8mm Forum: Elmo ST-1200HD: No Get-Up-And Go!

This is topic Elmo ST-1200HD: No Get-Up-And Go! 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=012877

Posted by Steve Klare (Member # 12) on April 01, 2019, 10:07 AM:

I'm having a little trouble with my ST-1200HD. Sometimes when I shift into forward, I get a pathetic hum, but no transport motion at all. Other times I get really low film speed (-can't even be 10FPS) and it gradually and unsteadily climbs up to 24 FPS after some tens of seconds.

Many times it's just fine, but still I don't trust it.

I have some opinions of what's going on here, but I'd like to hear what other people have experienced over the years.

Posted by Mike Brantley (Member # 6275) on April 01, 2019, 10:34 AM:

No help here, but I also observe a similar phenomenon with the ST-1200D that was recently gifted to me. For a few seconds there is no motion, only a hum, followed by a slow movement. Usually I turn everything off and then advance the knob to warp speed again (er, forward, 24fps), and away we go with no further difficulty.

It's something for me to diagnose eventually, but for now the problem is only brief.

I know, no help to you at all. I'll watch your thread, because maybe it will help *me*! Heh.

Posted by Jim Schrader (Member # 9) on April 01, 2019, 10:35 AM:

motor giving out? im sure leon can tell you what it is.

Posted by Will Trenfield (Member # 5321) on April 01, 2019, 12:43 PM:

I had a similar problem on an Eumig. Sometimes it would struggle to get going. It was the belt although it looked ok. It seems as a belt ages it can stretch, lose its shape and develop flat spots or so I was told by an old hand a while back.

Posted by Janice Glesser (Member # 2758) on April 01, 2019, 12:49 PM:

Hi Steve...I guess your motor might be going. Is this your primary projector that you run often or does it sit still for long periods of time? When I don't use mine for days it has a delay in starting...but once the motor kicks in the speed is good.

Your motor issue isn't quite the same as mine, but you might want to add some drops of oil to the motor to see if this helps. This was a recommendation from Frank Arnstein a few years back.

You might remember this extensive thread:
http://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=010038

Posted by Graham Ritchie (Member # 559) on April 01, 2019, 02:58 PM:

It does sound like the motor is getting tired. I have never had a ST1200 apart but would head for the commutator and the build up of deposits between each of the segments and gently scrape that build up away with a thin craft knife plus giving the commutator a good clean with some fine wet or dry to get the grime of it.

from the internet...I feel nine times out of ten this area is where most motor problems come from, providing there is still some life in the brushes

Posted by Chip Gelmini (Member # 44) on April 01, 2019, 07:11 PM:

I used the HD's for 14 years before the GS model. Never had this happen to me. Worn belts were changed about every 5 years as preventative servicing.

But now after several years of GS - one of the HD's has a similar problem. Taking a close look, the rubber rollers for 18 and 24 have softened up. So do not forget to check this as well.

CG

Posted by Steve Klare (Member # 12) on April 01, 2019, 10:09 PM:

My own guess is that my motor is nearing retirement, but Janice has a point: I haven't been using this machine a lot lately. I've done Motor swaps on other Elmos and can't say I had a lot of fun!

-maybe before I go that way I'll put some running time on it and see what happens. (Always try cheap and easy first!)

Graham: among the ST's, ST-1200 is the only example with a brushless motor.

Rollers and belts are in good shape and traction on the shutter wheel surface seems pretty solid.

-any other ideas?

I appreciate them!

Posted by Graham Ritchie (Member # 559) on April 02, 2019, 01:21 AM:

Thanks for pointing that out Steve.

All about the supply to the motor, is there anywhere in the circuit where there could be some sort of resistance to it getting enough amps...eg old contacts, that type of thing.

One more thought has the motor got a capacitor that might be giving out?

Posted by Rob Young. (Member # 131) on April 02, 2019, 01:40 AM:

Steve, is your HD the version with the rubber around the shutter?

This happened to my ST many years ago. It would take a while to get going. The rubber can soften over quite some time before it finally starts to noticeably disintegrate.

After the rubber was removed all was fine again.

Posted by Steve Klare (Member # 12) on April 02, 2019, 07:13 AM:

-actually mine has new rubber around the shutter. I replaced it a couple of years ago.

