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Posted by Lars Pettersson (Member # 762) on February 19, 2009, 01:51 AM:
I have a question for the John Whittles out there concerning cleaning/tweaking optical on an Eiki NT2.
I run features on an NT2. The machine was in very nice shape when I got it, more or less mint, though it had seen some use. I clean the film path regularly when I use the projector, but Iīm ashamed to say Iīve never cleaned the optical sound section, and the reason for this is simply that Iīm an advocate of the "if itīs not broken, donīt etc"-school, so since everything always worked on this machine, Iīve been reticent to fiddle with it. ![[Roll Eyes]](rolleyes.gif)
Iīm fond of 1970s american films, and realise thereīs a limit to the quality of optical sound of that vintage. Itīs just that, a while back I tried running one print on a Bauer P8 (I havenīt run the whole print as there are problems with spool size, lenses etc) and was surprised by how much better the optical sound was -it sounded fuller, clearer, simply better, whereas the Eiki sounds thinner, more "telephone line". I never run features on the PT8, so it doesnīt see a fraction of the mileage of the NT2, and was clean as a whistle when I got it.
So my question is simply how much would dirt in the optical sound area affect sound quality, could it in fact be the whole difference between the two machines, and how would one best clean, or even tweak this part of the machine?
Cheers
Lars
Posted by Michael O'Regan (Member # 938) on February 19, 2009, 02:56 AM:
Hmmmmm....
I'll be interested to hear any replies on this.
I also had a P8 for a while and I now use an Eiki RM-1.
The Bauer had some other problems but, I too found the sound reproduction to be much fuller than the Eiki.
-Mike
Posted by Jean-Marc Toussaint (Member # 270) on February 19, 2009, 03:07 AM:
From a past experience with an NT2, dust on the lens and cell plus an ageing exciter lamp often result in a less than average sound quality.
Posted by John Whittle (Member # 22) on February 19, 2009, 10:49 AM:
Prior to getting into the amp itself, there are three things involved in optical sound pick-up and the same problems apply to both the Elmo CL and the Eiki NT/SL series. (Early Eiki machines had some strange equalization but that was back in the first MS860 years of the late 1960s).
There is the exciter lamp, the optics and the solar cell.
The exciter lamp is often replaced with the WRONG code. The correct lamp is BRK (4v .75 amp is my memory is right). As Jean-Marc said this can cause problems. Dirt or marks on the lamp will cause a lower sound output. BUT the biggest problem is they are often replaced with the wrong lamp. The quickest check is to look at the filament of the lamp. It HAS to line up so it's line is across the width of the film. If the lamp has been replaced with a BAK, the filament will be vertical, output will be down and sound low and tinny.
The focus of the optics is not something to be checked "for fun". You need a meter (with a needle not one of those LCD things) to connect to the audio output and a special sound focus film strip which has a 7,000 hz tone recorded on it. The way the optics are focused at the factory is they are slightly defocused for B wind (standard) prints so that you have a lower output for A wind prints. To adjust this it is necessary to release the clamp and then while running the film in the B wind position to move the optics until you get max output. If you have any A wind prints, you'll want to back this setting done a little, turn the film over and check it in A wind position. The SMPTE Jiffy Test film has a sequence where the sound focus is checked with a 5,000 hz section and it has a spliced in piece in reverse emulsion position so you can hear the change in output.
Lastly is the solar cell. These are located in the casting and have two fine wires (red and black) that go out to a terminal where there a jumper with a connect to go to the amp is soldered. The solar cell itself is in a little plastic tube piece to protect it and this often turns yellow with age. This doesn't seem to make much difference and if you extract it, be care because the piece is fragile and could easily crumble on you with any force at all.
If you have problems with sound if you use a non-sync source input into your amp, then there may be problems with the equalization in the amp itself. That's a topic that's too detailed to get into here since there are many many different amps and revisions in all these projectors. The worst are those that had those big black boxes on them that contain a full amp. When those go, they're gone.
The solar cell is "loaded" on the amp with a 48k resistor. If this is missing it can cause sound output problems, but I doubt that you'll had that problem. Again it's something that dates back to the first solid state amps used in the MS-860s.
