8mm Forum: Elmo ST-1200: new belt and spring but speed & sound issues

This is topic Elmo ST-1200: new belt and spring but speed & sound issues in forum 8mm Forum at 8mm Forum.

To visit this topic, use this URL:
https://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=006770

Posted by Akshay Nanjangud (Member # 2828) on January 06, 2012, 10:43 PM:

Hi guys,

I got myself this Elmo ST-1200 yesterday.

Users of this projector should identify this shroud (?) that covers the lamp. The glass, as the picture shows, is cracked. Can I buy this glass somewhere? If I can't, can I do without it?

My ST-1200 seems to have only one belt. On touching, it leaves light black marks. It seems to have lost elasticity. This obviously need replacing. What confuses me is the eBay seems to sell 3, 4 and 5 belt sets. Can someone please explain why?

Finally, the drive pulleys don't seem to touch the shutter. In picture, the pulleys A and B don't make contact with the Shutter(?) for any 18 or 24 fps. Is this how it should be? Will a tight new belt establish contact?

Please help.

Posted by Steve Klare (Member # 12) on January 06, 2012, 11:15 PM:

If it's what I'm thinking it is, that glass is a heat shield so you can operate the ST-1200 in single frame mode without the lamp burning the film. I think what you are seeing is actually a stress relief in the glass and not actually a crack.

It's interesting: Steve Osborne is quoted in this thread as recommending this shield be removed to increase light output (if you don't use single frame) My ST-1200 came from Steve Osborne, and doesn't have it!

ST-1200 Heat Shield

The different belt numbers are partially because there are different models of the ST-1200. For example the ST-1200HD has a footage counter that the others don't have, and there is a belt just for that. I think isellprojectorbelts also sells partial belt replacement kits.

Here is a .pdf of the ST-1200 service manual: since I haven't had to replace mine (yet), I bet it has a lot of details I don't.
ST-1200 Service Manual

My 18FPS roller doesn't quite touch my shutter wheel, I think it is possible to adjust the rocker assembly to fix this but I haven't tried it yet. (I don’t use this machine for 18FPS.)

Posted by Jon Addams (Member # 816) on January 06, 2012, 11:21 PM:

Akshay,

I see Steve and I were typing almost at the same time but he being a faster typist than me was able to post first. [Big Grin]

The glass comes in two pieces, it is designed this way so the heat from the lamp can escape. The glass is correct.

The Elmo ST-1200 uses 2 belts, one runs from the motor to the shutter's shaft, and the other runs underneath the top, from the front to the rear spindles so they can rotate.

The belt(s) you need are on eBay, just do a search for ST-1200 belts.

I hope this helps.

Jon

Posted by Pasquale DAlessio (Member # 2052) on January 07, 2012, 12:11 AM:

Akshay

Congratulations on buying a great projector. I have one. You can get the belts from Steve Osborne at:
The Reel Image
2520 Blackhawk Rd
Kettering OH 45420
937-296-9036 voice
937-296-1084 fax

AS far as the rollers, you can adjust them in 2 places. Since you now have the manual, check that section. It is not a hard job.

PatD

[ June 07, 2014, 06:39 PM: Message edited by: Pasquale DAlessio ]

Posted by Akshay Nanjangud (Member # 2828) on January 07, 2012, 02:55 AM:

Guys, thanks so much for your replies. Armed with your suggestions, I hope to make some progress tomorrow. You guys seem to have answered everything!

Posted by frank arnstein (Member # 330) on January 07, 2012, 04:34 AM:

Yes, seems to have covered it all,,,, yet, from the picture, there appears to be a very important extension spring missing from your projector. It provides the pressure needed to keep the rubber drive rollers against the shutter edge. Without that spring, No Drive. Near the arrow A is a hole where the top end of the spring should be in. The hole for the other end is some where behind. Get a few extension springs and see if you can fit one that will give the right amount of tension for the friction drive to work ok. You might even find the old spring fallen in behind the works.

Let us know how you go after fitting belts and a spring.

dogtor [Wink]

[ January 10, 2012, 12:28 AM: Message edited by: frank arnstein ]

Posted by Akshay Nanjangud (Member # 2828) on January 07, 2012, 02:56 PM:

Steve, Jon, Pasquale and Frank - thanks a lot. I read the very informative thread on the heat shield, had already given the service manual one quick look (must read it more closely) and the clarification on the number of belts was very helpful.

Frank, you mention a spring that is supposedly missing. Can you (or anyone) tell me more from the picture below?

I believe my model of the ST-1200 didn't have the spring. The reasons for my belief aren't technical but the superb condition in which I purchased the projector. Please see the pic below and comment.

