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Sherlock Ohms

Fuse Holder Mismatched to Fuse

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ASmith
User Rank
Iron
Offended Repairman
ASmith   5/20/2013 12:33:07 PM
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I once watched a repairman reseat an internal connector on our (then) recently purchased Mitsubishi DLP TV with an apparent overheating problem.  I think I offended him with an ill-timed comment like "I could have done that".  When he left, the TV no longer worked -- investigation revealed he had left the connector disconnected.  That was easy enough to fix, and with a little help from various forum posts, the problem was eventually solved by bending the contacts in the connector to ensure a solid connection for the temp sensor wires.  Unfortunately it seems people can at times be easily offended when their knowledge or expertise in a particular area (which may be tenuous) seems threatened.

mrmikel
User Rank
Iron
Re: Offended Repairman
mrmikel   5/21/2013 10:33:51 AM
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This is one situation where you really can not go wrong if a proper repair is done either.  Replacing a fuse and holder so long as they are properly rated should never affect machine operation.


Either the repairer is incompetent or a liar when such an obvious failure occurs.


I learn from my customers all the time.  They can do things mechanically in 5 minutes that would take me 5 hours.

WV1800es
User Rank
Bronze
Better solutions-
WV1800es   5/21/2013 11:36:17 AM
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Back in the days when my hair was a lot closer to the top of my head, a friend came over with his Fender guitar amp for repair. It needed a couple of new filter capacitors, and my buddy said, "I'm tired of CHANGING FUSES!!"  So, as a part of the repair I replaced the 3AG fuse holder in the chassis with a circuit breaker.  He still talks about how GREAT that idea was, to this day- "I just push the button, and keep on Jamming!"

tekochip
User Rank
Platinum
Re: Better solutions-
tekochip   6/3/2013 7:21:23 PM
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 Being a huge Fender fan, I gotta ask, why in the world was the fuse blowing? The only one I ever took out was when my drummer knocked a Coke bottle off my amp and something akin to a Mentos fountain showered my 6L6s. The Coke shorted the plate to the filament, wiping out a 6L6, opening the hum balance control and burning the fuse. Fortunately there was a spare amp because it was the opening tune.


William K.
User Rank
Platinum
Re: Better solutions-
William K.   6/3/2013 9:39:18 PM
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In aFender amp there are a few things that will make a fuse pop. A leaky filter cap will certainly cause a problem, as will a leaky cap across the cathode bias resistor. But the very nastiest ones are tose capacitors coupling to the output tube grids, because a leak there will also cause the tube life to be shorter by a large amount and possibly burn the output transformer, an item expensive to replace, if it can be found at any price. That is why I recommended replacing them with 600 volt units, or even 1000 volt caps. And the low leakage ones were the best choice.

William K.
User Rank
Platinum
But fuse substitution is not a trivial thing
William K.   5/21/2013 12:09:29 PM
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Replacing a fuseholder not sized for the application is one area that does make sense, and as long as a similarly rated fuse is used, or the same type in the better holder, there should be no problem. But it is important to understand just exactly what the fuse is supposed to be protecting, and how that protection must occur. Sometimes the fuse must clear very rapidly so as to avoid a fatal dose of power to some item, while other times the fuse is intended to protect something from overheating during a much longer instance of a minor overload. And at all times the fuse must be able to interrupt the power in case of a massive short circuit.. So there are some considerations.

In the case of the cranky techmician, some are simply unwilling to ever admit any product deficiancy, while others presume that their knowledge, however small it may be, is all inclusive. There are also situations, such as I had at one job, where the boss had a standing order to never admit to anything being an equipment problem, even if we were fixing something for free under warranty. And it is also quite possible that they knew exactly what the problem was and refused to fix the steady source of income. Or, it could have been a good tech having a really bad day.

Good detective work nonetheless.

notarboca
User Rank
Gold
Re: But fuse substitution is not a trivial thing
notarboca   5/31/2013 11:34:18 PM
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This was a good fix; don't know that I would have realized what the problem was and fixed it.  We had an office copier that was always on the fritz, finally bought a manual, and was told to fix it.  It worked for the entire 12 year time I was there, but they finally stopped making parts for it.

taimoortariq
User Rank
Gold
Repairing laptop power supply
taimoortariq   5/25/2013 4:25:33 PM
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I used to have problems with my laptop power bricks regularly after I burned my original power brick. After that i started buying the cheap ones(not original ones). They used to heat up real quick and then eventually they would stop working. I was really annoyed by this, since I had to buy a new powerbrick every time this happend. But when this happend with my last powerbrick, I got really annoyed and smashed it on the floor, it poped open, and then I saw that the connector pin was actually loose. Then I realised that because of so much heat the solder must have melted, leaving the connector pin loose( that explained why the led light used to flicker when I pressed the connected cable inside). 

I soldered the connector pin back with my soldering iron and Bravo!! it is still working till the present date :).

Now, probably I will not throw my powerbricks away and waste money.

William K.
User Rank
Platinum
Re: Repairing laptop power supply
William K.   6/1/2013 4:22:19 PM
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While I do not recommend smashing power bricks on the floor, I certainly agree with opening them to see what has failed. Poor solder connections are one of the easy to repair problems, and I am happy that the repair has continued to work for you. Of course, being open with no case probably makes the power supply run a lot cooler, which also helps.

ndjalva
User Rank
Iron
Re: Repairing laptop power supply
ndjalva   6/3/2013 4:51:18 PM
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NEVER expect a service teck to know the answer, It was not on the page.......

I have nothing more to say.

tekochip
User Rank
Platinum
Breaker Replacement
tekochip   6/3/2013 7:14:36 PM
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I had a plasma TV that would frequently open its ill-sized, mini fuse. I was sure it was simply getting too hot in the fuse holder, so I replaced the fuse with a breaker that was carefully selected to have the same current and trip time specs.


William K.
User Rank
Platinum
Re: Breaker Replacement
William K.   6/3/2013 7:22:33 PM
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So I am wondering if the replacement breaker worked out as intended? Or NOT?

tekochip
User Rank
Platinum
Re: Breaker Replacement
tekochip   6/3/2013 8:29:04 PM
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It worked perfectly.  The replacement breaker was huge, but the spec was perfect.

Noswad
User Rank
Gold
Why???
Noswad   6/19/2013 4:04:43 PM
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The repair technician had a nice and easy repair going that he could make a nice profit on and you went and screwed it up.

Cadman-LT
User Rank
Platinum
Re: Why???
Cadman-LT   7/16/2013 11:08:33 AM
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Noswad...I think you got that right!!

Cadman-LT
User Rank
Platinum
Re: Why???
Cadman-LT   7/16/2013 11:14:36 AM
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And to think. I actually held repair technicians above most car mechanics. I guess it all depends on the person.

Lisa hanawalts
User Rank
Iron
Resposibility of electrician!!
Lisa hanawalts   5/9/2014 3:02:05 AM
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Electrical technicians have a big resposibity to be carefully solve electrical fault. Because electrical technical 's one mistake can lead to loss of property and life. I understand above problem how technical without knowing problem changes the fuse.

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