8mm Forum


  
my profile | my password | search | faq | register | forum home
  next oldest topic   next newest topic
» 8mm Forum   » 8mm Forum   » That awful Elmo Lamp Socket

 - UBBFriend: Email this page to someone!    
Author Topic: That awful Elmo Lamp Socket
Paul Adsett
Film God

Posts: 5003
From: USA
Registered: Jun 2003


 - posted October 02, 2012 09:22 AM      Profile for Paul Adsett     Send New Private Message       Edit/Delete Post 
Getting dim pictures from your GS1200 or ST1200? Don't blame the bulb, blame that awful lamp socket design. You know, the one where the bulb slides sideways into the ceramic socket.
My light output was getting terrible on my GS, and I thought it was time to replace the bulb. On removing the bulb I found that one pin of the bulb had totally eroded, and the socket contact had disintegrated. The reason for this is inherent in the Elmo lamp socket design, which has a spring loaded flat contact pushing on the outside diameter of the circular lamp pin. So what you essentially have is a line contact, which of course has ZERO contact area! So you have a very high contact resistance, and the result is sparking at the contact interface which eventually eats up the pin of the bulb and the socket contact. Before that happens though you start getting a dimmer and dimmer picture, because the bulb is not getting the full 24 volts - there is a big drop in voltage across that lousy contact.
I have replaced my GS sockets several times, and the scenario is always the same - they eventually self destruct. Well, no more. I have replaced my GS lamp socket with a regular GX5.3 socket which contacts the lamp pins fully around the surface of the pin. Result - truly brilliant pictures again!

--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj

 |  IP: Logged

Adam Deierling
Jedi Master Film Handler

Posts: 717
From: OH
Registered: Nov 2010


 - posted October 02, 2012 10:12 AM      Profile for Adam Deierling   Email Adam Deierling   Send New Private Message       Edit/Delete Post 
Paul, Could this be done on a st1200HD? How hard is it? What do the parts cost?

 |  IP: Logged

Hugh Thompson Scott
Film God

Posts: 3063
From: Gt. Clifton,Cumbria,England
Registered: Jan 2012


 - posted October 02, 2012 10:25 AM      Profile for Hugh Thompson Scott   Email Hugh Thompson Scott       Edit/Delete Post 
I wonder how many people are blaming the little glass filter on
this projector for light loss when it's actually the light socket.
I had this problem years ago Paul, and did the same as yourself
and put in a new connection,as the lamps were being ruined
long before their expiry date and junked because of the pin
being eroded.

 |  IP: Logged

Paul Adsett
Film God

Posts: 5003
From: USA
Registered: Jun 2003


 - posted October 02, 2012 12:35 PM      Profile for Paul Adsett     Send New Private Message       Edit/Delete Post 
That's exactly right Hugh. To put this problem in real terms, I found that the light output of my 200 watt GS1200 had dropped to a level comparable to my 100watt Eumig! That's how much these poor sockets can kill screen brightness!
The modification is very simple because you can still use the existing metal cradle that positions the lamp. All you have to do is cut the lamp wires as close as possible to the existing cermic socket, trim the wire ends, and attach a piece of terminal block. The terminal block makes it really easy to replace the socket again if you have to in the future. Remove the old cermic socket from the metal cradle by removing the two little nuts and bolts. Be careful not to spill nuts, washers, and springs into the innards of the projector. Now the new GX5.8 socket comes with flying leads. Trim the lead length to about 6 ins and insert into the terminal block and tighten all 4 screws. The socket will not quite fit through the rectangular hole at the back of the lamp cradle, so you simply file it out until it will slip through and you can push it fully onto the lamp pins (make sure you don't do this filing operation near the projector- remove the cradle first). There is plenty of room in the existing lamphouse to accomodate the little terminal block and the extra lead wire, but you do need to unscrew and remove that central plate from the black lamp house cover.
Job done!


