Film-Tech Forum ARCHIVE: 5-Star soundhead question

This is topic 5-Star soundhead question in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=006196

Posted by John T. Hendrickson, Jr (Member # 849) on 05-20-2004, 07:38 PM:

I want to replace the friction roller (G-1985) on the lateral guide roller in one of my 5-Star soundheads. Since I have not had occasion to work on this particular model, I see in the manual that there is a compression spring involved.

Springs always make me nervous. [Frown]

Is there any particular problem that I will encounter here?

Also, since I have read about problems with bearings in previous posts, would it also be a good idea to replace the 2 ball bearings (P-2360) at this time? These units have been running grind for over four years.

Posted by Paul G. Thompson (Member # 655) on 05-20-2004, 08:16 PM:

Replace the bearings also. Don't worry too much about the spring. It just is the return spring for the flange if a big fat juicy splice goes through. It won't bounce across the room and wind up in neverfindland.

Just be confident when you disassemble, and be just as confident when you reassemble. The manual should be very valuable for parts placement if you never did one before.

Posted by Josh Jones (Member # 447) on 05-20-2004, 08:16 PM:

Its not that bad. You will have to redo the buzz track when your done. Other than that, just remember which order the parts go in and its really easy.

I've been told by a few techs that if you can put your finger on the casting of the lateral guide assembly, IE, right above the bearings while the machine is running, and not feel any rough vibration or grinding, the bearings are fine. If they feel rough, replace them.

Josh

Posted by Steve Guttag (Member # 268) on 05-20-2004, 08:28 PM:

RE: The G-1985....only use a genuine Simplex G-1985....the knock offs uss too hard a rubber and the roller will bounce. This won't show itself so much with just analog sound but with digital basement readers...it will cause too much vertical unsteadiness.

Steve

Posted by Brad Miller (Member # 2) on 05-20-2004, 08:33 PM:

Bah, replace it with a rubber cleaner insert from a Kelmar film cleaning machine cut to the proper width. That way you don't have that stupid roller embedding dirt into the emulsion of the film. Works great for analog 5 Stars, not sure about basement readers in a 5 Star.

Posted by Paul G. Thompson (Member # 655) on 05-21-2004, 02:16 AM:

I say BAH also, but on a different part of the repair process.

If you leave the roller closed while you run out the door to go home, and you do it enough and long enough, those rollers can and will develop flat spots. Just ask any drive-in owner that closed his theater for the season...and months later reopened only to find a corrosion mark on the scanner drum and a flat spot on the roller because they forgot to open it on the night of closing from the season.

Seen it happen.

I think the bearings should be replaced while you have it dismantled. They are cheap....and with the crud or corruption that can screw them up, it is well worth the effort. Even if they appear to pass the rumble test, that won't mean they will be that smooth 6 months from now. They are still old bearings with high milage, and bearings do fail at the most inconvenient time such as an extended holiday starting on a Friday night!!

I learned from my Uncle Fritz years ago a simple fact. "If you don't have the time to do it right the first time and buy an inexpensive part to complete the job correctly, when are you gonna find time to do it over again and spend even more money?"

Uncle Fritz was not on the Fritz when he said that.

It is like overhauling an engine and not renewing the rod or main bearings because they "looked OK", or not taking the crankshaft journals down to the next nominal size because they were .0005" out-of-round.

As Josh said, run a Buzz track when you get done. Remember - emulsion side to the rear! [Smile]

Posted by Mark Gulbrandsen (Member # 72) on 05-21-2004, 08:10 AM:

"I think the bearings should be replaced while you have it dismantled. They are cheap....and with the crud or corruption that can screw them up, it is well worth the effort."

Paul is absolutely correct on this... but I go one step further and also replace the shaft which will normally show quite a bit of wear from the sliding of the rubber roller on it. All of the parts in the guide roller assy are pretty cheap!

Mark

Posted by Nic Margherio (Member # 273) on 05-22-2004, 01:35 PM:

Brad, I have replaced the G-1985 on a reverse scan analog/digital (white light exciter with light pipe) using a modified Kelmar endcap rather than the rubber expansion part. I can tell you that it works equally well for digital and analog. Typically DA20 error rates are 2-3.

