8mm Forum: Elmo GS1200 Light fault...HELP Please

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Posted by Mark L Barton (Member # 1512) on January 15, 2017, 04:23 PM:

Hello, my Elmo GS1200 has developed an issue whereby, I go to play and then when I turn the lamp on I get a 'clunk' and no light? Any thoughts welcome, thank you

Posted by Graham Ritchie (Member # 559) on January 15, 2017, 07:43 PM:

Most of the problems you get, regarding the lack of light is due to a failure of the lamp socket itself. Over time those tiny contacts simply burn out. [Frown]

The contact between the lamp pins and the socket are inadequate and always have been for the current the lamp draws and over time they give up.

Posted by Andrew Woodcock (Member # 3260) on January 16, 2017, 06:11 AM:

First of all, see where the supply to lamp holder ends.
ie Trace from transformer and fuse, through to switch and lampholder by using a multimeter.
No supply is needed as you are merely testing for continuity of a circuit.
if the supply appears good right up until the lamp pins, as Graham says, it will more than likely require a new lamp holder connector.
Bender & Wirth are both the most durable and reliable I've found.
Do however, ensure you select the correct type for your current rating of your particular lamp.
In this particular case, aim for a 10 amp lamp connector to give yourself just a little head room.

[ January 17, 2017, 06:45 PM: Message edited by: Andrew Woodcock ]

Posted by Mark L Barton (Member # 1512) on January 17, 2017, 02:29 PM:

I have pre heat of the lamp but no hi/low power on? Checked with a new lamp , exactly the same, pre heat but no final power. My other GS1200 works as it should. Help needed........

Posted by Andrew Woodcock (Member # 3260) on January 17, 2017, 04:35 PM:

The pre heat facility and the actual full voltage supply to the lamp will be two separate circuits.

If you've traced as far as you can and you cannot find the fault, send it to Bill Parsons as he is our resident Elmo expert here in the UK.

Posted by Paul Adsett (Member # 25) on January 17, 2017, 06:31 PM:

Mark, you really must take Graham's advice and install a new lamp socket. The fact that you have preheat does NOT mean that the lamp connector is OK, as the socket may still be able to carry the low preheat current, but not the full 8 amps operating current. This is a very common observation with all these halogen lamp sockets.
Change the socket.

Posted by Andrew Woodcock (Member # 3260) on January 17, 2017, 06:37 PM:

But then there's the other fault now Paul, apparently to do with the electronic speed regulation.

That's why I suggested he simply hands it over to Bill for a quick remedy to both issues.

Posted by John Hunter (Member # 4925) on February 08, 2017, 01:36 PM:

Andrew, I have the same trouble with my GS. I was showing some of our holiday films onto a 4 foot screen. At the time it looked not as bright as a GS should be on a 4 foot screen, but I kept going.
The next day I tried to find the fault, but this time the lamp would not light at all. New lamp, same. A few days later I tried again, this time lamp on but not as bright as it should have been.
This was 2 weeks ago!! As you said to Mark change the lamp socket. Went to Bender & Wirth site, but got mixed up with all the lamp sockets listed- please which one do I buy??.
Thanks, john in scotland

Posted by Andrew Woodcock (Member # 3260) on February 08, 2017, 01:55 PM:

Are you certain its the lamp socket in this case John?

Posted by John Hunter (Member # 4925) on February 08, 2017, 02:04 PM:

Andrew. I think so, as it is intermittent. I hope it is not relay RY303. I have both the service manual and parts list-I bought these before I found it was a REALLY COMPLICATED machine. The first time when it seemed the light output was down, after every one had gone, I took the lamp out, looked at the pins, put the lamp back in, and it would not work at all.
john

Posted by Andrew Woodcock (Member # 3260) on February 08, 2017, 02:05 PM:

Have you got a multimeter John?