 -

 -

[ June 05, 2017, 09:42 AM: Message edited by: Paul Adsett ]

--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj

 |  IP: Logged

Mal Brake
Jedi Master Film Handler

Posts: 591
From: Neath, South Wales, UK
Registered: Jun 2003


 - posted October 02, 2012 05:36 PM      Profile for Mal Brake   Email Mal Brake   Send New Private Message       Edit/Delete Post 
Hi Paul,
Totally agree with your post except isn't there a chance the plastic around the terminal block will melt from the heat given off by the lamp?

The reason I say this is because some years ago a friend and myself picked up an Eumig 938S for just £80. The only thing wrong was the previous owner had carried out the same modification. The plastic had melted leaving a waxy goo in the lamphouse and of course exposed terminals.

--------------------
I'm gonna live forever or die trying

 |  IP: Logged

Paul Adsett
Film God

Posts: 5003
From: USA
Registered: Jun 2003


 - posted October 02, 2012 07:29 PM      Profile for Paul Adsett     Send New Private Message       Edit/Delete Post 
Hi Mal,
Good to hear from you.
The socket that I used is all ceramic construction, so no danger of melting there. I was concerned about the insulation around the wire pigtails, but I ran the lamp on full power for an hour, and there was no sign of the insulation melting up next to the ceramic block, so for the particular connector that I used it is a non-issue. Certainly a plastic connector would melt almost immediately.

--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj

 |  IP: Logged

Tom Photiou
Film God

Posts: 4837
From: Plymouth U.K
Registered: Dec 2003


 - posted June 23, 2017 03:21 PM      Profile for Tom Photiou   Email Tom Photiou   Send New Private Message       Edit/Delete Post 
Paul, Thank you for your PM the other day, looking at this here, (sorry if i sound stupid), How is the bulb actually held in place? is it just the ceramic connector holding it in?
There are so many of these ceramic holder available, these are just a couple i found but i want to ensure the quality is there so it doesn't either melt or fall apart,

http://www.ebay.co.uk/itm/Halogen-Light-Bulb-Lamp-Holder-GX5-3-Ceramic-Pack-2-/250881761335

http://www.theinternetelectricalstore.com/hldr-gx53-kanlux-ceramic-socket-lead-72109-4442-p.asp?gclid=CjwKEAjw-LLKBRCdhqmwtYmX93kSJAAORDM6hUtysp4-8jsqa7Ajhy1k5xbH0aI2XVVyqiIpnmmq2B oCNVrw_wcB

https://www.amazon.co.uk/Ceramic-Holder-Halogen-Socket-35-MR11-MR16-Base/dp/B003YGVBL4

Three totally different sources, all very cheap, all ceramic. Any thoughts [Wink] ?

Thanks in advance.

 |  IP: Logged

Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003


 - posted June 23, 2017 03:39 PM      Profile for Steve Klare   Email Steve Klare   Send New Private Message       Edit/Delete Post 
I had an adventure with this.

I bought a cheapy and within a couple of months the socket pin holder burned up on one side and took the lamp pin with it.

I went to the guy I buy lamps from and asked his advice. He recommended something better, and not that much more expensive, which actually had safety agency markings on it.

-that one has been in there several years without any problems.

(Sometimes you get what you pay for!)

--------------------
All I ask is a wide screen and a projector to light her by...

 |  IP: Logged

Tom Photiou
Film God

Posts: 4837
From: Plymouth U.K
Registered: Dec 2003


 - posted June 23, 2017 03:53 PM      Profile for Tom Photiou   Email Tom Photiou   Send New Private Message       Edit/Delete Post 
Steve, could you point me in the direction of what you bought as an example?