I did notice that if I use the 18/24 select to lift the roller off the shutter wheel the unloaded motor doesn't speed up as much as I would expect.

Graham, I think the power for the motor is a pretty direct feed once you get past the switches.

-but hanging a meter on it would make sense.

For the moment I'm making an effort to run it every day. (These things hate idleness.)

Posted by Rob Young. (Member # 131) on April 02, 2019, 08:06 AM:

Rules that out then. And no sign of the square shaped drive belt being tacky?

Posted by Steve Klare (Member # 12) on April 02, 2019, 08:09 AM:

Good question, but it's what I call a five year belt and I think we are in about year 3 right now. (Mine usually snap before they go sticky.)

(I'll check anyway)

Posted by Rob Young. (Member # 131) on April 02, 2019, 08:16 AM:

Worth checking Steve, as mine have definitely gone tacky first. As a result, there is sometimes some rubber deposit in the grooves of the relevant drives.

Maybe worth checking and cleaning them up. I suppose if that doesn't help, take the belt off and see how the motor performs with no load?

A lot of so called replacement belts for this one are actually round and don't perform so well.

Posted by Leon Norris (Member # 3151) on April 03, 2019, 07:01 AM:

Steve, This is common with the st1200s. Well its either the micro switch or the motor capacitor! Just try this undo the main motor belt. Then turn it on. See what happens. If the motor still hums and does not move than its one or the other. The motor micro switch or motor capacitor! Now if motor runs as soon you turn on than its the belt! So give it a try!

Posted by Lee Mannering (Member # 728) on April 03, 2019, 07:50 AM:

Minor drift off topic. Yes Will the 900 range are now suffering it seems from belt stretch and I am near end of my Eumig belt stock. Anyone will soon know when they are going as the jockey guides bang against the chassis causing one hell of a noise. As far as I know no new genuine toothed belts are out there which is a worry. I was lucky and it was sheer luck to buy the genuine remaining stock from Axco back then and swapped a few in my time over the years.

We are reaching a critical time for new old stock genuine spares now for all 70's/80's machines so if you have a good projector whatever make take care of it. I'm not sure whether I should say thankfully most of us are of a certain age where these will see us out or not but why state the obvious.

Sorry back to Elmo. [Cool]

Posted by Paul Adsett (Member # 25) on April 03, 2019, 08:18 AM:

Lee, I just replaced a belt for my Eumig 926GL that I got from Van Eck. Seems to work OK, although perhaps a little more noisy.

Posted by Steve Klare (Member # 12) on April 03, 2019, 08:54 AM:

Leon?

Do you have the specs for the motor capacitor(s)? I have a schematic (we all do: I sent them to the manuals section), but I don't know what the capacitance and voltage are.

(Might as well replace them sometime when I have it apart.)

Posted by Janice Glesser (Member # 2758) on April 03, 2019, 03:45 PM:

Steve if it's the C202 cap...it's 19uF/125v

Posted by Steve Klare (Member # 12) on April 03, 2019, 03:53 PM:

Yes,

I'm seeing C202, C203 and C204.

(C205 is dotted in, kinda of like "Sometimes Y" in the vowels!)

I read the schematic to say the motor is meant for 100V, so I guess we can't cheat on the 125V rating!

Thanks, Janice!

Is there story here? Have you changed these?

BTW: I've been running the machine empty (no lamp) like a half hour a day. So far so good: cold start seems improved. The best time to do this is mornings while I'm having breakfast. My wife and my son have both walked in on this scene and said "What are you doing?!".

Posted by Janice Glesser (Member # 2758) on April 03, 2019, 05:06 PM:

Steve...I think the only cap related to the motor is the C202. I looked into the caps when I first got my ST1200HD with the delayed start issue. I couldn't see anything wrong with the cap so I did not replace it. I checked the connections to the transformer...looked OK. I did oil the motor bearing which seemed to help. I did not put a belt on the shutter...and I think I adjusted the clutch roller and added an additional spring to create more tension. You can refer to the old thread I posted above.

That's about all I remember doing and my machine although still has a slight delay in starting ... now starts up within 8-12 seconds of turning the knob to still. Once I hear the motor start I put it in forward. I think just running it more often seems to be the cure at this point as long as once it gets going the speed is good.

Posted by Steve Klare (Member # 12) on May 13, 2019, 08:32 PM:

I have an update on this one:

I hung a voltmeter on that capacitor and measured 100 VAC with the machine operating.

