-lock bag. Then I got a fresh batch of new capacitors, tested each one first, and installed them in one go. I carefully checked off each capacitor on my list as I went. (Another tip: I colorize the top of each new electrolytic capacitor with a red magic marker so I can readily see if I've missed something later.) This was about 30 capacitors. It's very easy to put one in backwards, as you well know. I was very, very careful. I apply power, and... BOOM! One cap literally got blown completely out of the monitor! It sailed past my ear and landed about three feet away! It was a small one, a 10 uF, 50 volt job, but it learned how to fly that day. Well, poop. I quickly removed power and found the location of the fried capacitor. I checked my notes again. Something in my gut told me to re-double-check. I went back through the bag of original capacitors and checked off each cap's value and voltage rating. Now, here's the golden moment: I found my mistake. I had the right value of capacitance, and I'd installed it correctly. My mistake was the voltage rating. I had installed a 50-volt capacitor, which is what the original capacitor was rated for. But... The original capacitor had some white rubbery gunk on it; that had been applied on the circuit board at the factory to keep parts and wiring from moving around much. It's basically a rubberized version of hot glue. This white gunk had hardened all over one side of this cap, and it had masked something critical: one digit. That's all, just one digit. I removed the gunk. The original capacitor was rated for 250 volts, not 50! No wonder the replacement cap exploded. So, keep this in mind the next time you're replacing a bunch of capacitors or other electronic parts: make sure you can read ALL the numbers and letters on them!!! Matt J. McCullar- Hide quoted text - - Show quoted text - 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 Heavily and without prejudice. |
#11
Posted to rec.games.video.arcade.collecting,sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
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. "Jerry G." wrote in message ... 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. ====== On Dec 7, 9:45 pm, "Matt J. McCullar" wrote: Something I learned the hard way... I was replacing a bunch of electrolytic capacitors in a video monitor. I removed the originals all at once, taking careful notes about each location, its reference designation, and the value and voltage of each capacitor. All the original caps went into a zip-lock bag. Then I got a fresh batch of new capacitors, tested each one first, and installed them in one go. I carefully checked off each capacitor on my list as I went. (Another tip: I colorize the top of each new electrolytic capacitor with a red magic marker so I can readily see if I've missed something later.) This was about 30 capacitors. It's very easy to put one in backwards, as you well know. I was very, very careful. I apply power, and... BOOM! One cap literally got blown completely out of the monitor! It sailed past my ear and landed about three feet away! It was a small one, a 10 uF, 50 volt job, but it learned how to fly that day. Well, poop. I quickly removed power and found the location of the fried capacitor. I checked my notes again. Something in my gut told me to re-double-check. I went back through the bag of original capacitors and checked off each cap's value and voltage rating. Now, here's the golden moment: I found my mistake. I had the right value of capacitance, and I'd installed it correctly. My mistake was the voltage rating. I had installed a 50-volt capacitor, which is what the original capacitor was rated for. But... The original capacitor had some white rubbery gunk on it; that had been applied on the circuit board at the factory to keep parts and wiring from moving around much. It's basically a rubberized version of hot glue. This white gunk had hardened all over one side of this cap, and it had masked something critical: one digit. That's all, just one digit. I removed the gunk. The original capacitor was rated for 250 volts, not 50! No wonder the replacement cap exploded. So, keep this in mind the next time you're replacing a bunch of capacitors or other electronic parts: make sure you can read ALL the numbers and letters on them!!! Matt J. McCullar |
#12
Posted to rec.games.video.arcade.collecting,sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
On Sat, 08 Dec 2007 02:45:31 GMT, "Matt J. McCullar"
wrote: Something I learned the hard way... I was replacing a bunch of electrolytic capacitors in a video monitor. I removed the originals all at once, taking careful notes about each location, its reference designation, and the value and voltage of each capacitor. All the original caps went into a zip-lock bag. 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. |
#13
Posted to rec.games.video.arcade.collecting,sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
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? 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. |
#14
Posted to rec.games.video.arcade.collecting,sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
Matt J. McCullar wrote in message
t... 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? 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. 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 http://home.graffiti.net/diverse:graffiti.net/ |
#15
Posted to rec.games.video.arcade.collecting,sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
"Jerry G." wrote in message ... 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. ====== 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 |
#16
Posted to rec.games.video.arcade.collecting, sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
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). |
#17
Posted to rec.games.video.arcade.collecting,sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
Ken Layton wrote:
Common sense dictates that you change one capaitor at a time. 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. -- Dec. 6 (Bloomberg) -- Government officials and activists flying to Bali, Indonesia, for the United Nations meeting on climate change will cause as much pollution as 20,000 cars in a year. |
#18
Posted to rec.games.video.arcade.collecting,sci.electronics.repair
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When replacing capacitors in a video monitor...