John
Posted by Lars Pettersson (Member # 762) on February 19, 2009, 11:50 AM:
Thank you John, Jean-Marc and Mike for your answers. ![[Smile]](smile.gif)
Iīll check to see if I have the correct exciter lamp first thing in the morning. What would be an OK way of cleaning these components? Compressed air? Alcohol on a q-tip?
Any thoughts on the Bauer P8 -could it simply have superior optical sound? I guess itīs a younger construction (?)
Cheers
Lars
Posted by John Whittle (Member # 22) on February 20, 2009, 11:35 AM:
To clean, only clean the exciter lamp (remove lamp and clean with glass cleaner, re-install with rag so you don't leave finger prints), with exciter lamp out, just blow out dust from back of lens assembly. If you're worried about front of optics, clean with Q-tip with lens cleaner.
I wouldn't touch the solar cell, blow out any dust. (The solar cell is in a casting under the sound drum so you have to remove the flywheel, then the drum and shaft and then two screws to get to the casting holding the solar cell.
As for the difference in sound between the NT and the Bauer. The first thing I would suspect is the speaker. If you're using the built-in Eiki speaker, the sound is not what's on the film and what the projector can reproduce. Use line-out from the amp on the projector to a stereo where you have better amplification plus various controls over loudness and treble and base.
How you connect is different for different models. As I recall there is a line out on the chassis of the amp inside the projector. Later machines (SNT/SSL) use an extra lead in the speaker connector when you use a tip/ring/sleeve and the speaker connects to tip and sleeve and the line out is ring/sleeve.
John
Posted by Lars Pettersson (Member # 762) on February 20, 2009, 02:26 PM:
Thank you John! Iīm using the line out socket in front of the machine, Itīs really speaker level, but a friend of mine supplied me with a little box that "takes it down" to normal line level, and from there I plug into an amplifier/speakers. In the past Iīve also plugged straight from the Eiki socket to a mixing board, this was a Studer board that could take even levels that strong. In both cases the sound quality was about the same, so weīre not talking distortion on account of the level. The sound quality is by no means terrible, itīs just that when the Bauer sounded better, I started thinking there must be more to be had from the Eiki.
Iīll carry out the tips you suggested and report back!
Also, for quite a while when I had just aquired the projector, I felt the sound quality left a lot to be desired, but then it dawned upon me, when I looked in the userīs manual, that the treble/bass controls were crucial to good sound reproduction! They were just in random positions, as I thought I was tapping a completely clean signal out of the socket. As it turns out, you can improve the sound output a lot with these, and then further tweak it on the soundboard of course.
Cheers
Lars
Posted by Jean-Marc Toussaint (Member # 270) on February 21, 2009, 01:39 AM:
Lars, as John mentions, there's indeed a line out on the NT2 chassis, INSIDE the machine. Open the back and look at the rear, you'll see a cinch socket. You'll get better sound out of this, especially if you tab into an Hifi amp.
Posted by Lars Pettersson (Member # 762) on February 21, 2009, 06:33 AM:
Merci beaucoup, Jean-Marc! Je līessayerais immediatement lundi matin!
Cheers
Lars
Posted by John Whittle (Member # 22) on February 21, 2009, 10:07 AM:
There are two parts to the sound channel chain. The mechanical scanning and the electronic. To check the electronic you need to plug a signal source into the input for the solar cell and supply a sweep frequency and see what's coming out of the amp. If there are any drifts in frequency, check for out of spec caps or resistors in the tone circuits and feedback to the pre-amp.
For the mechanical scanning, you need some test films. For sound focus you need a SMPTE 7K Hz recording. To check the full system I had a sound house and lab make up a special 16mm "0" vu frequency sweep test films running from 50 hz to 7,000 hz.
I could then play the film on any projector and adjust the focus and then run the frequency sweep and adjust the amp.
Remember that 16mm optical sound is limited in dynamic range and frequency response (even 35mm optical sound will top out at about 10,000 Hz). Most 35mm optical sound tracks (dolby stereo) are recorded at 1/2 speed to get the max out of the light valve.
16mm tracks are generally recorded with roll off above 5,000 hz and a bump in the "presence" area to make the track sound better. Tracks are often heavily compressed reducing dynamic range.
