8mm Forum: Lamp burns after few hours...

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Posted by Flavio Stabile (Member # 357) on September 26, 2011, 10:21 AM:

Hello everyone!

My FUMEO Super 8 9120 has started to burn the lamps too frequently...
It uses 24V 200W lamps, but since few days it started to burn them after few working hours only.
I exclude the problem is in the lamps and so I wonder what could be the cause of this issue...

I measured the voltage to the lamp connector and my digital multimeter signs a voltage betweeen 24,5 and 25 volt.

Any idea? Anything else to check?

Thanks
Flavio

Posted by Steve Klare (Member # 12) on September 26, 2011, 11:09 AM:

If the Volts are right, the Watts should be too. If the Watts are right, the temperature should be right.

...should be.

Maybe there is something wrong with the stream of cooling air that's supposed to flow over the lamp.

Is there some electric fan in there that's either slow or stopped? Is there some passage or vent that's become blocked with dust or other debris?

Is that voltage with or without the lamp in circuit? If it's in-circuit it's a touch high. Is your input voltage selection right for your local house current?

Posted by Flavio Stabile (Member # 357) on September 26, 2011, 02:17 PM:

Hi Steve,

the electric fan works correctly, at least I suppose... NOt sure if it slower than normal, but it works.

The voltage was measured without the lamp inserted.
The voltage selector is set to 220 volt which corresponds to our value in Italy.

Posted by Steve Klare (Member # 12) on September 26, 2011, 02:34 PM:

OK, it's fine if the voltage is a little high with the lamp out: when a lamp is installed it will load it down, hopefully to specified. Probably they counted on this when they designed the machine.

Things that kill lamps sooner are temperature, vibration and surge currents and surge currents are a longer term thing (certainly not "hours", "months" maybe).

Posted by Flavio Stabile (Member # 357) on September 26, 2011, 03:32 PM:

Indeed the temperature seems to be a bit too high...
The lamp front cover becomes hot after few minutes, and I'm not sure the air flow coming from the internal cooling fan is sufficient to dissolve the heat produced by the lamp, even after only few minutes...

Posted by Steve Klare (Member # 12) on September 26, 2011, 10:57 PM:

Here's a thought:

Try to find the voltage rating on the fan, then try to measure the voltage driving it.

Less voltage=less air. A 12V fan with 8 volts spinning it will be downright lazy.

Also:

Fans typically die because their bearings wear out. Is the fan smooth and quiet?

In most of the electronic equipment I work with, fans are the #1 cause of premature failure. They make other parts last longer by keeping them cool, but the fans themselves usually die before everything else.

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