8mm Forum: Eumig S938 Lamp Voltage

This is topic Eumig S938 Lamp Voltage in forum 8mm Forum at 8mm Forum.

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Posted by Paul Adsett (Member # 25) on September 10, 2019, 11:17 PM:

If you own a Eumig 938 or any of the 900 series projectors it is well worth checking the voltage at the lamp (with a good lamp plugged in and illuminated). I found that the lamp on my 938 was only getting 14.2 volts and the picture was unacceptably dim. So I changed the transformer tap from the normal USA 117 volts to the 110 volt tap on the transformer. This brought the voltage up to 15.1 volts which is where it should be, and boy what a difference in screen brightness - really impressive with an f1.0 lens! [Smile]

Posted by Mathew James (Member # 4581) on September 11, 2019, 07:00 AM:

Good to know Paul! I'll have to test as well.

My understanding is that the median is 117v and thus why some things use it. The reason you may be getting more voltage at 110V can be due to the distance from the transformer on the pole.
You can read sometimes more than 120V if close and as low as 107 if some distance away.
It will be interesting to know. I am right in the heart of the City so i would be very close to a transformer i think....

Posted by Paul Adsett (Member # 25) on September 11, 2019, 09:38 AM:

My measured line voltage today at the wall socket is 120 volts, so I don't think that is the issue for me. It must be that the transformer in my particular projector is putting out less voltage (14.2v) than the lamp requires (15.0v). This could be either due to manufacturing tolerances (seems excessive at -5.3%) or a deliberate under running of the lamp by Eumig to extend lamp life, or a combination of both. Personally I will take a much brighter picture at the expense of lamp life any day of the week. Would have been nice if Eumig had fitted a HIGH-LOW lamp switch on the 938 like they did on the 824.
I would be interested to know from Steve if he thinks setting my transformer connection at 110 volts (in order to get 15.0 volts on the lamp) will have any adverse effects on the amplifier electronics.

Posted by Leon Norris (Member # 3151) on September 11, 2019, 10:27 AM:

Paul, what type of lens did this machine come with?

Posted by Paul Adsett (Member # 25) on September 11, 2019, 11:41 AM:

Leon, the OEM lens is a Eumig f1.3 14-30mm zoom lens with the exclusive Eumig optical levelling feature, where the outermost objective lens slides along a rack and pinion track so that the image can be very easily levelled on the screen. It's actually a respectable performing lens although obviously not in the same class of the Elmo f1.0 zoom or the Kodak Ektar f1.0 22mm lens,

Posted by Steve Klare (Member # 12) on September 11, 2019, 12:00 PM:

Hi Paul,

Am I the "Steve" you mean? (Such a common name I don't usually answer when somebody yells it out!)

I would imagine that Eumig would design some reasonable voltage overhead into their amplifiers. Moment to moment, and place to place the line voltage is changeable: 8PM in July with the whole neighborhood lit up and using AC, electric stoves, dishwashers and food processors to 3AM in October with nothing running but alarm clocks and some guy down the street sitting alone in the dark, pounding away on some film forum!

They can't afford to run too close to the top end.

(By the way, have you poked an outlet and measured what your line voltage is? It IS AC season...)

As far as the amplifier power, I think you will personally provide a correction. I would expect the volume at a given knob setting to go up as the voltage goes up, but I would also expect your ear-brain-hand system to turn it down just a smidge, even if you don't realize you are doing it!

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