 |  IP: Logged

Paul Browning
Phenomenal Film Handler

Posts: 1006
From: West Midlands United Kingdom
Registered: Aug 2011


 - posted June 23, 2017 04:28 PM      Profile for Paul Browning   Email Paul Browning   Send New Private Message       Edit/Delete Post 
Tom, the ceramic base is not that important, what is though is the connections made at the pins, avoid the flat style connections as these arc, and erode the pins, the enclosed style connector is more suited, most disco type suppliers do these type, as many of the earlier lighting effects used 24v 250 watt projector lamps. Martin lighting used this lamp base, and many years later are still working fine. Certainly go for the silicone type cables, unfortunately I would suggest just soldering the cables to the pins, this would eliminate any "spark erosion" at the pins, but this style of stranded cable is almost impossible to solder.

 |  IP: Logged

Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003


 - posted June 25, 2017 06:53 AM      Profile for Steve Klare   Email Steve Klare   Send New Private Message       Edit/Delete Post 
Hi Tom,

This is the one I bought:

EFR Socket

It's pretty rare among these that it actually specifies a maximum operating current. A big part of the problem here is that we are operating a fairly high power device on low voltage. That means a lot of Amps and this puts a beating on things like socket contacts.

These are rated for up to 12 Amps. 150W/15V=10 Amps, so we are in!

Mine have the threaded sockets, so they are the Mitronix ones. I don't think they are particularly better (or worse) than the Buhl ones: maybe that's the stock he had that week.

I'll say this much: I bought three of them anticipating problems, but it's been a couple of years now and I'm still operating on the first one.

[ June 25, 2017, 09:05 AM: Message edited by: Steve Klare ]

--------------------
All I ask is a wide screen and a projector to light her by...

 |  IP: Logged

Tom Photiou
Film God

Posts: 4837
From: Plymouth U.K
Registered: Dec 2003


 - posted June 25, 2017 02:23 PM      Profile for Tom Photiou   Email Tom Photiou   Send New Private Message       Edit/Delete Post 
Thanks Steve, appreciated.

I found this on Amazon today,

https://www.amazon.com/dp/B01H5SUQ2Q/?tag=phpprogramme

i'm not buying this, i stumbled on it by luck during a search but this is the closest thing i have ever seen to the original Elmo holder assy, and i ts on Amazon [Eek!]

 |  IP: Logged

Janice Glesser
Film Goddess

Posts: 3468
From: Sunnyvale, CA USA
Registered: Sep 2011


 - posted June 25, 2017 07:27 PM      Profile for Janice Glesser   Email Janice Glesser   Send New Private Message       Edit/Delete Post 
Tom...That's a QLV-1 Lamp holder. I buy these to do lamp upgrades on several brands of projectors. That Amazon price is way too high. You can get these off Ebay for $9-$10. In some cases I have to remove the socket on the QLV-1 and use the plug-in type shown in Paul's modification.

--------------------
Janice

"I'm having a very good day!"
Richard Dreyfuss - Let It Ride (1989).

 |  IP: Logged

Paul Adsett
Film God

Posts: 5003
From: USA
Registered: Jun 2003


 - posted June 25, 2017 08:10 PM      Profile for Paul Adsett     Send New Private Message       Edit/Delete Post 
quote:
How is the bulb actually held in place? is it just the ceramic connector holding it in?

The bulb is held in place exactly as normal, by the hinged part of the lamp holder which swings down and clamps the front edge of the bulb. The only modification to the original Elmo lamp holder is the removal of the original socket, and the filing out of the hole at the back of the metal lamp cradle.

--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj

 |  IP: Logged

Tom Photiou
Film God

Posts: 4837
From: Plymouth U.K
Registered: Dec 2003


 - posted June 26, 2017 01:01 AM      Profile for Tom Photiou   Email Tom Photiou   Send New Private Message       Edit/Delete Post 
Thanks Paul. I see what your saying there.

 |  IP: Logged



All times are Central  
   Close Topic    Move Topic    Delete Topic    next oldest topic   next newest topic
 - Printer-friendly view of this topic
Hop To:

Visit www.film-tech.com for free equipment manual downloads. Copyright 2003-2019 Film-Tech Cinema Systems LLC

Powered by Infopop Corporation
UBB.classicTM 6.3.1.2