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. "William" wrote in message ... "Matt J. McCullar" wrote in message et... Something I learned the hard way... I was replacing a bunch of electrolytic capacitors in a video monitor. I removed the originals all at once, taking careful notes about each location, its reference designation, and the value and voltage of each capacitor. All the original caps went into a zip-lock bag. Then I got a fresh batch of new capacitors, tested each one first, and installed them in one go. I carefully checked off each capacitor on my list as I went. (Another tip: I colorize the top of each new electrolytic capacitor with a red magic marker so I can readily see if I've missed something later.) This was about 30 capacitors. It's very easy to put one in backwards, as you well know. I was very, very careful. I apply power, and... BOOM! One cap literally got blown completely out of the monitor! It sailed past my ear and landed about three feet away! It was a small one, a 10 uF, 50 volt job, but it learned how to fly that day. Well, poop. I quickly removed power and found the location of the fried capacitor. I checked my notes again. Something in my gut told me to re-double-check. I went back through the bag of original capacitors and checked off each cap's value and voltage rating. Now, here's the golden moment: I found my mistake. I had the right value of capacitance, and I'd installed it correctly. My mistake was the voltage rating. I had installed a 50-volt capacitor, which is what the original capacitor was rated for. But... The original capacitor had some white rubbery gunk on it; that had been applied on the circuit board at the factory to keep parts and wiring from moving around much. It's basically a rubberized version of hot glue. This white gunk had hardened all over one side of this cap, and it had masked something critical: one digit. That's all, just one digit. I removed the gunk. The original capacitor was rated for 250 volts, not 50! No wonder the replacement cap exploded. So, keep this in mind the next time you're replacing a bunch of capacitors or other electronic parts: make sure you can read ALL the numbers and letters on them!!! Matt J. McCullar 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. |
#19
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TIP: When replacing capacitors in a video monitor...
On Fri, 7 Dec 2007 19:28:02 -0800 (PST), "Jerry G."
wrote: 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 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. |
#20
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TIP: When replacing capacitors in a video monitor...
In article ,
clifto wrote: Ken Layton wrote: Common sense dictates that you change one capaitor at a time. 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. That's a prime way to miss out soldering things. It may be the way a factory makes things but no use for home construction. Start with the things least effected by heat - resistors etc - and end with the semiconductors. Perhaps your method clarifies why you talk about unsoldering when building a kit. ;-) -- *One tequila, two tequila, three tequila, floor. Dave Plowman London SW To e-mail, change noise into sound. |
#21
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TIP: When replacing capacitors in a video monitor...
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. I sure would like to know what the value in the above plan is. That is absolutely the worst way to approach a monitor cap kit. Do the job one cap at a time and the values on the caps and silkscreening will all make sense and it will be apparent if there is an error with either the silkscreening or value of the item being replaced. |
#22
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TIP: When replacing capacitors in a video monitor...
On Dec 8, 1:46 pm, "Dave Plowman (News)" wrote:
In article , clifto wrote: Ken Layton wrote: Common sense dictates that you change one capaitor at a time. 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. That's a prime way to miss out soldering things. It may be the way a factory makes things but no use for home construction. Start with the things least effected by heat - resistors etc - and end with the semiconductors. Perhaps your method clarifies why you talk about unsoldering when building a kit. ;-) -- *One tequila, two tequila, three tequila, floor. Dave Plowman London SW To e-mail, change noise into sound. I dunno about that. From the way Ken describes his work he and I do cap kits in pretty close the same way. I change one cap at a time but solder them all at the same time. Have yet to miss one in 20+ years.... Matt |
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TIP: When replacing capacitors in a video monitor...