Replacing this part has one small drawback though. Without the G-1985 part contacting the film and thus the impendance drum, it takes about 4-5 seconds longer for the impendance drum to reach full speed at start up. I have done extensive listening tests though and find it difficult to impossible to detect distortion at startup on a typical soundtrack. It is audible, however, if the soundtrack was a pure tone, such as Dolby tone. This was one of the problems Strong had when designing the Apogee. If your automation system allows you to adjust the cue-in time parameter, you could increase it to say 10 or 12 seconds which would allow enough time for the drum to reach speed.

On balance, no longer having the "dirt embedder" conact the emulsion side of the film FAR outweighs this drawback.

Posted by Christopher Seo (Member # 7) on 05-22-2004, 05:40 PM:

I wonder if there is any risk of the modified sound drum scratching the beginning of the reel in a changeover situation.

Posted by Jon Miller (Member # 163) on 05-23-2004, 01:08 AM:

I decided to replace the pinch roller on my RCA 9030 (with a Simplex X-L atop) with a metal spacer. For those unfamiliar with RCA soundheads, it has a lateral guide assembly design almost identical to that of the Simplex soundhead. As Nic suggested, the sound drum does take a little extra time to stabilize at operating speed.

Without the pinch roller, the soundhead becomes sensitive to the slack between the projector head idler sprocket and the sound drum. Two sprocket holes' worth of slack (measured with the lateral guide assembly open) works fine. Any more slack and the sound degrades to a harsh, fluttery mess. I think too much slack allows the lateral guide assembly to vibrate, thus causing flutter.

As far as film damage with the new arrangement, I have not noticed any.

Posted by Steve Guttag (Member # 268) on 05-23-2004, 01:12 AM:

It flat out wont work for a changeover operation...the sound drum will need to be up to speed before the changeover...the stock 5-star, if threaded properly (only one full perforation backed off from full tension (where the damper arm contacts the stop pin being considered full tension...not when the pinch roller rises up) will get the 5-star up to speed prior to changeover. Depeding on your motor (sync, or Async) and flywheel mass, your results may vary.

Steve

Posted by Mark Gulbrandsen (Member # 72) on 05-23-2004, 08:26 AM:

Weather you like the lay on rubber roller or not I would never reccomend anyone to take it out... The Simplex scanner was dssinged to work properly with it in the first place. Not only is it there to bring the drum up to speed quickly, but it also acts to keep film flutter that is developed before the scanner out of it. Also be aware that the edge giuding flanges can become extremely sharp when they become excessively worn to the point that they can act like a rotating knive. The sound drum is designed to support the film in its picture area, not at its edges. On the Century sound heads this works fine but by proper design as the film is sufficiently curved around the Davis rollers and is stiff enough from this double curve to remain perfectly flat at the scanner. Sufficient film stiffness probably will not happen cinsistently in the 5 star scanner because there is not much wrap at the point the impedance roller lays on the film.

Leaving out a critical part is a bad way to try to make something better. In order for this to work correctly one would first need a sound drum that is designed to have the film supported at its outer edges, similar to Phillips, or Cinemecanicca sound drums. I always thought these were by far the best designs for a scanning drum ad that all sound scanners should be designed this way.

Mark

[ 05-23-2004, 09:48 AM: Message edited by: Mark Gulbrandsen ]

Posted by Brad Miller (Member # 2) on 05-23-2004, 03:16 PM:

Hey, you've been screaming "synthetic oil" since forever and the manufacturers for the most part haven't been recommending it...but you keep preaching it anyway because you have tried it and know it is a better solution. This is no different.

Try it before you knock it. The benefits FAR outweigh any disadvantages. It is easily proven that a print ran on a Simplex shows wear over time noticeably faster than a print ran on a Century. This is due to that stupid roller. Get rid of it and the wear over time is pretty much the same between the two machines.

Posted by Mark Gulbrandsen (Member # 72) on 05-23-2004, 04:02 PM:

Brad,
I tried this about 15 years ago and came to the conclusion that I posted above... that you also need a sound drum with supporting edges for the film.
Christie has been using Synthetic oil for 20 years in the Ultramittent, LaVezzi has reccomended it for use in the Century for at least 10 and sells the oil so you can do it. Strong is about to introduce a synthetoc fill for the Apogee.

