Interesting

has only one side got the proper phosphor?   or did it used to work? 

Sorry just read you post properly.. so it has always done this.. I would say a problem with the phosphor coating..

Note if the UV is getting out through the "dark side" it is an extremely bad idea to look directly at it... clear safety specs should be used

Take the tube out and measure resistance between the prongs at each end. I am guessing the heater element is failed at one end.

Once the arc is established the heaters don't do anything. This tube already has the arc established or else there would be nothing to activate the phosphor.

If the problem is what I think it is, I'd love to get hold of this tube to show my electrical students

mdooher:

 

Interesting

 

has only one side got the proper phosphor?   or did it used to work? 

 

Used to work.

elpenguino:

 

Take the tube out and measure resistance between the prongs at each end. I am guessing the heater element is failed at one end.

 

Nope, that can not be the problem.

The heaters at each end are to make it easier for the lamp to strike. Once this happens then the current through the mercury vapour goes from one end to another, that should men the entire tube works, not 1/2 of it.

You used to be able to get resonant systems that ended up putting a few kv acro the two ends without the need for a starter/heater.

Once the tube strike there would be somewhere about 90v across it, and IIRC from 40+ years ago they are effective a negative resistance device, ie the more current you put through them the lower the resistance gets,  so they are current controlled via the ballast.

The lights are all tied into movement sensors, this starts up just as quickly as the other lights, but only 1/2 of it works.

mdooher:

 

Once the arc is established the heaters don't do anything. This tube already has the arc established or else there would be nothing to activate the phosphor.

 

If the problem is what I think it is, I'd love to get hold of this tube to show my electrical students

 

I shall "Acquire it", where about do you teach ?

I am in Palmy.

sir1963:

 

mdooher:

 

Once the arc is established the heaters don't do anything. This tube already has the arc established or else there would be nothing to activate the phosphor.

 

If the problem is what I think it is, I'd love to get hold of this tube to show my electrical students

 

 

 

 

I shall "Acquire it", where about do you teach ?

 

I am in Palmy.

 

Otago Polytechnic...so might be tricky

sir1963:

 

elpenguino:

 

Take the tube out and measure resistance between the prongs at each end. I am guessing the heater element is failed at one end.

 

 

 

 

Nope, that can not be the problem.

 

The heaters at each end are to make it easier for the lamp to strike. Once this happens then the current through the mercury vapour goes from one end to another, that should men the entire tube works, not 1/2 of it.

 

The fluoro is a simple device so the problem is probably simple. 'Acquire' it and check the basics and let us know.

Actually, be interested if they have fitted an LED replacement there and 1/2 of it is DOA.

As I say, I must acquire this as I am curious.

Did not bother looking too Close today as I had a migraine and have spent the last 2 days tracking an intermittent set of faults in an Ice Maker at work.

Effing thing....

Tomorrow will be a round of centrifuge repairs...oh yay...

Blue ends are LED replacements.

Work sparky refuses to fit them because it either means modifying the fitting or leaving the ballast in there with the fuse starter on the old magnetic ballast ones.

richms:

 

Blue ends are LED replacements.

 

Work sparky refuses to fit them because it either means modifying the fitting or leaving the ballast in there with the fuse starter on the old magnetic ballast ones.

 

That makes sense.

DUH me...bl00dy migraine stops the brain somedays.

I had already done this change on an anaerobic chamber that I modified last year , the old system was 110v and it got converted to 230v