Electronics Ballast Repaired
The St. Kilda Repair Café in Melbourne, Australia provides a free service to the community for the repair of household items of all kinds, saving them from being sent to landfill. Staffed by volunteers, it operates on every second Sunday of the month.
A recent item presented to me for diagnosis and possible repair was a three fluorescent tube fish tank lamp, which the owner reported as not working on any of the three lamps. A quick test confirmed this, so investigation began by removing the tubes (which were independently confirmed as operational) and observing that the Ballast needed to start and run fluorescent lamps was all electronic.
The electronic ballasts were in three aluminium channels (one per tube), so to get an idea of the scope of the problem, one was removed for diagnosis. The printed circuit board is narrow and long, but all the components are old style through-board types and therefore readily examined.
The two photos show part of the component layout at each end of the board.
The Repair Café has little by way of electronic diagnostic equipment, so I took the lamp home for further detailed investigation.
It didn’t take long to identify that the two high voltage transistors, type MJE 13003 (QV1 and QV2) were both dead, as were the two high voltage electrolytic filter capacitors (15uF, 250volt), as well as most of the resistors. There are two 1.5 ohm, two 15 ohm quarter watt carbon resistors and two 680 k ohm 1 watt carbon resistors on the board, all deceased except for one of the 680ks.
That was the outcome for the first board examined.
The ballast is essentially a Switch Mode DC to DC converter that provides the high voltage necessary to start the fluorescent tube.
As I was unable to source the high voltage electrolytics and the transistors locally, I contacted the owner to confirm that he was prepared to wait for overseas delivery of these devices. The cost was quite low, but the wait time likely to be 6 weeks. The owner was keen to have the lamp repaired, so orders were placed for the long lead time components and locally sourced resistors were purchased.
In the meantime, there were two further ballasts to be diagnosed, and the same damage for these was expected. What a nasty surprise when the next two boards were autopsied. Both had signs of large current flow through the full wave mains rectifier, with exploded trackwork evident.
The diode types used in the full wave rectifier are types 1N4007, and although only two in the bridge on each ballast were shorted, all were replaced as a precaution. The likely cause of the overload is suspected to be water vapour condensation, but there is no confirmation for that. The exploded track was bypassed using the replacement diode leads as shown. Ugly, but effective.
At the completion of the long wait for the high voltage parts, all faulty components in the first board examined were replaced, with all other parts checked in the process. This board was then hooked up to a fluorescent tube and a 240 volt ac mains lead was attached, then in a safe (outside workshop) environment, a “smoke test” was conducted.
No smoke.
With confidence thus gained, the remaining two boards were also repaired and tested individually prior to reassembly of the three-tube unit, and a final bench test.
These lights are very bright, and very purple to assist with water plant growth.
The completed item was returned to the customer, and since I have heard nothing further from him, it’s assumed he is happy with the outcome.
Roger Owens is a retired Electronics Engineer from Melbourne, Australia who enjoys exercising skills learned over many years in hands-on roles in Communications Engineering. Volunteering at the St. Kilda Repair Café provides an interesting and rewarding outlet. A strong hobbyist interest in all things microcontroller helps with diagnostic and test techniques. At age 72, there is always something new to learn.
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Parasuraman S
April 15, 2023 at 8:02 am
Excellent service both ways! May God bless you!
moshe
April 15, 2023 at 8:36 am
very nice..Its great when one fixes the unfixable!
Tom Phillips
April 15, 2023 at 10:37 am
Good job Roger for a very good cause!
Albert van Bemmelen
April 15, 2023 at 3:19 pm
Nice job Roger! Luckily the electrical damage to the pcb tracks was still fixable.
Waleed Rishmawi
April 15, 2023 at 3:40 pm
a very well done job repair. it is nice to meet you as well. have a blessed day
Imoudu.O
April 15, 2023 at 4:48 pm
Good mercy work for the less privilege I guess!!. What's "smoke test" Thanks for sharing.
Roger Graham Owens
April 30, 2023 at 8:00 am
Smoke Test - Apply power and see if any components release their captured smoke 🙂
Imran
April 15, 2023 at 5:31 pm
Thank you for giving up your time for a good course.. Well done mate
Mark
April 15, 2023 at 6:09 pm
Good job Roger!
Sounds like the Repair Café is an excellent idea.
Great to have another Ozzie on board.
I'm above you in NSW
Roger Graham Owens
April 30, 2023 at 8:01 am
I struggle under the weight 🙂
Brian Fields
April 15, 2023 at 6:55 pm
Appreciate your posting this Roger. As a retired engineer myself, I too volunteer for our local repair cafe, and get a good deal of satisfaction from bringing dead items back to life.
Roger Graham Owens
April 30, 2023 at 8:03 am
Where is your Repair Cafe Brian? There are not too many around, but it can be very rewarding and helps keep your skills sharp. Roger.
Emma
April 15, 2023 at 7:16 pm
Kudos to you sir
vydelingum Nazir
April 17, 2023 at 3:41 pm
Good job Mr. Roger. Avery has a good initiative for reducing electrical waste in nature.
Joven
April 17, 2023 at 8:12 pm
Working free for a good cause is rewarding. The joy of helping others is priceless. God bless!
NATARAJAN
April 17, 2023 at 10:10 pm
Mr.Roger
Thanks for sharing a nice repair and service experience.
May god bless you to educate novice technicians like me.
Mendis
April 18, 2023 at 1:20 am
Good job.
maurice
April 19, 2023 at 11:20 pm
I've also helped at a repair cafe and it's really fun to do. Educational, meet new people and you also help other people and the environment. In this case the ballast just looks like one from a standard cfl lamp. In many places in the Netherlands and Belgium, such as supermarkets and shops that sell electronics, you have special waste bins for defective LED and CFL lamps, for defective electrical appliances (e-waste) and empty batteries and accumulators for recycling. No idea how it is in other countries. But next time you could get defective cfl lamps for components to reuse. I've been doing that since I was young 😉 I didn't have (and still don't) have a lot of money so reusing and repairing e-waste is a lot of fun. And because of that I can have a lot of nice electronics that I normally can't afford. I have found a lot of nice electronics and repaired things from these e-waste bins. I think that 80 percent of my electronics at my house, but also at my mom and brother's house, are electronics that I have repaired.
Roger Graham Owens
April 30, 2023 at 8:06 am
e-waste is a big world wide problem Maurice. I hope you have plenty of storage space for your recovered components. Don't make the mistake of burying yourself in it though :-). Roger