I've noticed the non-start happens most of the time when the machine has been idle, so I set it aside for a week and tried it again.

-56 VAC and a stalled motor! (Second try:100 VAC and 24 FPS)

-not what I wanted to see: it sounds more like a funky switch than a capacitor and the capacitor would be a lot easier to replace.

I've done these switches on other machines: not fun!

Posted by Janice Glesser (Member # 2758) on May 13, 2019, 10:52 PM:

Thanks Steve ...Very interesting. There has been no change in how my projector behaves, which is just as you described. Since it is a known behavior I'm willing to live with it. If it was the cap...well I could replace that...but I have no motivation to attempt replacing a switch. As long it eventually starts and runs good...I'll leave well enough alone. [Smile]

[ May 14, 2019, 10:13 AM: Message edited by: Janice Glesser ]

Posted by Steve Klare (Member # 12) on May 14, 2019, 07:58 AM:

I'm with you there, Janice. I can live with this for a while. I did the switches on one of my ST-800s and it was basically a full Saturday, but in that case the lamp was staying on with the machine stopped!

This is the kind of thing I'd do while I had the projector apart for something else.

What I'd like to do is especially when the machine has been idle, work the switches before I apply power. If it is a switch, this should prevent the stall. If it's not a switch it shouldn't make any difference.

The shame of it is ceiling fans use motor capacitors and I found some pretty close electrical equivalents pretty cheap!

Posted by Rob Young. (Member # 131) on May 14, 2019, 09:48 AM:

Hi Steve, good to keep updated on this.

What exactly are you referring to when you say switches?

I've recently revived my ST and would like to keep it going for as long as possible.

So all updates on repairs are valued! [Smile]

Posted by Leon Norris (Member # 3151) on May 14, 2019, 10:18 AM:

Steve, it sounds like its ether the motor capacitor or the motor it self! I came across this problem many times with this machine! They are getting old! Things are wearing out! I am all out of motors and that capacitor for this machine. One good thing is Elmo made a lot of them. There's plenty of them around!

Posted by Steve Klare (Member # 12) on May 14, 2019, 10:37 AM:

I've thought about the motor, but I'm not ready to go there just yet!

I've changed motors: another busy Saturday!

I think if I work the switch and the problem persists, I'd try changing the capacitor first.

-nothing wrong with having a new motor and a new capacitor!

Posted by Leon Norris (Member # 3151) on May 14, 2019, 10:40 AM:

Good luck Steve!

Posted by Steve Klare (Member # 12) on May 14, 2019, 10:42 AM:

I've heard tales of those with just ONE machine!

-can't imagine that!

Posted by Leon Norris (Member # 3151) on May 14, 2019, 10:43 AM:

It pays to have a spare!

Posted by Rob Young. (Member # 131) on May 15, 2019, 12:42 PM:

Just to back to switches. Do you guys mean the forward / reverse controls?

Or lamp controls?

If a switch is clean, should it need replacing?

Any advice appreciated!

Posted by Steve Klare (Member # 12) on May 15, 2019, 12:46 PM:

This is about motor control switches.

I think this far down the road the contact plating is worn off and we're trying to operate through an oxide film.

For the motor there are two of these switches activated by a cam from the control knob plus a third one for the lamp. These are mounted in this complicated assembly buried deep within the machine: by the time you go to all the trouble to get to them, you may as well replace all three and be done with it!

It's not elective surgery: as long as I can get satisfactory operation out of it I'm going to deal with more urgent things!

(My rear brakes were making noise this morning...)

Posted by Rob Young. (Member # 131) on May 15, 2019, 01:30 PM:

I agree, my other halves car is currently loosing coolant.

But given the age of our machines, wouldn't just a good squirt of contact cleaner / lubricant sort the switches in the short term?

Posted by Steve Klare (Member # 12) on May 15, 2019, 01:41 PM:

In all honestly, I've never tried that! The problem here would be getting to the switches.

Most switches I know are pretty sealed up, does this work through the crack between the housing halves?

I had it in mind to replace all 4 sets of brake pads before inspection this July. -seems my rear pads are seconding the motion!

My question is why does this always seem to happen in the first half of the week? If it was Friday night I could fix it tomorrow!

UBB.classic^TM 6.3.1.2