Handouts from the Platter Maintainance course. To view a specific section click on one of the headings below.
RE 1 Operating relay 50Hz – the main supply relay
RE 2 Pulse relay (supplies 220v to plate motors)
RE 3 Continuous supply to plate motors
RE 4 Adjustable timing relay – keeps the take up plate running as the projector stops so that the film doesn’t loop.
RE 5 Plate speed fast/slow – activated by SK5 on feed unit
RE 6 Plate speed fast/slow – activated by SK6 on feed unit
RE 7 Timer relay (supplies T1) – energised when a plate is programmed to feed. Enables plate full speed for lace up.
RE 8 X or Y stop (arm controlled) – stops platter and projector when take up arm goes back and hits microswitch SK2
RE 13 X or Y stop (arm controlled) – same as above for the other projector (where fitted). As only one projector is usually present these days, one of these relays is not used, and may even be missing. If there are still 2 in the programmer, one can be used as a spare.
R1 & R2 Resistors with adjustable wipers. If these are set wrongly, or are faulty, there will be problems with the feed plate (see table for details).
M1 & T1 Motor M1 is coupled to control transformer T1 via a gearbox. T1 supplies the rectifier for the feed plate via various contacts.
SK7 & SK8 These microswitches control how far the wiper can travel on T1.
GR1 – 4 The rectifier card. If this blows none of the plates will rotate when programmed to feed. There is another rectifier card in the make up table which can be used in an emergency.
Early models had only one pin; a later gearbox will have two pins, so is less likely to cause problems. There have been instances of the pin breaking following a polyester wrap, or it may just break through natural wear and tear.
When it breaks, the wiper arm on T1 (variac inside the programmer) remains in the position it was set at just before the pin broke, thus the speed of the feed platter can no longer change. The platter may be going much too fast, or too slow.
A spare pin, or spare gearbox should be available. If not, a small nail can be used as an emergency measure.
If this happens, the show can be continued by controlling the speed of the feed platter via the make up table.
There is a spare rectifier card inside the make up table. This can be used in an emergency.
Depending on which of the microswitches has failed, the platter will either be over, or under feeding. If this happens, always try a spare feed unit first. If everything works as normal, then you know the feed unit was at fault. If the problem still persists, then the fault is in the programmer. Microswitches can be tested using a multimeter.
If the platter doesn’t run smoothly on either take up or feed, then the problem lies in the motor. Check the condition of the motor brushes (don’t forget to turn the power off first). If they are less than ¼" long or one is much longer than the other, then it’s time to change them. It’s also a good idea to clean the commutator of the motor every 6 months.
If you are having problems with the feed platter then the speed can be controlled manually using the make up table.
Make sure the switch on the table is set to the make up position.
Instead of selecting feed for the relevant platter when you start the projector, select take up for both plates. This will enable you to start the projector with both plates running before switching over to manual control via the table.
For a smooth change over, get the spare plate running at the speed you wish the feed plate to run. Then switch over, and make any fine adjustments.
Once you have the plate running at a constant speed, neither over nor under feeding, it is possible to leave it for around 5-10 minutes at a time. However, adjustments will need to be made as the amount of film on the plate lessens.
If you lose take up rather than feed, then the speed of the take up plate may also be controlled via the make up table, but this is a lot more tricky, and will require more frequent adjustments.
