fluorescent ballast replace question

[paulmars]

needed to jiggle bulb to get it to fully light up. cleaned and tightened the electronic contacts and that did not help. bought new bulbs and they worked fine for 2 months. now we jiggle again. How can I be sure its the ballast?

tks,
pa

 

[Minder]

If this is a standard fluorescent fixture and not and older style with a start switch or a mag lamp etc with electronics, there is not much else apart from the ballast and a bad contact on the lamp pins.
More info on the fixture needed.
M.

 

[paulmars]

bought new 20 years ago. does that help?

 

[Tha fios agaibh]

How can I be sure its the ballast?

Because you've covered the only other possibilities.

Often a failing ballast will not produce enough current to light the lamps.
As the lamps age, they draw more current.
That's why it worked good for a few months.

Best to just replace both ballast and lamps.

 

[paulmars]

with one of these spare ballasts?:

Philips Advance REB-4P32-SC

Magnetek 413-c-tc-p413ctcpdiyi 043168897099

or used: FULHAM PONY npy-120-226-cfl

pa

 

[Bluejets]

Economically, it's better to get the whole fitting replaced. 20years is a pretty good run.

 

[duke37]

I have never known an inductive ballast fail. They often go noisy with an annoying buzz.
The reason the tube will not light could be an old tube but these will often flicker before they fail completely or could be the starter which has to withstand a large voltage to start the discharge.
Wiggling to start it will do the job of the starter if the connections are not perfect. Try a new starter.

 

[Minder]

I have replaced a few, that is why Home Depot (N.A.) stock them as parts!
M.

 

[Bluejets]

Balasts do fail and will either go open circuit or short out, the latter causing tube elements to blow clean out.
Depending on tube size, balast resistance should be somewhere around 40R.