8mm Forum: Estimated Magnetic Head Lifetime

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Posted by Phil Murat (Member # 5148) on August 22, 2018, 02:57 AM:

Hello,

Exepted GS1200 who is featuring "Extra Long Life" Heads (reading head), the life of "Classical" heads is estimated around 200 Hours.
I have experienced this with a Beaulieu for which I have to replace Heads between 200 to 300 Hrs (Films used were not lubricated in that case).
This approach depends on :

- Quality of films tracks (Bonded or painted)
- Film lubricated or not
- Heads proper positionning
- Heads press condition

This give an idea how to anticipate spare heads quantity you'll need......

Posted by Tom Photiou (Member # 130) on August 25, 2018, 01:27 AM:

All i can add is that in 40 years in the hobby and thousands of hours of viewing in that time, my 1200HD still has the same heads. I have had the head pressure pads replaced as when worn, these can cause scratching. Something must have been seriously wrong if they go after a few hundred hours [Wink]

Posted by Phil Murat (Member # 5148) on August 25, 2018, 09:26 AM:

Yes Tom, GS1200 Head (ST 1200 Seems to look same design) is simply great !!!

Did you keep your former Head press pads ? I assume it is possible to re-cut them to give them a second life .......

What do you think ?

So , to be confirm

Posted by Tom Photiou (Member # 130) on August 25, 2018, 10:59 AM:

We have two more full pressure pad assembly's left plus two single pads.
These wear flat and can cause some scratching to the left and right of the image. I was told that it is possible to file them again but this will only have a limited life. My main 1200HD has had one new set of pads and springs and then around 10 years after , (recently), it has had a brand new pressure pad assembly. I would imaine if you have a lot of movies in your collection that has that awful bumpy rouge stripe used on later releases then this , (IMO) would be pretty rough on the heads and pressure pads.
This was job i had done professionally as anything to do with the heads is a bit too delicate and a slip or wrong turn could do more harm than good. Plus i would imagine it needs to be set up properly.
If anyone on here has ever changed the pressure pad assy then please share the procedure on here. It would be one of the more useful threads of late [Wink]

I was surprised to hear of your Beaulie as this seems to me to be a very high quality projector. I cannot imagine those heads would only last a few hundred hours, unless of course your running rough films with no lube and dozens of poor splices or something. This is a high end projector. [Wink]

[ August 25, 2018, 03:38 PM: Message edited by: Tom Photiou ]

Posted by Paul Adsett (Member # 25) on August 25, 2018, 11:14 AM:

When I purchased a spare Eumig 800 series head back in 1990, the life of the head was stated to be 150 hours. This seems ridiculously low, but it is probably based on some percentage of high frequency loss, that is when the frequency response of the sound head falls significantly below the new head specs. It does not mean that you cannot run sound films beyond 150 hours,just that you will no longer be getting optimal performance. I have had Eumig 800 series heads that have worn to the point of very muffled and low output sound so that they are totally unuseable. Not sure how many running hours it took to get to that point, but it was very probably much less than 1,000 hours. Elmo heads just seem to last forever. The head pressure pads on the Elmo's are very easy to replace, and the exploded view in the GS1200 manual is pretty self explanatory. I don't think it requires any special level of expertise to do this job.

Posted by Maurizio Di Cintio (Member # 144) on August 26, 2018, 05:11 AM:

There has always seemed to be two different groups of sound heads for S/8 projectors: the European type (usually made of permalloy which offers good performance but is relatively soft and not long lasting) and the Japanese type (made of ferrite or sendust alloy - Elmo/Goko - for better performance) both of which are very tough and wear-resilient. All Japanese projectors that I have used in my 35+ being in the hobby have hardly ever needed to have their S/H replaced (exception: Elmos still have their original heads with no exception); on the contrary Eumigs and Bauer (although to a somewhat lesser extent) need much more frequenbt S/H replacements. Worth mentioning: the Italian manufacturer Photovox heads (Fumeo are equipped with these heads) seem to be very much as tough as Japanese heads. Of course pressers' force and film lubrication/ paste/stripe quality are also to be factored in but all things being equal, Jap heads stand the test of time several times better than their European counterparts.