|
FAULT: None of the 3 plate motors rotate. CAUSE: Blown fuse Motors have no field voltage; field rectifier defective. RE 1 not activated. SK 1 defective. |
REMEDY Replace fuse. Test GR 1 for short circuit. Replace GR 1. Test SK 2, whether 61E is included in the appropriate switch position. Check SK 1 connections. Replace switch. |
|
FAULT: Feed motor too slow and cannot be accelerated. CAUSE: SK 5 defective (feed unit microswitch) RE 5 defective. |
Replace SK 5. Replace RE 5. |
|
FAULT: Feed motor runs with jerks ie. Only after SK 5 has changed over. CAUSE: Resistor R1 defective, phase of T1 is only applied when RE 5 is energised. |
Replace R1. Set wiper to approximately 200W . |
|
FAULT: None of the 3 plate motors rotates during feed. CAUSE: Control transformer T1 defective. Microswitch SK 6 (on feed unit) stuck, so that motor M1 may overshoot end switch SK 8 and transformer end position. Hollow pin breaks off drive shaft. RE 6 defective. |
Replace T1. Check transformer and drive for damage and replace if necessary. Check SK 6 and replace. Replace pin. (Use a small nail in emergency) Replace relay RE 6. |
|
FAULT: Film on feed plate activates SK 6 for too long. CAUSE: R2 defective, control motor receives no voltage. |
Check R2 and replace if necessary. |
|
FAULT: Pilot light for transformer reset (T1) does not light up. CAUSE: LA 1 defective. Microswitch locking button defective, RE 7 not energised. Microswitch SK5, 6 or 7 defective. Defective hollow pin on driveshaft. |
Change lamp. Press other locking button to energise RE 7. Check the transformer and drive system for damage. Replace pin. Replace SK 5, 6 or 7. |
|
FAULT: Feed plate has too slow a starting speed. CAUSE: Pressure of motor wheel insufficient, causing slip. Basic speed too low. Friction wheel of motor dirty. |
Check pressure spring. Increase pressure. Adjust switching cam of SK 7 to the left. Clean. |
|
FAULT: Feed plate has too high a starting speed. CAUSE: Basic speed too high. |
Adjust switching cam of SK 7 to the right. |
|
FAULT: Film on feed plate activates SK 6 too long. CAUSE: Resistance of R2 too low. |
Adjust wiper of R2. |
|
FAULT: In projector ‘stop’ position, transformer goes to maximum position and green light glows. CAUSE: Lever of microswitch of locking button stuck (mechanically) |
Adjust lever. |
|
FAULT: None of the 3 plate motors rotates during take up. CAUSE: Transformer T2 (under middle plate) defective. Carbon brush of transformer wiper does not make contact. |
Replace T2. Adjust basic speed with swivel arm fully pulled back; disc should only rotate slowly. Re adjust wiper spring. |
|
FAULT: Take up plate has too high an initial speed. CAUSE: Gear of T2 out of alignment.
T2 loose. |
Pull back swivel arm completely. Gear should no longer mesh with gear segment. Re adjust gear wheel. Adjust transformer. Tighten fixing screws. |
|
FAULT: The drive motor of one of the 3 plates does not start. CAUSE: Rectifier of motor armature defective. Carbon brush on motor worn. |
Replace. Replace carbon brush. |
|
FAULT: Feed plate creeps in hot weather. CAUSE: Basic speed of plate may be too high. Feed unit needs to be set for hot weather. |
REMEDY: Check basic speed and adjust if necessary. Set feed unit correctly. |
|
FAULT: Feed plate too slow in cold weather. |
Adjust feed unit for winter.
|
|
FAULT: Feed plate doesn't work at all (but plate works for take up) |
Check microswitch on take up arm. If it is faulty, or has jammed in then the feed plate won't work. If jammed, prise out with a small screwdriver. |
|
FAULT: Film winds on very loosely. Take up fails. |
Check take up spring. On early models it wasn't strong enough, and sometimes snapped. As an emergency measure, a bungy strap stretched along the take up arm will work. This can also be used to make a film wind on tightly if it needs to be moved. |
|
FAULT: Card failures. |
If a card fails, one of the other cards may be used to get the plate working again. Always switch off power when changing cards. A faulty feed unit may cause a card to blow. |
|
FAULT: Main fuse blows. |
One of the cards may be defective. If a platter lamp blows, it may sometimes also blow the fuse. Use an anti-surge or slow blow fuse to prevent this. Don't try to put a new lamp in with the power on. |
|
FAULT: When starting a programme, the take up arm goes all the way back, tripping the microswitch. |
Basic speed of plate too slow. |
|
FAULT: Take up fails intermittently after film has been running normally. |
Check connections on end of take up arm. |
|
FAULT: Feed unit arm dragging on base plate |
Check nut on top of feed unit pot is tight. |
Make a loop of film exactly 80 frames in length (5'). Place this on the take up arm of the plate you wish to time.