Matt, I absolutely agree with you. Anyone whom has done any repairs
at all has made mistakes. Live, learn, move on and above all, respect electricity! Scott C. Matt J. McCullar wrote: 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? 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. |
#24
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TIP: When replacing capacitors in a video monitor...
Dave Plowman (News) wrote:
clifto wrote: Ken Layton wrote: Common sense dictates that you change one capaitor at a time. 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. That's a prime way to miss out soldering things. It may be the way a factory makes things but no use for home construction. Start with the things least effected by heat - resistors etc - and end with the semiconductors. Parts count X 2 = number of joints for the job described. Sanity check afterwards: parts count X 2 = number of joints to deflux. Perhaps your method clarifies why you talk about unsoldering when building a kit. ;-) Preparation, you big silly. With a kit I always check the boards, use steel wool or whatever as necessary, check for obvious damage (hold it up to a light to look for cracks), etc. -- Dec. 6 (Bloomberg) -- Government officials and activists flying to Bali, Indonesia, for the United Nations meeting on climate change will cause as much pollution as 20,000 cars in a year. |
#25
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TIP: When replacing capacitors in a video monitor...
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? We're talking about 25-30 year old monitors, I fix a lot of these, the new caps are usually far smaller physically than the old ones, plenty of modern 250V caps are smaller even than the old 50V caps. |
#26
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TIP: When replacing capacitors in a video monitor...
"Jay" wrote in message . .. 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. Not to point any fingers, but there's a few "professionals" around here who seem to have forgotten that everyone started out as an amatuer at one point or another. I wasn't born knowing anything about electronics, and I've never been formally taught, I've picked it all up on my own through doing it. |
#27
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TIP: When replacing capacitors in a video monitor...
"N Cook" wrote in message ... Matt J. McCullar wrote in message t... 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? 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. 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 There are on a lot of things. The really fun one is the G07 chassis, they made zillions of them, one of the caps has the polarity silkscreen wrong on one side of the board, thankfully it's right on the other side, but then how do you know which one is right? Pays to make a mental note when you pull the part out. |
#28
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TIP: When replacing capacitors in a video monitor...
I sure would like to know what the value in the above plan is. That is absolutely the worst way to approach a monitor cap kit. Do the job one cap at a time and the values on the caps and silkscreening will all make sense and it will be apparent if there is an error with either the silkscreening or value of the item being replaced. You must have a lot of free time, or not so many monitors. When you've got half a dozen monitor chassis' stacked on the bench, any tricks to speed up the process are worthwhile. I tend to go for an assembly line approach, and change groups of 4 or 5 caps at a time on each board. Pull them all, put in all the new ones, solder them all, clip, then repeat with the next group and mark off the checklist as I go. |
#29
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When replacing capacitors in a video monitor...
All it proves is he is human like the rest of us. As long as you don't make
the same mistake, you have learnt something/ |
#30
Posted to rec.games.video.arcade.collecting,sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
hi, i`ve know properly trained service people in public and THE MILITARY
who have made much worse mistakes than that, mistakes my friends 14 yo son wouldnt even make. "Jerry G." wrote in message ... 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. ====== On Dec 7, 9:45 pm, "Matt J. McCullar" wrote: Something I learned the hard way... I was replacing a bunch of electrolytic capacitors in a video monitor. I removed the originals all at once, taking careful notes about each location, its reference designation, and the value and voltage of each capacitor. All the original caps went into a zip-lock bag. Then I got a fresh batch of new capacitors, tested each one first, and installed them in one go. I carefully checked off each capacitor on my list as I went. (Another tip: I colorize the top of each new electrolytic capacitor with a red magic marker so I can readily see if I've missed something later.) This was about 30 capacitors. It's very easy to put one in backwards, as you well know. I was very, very careful. I apply power, and... BOOM! One cap literally got blown completely out of the monitor! It sailed past my ear and landed about three feet away! It was a small one, a 10 uF, 50 volt job, but it learned how to fly that day. Well, poop. I quickly removed power and found the location of the fried capacitor. I checked my notes again. Something in my gut told me to re-double-check. I went back through the bag of original capacitors and checked off each cap's value and voltage rating. Now, here's the golden moment: I found my mistake. I had the right value of capacitance, and I'd installed it correctly. My mistake was the voltage rating. I had installed a 50-volt capacitor, which is what the original capacitor was rated for. But... The original capacitor had some white rubbery gunk on it; that had been applied on the circuit board at the factory to keep parts and wiring from moving around much. It's basically a rubberized version of hot glue. This white gunk had hardened all over one side of this cap, and it had masked something critical: one digit. That's all, just one digit. I removed the gunk. The original capacitor was rated for 250 volts, not 50! No wonder the replacement cap exploded. So, keep this in mind the next time you're replacing a bunch of capacitors or other electronic parts: make sure you can read ALL the numbers and letters on them!!! Matt J. McCullar |
#31
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TIP: When replacing capacitors in a video monitor...
