8mm Forum: Calling all Eumig S938 experts

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Posted by Ronald Kwiatkowski (Member # 3349) on December 19, 2012, 07:30 AM:

Hi everybody,
I got this nice Eumig S938 from ebay, and there is a bit of mending to do. I am however not the expert mechanic, so I'll tell the symptoms and what I see from here.
Everything starts fine, I did pass a 200-feet cartoon, which played well, only the sound would weep slightly. When I tried to pass a 400-footer, the machine started rattling halfway through, the picture wouldn't stand still, sound was weeping heavily. Frame rate seemed to lower, so I tried the frame rate button. It is supposed to go smoothly from 24 to 18 frames and back. However frame rate dropped down considerably, something like 3 frames a second. When I cranked it back to 24, it more or less gained normal speed again, I suppose around 20 frames. I opened the machine front and back, and saw the source of the rattling, which seemed to be quite inaccessible. As I said I'm not the expert, and my vocabulary may be inadequate. Front view, left side, next to the frame rate button. I think it is the main "axis-thingy" coming out of the motor, (the axis which gets that broad belt to turn down to the big wheels). The axis-thingy is vibrating (like being pulled up and down), the more and heftier the later in the movie. I suppose that vibrating explains all the other symptoms, the weeping sound, the fact that the picture doesn't stand still. What else? Oh, the button in the back (which you use to manually transport the film), I noticed that it can be "clicked" in (working) and out (not working), I'm not sure if this is supposed that way. Also the frame rate button can be pushed in, it changes speed, but I can't figure to what purpose or if it is supposed to happen at all. Filmpath was cleaned by me with alcohol, and I dusted the insides. Belt seems fine. I have not applied any grease or stuff anywhere.

I will have a look with a friend mechanic and super 8 lover, but in the meantime, maybe one you has pinpointed the exact and uncostly solution.

Thanks an awful lot, help me get Christmas back [Big Grin]

Ronald

Posted by Pasquale DAlessio (Member # 2052) on December 19, 2012, 07:40 AM:

Hi Ronald

Can you please post a picture? That would be a tremendous help to us so we can in turn help you. Also, if you can circle the item in question that would be even better.

Thanks

PatD

Posted by Maurizio Di Cintio (Member # 144) on December 19, 2012, 10:40 AM:

Regarding the clicking inching knob (in/out) that's perfectly regular, a very clever design indeed: normally the knob does not turn; only when needed, you push it inward so the outer knob gets to engage the main shaft and you can rotate it manually. Also no problems with the fact the speed change knob can be pushed in: that's normal too.

As for the real flaw, based on what you described there might be a problem with the auxiliary and/or main shaft; could you please post close ups of the bearers of the auxiliary shaft (the shorter one, coming in direct contact with the motor), and the belt transmission assembly, especially the tensioning rollers which the toothed belt runs through, as well as their elastic supports.

Posted by Ronald Kwiatkowski (Member # 3349) on December 19, 2012, 08:14 PM:

Pictures, who would have thought of that [Big Grin]

here we go:

This first picture shows the frame rate button and the "big wheels" (are those the ones you're never supposed to touch except with alcohol?).

This is a bit up the frame rate button. I noticed now that the "Axis-Thingy" is not the axis coming out from the main motor (which is probably just up a bit). The belt is sort of moving around the axis-thingy, which - as I suppose now - serves to make the take up reel rotate. I suspect it to be connected to the backside button for manual transportation.

Same thing, seen from a bit more to the right. I suppose the big upper wheel is the main motor wheel, I could be wrong though. Anyway, what's rattling and vibrating is the axis-thingy hitting against that piece of metal on the right. As more and more film rolls up on the take-up wheel, the rattling increases and overall speed decreases. Maybe it's only a greasing matter.

Just to be complete: the backside with the manual transportation button.
Thanks very much, guys!

Posted by Maurizio Di Cintio (Member # 144) on December 20, 2012, 02:44 PM:

Spot on! The shutter shaft is too hard to be put in rotation, so the "axix thingy" (as you call it) tend do have those tiny rollers move too outward, instead of keeping the belt firmly in position around the main shaft. This way the rollers touch the piece of metal you highlighted. All the rest of the machine seems to be in good shape, but you have to clean old grease around cogs etc of the shaft as well as the shutter assembly; in fact old grease may get sticky. The symptom you described is an obvious evidence of this. The rattling noise increases with the amount of film transported because the tension varies throught the process.

Also some rubbing of the big discs with finest sandpaper will help: this way you'll gain some more grip back between the mnotor's pulley and the rubber surfaces of the discs, increasing transport torque. And yes, you shouldn't touch those discs but with isopropil alcohol (the type you would use to clean magnetic sound heads and rubber pinch rollers in tape recorders,as other types of alchol may harden the rubber and this is something you don't want to do). So clean the discs and sand them right after.

Good luck.

Posted by Ronald Kwiatkowski (Member # 3349) on December 21, 2012, 04:49 PM:

Thanks an awful lot, Maurizio. I did as described, cleaned from old grease, applied new grease, cleaned and sanded the discs. Worked very fine, until the very end of a 600-footer, when the problem slightly reappeared. So I'll check the greasing again, I may have missed something. I'm not too keen on sanding the discs again, as I read in another thread, the rubber might come off too much. Somebody said something about a spring that's too tight, but apparently it's difficult to adjust it. Well, anyhow here's the punchline:
the fan for the lamp isn't working, at all. [Roll Eyes]

The fuse seems ok though. Surely enough, the lamp bit the dust, this very evening (it must have been old though, intensity wasn't that great). Any ideas what might be wrong with the fan?
Thanks again [Big Grin]

Posted by Hugh Thompson Scott (Member # 2922) on December 22, 2012, 10:02 AM:

It might be Ronald that the fan might needs a bit of lubrication
or something might have jammed it, I'm no mechanical genius either, but just check it's running free.A point with the ball and disc, you might want to give the ball a bit of a roughing to help it grip the disc.Make sure that the blades aren't catching anything.

Posted by Maurizio Di Cintio (Member # 144) on December 22, 2012, 01:47 PM:

Hi, guys! I agree with the last two posts, especially as regards the motor pulley might need some cleaning. Use alcohol but try not to touch the rubber discs. The lamp cooing fan might be stuck, like Hugh suggested: try hei remedies. Should they not suffice, the motor might nìbe burnt, but it shouldn't be so serious; after all it looks like a rather common DC micromotor; try determinig its voltage by using a multitester, and get a new one from a tape deck servicing facility that might fit in the machine as regards size and performance. Keep us posted, Ronald, and good luck.

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