John
Posted by Lars Pettersson (Member # 762) on February 21, 2009, 12:27 PM:
Thank you John! First thing monday Iīll apply a little careful cleaning and tap the sound from the line out INSIDE the machine.
Chances are this will go a long way towards better sound!
By the way, is this line out more or less 0VU or is it also affected by the volume/treble/bass knobs?
Cheers
Lars
Posted by John Whittle (Member # 22) on February 21, 2009, 02:10 PM:
I'd have to pull a schematic to check, but I think it's unbalanced after the volume/tone circuit. You can easily do a tap ahead off the volume control and run it thru a little decoupling capacitor.
Some of the telecine conversions had a balanced out, but this model is unbalanced.
John
Posted by Lars Pettersson (Member # 762) on February 21, 2009, 03:53 PM:
Thank you John! "it's unbalanced after the volume/tone circuit" means I should pay attention to the volume/treble/bass settings for best performance, right?
Cheers
Lars
Posted by Josef Grassmann (Member # 378) on February 21, 2009, 06:42 PM:
Dear Mr. Pettersson,
from my repair experience the Eikiīs quite often shown defective printed circuits boards.
Very tricky failure, difficult to find, when somebody did built in an amp-unit from another Eiki.(repair one projector and use parts from 2 or 3 projectors). As there have been several importent modification within the amps.
From here it is difficult to say whatīs wrong with your Eiki.
If you canīt solve the problem, you could send us the amp-unit and the exiter lamp, only.
And state serial-No. of projector.
Then we will built in both items into our projector and measure the amp.
Frist check that take up spindle turns very smoothly. Put a 240m reel with film on take up spindle and hold film end / start downwards by two fingers. Switch projector in forward mode. The tear should be very smoothly / constant.
Check from rear side that rubber wheel drives flywheel of sound drum in reverse mode, only. At forward projection there must be approx. 0.5mm to 1mm clearance between both.
Best Regards
Josef Grassmann
Posted by Steven J Kirk (Member # 1135) on February 21, 2009, 07:04 PM:
Wait a minute... I use NT 1s. There's a line out inside? Surely that's the jackplug for the internal speaker? On the speaker out at the front this is not a line level out of course. I use a step down device sourced from car audio by Boss. This changes the impedence, which surely is crucial. I get very good sound from the NT 1s. This speaker output is changed by the treble and bass and I set them routinely at treble almost full up and bass cut almost full down. Then I go to a Yamaha AV amp and Kef floorstanders.
'By the way, is this line out more or less 0VU or is it also affected by the volume/treble/bass knobs?' - One or the other. 'Line out' is taken to mean it goes to an amp. It's not from an amp.
Pretty good sound. Don't use the speakers in the case they are not great, IMO.
Posted by John Whittle (Member # 22) on February 22, 2009, 08:34 AM:
Steven,
There is indeed a jack for a line out inside the case as well as the jack for the internal speaker.
In "Eiki" language, a line out means that it's just line level but does indeed happen after the volume control and tone controls.
As previously mentioned, there are a wide number of amps that were used in both the R series and N series machines and you have to sort them out by serial number and country. Much more variable were the amps in the MS and ST series, however.
As long as you have an amp with discrete components and not from the period with huge integrated amp cards, you can trouble shoot the machine.
John
Posted by Lars Pettersson (Member # 762) on February 22, 2009, 09:36 AM:
Thank you John, thatīs wonderful news! I checked out the manual and there it says "rear cover speaker jack" but both your earlier post as well as Jean-Marcs suggest thereīs an additional socket there somewhere. Iīll find it tomorrow. Or is there some "ring/tip"-deal with this socket being both line and speaker level, depending on how you connect to it?
I actually have a couple other questions for you should you see this:
1. As you remarked elsewhere, and this is certainly my experience, when running large wheels, you get unsteady picture at the very beginning of such a reel (excessive torque on the take-up?) as well as at the end (front arm spinning wildly due to small diameter core). Can ANYTHING be done to alleviate this or is it just straight physics? Iīve been toying with the idea of applying a small motor on the rim of the front arm reel to help it spin towards the end.