hi, also , so overnight people become fully trained techs ?? i bet u
$1000 that , they got interested in electronics , and made stuff ups as USUAL when starting any hobby . just because u might be a tech , does not mean YOU DO NOT MAKE STUFF UPS. you learn from experiance . and people CAN DO THE WORK THEMSELVES and have saved a few dollars. thats why we have fully trained techs because people start of with electronics as a hobby and make screw ups.. , and think , hey , what makes this tick , ???if i do,,,,,,,, etc.. "Jerry G." wrote in message ... 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. ====== On Dec 7, 9:45 pm, "Matt J. McCullar" wrote: Something I learned the hard way... I was replacing a bunch of electrolytic capacitors in a video monitor. I removed the originals all at once, taking careful notes about each location, its reference designation, and the value and voltage of each capacitor. All the original caps went into a zip-lock bag. Then I got a fresh batch of new capacitors, tested each one first, and installed them in one go. I carefully checked off each capacitor on my list as I went. (Another tip: I colorize the top of each new electrolytic capacitor with a red magic marker so I can readily see if I've missed something later.) This was about 30 capacitors. It's very easy to put one in backwards, as you well know. I was very, very careful. I apply power, and... BOOM! One cap literally got blown completely out of the monitor! It sailed past my ear and landed about three feet away! It was a small one, a 10 uF, 50 volt job, but it learned how to fly that day. Well, poop. I quickly removed power and found the location of the fried capacitor. I checked my notes again. Something in my gut told me to re-double-check. I went back through the bag of original capacitors and checked off each cap's value and voltage rating. Now, here's the golden moment: I found my mistake. I had the right value of capacitance, and I'd installed it correctly. My mistake was the voltage rating. I had installed a 50-volt capacitor, which is what the original capacitor was rated for. But... The original capacitor had some white rubbery gunk on it; that had been applied on the circuit board at the factory to keep parts and wiring from moving around much. It's basically a rubberized version of hot glue. This white gunk had hardened all over one side of this cap, and it had masked something critical: one digit. That's all, just one digit. I removed the gunk. The original capacitor was rated for 250 volts, not 50! No wonder the replacement cap exploded. So, keep this in mind the next time you're replacing a bunch of capacitors or other electronic parts: make sure you can read ALL the numbers and letters on them!!! Matt J. McCullar |
#32
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When replacing capacitors in a video monitor...
i see jerry g hasent replied....
****. "Vaxx" wrote in message u... All it proves is he is human like the rest of us. As long as you don't make the same mistake, you have learnt something/ |
#33
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When replacing capacitors in a video monitor...
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#34
Posted to rec.games.video.arcade.collecting,sci.electronics.repair
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TIP: When replacing capacitors in a video monitor...
"mark krawczuk" wrote in message ... "Jerry G." wrote in message ... 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. The other good reason they warn them is to stay in business. 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. Fact is that anyone can make a stupid mistake, or in the case of the OP a very legitimate error. In my 30 year involvement with Ham Radio I know personally of a few guys that became instantly deceased by coming across the B+ supply of a final amplifier circuit that they designed, built, and used for years and years before they screwed up. Many of the tube type amps run 4-8kv at 1-2 amps DC. Even forgetting to discharge the filter caps can kill you deader than dead. IMHO anyone working on this stuff needs to remain paranoid of safety errors. In the case of the OP, a good schematic would have shown the 250v cap and avoided the error. -W |
#35
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When replacing capacitors in a video monitor...
I firmly believe that if you don't make mistakes, you never actually
learn anything. I'm not a pro, just an experienced amateur, and how I approach a cap kit depends on the chassis. For G07's and K4900 and K7000, I generally change the caps in groups because I've done so many of them. Most other monitors I just do one at a time to make sure I don't miss anything. James |
#36
Posted to rec.games.video.arcade.collecting,sci.electronics.repair
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When replacing capacitors in a video monitor...