Posted by Paul Browning (Member # 2715) on February 08, 2017, 02:35 PM:

Just type on ebay 24v 250w lamp holder and you will get a few hits. These are a standard lamp holder for downlighters and a vast range of other use's, most have the heat resistant leads and ceramic base. You can choose the one closest to your own, simple to fit, but from experience difficult to solder.

Posted by John Hunter (Member # 4925) on February 08, 2017, 02:42 PM:

Andrew. Yes I have multi meter, and Paul, thanks for tip on ebay.

Posted by Andrew Woodcock (Member # 3260) on February 08, 2017, 04:37 PM:

Though it is very much against first principles, some things at times DO have to be tested "live" if you are working to a budget and don't want to waste time as well as money.
If you feel confident John, i was going to suggest you measure the voltage at the point the lamp holder leads are soldered back to the switch / transformer.

The reason being, from the symptoms you are describing, it isn't typically what you would expect to see if the lampholder was faulty.

Typically as these are coming to the end of their serviceable life span, you see the lamp going on and off in quick succession.
You also commonly see arcing to the lamp pins in evidence, or blue discolouration to the lamp pins.

Often the lamp pins will stick in the holder where they have virtually welded themselves to the holder contacts, in a similar manner that relays and contactors do the same after prolonged use.

Have you seen any of these symptoms to suggest that it is definitely your lampholder that is at fault here?

Incidentally, any lamp holder works well to begin with, I only endorse B&W Lamp Holders as i have found over the years that these last the longest with the least hassle.

By all means, if you are certain it is the lampholder, then take Paul's advice, but if you do insist on a B&W lampholder if you are perhaps a heavy user of your machine, then the type you would need is this one pictured here.

Model number- 881 rated at 10 amps.

This gives you a little headroom on the maximum current capacity of this which adds to its longevity.

Ensure the cables are well insulated all the way back to their soldered joints also.
Here is one I fitted a few years back now,..

I find they work better and last longer with the holder mounted in a horizontal plane rather than vertical as is often seen.

Posted by John Hunter (Member # 4925) on February 08, 2017, 05:22 PM:

Andrew. Thanks for all the info in your post. When I looked at the pins I did not see any bluish marks, although I was not sure what I would find. On the point of sticking, that may be clue. I did have trouble getting the lamp out at my first attempt, and I thought it may have been the bracket that was stiff, never thought of the lamps pins sticking to the contacts. It came out on my second attempt. Looked at the transformer drawing in the service manual, but does not indicate which wires go to where. The wires at the lamp socket are heavy duty white ones. Tomorrow I will get my meter out and check the voltage at the lamp pins first. I must say that I have looked at the wires at the transformer, and the soldering is dreadful not good enough for a unit made by elmo. That's in my opinion. Will check voltages and let you know what I find.

Posted by Andrew Woodcock (Member # 3260) on February 08, 2017, 05:51 PM:

John, pound to a bag of shit, it won't be the original soldering done by Elmo what you are now seeing.

Take care mate and keep your hands well well away from any mains voltage points, transformer windings and all other tappings!!

Wear insulated gloves if possible and ensure the probes of your meter go only where you need them to.

Only attempt to do this if you feel you are both experienced and qualified to do the work.

Before attempting any of this, trace your two lamp cables back to origin without the machine even plugged in.

Take readings on Low and High Lamp setting.

Remember to place your meter on the A.C. range above 24v

Good luck and STAY SAFE

Posted by John Hunter (Member # 4925) on February 09, 2017, 02:22 PM:

Andrew. I traced the wires from the lamp socket back to the transformer as best I could, and found nothing to worry about. I then got my meter out, and checked the voltage at the lamp socket and found them to be only a volt or so down from what they should be. As a check I took a reading at the trans, and found them the same!! The lamp would not stop working!! I pulled the wires behind the socket, moved them at the trans, but the lamp did not flicker. Now I wonder if I have been mislead, and the fault is elsewhere. As in my first post to you, I said the picture was not as bright on a 4 foot screen as I thought it should. Taking the lamp out, putting it back, then the lamp not working at all, may have hit a point on the socket that was about to give trouble in near future. But, the 4 foot screen I used, was bought on e-bay some years ago, and this was the first time I used it. In the past I used an 8 foot screen permantly mounted in the bay window-good on wide screen films-but my wife wanted a different curtain rail and curtains, so it had to come down!! The circuit diagram showed no tappings on the transformer input, and is not provided, but the Elmo label on the rear of the machine, states its a 240v projector. I metered the mains, and found it to be 230. I have always assumed it to be 240. It may be the reason for the drop of a volt or so at the lamp. I am always careful with high voltages. I am a radio ham, and some years ago while working on the back of my transmitter which was in a 6 foot cabinet, and I was working on the power supply in the bottom, I touched a point at 1500v and I was flung against the wall. I was lucky my other hand was not touching the earth, or I would not be having trouble with my gs1200!! So this trouble could be caused by a ebay scree.

Posted by Maurice Leakey (Member # 916) on February 09, 2017, 03:18 PM:

Since the "Electrical Safety, Quality and Continuity Regulations 2002" came into force the UK declared voltage has been 230.
However, there is quite a tolerance applied to this figure. The 230v can therefore vary between plus 10% and minus 6%.

Posted by John Hunter (Member # 4925) on February 09, 2017, 03:54 PM:

Maurice. Thanks for the info, I was not aware of that regulation.
I have a 6 foot tripod screen, too big to use often, but it may prove a point. It was just about 2 weeks after my film show, and not looking a bright picture, that this subject came up, and thinking it may have been the same with my gs1200, that I got into it.
john

Posted by Andrew Woodcock (Member # 3260) on February 09, 2017, 04:48 PM:

It seems all is working ok then John aside from your screen?

Posted by Maurizio Di Cintio (Member # 144) on February 09, 2017, 05:46 PM:

If there is a "clank" when the light goes down for a very short time, then it should be a relay box in the innards of the machine: it's transparent so you can see all of the contacts. It shouldn't be too difficult to find a spare. But I hope the problem is elsewhere.

Posted by Paul Adsett (Member # 25) on February 09, 2017, 08:01 PM:

You are wasting your time (and ours [Smile]

) until you have replaced the lamp socket as Graham and I have suggested. The voltage on the lamp leads tells you that the transformer is supplying the correct voltage to the lamp, BUT the contacts are not capable of carrying the 8 amps current. Please replace the lamp socket and you will find that it fixes the problem and your screen illumination is better than ever.
Also, instead of trying to solder the lamp wires, I would recommend that you cut the lamp wires in the lamp housing, close to the old socket, and use a screw type terminal connector to connect up the wires from the new lamp holder. That way, any future replacement connector (and you will need one every few years) can be hooked up in a couple of minutes.

Posted by Andrew Woodcock (Member # 3260) on February 10, 2017, 12:08 AM:

Paul's right here of course John, except to say the symptoms you described at the beginning are nothing at all like when a lamp socket is ending its natural lifespan.

On and off in quick succession is what you normally begin to witness with on only being after you have played around with the sloppy socket connections. Sometimes even a slight strobing effect from the lamp due to poor connection intermittently.

But to describe the lamp brightness as being slightly less bright than normal, when lit, had me doubting in this case, that it could be the lamp socket.

I personally, never advocate cutting the original lamp cables and joining them. This can sometimes only add confusion to the situation especially if the original soldering isn't right to begin with like you are describing above.

Then you are simply adding something decent to something not and probably just rendering it useless from the outset.

You need to start from the beginning to eliminate this component altogether from the equation.

Posted by John Hunter (Member # 4925) on February 10, 2017, 01:52 PM:

Many thanks Guys for the detail post about my light fault on the gs1200. I will now change the lamp socket as advised, and it should end any problem. Thanks again for all your help.
john

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