Re: BTR Lamp failures

On Thu, 03 Jul 2008 18:49:58 +0100, David McCall <mccallmail@[EMAIL PROTECTED]
>  
wrote:

> "Islander" <islander@[EMAIL PROTECTED]
> wrote in message
> news:0evp6451fkj7qgtuv8097fqqtg8rt8j185@[EMAIL PROTECTED]
>> We have 12 Stand 6"fresnels in our inventory. Age - 10 yrs old, same
>> as the rest of our inventory.  This past year I am going through GE
>> BTR lamps in these like crazy.  I use one specific brand from our
>> supplier and never had any problems with them until 2 yrs ago when we
>> relamped.  They all seem to blow when doing a lamp check when first
>> firing up he board. They always fail with two black marks on he side
>> of the glass in the middle and the filaments are rolling around in the
>> glass.   No finger prints on the glass.  mainly cuz I use editors
>> gloves to change them.
>>
>> I have taken to setting the patch for these dimmers to be 95% at full
>> on the channel  but just blew another one the other day.  I have also
>> set the focus slightly in from full flood on all fixtures so they lamp
>> is back from a lens a bit. Still it blows.
>>
>> Other thing I note these lamps are getting very hard to get in and out
>> of the sockets.  Hard even when they were new. The difference in the
>> size of the two flanges is difficult to see when in the dark catwalk.
>> My maglight helps but I don't have 3 hands.  <grin>
>>
>> Anyone else experiencing difficulties with this.??
>>
>> cheers
>> Marv
>>
> The fact that they are getting hard to put in may mean that the socket
is
> getting pitted from arcing. The actual contact area is really small on  
> those
> types of sockets and often they don't make a good contact with the l
> amp base. This can cause the base to heat up enough to cause a failure
> in the connection with the filiment. The result can be a failed lamp
that
> looks to be OK. You might want to change the sockets. I've been told
that
> some plases routinely replace the socket on fixtures 5000 watts and over
> every time they pull a lamp that shows the slightest sign of arching.
>
> I'm not sure if it could cause filiment failure as well.
>
> David
>
>

That's just economics though, I do that on 650W bases as the bulb costs  
far more than the base.