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Author Topic: speco platter problem Bill Hall Film Handler Posts: 30 From: Owen Sound Ontario Canada Registered: Jul 2018 posted 08-15-2018 09:12 PM                     HI I have removed the two chocolate bar shaped bridge rectifiers from the platter and took them to be checked. I also took the tube shaped unit that looks like a glass tube with pins on it and I was wondering if they ever gave much trouble. My basic problem is a short that puts the breaker in the panel to the off position so I hope that by replacing the two bridge rectifiers will fix the problem. The one was 100 ohm and the inner one was 250 ohm so I hope that these are the right values for the platter to operate. I hope to be able to see a movie on my screen soon. Thank You Bill Hall  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 08-16-2018 02:49 AM                     that glass tube contains the contacts where the magnet from the finger on the brain goes over to make contact to enable the platter motors. You adjust that magnet to make the finger react soon or late to engage the motor. The variac at the end of the spiral rod controls the motor speed.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 08-16-2018 10:13 AM                     also be carefull the tab on the SCRT in the feed is laive at110v  |  IP: Logged John Eickhof Jedi Master Film Handler Posts: 588 From: Wendell, ID USA Registered: Jan 2000 posted 08-16-2018 10:27 PM                        the 'chocolate bars' are power resistors and are not your problem, they are used in line with motor when taking up film. the bridge rectifier is most likely shorted and it is a small round 8 pin plug in device at the very top of the control box, most likely you had two switches selected to the same function at the same time, do the switches light up when selected ? if so the small 24 volt transformer is good and is not causing the direct short, if they dont light then the transformer is most likely shorted, this will happen if two of the same buttons are in and also can happen if one of the button indicator lamps has dislodged from its socket and thus shorts out the unfused transformer. early speco platters had a four diode bridge soldered into the circuit in lieu of the later plug in device. they use either 4 each 10 amp 250 volt diodes or a 10 amp 250 volt square dridge rectifier, all are available at a good electronics store. one more thing, it could be a shorted drive motor, un-plug the motors and see if the fuse holds, then plug in one at a time and if the fuse blows, that motor is bad. they used field wound bodine motors. i have parts in stock for the platters but i suggest you talk with someone with more electronic knowlege than your self and repair should be very simple.  |  IP: Logged Bill Hall Film Handler Posts: 30 From: Owen Sound Ontario Canada Registered: Jul 2018 posted 08-17-2018 09:08 PM                     Hi thank you for the reply. I did go to Toronto to a projection booth repair station and the technition there suggested that the two chocolate bars are ok as they look very good in colour so not hot or burnt. The man did as you suggest the tube shaped piece with the pins may be the problem. When the film got curled up on the center of the platter it pulled the samll arm over the little rubber bumper so it took a bit of time to unravel the film. So sad however as long as it can be fixed I am happy and next time will be much more careful if the film does rap up on me but the speco platter has worked well and very steady so I soon hope to see a movie and to find a few more prints to enjoy soon. Many thanks for your help folks and i will give an update when I can get the projector and platter up and running. Thank You All Bill Hall in Ontario  |  IP: Logged Bill Hall Film Handler Posts: 30 From: Owen Sound Ontario Canada Registered: Jul 2018 posted 09-08-2018 04:10 PM                     I have been working on the platter and noticed a blue wire to ground was hooked up to the white wire. I disconnected it and my power stayed on but the lights did not come on the switches nor did the motor try to move the platter for me. I had not seen a wire going from ground to neutral before so a little uncertain why this would be. If i hook it back up the breaker goes to off right away so am at a standstill for the moment now . Any ideas . I also did a voltage check and have next to no voltage at the bottom of the chocolate bar things . Bill  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 09-09-2018 09:54 AM                     Ok, I am at the end of my patience and this will be my last time trying to help you since you don't seem to care to listen to a 40 year electrician and 30 year cinema technician... The problem is NOT in the platter! Based on this new information, you have (and as I said before in the other thread, still have) problems with your house wiring, this new information points to the hot and neutral being reversed at the outlet. quote: from other thread quote: The breaker is 15 amp and last night worked well and today after a lot of rain it just blows the breaker. You have a problem with your house wiring.....get it checked by an electrician ASAP. The platter has nothing to do with this... Get it fixed by a professional electrician before you end up getting seriously hurt or starting a fire.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 09-09-2018 11:25 AM                       I don't know if this has been covered but in order to prove or disprove the plug or external AC polarity being backward, buy one of the widgets that plug into the outlet. The lights that show will determine correct or incorrect polarity.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 09-09-2018 01:45 PM                     Since it is residential, don't overlook that the breaker may be a GFCI type which would trip on most any ground leakage too. Since the platter is or should be fused at 3A, that should blow long before a 15A breaker, as Tony has indicated if it was platter wiring related...unless you have a GFCI breaker, in which it will trip with as little as 5mA current disparity between hot and neutral.  |  IP: Logged Bill Hall Film Handler Posts: 30 From: Owen Sound Ontario Canada Registered: Jul 2018 posted 09-10-2018 08:38 PM                     HI I have replaced the cord from the power source to the bottom of the tower. The wire is brand new. The power stayed on this time and the lights on the switch box did not come on so I may have a problem with the transformer. I do have a licensed electrician coming very soon to check over connections and he now has a schematic of the wiring so I am confident that the electrician will find the problem. One item of interest is there was a wire a blue on that was fastened to the ground or the frame of the platter tower and it was connected to the neutral which I found strange as I understand neutral is like ground potential so will wait till the electrician has an opportunity to study the wiring and then he will come . Thank You  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 09-11-2018 11:28 AM                     Somewhere along the line here Bill created a separate thread instead of replying to this thread. I am closing that other thread. here  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 09-13-2018 11:33 AM                     When something draws power from a wall outlet, it gets 120V from the "hot" side (black wire). naturally the power has to have a complete circuit, the return side is neutral (white wire). Ground is a safety connection: if the hot side touches the chassis somehow, power flows to ground and - if the touch is secure and strong enough - blows the fuse/breaker and the thing doesn't sit there with 120V on the chassis ready to shock anyone that touches it. Neutral is close to ground voltage, ground and neutral are usually connected together at the step-down transformer from your utility HV distribution system. Neutral voltage at the plug is not necessarily equal to ground ... because Ohm's Law. Current through a wire creates a voltage drop. As soon as you draw power, the neutral voltage rises proportional to the load current and the wire gauge. GFCI breakers and outlets compare current in the hot and neutral wires which should be exactly equal. If the ground and neutral are tied together in a load that's plugged into a GFCI breaker or outlet - it will trip as soon as power is drawn because some current will take the path to ground instead of to neutral. Ground and neutral should never be connected at a load device.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 09-13-2018 03:58 PM                     quote: Dave Macaulay the return side is neutral (white wire) Question on this: What purpose does the "Floating neutral" strip in the panels do in a circuit if current comes from black, flows through a circuit and heads back out on the neutral leg in the wall outlet? What happens here to get a complete circuit? thx - Monte  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 09-13-2018 08:37 PM                     quote: Monte L Fullmer Question on this: What purpose does the "Floating neutral" strip in the panels do in a circuit if current comes from black, flows through a circuit and heads back out on the neutral leg in the wall outlet? What happens here to get a complete circuit? thx - Monte Monte, the reason neutrals are isolated at all points except at the main panel (or in some cases, main disconnect), has to do with the way electricity flows. The normal path in a circuit utilizing a neutral is the flow from hot (out from the source) through the neutral (back to the source.) I will leave out the details of how 208, 240, and 480 volt circuits work for this discussion. (Hint: It has to do with phase angles of the alternating current.) Now, to dispel a myth: Electricity DOES NOT SEEK GROUND! Electrical current takes ALL available paths back to its source, with the total current being divided amongst the paths based on each path's resistance. (More resistance = less current flow in that path.) Note: The origin of the ground myth comes from the fact that the majority of electrical systems, both utilization (consumer level voltages) and distribution (and sometimes transmission) level voltages have a grounded conductor (neutral.) The neutral is tied to a grounding electrode (ground rod) or other means to electrically bond it to earth (the ground.) This neutral/grounding connection, in a properly installed electrical system, is done ONLY at ONE point, usually the Main service panel or Main service disconnect. Now, in the case of subpanels (very common in projection booths), and in the wiring of circuits, the neutral (grounded conductor) is kept separate from the ground grounding conductors, because normal currents on the neutral will share with the grounding conductors if they are connected. That can cause a voltage rise and sufficient current flow on the grounding conductors (and any equipment that has a grounded case, like projectors, motors, etc.) This current, even though it is on a grounded object, can (and will) easily divide and flow though a person, with the current again in proportion to the resistances of the object and the person. This can, and most definitely has, resulted in electric shocks, electrocutions and fires. For many years, domestic clothes dryers and ranges were permitted to use the neutral as a grounding path.. (3-prong stove/dryer cords.) The dividing currents I spoke of caused many people to get shocked (even though technically the appliance was wired correctly.) Several National Electrical Code cycles ago, that was changed. ALL NEW and rewire installations MUST be done with a 4-prong cord set (Hot, Hot, neutral, ground.) EXISTING 3-prong setups are allowed to remain in use until a rewire (or in some areas, a main or subpanel replacement) is done. If you want to learn a lot about the hows and whys of proper grounding (handy knowledge for any tech or projectionist) search for "Mike Holt" and his Code forums and videos on the subject of grounding.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 09-13-2018 09:18 PM                     ^^^^^^ Good stuff in that post.  |  IP: Logged

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