Mark

Posted by Brad Miller (Member # 2) on 05-23-2004, 04:12 PM:

Odd how I have routinely had excellent results for many years, yet you haven't. My first conversion was 10 years ago and that projector has been running in daily use since then with no problems. Hmmmmmm, yeah that sure is bizarre. [Roll Eyes]

Posted by Steve Guttag (Member # 268) on 05-23-2004, 04:34 PM:

I dunno Brad, yours and my "in-the-field" results differ more than not...take emulsion-in versus out...In these parts...emulsion-in polyester or otherwise still yields the most stable focus...yet in your part of the world it does not.

As to Mark...most of his posts are "This is the only right way" so why would this be any different.

One problem of using synthetic oil from the start of freshly machined items is that is makes the break in period intermably long...I tend to start with real and then move to synth.

Steve

Posted by Gordon McLeod (Member # 33) on 05-23-2004, 05:11 PM:

Emulsion in up here yeilds more stable results too and the orginal rubber roller from strong definitley yeilds better results on most basement readers than the OEM ones and as for synthetic oil I think everyone knows my opinions on that issue

Posted by Mark Gulbrandsen (Member # 72) on 05-23-2004, 06:44 PM:

Steve,

Most of my posts are related "From expericnce", not that "I say this is the only right way" as you state. I thank god that I'm right only some of the time as is everyone else here, so I generally speak from experience instead. Much of my input in past years is also because of the fact that I also care enough to buy what ever test gear is deemed necessary to make or break a point and or to do a test properly on some piece of equipment. Flutter is only one thing that I've measured, and on just about every optical reproducer in existance... ripple and inrush are another two and so on and so forth. Certainly you don't have any objection to me trying to do things the right way. Not many other dealers or techs care much about some of the minor things that I do.

As for the roller issue all you have to do is measure the difference with a W&F bridge and 3khz flutter film. Without the rubber roller higher flutter is easily measured on the 5 star, on the 4 star its not as high but still higher than with. The idea of eliminating the roller was not mine.. like Brad I also liked the idea at first.... I just had happened to aquire a couple of 4 stars with a steel spacer in them instead of the rubber roller. All of my tests were carried out with same manufacturers projector heads mounted on the sound heads, X-L on Simplex, Kakee model 21 projector on Kalee sound head, etc., all tests were also done with asynchronus motors so as not to spoil or possibly increase the flutter reading with the pole hunting that sometimes comes from certain types of sync motors. Steve K may remember some of these tests as I believe he helped do some of them and I seem to remember him also thinking that it was a great idea to eliminate the rubber roller. All tests were carried out with Acetate Flutter film not Estar.. so I can't speak for estars effects on flutter in these reproducers but that would be an interesting test to perform.

In regards to synthetics I agree that break in time is alot longer, but break in time really isn't a factor in a projector except for seeing a diminishing amount of metal and phenolic or fibre particles in the lubricant. According to Mobil who manufactures the majority of the worlds synthetic oil when having had regular oil in a mechanism the effectiveness of a pure synthetic will always be somewhat stymied by other contaminants of the regular oil of which traces will long remain in a given mechanism. If you're willing to tear down that mechanism and clean off all the origninal regular oil then you will see very effective results when using synthetic, but of course with some mechanisms that are not dowel pin located you're right back at square one and have to break in the mechanism all over. This is one reason why many high end car manufacturers are filling engines with synthetics right at the factory these days. I believe the Corvette and Porchse are among them.

Mark

Posted by Brad Miller (Member # 2) on 05-23-2004, 07:32 PM:

Mark, I've no idea how similar the 4 star and the 5 star soundheads are (never seen a 4 star), but this trick works dandy on a 5 star. It will not work on SH-1000 type soundheads. People with those are just screwed. [Razz]

Posted by Mark Gulbrandsen (Member # 72) on 05-23-2004, 08:33 PM:

Brad,

The 4 star is the same as the SH-1000. It does work but takes forever for the stabilizer to get up to speed. The reason the 5 star drum comes up to speed faster is because of the spring loaded and damped stabilizer roller. A similar sprung and damped roller between the projector and 4 star soundhead stabilizer will cause it to speed up about the same as on a 5 star.