Right now though I am much more concerned about a different issue than heads duration: it seems that starting Sept 1st, halogen lamps will not be manufactured any longer and we'll have to rely on existing stock until they are depleted. This is due to new European environmental regulations favoring long lasting, low consumption lams. Even if there is an extra European manufacturer of these, they will not be permitted anymore in Europe. Any input on this?

Posted by Tom Photiou (Member # 130) on August 26, 2018, 06:47 AM:

Poxy European Laws again!! I guess its a case of having to stock up, i would have thought by now with LED technology that our sorts of bulbs would have an equivalent. I have read about the possibility on this but not really heard anything substantial.

Posted by Martin Dew (Member # 5748) on August 26, 2018, 07:13 PM:

Maurizio, I think the EU directive is only for tabletop lamp-type bulbs, and not the mirror arc type used in recessed ceiling lighting, and therefore presumably our projector bulbs too. It would be good to get this confirmed though.

Posted by Dominique De Bast (Member # 3798) on August 27, 2018, 04:33 PM:

Martin, it's not clear at all. I read that halogen will be banned from 1st September. Only existing stocks will be allowed to be sold. The only exception I saw are "integrated lamps" (the given example was "like in an oven") and the lamps with G9 and R7s bases. I hope the projection lamps are not on the banned list but I couldn't find any mention of this.

Posted by Steven J Kirk (Member # 1135) on August 27, 2018, 05:53 PM:

Next year the 'European' laws won't count. Get ready to lobby your local MP about consumer issues like this...

Posted by Martin Dew (Member # 5748) on August 27, 2018, 07:13 PM:

Too right, Steven. Thanks for stating that. I'm looking forward to an era of accountability again.

Posted by Brian Fretwell (Member # 4302) on August 28, 2018, 02:38 AM:

The entertainments industry has been lobbying for an exclusion for lamps in theatre and other lighting. I would hope that as they say they have had some success this might extend to projector lamps. Remember also that A1/231 lamps were used in thing like dentist's inspection lights as well as projectors.

Posted by Mark Todd (Member # 96) on August 28, 2018, 06:40 AM:

I think you might be surprised how many European !!! laws they still impliment if it suits them.

Plenty of EU countries ignore ones they don`t like which we could easily have just done and saved a stack of cash.

Lets hope there is an exception to these bulbs.

Or we will have to buy them from abroad !!!

Is there an LED option looming ? or more simple HID set up.

Best Mark.

Just looked these up !!!

https://www.djkit.com/replacement-lamps/xenpow-hid-150-lamp.html

Posted by David Hardy (Member # 4628) on August 28, 2018, 11:26 AM:

I bought a Eumig 710D dual sound projector around 1972/73.

I still have it and have never had to replace the sound heads or pressure pads.

The only problem it has is speed slowing down issues.

Not bad for a machine that has had regular use all that time. [Smile]

Posted by Maurizio Di Cintio (Member # 144) on August 30, 2018, 11:48 AM:

David, the problems with Eumig sound heads started with series 800 and worsened with the last one seires 900. The sound heads for your projector are totally different, bigger and more wear-resistant...

Posted by Paul Adsett (Member # 25) on August 30, 2018, 04:11 PM:

That's very interesting Maurizio, I had no idea that the 900 series heads wear down faster than the 800 series. But I do follow your excellent tip of running mono films on the 938 with the track 2 pressure pad removed. Hopefully this will greatly extend the life of the track 2 head.

Posted by Brian Fretwell (Member # 4302) on August 30, 2018, 05:18 PM:

The 926 balance stripe head I believe was worst for this, I know mine didn't last long. I must retry it and see if it is the head and not the pressure pad though.

