Help needed with electronic circuit from boat lights

RichardS

RichardS

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One of the 12V twin T5 300mm 8W fluorescent lamps on my boat has failed. It's been a bit dodgy for a couple of years occasionally going out and then coming back on again but last week it went out never to return. :(

I've checked the 12V electrics and the failure is something to do with the ballast circuit, something which is well beyond my experience.

Looking at the circuit board, my suspicion is that it is probably the yellow transformer which has failed. However, there is no writing on the transformer so I've no idea whether I can buy a similar one as I don't know what output voltages I'm looking for. The transformer has 4 connections to the PCB at each side so 8 connections in total although 3 of the 4 on one side all connect together on the PCB.

Does anyone know what type of transformer this is likely to be?

Thanks for any help.

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Richard
 
Possibly your better long-term solution would be to throw the inverter board away and replace the tubes with T5 LED tubes - you'd need to wire the end fittings directly to the 12v supply. "Warm White" tubes may be friendlier.
 
Measure the length of the tube and get an equivalent led tube. I expect some one here can recommend a supplier. Lower consumption.
 
pvb said:
Possibly your better long-term solution would be to throw the inverter board away and replace the tubes with T5 LED tubes - you'd need to wire the end fittings directly to the 12v supply. "Warm White" tubes may be friendlier.
Click to expand...

That's exactly what my Son keeps saying so now I'm coming round as you're quite right in that I could easily re-wire the thing whilst it's in bits.

Can you get LED's in a T5 form factor?

Richard
 
That's probably a multi-winding transformer which not only increases the 12V to 250 or whatever, but also forms part of the oscillator circuit.
If you look at google images for '12V fluorescent circuit', you'll see a lot of possible circuit configurations.
Eliminate those which have too many transistors....
I would suspect our chances of fixing this are slight to nil.
However, my starting point would be to test/replace the transistors.
If you can find a part number on them, then a data sheet, a multimeter may show they are not happy.
Then the capacitors are easy to check if you have the right meter, and can read their values.

Take care though, these things can sting if they work!

The suggestion of replacing with LEDs sounds good.
 
RichardS said:
That's exactly what my Son keeps saying so now I'm coming round as you're quite right in that I could easily re-wire the thing whilst it's in bits.

Can you get LED's in a T5 form factor?
Click to expand...

Yes, Google is your friend. Around £15 for a 300mm tube, probably only about 3W power consumption, so about half the current your fluo tubes took.
 
pvb said:
Yes, Google is your friend. Around £15 for a 300mm tube, probably only about 3W power consumption, so about half the current your fluo tubes took.
Click to expand...

Don't the "replacemnt for fluorescent" LED tubes expect 230 volts not 12 volts? Just like to original mini-fluorescents. So if your transformer and circuit are faulty .....
 
I changed all my old fluorescent lamps to LED but I used the stick on strips throwing away all the fittings except the switch and soldered the wiring.


Some I fitted cloth worm white and red LED on seperate switched so I can have white or red lights.

You can even have different number of strips to give different light outputs or multi level lighting or both warm and cool white to give different types of light.

Lots here

https://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=LED+strip+lights&_sop=15
 
jwilson said:
Don't the "replacemnt for fluorescent" LED tubes expect 230 volts not 12 volts? Just like to original mini-fluorescents. So if your transformer and circuit are faulty .....
Click to expand...

No, you choose 12v T5 300mm tubes, and simply rewire the end sockets direct to the 12v supply, rather than to the little inverter circuit board.
 
I've taken the advice of the forum and ordered a T5 LED replacement.

I've gone for an expensive but very bright warm-white tube from a supplier I've had good service from before as the reviews suggest that this one tube will be much brighter than the two original fluorescents and even brighter than two cheaper T5 LED replacements.

Whilst I had the fitting in pieces I should have considered the replacement option more seriously as that is the perfect time for a bit of soldering. :encouragement:

Richard
 
Just thought I'd finish the thread off.

Having removed the ballast circuit and re-soldered the connections, this is the light with the 3W LED replacement tube in place on the kitchen table.

It looks exactly like the original fluorescent warm-white tubes in that it is a solid bar of light with no individual LEDs visible which I think looks rather smart. I also reckon that the reviews were right and that it probably is as bright as both the original 8W tubes together which, at the price, is definitely "a good thing". :)

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Many thanks to those above who prompted me to get the soldering iron out and make the change. :)

Richard
 
Just to explain, as said the transformer switches the 12v to several hundred volts to start and light the flouro tube. This high voltage requires a lot of turns on the transformer secondary. This must be made of fine copper wire. Fine copper wire does not survive well in a boat environment. hence 12v flouros tend to fail in a boat almost always from failed inverter and from failed transformer. ol'will
 
William_H said:
Just to explain, as said the transformer switches the 12v to several hundred volts to start and light the flouro tube. This high voltage requires a lot of turns on the transformer secondary. This must be made of fine copper wire. Fine copper wire does not survive well in a boat environment. hence 12v flouros tend to fail in a boat almost always from failed inverter and from failed transformer. ol'will
Click to expand...

Thanks Will .... that supports my gut feeling that it probably was the yellow transformer which had failed. :)

Unfortunately, the transformer has no writing on it so I didn't know how to replace it anyway. The move to LED is a good one which I did a few years ago with all the recessed lights in the saloon and cockpit but the forumites above gave me the push needed to make the change for the fluorescents where it's not a simple bulb replacement.

Richard
 
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