I have worked on chassis that have had the incorrect value of caps
installed. (Which is why they weren't working in the first place). Honest to God, they must have had something like a 220 uf @ 160v cap in place where a 22uf@50v belonged. The person that worked on it before must have just stuck whatever cap they had sitting on the bench in whatever spot was open. So, moral of the story...always use a cap list. Many times these have been updated with new values anyway to fix issues with particular types of chassis. The jamma fix for the G07 comes to mind. FWIW, I desolder a cap, stick a new one in and move on. Then I solder all the legs and clip all the legs. Then I look at the complete bottom of the chassis with a magnifying lamp to look for suspect soldering from previous repairs or solder splotches. Yes, Matt knows what he is doing. I would like to repeat one of my rules I have posted before. Never do a cap kit when drunk. You're just going to have to do it again. Pat D. |
#37
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TIP: When replacing capacitors in a video monitor...
On Mar 9, 6:50*pm, "Clams Canino" wrote:
Fact is that anyone can make a stupid mistake, or in the case of the OP a very legitimate error. In my 30 year involvement with Ham Radio I know personally of a few guys that became instantly deceased by coming across the B+ supply of a final amplifier circuit that they designed, built, and used for years and years before they screwed up. Many of the tube type amps run 4-8kv at 1-2 amps DC. Even forgetting to discharge the filter caps can kill you deader than dead. * That ain't no ****.....serious current at that voltage. Actually I'd think it to be a little more current for large x-mitter tubes. I pay the bills working on music equipment and a lot of that is tube guitar amps. A 500v electrolytic installed reverse polarity makes a serious racket and a huge mess (along with a rank stench) when they vent. My general rule is check polarity after replacement, then again before power up. I've never put one in backwards, but I've had 'em go postal on the bench due to excessive leakage current.....should've been monitoring the temp since they were 20+ yr old caps. I did have an amp come in once with someone else's cap job already done and a bias filter cap in backwards. How that didn't go ka-blooey I'll never know. IMHO anyone working on this stuff needs to remain paranoid of safety errors. *In the case of the OP, a good schematic would have shown the 250v cap and avoided the error. Actually he should have pulled off the glue-gunk to verify what came out. Going by a list and checking them off as they were replaced should've raised a red flag. |
#38
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When replacing capacitors in a video monitor...
"Pat D." wrote in message news:IobBj.1821$yD3.280@trnddc05... I would like to repeat one of my rules I have posted before. Never do a cap kit when drunk. You're just going to have to do it again. Ummmm, It's prolly safe to say that one should never do anything more technical than tying your soes when drunk. -W |
#39
Posted to rec.games.video.arcade.collecting,sci.electronics.repair
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When replacing capacitors in a video monitor...
"Pat D." writes:
I have worked on chassis that have had the incorrect value of caps installed. (Which is why they weren't working in the first place). Honest to God, they must have had something like a 220 uf @ 160v cap in place where a 22uf@50v belonged. The person that worked on it before must have just stuck whatever cap they had sitting on the bench in whatever spot was open. I've also seen a board that was marked wrong from the manufacturer. Once upon a time, there was a PDP-11 that ran Unix, about 1975. DEC core memory was expensive, so we had a box of some third-party memory, maybe Dataram. It interfaced to the Unibus via an assembly that pretended to be a Unibus jumper between adjacent backplanes, so it didn't take any slots of its own. One day, we had it apart, and I noticed there was a little tanalum capacitor that was clearly dead. I figured I might as well fix it, replacing it with another tantalum of the correct capacitance and equal or higher voltage rating, carefully orienting it according to the "+" marking screened on the circuit board. Put it all back together and turned on the power, and there was the smoke and smell of a fried tantalum. So I looked at it again, and traced circuit foils from the plus and minus supply pins on the Unibus connector. (This was a 5 V bypass cap, so it connected directly to the power supply pins). Sure enough, the "+" in the silkscreened marking was adjacent to the *negative* lead of the capacitor. I installed another cap "backwards" relative to the marking, and it was fine for the rest of the life of the machine. Dave |
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