Mark

Posted by Gordon McLeod (Member # 33) on 05-24-2004, 07:35 AM:

Also Mark the 4 star has a double flywheel (one iside the other coupled via a viscus oil) and it needs the higher pressure than the solid one on the 5 star

Posted by Brad Miller (Member # 2) on 05-24-2004, 11:41 PM:

Yes Mark, I am well aware of the damper roller and why it works. I've tried it before on an SH-1000 and after ramping up the projector twice gave up on that idea...just like you did.

You should however try the mod in a real 5 Star though. I will do the Guttag-test this week and see how long it takes for the damper roller to relax back into running position after startup for changeover houses.

Posted by Wolff King Morrow (Member # 2226) on 05-26-2004, 01:13 PM:

I've got a quick question about the 5-star sound head I figured I could ask here.

When I first started doing projection last year, I was trained (along with all the other projectionists) to thread the damper roller such that it was half-way in between the screw guards. Eventually I developed the habit of pulling the damper more towards the right "silver" screw rather than in the middle as normal. Lately, we started having problems with analog sound not being detected in one of the projectors. This never happened to me, which I assumed was because I had been threading it differently than everyone else. I went back and swabbed all the lenses to be certain after hearing about the problem.

Anyway, I found the 5-star Sound Head manual and it states that the damper "must be pulled to the stop-point and then back off one sprocket". Unless I'm mistaken, this sounds a lot like what I'm already doing. I just want to have this confirmed by more experienced projectionists before I adopt it as the official way we thread up. Thanks!

Posted by John T. Hendrickson, Jr (Member # 849) on 05-26-2004, 08:00 PM:

Wolff- That is correct. Steve Guttag discribed it best: one full perf backed off from full tension.

My parts have been ordered from Strong. I will be replacing the friction roller, bearings, and roller shaft. I also ordered some additionals of these parts in anticipation of other heads going south.

Thanks to all for your advice.

Posted by Josh Jones (Member # 447) on 05-30-2004, 05:39 PM:

Although I would tend to believe the engine crankcase enviroment to be completely different from the projector gearcase enviroment, at least on sportbikes, they are coming from the factory with synth oil.

Josh

Posted by Mark Gulbrandsen (Member # 72) on 05-30-2004, 05:45 PM:

Josh,
You are exactly right!! The crankcase environment is far harsher than a projector... and hence synthetic oil when used in a projector can last a long long time... at least if it wasn't for all the particles that never get filtered out in most projectors.

Mark

Posted by Josh Jones (Member # 447) on 05-30-2004, 05:56 PM:

I have also heard that, like others have said, it is better to break in a machine, or engine for that matter, with dino oil, as the break-in period is shorter, and in the case of engines allows the piston rings to set correctly. After break-in, then switch to synth oil.

A friend of mine who techs has said that as of late he has been switching XL's to brenkert oil. he said it seems to fix a lot of problems, and amazingly, they dont leak any worse than before the switch!

Josh

Posted by Paul G. Thompson (Member # 655) on 05-30-2004, 10:47 PM:

AW ISO-10 High-Speed Spindle Oil is great for projectors that have nothing but bushings instead of ball bearings. The only ball bearing Brenkert had was the thrust bearing on the main input shaft. Everything else in that machine was bushings.

I would be just a little afraid to use ISO-10 in a projector that is equipped with ball bearings up the Gazoo.

I honestly don't know how well they would stand up to such a thin oil. Seems to me it could lead to an early bearing failure. True, it probably would not really cease because there is no real load on the bearing - so it might be OK.

I have seen bearing failures on equipment that had nominal loads on the bearings where the oil viscosity was too light.

An example is a roller bearing crankshaft with roller bearing rods. Harley Davidson comes to mind....

But on the same token, many jet aircraft engines used synthetic oil for lubrication. It was known as MIL-PRF-6081 (formerly known as MIL-L-6081) Lubricating Oil Grade 1010.

I am trying to find out just how heavy that stuff is, but I have had no real luck yet. However, the last time I shook the crap out of a can of that stuff, it rattled around in there like one would expect to hear from just plain old Texaco WF-31. Slightly heavier than ISO-10.