2. In an ancient thread on light output you listed pretty much everything that could be done about it; faster stroke, condenser lenses, etc. Among this you mentioned perforating the non-prime shutter to let more light through. I was intrigued by this and tried it out on an 8mm projector and to my delight there was a significant increase in brightness, actually now the half-light setting matched the prior full-light setting, and there was no problem with flicker. Could I do this on the NT2 or would you advise against it (excessive heat at gate, imbalanced shutter, flicker). I would love to hear your opinion on this.
I donīt know if I should start a new thread with this, I guess the moderators will inform me, should this be the case.
Cheers
Lars
Posted by Steven J Kirk (Member # 1135) on February 22, 2009, 09:20 PM:
I wonder if my UK 'Elf' branded Eiki machines are different. I shall have to go looking.
My machines are in the 42000s serial numbers. Anyone have an idea when this might date them?
[ February 22, 2009, 11:47 PM: Message edited by: Steven J Kirk ]
Posted by John Whittle (Member # 22) on February 23, 2009, 02:26 PM:
Well I dug out my NT service manual (it's dated May 1, 1980 by the way). Now my NT serivice manual is part of the 2000A & N service stuff, but I couldn't find a line out on the amp in the book. Now the NT I used to have was a Telecine version and it did have a line out and there is a hole on the center of the back amp where the jack would have been mounted. There is a board mounted VR (VR4) which sets the max signal to the volume control (VR3) which is after both the treble and bass control. So to make the tap, one could take the center off the volume control as the high side (there is a decoupling capacitor ahead of it in the circuit so a connection between the center of the volume control and ground would provide you with a variable output with the projector still suppling the base and treble adjustment.
Now for take-up problems:
Eiki started using the cork lined drum with the introduction of the MS-860. The earlier machine (MS-850) had a fabric clutch which looked alot like the take-up from a Bell & Howell 100-200-300 series. As the film increased on the reel, the additonal weight provided more torque to take up the film.
I was never fond of the cork drum (and for a short period the other assembly appeared on a few RS machines and EX2000A machines) but the method of operation is a slight wobble in the end shaft allows more contact with the drive drum on the arm. What often happens is the cork is dry and there isn't sufficent slip on start up. Eiki's procedure is to lubricate the cork drum to allow for slippage. The recommended lubricant is Phonolube made by General Cement (which was quite common because it was used on turntables) and it's a light grease. Now while you won't find many turntables, the Phonolube is still available at least from MCM Electronics.
Now for the small diameter feed problem. I actually don't like small reels for this very problem, but the adjustment is the spring on the cork clutch inside the case on the feed arm. The problem is, when this is right for the small reel, you'll often expience spill from a 2000 or 1600 full reel so it's a touchy adjustment. The simple solution is to settle on 600 foot as your smallest reel for cartoons and shorts. It will also prevent the print from getting a bad curl in the base in storage.
My solution to the take-up problem is to replace the take-up arm. Eiki redesigned the part when they introduced the first slot loader (SL) with a flat belt and an internal mechanism which once again lets the weight of the reel determine the amount of torque applied to the film. You can actually easily replace the take-up arm on an NT with an arm from an SL. You might have to drill a hole to allow the latch on the NT to lock the arm, but otherwise it's just a part trade out and the arm works much better. While you're at it, you can change the feed arm as well, but you'll have to drill and tap some holes in the bottom shaft to mount the various parts on the NT to the SL arm. The upside is you won't have to use any round arm belts with their slippage anymore and rewind will be much better.
Eiki also modified the drive belt mid way through the SL series (I think it was with the SL-II) from a round belt to a flat 5v belt. Eiki sold replacement pulleys for the cam tank and the motor for both 50 and 60 and sound and silent operation along with the new heavy duty belts. This is also a major improvement, but I don't know if any of the parts are still available.
The NT is a nice heavy duty metal projector, but there are many engineering improvments in the SNT which I like much better.
As for light output, make sure your NT has a two blade shutter. Almost all US imports were with 3 blade shutters and as long as you only run sound speed, the 2 blade is a major improvement in light output.
If you're using the round arm belts, make sure you keep them clean and the pulleys the belts run on clean, but that the cork liner is lubricated and the shaft running thru the drive drum on the take-up arm is lubricated and that the bearings aren't worn and the washer and screw are in place and the proper parts.
