Electronic drive fluorescents

[robgraham]

I got two of these (why didn't I get a spare ?) out of a skip some years back (~2000).

One of them works fine but the other is an unwilling starter - switch on/flash/switch off/ wait for a count of 8/repeat about 6 times for light to start.

I tried changing the tubes around - no change. I put the bad one up in the new workshop when it was initially wind and water tight, and decided yesterday that it was time to change them over. I came to the conclusion it was easier to change the modules rather than the whole light, and the fault follows the modules.

I've got a basic concept of how these things work ( I am an electronics engineer), but does anyone know what the starting circuitry is likely to be like so that I can try and trace down the faulty component? The electronics is all discrete components

Thanks Rob

[Andrew Gabriel]

Not going to be able to advise on repair over usenet, except a common problem with ballasts of that age is arcing between PCB traces, which is caused by poor washing of the PCB during manufacture resulting in eventual breakdown, combined with the manufacturers being new to designing PCB's carrying 600V pulses and laying the tracks too close together. You might be able to fix by peeling off an affected track and replacing with a soldered insulated wire. Other than that, if there's no obvious damage, you'll have to fire it up with the PCB on a electronics workbench and try to spot arcing on the board or inside any components. Needless to say, these have dangerous voltages inside (significantly worse than mains), and may remain dangerous a long time after switch-off.

However, I suggest you get a new electronic ballast. Basic single tube non-dimmable are usually under £10 on eBay.

[Derek Geldard]

On some, & only some, it's a winding of a couple of turns per filament on the HF output transformer. All the power goes to the filaments until the tube strikes.

Or 7 or 8 quid for the Phillips "HF-matchbox"series at RS.

Derek

[NT]

There are several types of electronic ballset. Show us photos of the pcb and there's a small chance we can help.

What tube size/power is it running?

NT

[Bob Minchin dangling via a don]

Also if it one designed for running two tubes, they quite often don't like starting with only one fitted.

They do fail after many 1000's of hours running possibly due to capacitor failure more than anything else - rarely worth repairing as new ones are not that dear.

Bob

[Rob G]

You're right, Andrew - apart from the challenge of sorting it and it's going to be a suspect cap I reckon, Ebay looks to be my friend.

This is a twin 70W tube fitting, and I can get a "Philips 2 X TL-D 70 WATT..TWIN BALLAST..WARM START" for effectively pennies. Internet seems to suggest that TL-D tubes are something special, and what does 'Warm Start' mean?

Any guidance ?

Thanks all Rob

[Andrew Gabriel]

TL-D is a bog standard tube (I think it stands for Tube Linear, Double-ended), 6' in the case of a 70W one.

It will preheat the electrodes for a second or so before trying to start the tube. (Gives longer tube life unless the tubes are operated for more than 3 hours each time they're switched on, in which case it's no advantage over instant start.)

[Rob G]

Many thanks Andrew - all I need to know. Off now to Ebay !

Rob