A dead Exit sign brought back to life
A restaurant owner who lives nearby my shop brought this for repair. When I powered up the device, it did not come on but I heard some buzzing noise coming from inside the machine which is an indicator of the power supply issue.
The owner has about eight of these signs and he brought me one so I can find out what is wrong then work on the others.
I was very confident that I will get the job done because I have done signs repair, even in worst conditions than this one.
Only four screws to come out and was able to expose the device from inside.
The fault was very obvious because I could see the two bulged capacitors right away. That explained the buzzing noise I was hearing earlier.
They were 1000uf and 2200uf 16 volts each. As expected, it was an easy job because replacing these faulty capacitors restored the exit sign back to life.
As is seen in the photo, it was a mission accomplished but for some reason it was a mission with missing something.
This sign works on AC voltage and when the power is out, it supposed to work on DC voltages. My mistake is I did not check the charging of the battery on this device. The customer after taking the device came back the next day and informed me that the battery was not charging. I had to open the device once again and check either the battery is faulty or it was not getting enough power to charge.
After charging it for about two hours after I made sure it was getting the right power to charge, I unplugged it from the main power source but the sign stayed on for about two minutes then it went dead. It was the time to replace the battery. It was a 2.4 volts battery which combines two batteries in one, total of 1.2 each. I replaced it with this one.
It is higher in Amp ratings which I believe it would stay lit for a longer time when the power is out. I tested it in my shop and it worked like a charm.
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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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
11 comments on “A dead Exit sign brought back to life”
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You did good since NiCd cells are no longer used by using NiMh cells instead. If the GP 2700 mAh cells used handle the permanent/constant charge current of 85 mAh, it will be okay. And there is no need to change the Exit light charger power supply into a Lithium Ion cell charger.
Albert: the main source of this exit sign is AC. thanks for your input. have a blessed day my friend.
Hay Waleed,
Clever replacing these old Nicad batteries with smaller , but higher power AA batteries, i think thy are Ni-Mh??
regards
erik b.
NL
erik: yes they are. have a blessed day
Power supply problems are the most interesting!
Well done!
Ghassan: thank you and have a blessed day
Great job, Waleed! The original battery was probably expensive to replace, and your choice of AA NiMH batteries in a holder will greatly simplify replacing them in the future. I have done the same thing repairing LED emergency lights, and it works great!
Thanks for sharing
Regards,
George N.
George: thanks man. thanks for your input. have a blessed day
Hi Walid,
The replacement of the old NiCad battery with a new NiMh battery proves a success,but it should be noted that the difference between capacitances and charging currents requires discussion: the old battery with a capacity of 1700 mAh provides a charging current of 85 mA which saturates the battery in time of 1700 mAh / 85 mA = 20hrs, as shown in the photo the new battery at the bottom indicates a capacity of 2600mAh and an average charge of 10hrs @ 260mA; By keeping the same charger, the current 85mA seems non-critical and has no joule effect on the new battery since it is lower than its charging current 260mA, only the charging time will be longer: 2600mAh / 85mA = 30.58hrs, the triple of standard charge 10hrs. But no worries as long as this EXIT sign remains illuminating and gives an atmosphere to the restaurant.
GREETINGS
Abdellah: I appreciate it the input. the device I repaired does not run on charger so I am not worried about charging the device. it runs on AC power. the only time the batteries are used is when the AC power is out. so plenty of time to charge..have a blessed day
Hi Waleed, I understand this is a system running on AC power and including a battery that stores energy via a charger. That way you have completed a wonderful troubleshooting, especially a NiMh battery has a higher energy density of 30% compared to a NiCad battery.
Have at happy time