Posted by Jon Addams (Member # 816) on January 07, 2012, 04:20 PM:

Hi Akshay,

I believe the dogtor [Wink]

(Frank) is talking about the spring in the pictures below, looking again at your photos the spring in question appears to be missing and as the dogtor;) said "no spring - no drive" [Mad]

Jon

Posted by Graham Ritchie (Member # 559) on January 07, 2012, 04:41 PM:

First thats an excellent choice of projector, with a bit of tender loving care it will last forever. I bought mine back in 1979 second hand and its still going strong and would never part with it. That model I think was the first in the range "around 1975" of Elmo ST1200 projectors and has only one belt. Leave the split glass as is, the reason that all the hot air from the lamp is directed out the top and none indirectly towards the gate where your precious film is running.

I replaced the drive belt with O ring seal to match and works fine, cost $3.

Graham. [Smile]

Posted by Akshay Nanjangud (Member # 2828) on January 07, 2012, 04:44 PM:

Jon, the spring you mention is there. See pic.

Graham, the spring in your picture is indeed missing. Can this be bought? Can I just adjust the drive to always be in contact with the shutter at least for 24 fps?

Graham, what is this O-ring seal? Can I get it in ACE hardware or somewhere locally?

Posted by Graham Ritchie (Member # 559) on January 07, 2012, 04:50 PM:

The spring in the first photo I posted pulls the 18/24 rollers onto the shutter, you need it. not sure where you can get a spring but should be easy enough to find something that will do the trick. I took my old drive belt to a company here called "Seal Imports" and the assistant on the counter measured and matched it with there vast stock...very helpfull. The number was 239EPR O Ring IMP. hope that helps.

Graham. [Smile]

Posted by Steve Klare (Member # 12) on January 07, 2012, 04:53 PM:

I think Frank is actually talking about the spring up on the rocker that forces it to snap to either one side or the other. This is what provides the force that pulls the rollers onto the shutter wheel.

When you move the speed selector is there a lot of resistance to the motion until it's more than halfway there and then a strong pull into the other speed setting?

(EDIT: and now I'm the echo!)

Posted by Akshay Nanjangud (Member # 2828) on January 07, 2012, 04:57 PM:

Thanks guys. Now, I need that spring. I'll look around locally. Does anyone know of this: http://www.elmorepair.com/ ?

Is there any way of checking if the sound works on this projector being in the condition it is in?

Posted by Graham Ritchie (Member # 559) on January 07, 2012, 05:10 PM:

Just thought to add that when you change the belt you adjust the tension of it by moving that chrome "idler pully" to suit thats the one in your photo just below the two rubber drive rollers.

Graham

Posted by Akshay Nanjangud (Member # 2828) on January 07, 2012, 05:15 PM:

So, I got an O Ring seal for the drive (as Graham suggested, I like this for now) and a spring. The first few minutes the projector ran beautifully. The sound was superb too, as good as if not better than my Bolex SP-80. Life was good. If you don't believe me, take a look at the pic. [Smile]

First, the sound disappeared. I unscrewed and re-screwed the back cover several times but sound seems to have deserted me. Now the sound doesn't even start on re-threading.

Next, the ST-1200 started running slow. This happens when I turn the switch to F.

Does anyone have ideas?

[ January 08, 2012, 04:02 PM: Message edited by: Akshay Nanjangud ]

Posted by Steve Klare (Member # 12) on January 10, 2012, 03:17 PM:

Hi Akshay,

The ST-1200's biggest weakness is speed regulation. Mine will mosey up to 24FPS eventually, but it takes a while. I usually let it warm up before I project anything, and even then the sound runs a little bassy for the first 30 seconds or so.

Other than that you should make sure that the new belt you just put on is not too tight (or too loose). Adjust the idler pulley around and see if that speeds things up. (Be careful: there are dangerous voltages exposed with the cover off!)

There are loads of ways of losing sound.

1) Film not pressed down on the heads.
2) Bad connection between heads and sound circuit.
3) Bad connection between sound circuit and speaker.
4) Oxidation on contacts
5) Dead semiconductors in the sound circuit.
6) Loss of input power to the sound circuit
7) Dead speaker.
8) Selective deafness. (It's the reason my wife occasionally "loses sound". [Wink]

)

(etc., etc.,...)

When you turn the sound on, what do you hear?

-nothing?
-hum that changes with volume?

If there is some hum then when you run a film if you crank the volume is there just the hint of soundtrack there?

Do you hear anything if you plug headphones in?

The standard thing is to work the switches and jacks hoping to break some oxide, but being that you had sound recently this may not apply (no harm trying...)

Posted by Michael O'Regan (Member # 938) on January 10, 2012, 04:26 PM:

I also removed this glass shield from my 1200. Unless you plan on using still-frame it's of no use and it does block some of the light.

UBB.classic^TM 6.3.1.2