Exit Sign (for the second time) Repaired
If you recall the latest repair job about the exit sign that had bulged capacitors and the backup batteries were replaced? Well, today I got the same exact sign but with different repair fault. Take a look.
The same customer walked into my shop and with a big smile on his face carrying the same exit sign that I repaired for him a while ago. As he explained the problem, he said that since he is in the restaurant business, Things has to be checked by the safety committee to make sure everything in that restaurant is in the top shape.
One of the things that had to be added to the restaurant was an electricity backup generator. An engineer came and installed the generator; the moment he fired it up, a lot of things in that restaurant blew up.
It is a good thing the varistor was still up and running. If you check out the photo, the varistor was split in half and it had to be replaced. A lot of technicians, they go and take it out of the circuit and power up the device and it works just fine. If an incident like this happens again, the result would be more damage to exit sign.
This was the blown varistor and it had to be replaced.
Of course I had plenty of them are found in my shop. As you can see it was 7D471K but I replaced it with this 10D471K.
And the result was a working exit sign unless an engineer comes again and mess it up.
Mission accomplished.
This article was prepared for you by Waleed Rishmawi, one of our ‘Master Authors’ and currently working in the Bethlehem area of Palestine repairing electrical and electronic equipment.
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Note: You can check his previous repair articles in the link below:
https://www.electronicsrepairfaq.com/a-bus-warning-led-light-repaired
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Jestine Yong works as an Electronics Repair Lecturer in Kuala Lumpur Malaysia and his training website is http://www.NoahtechElectronicsTraining.com. You can check out his repair blog at http://www.JestineYong.com
8 comments on “Exit Sign (for the second time) Repaired”
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I understand that you fixed the defect Exit Sign by replacing the blown VDR. But that doesn’t explain why the VDR blew up right after an engineer installed and fired up a generator. And neither what was done to prevent this from happening again?
Albert: I am not sure what the Engineer did that caused this to happen and do not know what the engineer did to prevent this from happening again that is up to the customer and his Tech people.
Good Job!
Yogesh: thanks man. many blessings to you
It seems to be a case in which, by accident, the installer put the generator set to deliver 220 V in a 110 V premise (or 127 V, as here in Brazil). If this was the case, very likely he soon realized the mistake and corrected it, but at that time, the damage had already been made. My assumption must be correct, as other devices in the restaurant were also damaged, not only this UPS.
Henrique: I do not think that is the case here but it has to do with discharging capacitors by the time the main line electricity shutting down to the time the generator kicks in there was no time given for capacitors to discharge. I asked the engineer about it and I think that is what he tried to explain.
Yes I also believe the fault started by someone’s mistake and no one wants to take the blame.
Justice: in a way you are right because the engineer is trying to say it was not his fault and will not compensate for the damage he did yet he was asking for a high installation fees.