PL9 tube problem

[winston1]

A relative asked me to look at a lamp he was having trouble with. It was a ceiling mounted IKEA lamp with two PL9 tubes in series with a conventional magnetic ballast about three years old. Problem was one of the tubes had failed (continuous failing to start) so he had ordered 2 new tubes from Amazon. On fitting them the lamp did not work, nor did fitting one with the old good one.
I had a guess what the problem was but had to do some investigation to prove it. PL9 lamps have an internal starter and so they can be used in series it has to be a series type that can strike on less than half mains voltage. Could these ones have the wrong starter fitted internally? Shorting out one lamp and the other started perfectly so yes it did appear to be the case. To finally prove it I bent the tags back and opened the dud and one new lamp and transplanted the starter from the dud to the new lamp. Then it worked perfectly. Still got one new lamp with the wrong starter though. I have advised that in future he buys replacements from Screwfix.

The faulty lamps are labelled TBE Lighting but there is no mention of the country of origin.

 

[333rocky333]

In the past it was quite common in Bulkhead lights to have 2 x 7watt or 9watt pl lamps in series on i think was a 13 watt choke, never had any issues and always got standard lamps and i assumed they worked in series and also in a single fitting somehow

However 600mm x600 modules often had 2 x 18 watt tubes on a single 36w choke and it was designed to use two FS2 starters designed for aprox 120volt.
We often encounter normal 18watt FSU starters wrongly fitted and in a majority of cases the lamps dont strike, but sometimes they do seem to have worked for a while.
Next time im at the wholesalers dumping lamps i will look out for a old PL9 and see whats inside

 

[winston1]

What is inside is a small glass starter and RFI capacitor. Both types of starters look the same, and I have never come across anything but 120v starters in them until now. You can only test them by running them up on a variac with a series small load and see what voltage they strike at.