John
Posted by Steven J Kirk (Member # 1135) on February 23, 2009, 07:31 PM:
Terrific useful information! This is why I love this forum. I have two cosmetically nice NT 1s and a third a bit battered which is for spares ( and this has the metal lamphouse cover so I take it to be earlier.) The first two I intend to run for the forseeable future. I have the service manual from May 80 though at the moment these run well. They all have the round belts and are bog standard at the moment.
Posted by John Whittle (Member # 22) on February 23, 2009, 11:21 PM:
The earlier machines had the flat top metal lamp house, the later machines the plastic lamp house that peaked at the front and the later machines also had a microswitch when you moved the rewind lever and turned on the projector. Unfortunately you can't add that feature to earlier machines because they changed the casting to add a couple of bosses to drip and tap for screws to hold that switch.
The last refinement was the flat belt drive (which Eiki said was only necessary for heavy duty use).
John
Posted by Steven J Kirk (Member # 1135) on February 24, 2009, 05:25 PM:
On dating mine... they are NT42000 and NT42116. One has the undertray with the cutoff switch for the back casing. The other doesn't. Assuming neither has been changed since, the date when this mod was introduced would therefore date these two. Any idea when this was. Much appreciated.
Posted by John Whittle (Member # 22) on February 24, 2009, 11:24 PM:
Don't have any dates on the under tray, but have the following:
One-step rewind all NT after s/n31307 issued 11/20/80
Lamp house cover, same serial number but bulletin issued 8/20/81
but was issued to note new part number 314-32601
New 3V belt drive system NT series s/n 5001 and up issued 4/20/82
All warrenty and parts discontinued for Marc 300/350 issued 12/20/82
New front and rear leg assembly NT s/n 42802 and SL s/n43735 issued 12/29/83
Posted by Steven J Kirk (Member # 1135) on February 25, 2009, 03:59 PM:
Seems like my main two might be 82-3. I had one other machine that was in the 60000s and had the flat belt. Don't remember what the legs were like.
Posted by Lars Pettersson (Member # 762) on February 26, 2009, 04:41 AM:
John,
Mine also has the plastic lamp house, donīt know about any other features (microswitch, belts) but had obviously seen very little use when I got it. One funny thing though: When I got the projector and ran film through it, I couldnīt get the image really sharp, no matter what I tried, so I called my local technician for these matters, and although he wasnīt much into Eikis in particular, he soon discovered that someone had erroneously screwed on the claw tips the wrong way round, so that they slightly shook the film at every stroke! Once that was fixed, image has been rock steady and sharp ever since.
Any thoughts on perforating the non-prime shutter, John? Just curious, it already has the two-bladed shutter.
Cheers,
Lars
Posted by John Whittle (Member # 22) on February 26, 2009, 10:14 AM:
Lars,
Since you already have the two blade shutter, I don't know how much light increase you'd expect. Remember that with a two blade shutter and a very bright picture you'll see more flicker (this is true in the Cinemas as well as at home).
If you have an extra shutter to use to "experiment" with, then by all means have at it. You can make a shutter (I can't remember if the NT started using the bent tips or were flat like the MS and ST shutters). You can alternatively try making the equalizing shutter narrower rather than perforating it. It's just the "prime blade" (the blade that cuts the light while the claw moves) that has to fully cover the pull down, you could make the other blade somewhat smaller or even make two very small blades (i.e. a three blade shutter that's total dark time is less than the two blade shutter).
As side from the perforations which go back to the 1940s, there really hasn't been much research into shutters and their effect (just not much call for it today with smaller screens and bigger lamp houses).
Have fun and post your research.
John
Posted by Lars Pettersson (Member # 762) on March 03, 2009, 02:53 PM:
John,
Iīve been too busy to get anywhere near the Eiki lately but today I had a few minutes over and took a look at it. I noticed the opening on the two-bladed shutter is REALLY generous -the Eiki must have a fairly rapid pull-down then, right? That made me completely drop the perforation thought, because the light increase would probably be quite small.
I noted the serial number: 56 210 -from an archeological viewpoint, what vintage would this specimen be?
Lars
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