Posted by Maurizio Di Cintio (Member # 144) on September 02, 2018, 08:02 AM:

Probably my latest post is affected by the fact that, being a filmmaker more than a collector, I used to post produce sound (even rather complicated soundtracks) on my film with Eumig projectors; this entails a lot of stop and go, rewind, check, re-try which probably encreases head wear to a certain extent. I guess if you use projectors for regular screenings without stops, this will result in longer head life. Nonetheless soound heads on models 926, 936, 938 and 940 are indeed softer than other models, especially series 800's. These heads are a little smaller than previously, and above all, the thickness of the gap material is inferior to Series 800's. More to it by carefully observing the contact area of these heads, you can see they are made of layers of magnetic metal bond together: there are 4 layers for track 1 and only 2 for track 2! This makes the latter not only softer but weaker than the main stripe's head inasmuch as the two layers might easily come apart and the head becomes useless even if it were brand new: I have seen a couple of these machines with the balance track's heads in such awful conditions; probably some hard prints/splices had passed through them, but the main head was still unscathed. So these heads are more fragile to the point I suspect there might have been a few production batches where something went wrong; probably the binding agent or something that makes the two layers prone to come apart. To avoid this, I applied a tiny quantity of superglue (in gel) to the sides of the protruding part of the balance track which should prevent damages like the one described. This and the use of a 2-track pressure pad ONLY and IF required, has greatly increased the life of this particular head (my first 926 had its head refitted in 1991). In the future I'll exert same precautionary measure should I have to replace it again (and - I am afraid - the time has almost come). If only we could find something similar to replace it!!!!! But these heads are very unusual and rather short in height, so to the best of my knowledge there is no replacement other than the original ones. Which are now scarcer and scarcer....

Posted by Paul Adsett (Member # 25) on September 02, 2018, 10:45 AM:

Am I correct in saying that there are no new Eumig 800 or 900 series heads available anywhere?
I wonder why Eumig used such soft magnetic material, to improve frequency response perhaps?

Posted by Maurizio Di Cintio (Member # 144) on September 02, 2018, 11:39 AM:

To the best of my knowledge, Paul, you are right. Although perhaps in Germany, some specialized repair centre for our beloved euipment, might still have some spares; fact is these spares (if any) are not meant for resale: they are meant for the technician to install them in a projector. Therefore as long as retirement is still not an option, such technicians will be unlikely to offer these heads for sale. It's such a pity since these projectors are such fine machines they might go on indefinitely if it were not for their heads. But I take it you - Paul - use your S 938 primarily to screen features and this should help your sound head. The material used by Eumig is presumably permalloy but the problem does not lie primarily with it: after all Bauer/SIlma/Beaulieu heads are the same material... The problem IMHO lies in the manufacturing process which had not been thouroughly perfected at the time. Let's not forget these heads date back to an era when Eumig was about to have financial problems: lots of new products and ideas in the pipeline, but second thoughts too; R&D department probably was experiencing a lot of stop&go's, lots of pressure, and maybe the quality check left something to desire... We will never know...

Posted by Martin Dew (Member # 5748) on September 02, 2018, 02:38 PM:

That's interesting information, Maurizio, thanks. Yes, Paul, unfortunately it looks like there are no more heads available for the Eumig 900 series now. Even John White, our brilliant Eumig engineer here in Blighty (who was a former employee of Eumig distributor Johnsons of Hendon) cleared out the Avco complete UK parts inventory last year, and sadly there was no box of unused 900 series heads, which he was hoping to find.

My friends at Eumig Museum helped me out last year because I'm helping them with a couple of projects. They managed to find me a slightly used set of heads but their search took several months, went outside Vienna, and involved contacting ex-employees in Salzburg and beyond. I actually felt guilty that they had worked so hard to recover a set for me.

There was a thread on here where Edwin Van-Eck had considered rebuilding the assembly, but he had apparently found it cost-prohibitive. The balance head on the first S938 which I bought in 2016 is starting to lose treble, so I'm assuming it's on its way out. Wouldn't it be great if between us we could find a solution to allow these wonderful projectors to survive with full functionality into the future?

Posted by Paul Adsett (Member # 25) on September 02, 2018, 03:11 PM:

Yes that would be great Martin but if Edwin, with all his expertise, manufacturing facilities, and industry contacts has concluded that a new re-manufactured head is cost prohibitive, then we should not expect any.
Much as I love my 938 I know that in a few years it will end its days as a superb silent projector and I am convinced that, out of all my projector collection, the GS1200 will be the last stereo sound projector standing.

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