my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » 5-Star soundhead question (Page 1)

This topic comprises 2 pages: 1  2

Author Topic: 5-Star soundhead question John T. Hendrickson, Jr Jedi Master Film Handler Posts: 889 From: Freehold, NJ, USA Registered: Apr 2001 posted 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. 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.  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 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.  |  IP: Logged Josh Jones Redhat Posts: 1207 From: Plano, TX Registered: Apr 2000 posted 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  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 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  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 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.  |  IP: Logged Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 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!  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 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  |  IP: Logged Nic Margherio Film Handler Posts: 91 From: St. Louis MO, USA Registered: Dec 1999 posted 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.  |  IP: Logged Christopher Seo Jedi Master Film Handler Posts: 530 From: Los Angeles, CA Registered: Jun 99 posted 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.  |  IP: Logged Jon Miller Jedi Master Film Handler Posts: 973 From: San Diego, CA, USA Registered: Sep 1999 posted 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.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 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  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 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 ]  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 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.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 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  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 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.  |  IP: Logged

All times are Central (GMT -6:00)

This topic comprises 2 pages: 1  2

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.