[pure-silver] Re: ELC bulbs failing in D2 Dichro Head

Thanks Eric. I probably ought to do this regardless as I noticed the socket
is pretty old..  History suggests something else tho because I've gone thru
3 new bulbs, none of which lasted more than a couple seconds.
Jim
 

-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of EJ Neilsen
Sent: Wednesday, January 16, 2008 9:02 PM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: ELC bulbs failing in D2 Dichro Head

I'd check the sockets. My ELC were burning out fast although not quite right
away, and I replaced the sockets and the problem went away. A crack socket
will allow the juice to flow in unintended paths. POP!

Eric 

Eric Neilsen Photography
4101 Commerce Street
Suite 9
Dallas, TX 75226
http://e.neilsen.home.att.net
http://ericneilsenphotography.com
Skype ejprinter
> -----Original Message-----
> From: pure-silver-bounce@xxxxxxxxxxxxx [mailto:pure-silver- 
> bounce@xxxxxxxxxxxxx] On Behalf Of J Stewart
> Sent: Wednesday, January 16, 2008 7:31 PM
> To: pure-silver@xxxxxxxxxxxxx
> Subject: [pure-silver] Re: ELC bulbs failing in D2 Dichro Head
> 
> Thanks, All.
> I checked the voltage at the lamp socket. It read 26 VAC and 8 VDC = 
> 34 total. Is this enough to blow the bulbs as described?
> 
> My power source (Super Chromega Dichroic Lamphouse Cat. No. 412-021) 
> does not appear to have a triac. I.e., all wires are connected either 
> to plugs (i.e. to timer, to source, to stabilizer)or to/from the 
> transformer coils and various voltage connectors: this supply has 
> voltage connectors labeled 117V 110V 100V and others for a total of 8 
> pairs of connectors. All connections "look" sound. No wires are going 
> to anything that looks like a triac examples sent by Nicholas.
> 
> My stabilizer (Solid State Voltage Stabilizer CAT NO 404-841)- all 
> connections look sound. There is one 3-way connector not labeled that 
> could be a triac I guess.. In no case is the resistance between any 
> two of the terminals greater than 22 ohms.
> 
> Does this sound like the triac (or some equivalent circuit)has failed? 
> If I replaced something, would it be the power supply unit or the 
> stabilizer or both?
> 
> Again, thank you very much everyone.
> 
> Jim
> 
> 
> 
> -----Original Message-----
> From: pure-silver-bounce@xxxxxxxxxxxxx 
> [mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Nicholas O. 
> Lindan
> Sent: Wednesday, January 16, 2008 11:57 AM
> To: pure-silver@xxxxxxxxxxxxx
> Subject: [pure-silver] Re: ELC bulbs failing in D2 Dichro Head
> 
> From: "J Stewart" <jrstewart8@xxxxxxxxxxx>
> 
> > Folks, can anyone help me troubleshoot reasons why my lamps are 
> > blowing out within a few seconds of turning on my Dichro II color 
> > head (on a D2).
> 
> The power supply is busted.  Most likely the triac regulator.  I am 
> guessing how the supply works by extrapolation from other vendor's 
> supplies, so take this with a grain of salt as it may be quite wrong.
> 
> ELCs are 250W 24V bulbs, running at about 10A.  The voltage is 
> converted to 24V by a transformer in the power supply.
> 
> If the power supply is regulated then odds are it uses a triac (a sort 
> of transistor-like thingy) to do the regulation with the transformer 
> producing
> 28 volts or so.  The system is sort of an inside-out lamp dimmer:
> it keeps the lamp from dimming by always keeping it slightly dim.  It 
> adjusts itself if the AC power fluctuates so the dimness/light output 
> stays the same and the lamp always sees the 24V it wants.
> 
> When a lamp fails naturally it produces an arc for a fraction of a 
> second
> -
> the bright flash and pop when a bulb goes.  The arc is pretty much a 
> dead short-circuit and the current spike from the short circuit 
> destroys the triac, leaving the fuse that is supposed to protect the triac
intact.
> 
> This is the common failure mode of household lamp dimmers.
> 
> Triacs short-out when they fail.  For a lamp dimmer this means the 
> lamp is always at full brightness.  For your power supply this means 
> the lamp is not dimmed and is driven with 28V instead of 24V.  The 
> higher makes the lamp burn brighter for a short period and then fail.
> 
> If it is only the triac that has failed then it is fixable and 
> replacement triacs are generally available - Radio Shack even.
> 
> ==
> Nicholas O. Lindan
> Cleveland Engineering Design, LLC
> Cleveland, Ohio 44121
> 
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