Take the cover off the cards. Turn power off while doing this as it's easy to accidentally hit the cards with the metal cover.
Turn the power back on.
The cards, from left to right control the top, middle, and bottom plates respectively.
At the bottom of each card is a square grey/white pot.
Turn this until the plate rotates once every fifteen seconds (+ or – 1).
Once this is done it's a good idea to put a dab of nail varnish (every box should have some!) on the pot, as otherwise vibration tends to make it drift.
Ensure that the plate timing is correct before altering this, as otherwise you may have to do it all over again.
The CNR 3 plates have a tendency to 'creep' when the temperature rises above 75° F. The higher the air temperature, the worse this creep becomes, and if this happens after you have laced up, then by the time you go back to start the film, quite a lot of it may be wrapped around the feed unit.
If you simply turn down the speed on the feed unit, then during the colder months the feed plate won't go fast enough. In order to solve this problem, many people regularly adjust their feed units for 'winter' or 'summer'.
Winter setting
Summer setting
|
FAULT:Platter runs too slow for maximum feed/return Motor speed control not properly adjusted. Drive wheel slipping Motor brushes worn or making poor contact AC line voltage too low (less than 105 V) Platter binding |
REMEDY Check motor speed control Check spring tension on drive assembly. Check wheel condition. Clean or replace as required. Check drive motor brushes. Replace if worn below ¼" or unevenly worn. Check AC voltage. Check platter bearings. Clean and lubricate. |
|
FAULT: Platter runs too fast for maximum feed/return Motor speed control not properly adjusted. AC line voltage too high (more than 120 V) Light leaking onto control sensor. |
REMEDY Check motor speed control. Check AC voltage. Check end cap is on securely. |
|
FAULT: Platter runs all the time. Drive motor shorted. Defective wiring or connections. Light leaking onto control sensor. Motor speed control not properly adjusted. Film position sensor is sticking in ON position. |
REMEDY Replace drive motor. Check wiring and connections. Check end cap is on securely. Check the motor speed control. Determine cause of sticking. |
|
FAULT: Platter will not run at all. No AC voltage. Defective wiring or connections. Defective control sensor. Defective motor control card. Drive wheel loose. Fuse blown on motor control card. Defective platter mode switch. |
REMEDY Check switch and fuse. Check wiring and connections. Check LED is working. Check control sensor in another connector. Check motor control card in another connector. Check drive wheel. Replace fuse. Check motor brushes. Blow carbon dust out of motor (this can cause short circuits). Check P/C board on switch. If runners are burned off, replace switch. |
|
FAULT: Return arm will not take up film slack. Platter speed too slow. Film position sensor sticking. Motor drive wheel slipping. |
REMEDY Check platter speed. Determine cause of sticking and correct. Determine cause of slipping and correct. |
A film position sensor controls the speed of the platter which feeds film to the projector, and a return arm underneath controls the speed of the platter which receives film from the projector.
The control sensor consists of an LED light source and a photo conductor mounted opposite to it and separated by a short distance. The LED is maintained at a constant preset intensity and a rotating variable density filter operates between the LED and the photo conductor, driven by either the film position sensor, or the return arm. Increased/decreased light on the photo conductor causes an increased/decreased current to flow to the motor speed control card. The current is amplified and converted to DC for the drive motor.
NOTE: Touching card with power ON may give you a shock.
NOTE: These instructions are taken from the AW3 manual. If you have tried this method of timing and find you still have problems, have a look at the alternative set up instructions at the Film-Tech site, in the 'Tips' section.