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Author Topic: Orc 1000 problem Bill Duelly Film Handler Posts: 92 From: Roselle Park, NJ Registered: Feb 2006 posted 07-05-2012 05:33 AM                     I cant seem to get my lamphouse to strike. Here the symptons.... I turn it on and the spark gap sizzles/sparks. I had a brief flash from the bulb but nothing after that. I seemed to recall that power may be an issue with these and the voltage coming into the house was around 106/107 last night. This am, when it was up around 117, i tried again, no change. I have double checked the gap, which is one dime wide. The bulb has not shown any signs of problems and is clear. Any thoughts anyone? Many thanks  |  IP: Logged Pete Lawrence Expert Film Handler Posts: 192 From: Middleburg, PA Registered: Aug 1999 posted 07-05-2012 07:58 AM                     I don't claim to be an expert on these, but I have two of them I've been able to keep running for a number of years. If you can measure some voltages, here's what to look for. First remove the top cover. Mounted on the bulkhead in the middle you will find a plug-in relay. Remove that relay to keep the igniter from firing and frying both you and your meter. Look for a single blocking diode (stud mount package) attached to the bulkhead. The lamp side of the diode should have one or more ceramic bypass caps between the lead and ground. Main lamp current goes through this diode. I found this diode had failed on both of my M1000 lamps. Now some measurements. There is an interlock switch near the top of the bulkhead. You'll have to press that to get the lamp supplies to power up. Measure the DC voltage to ground on both sides of the diode mentioned above. The lamp side (boost supply) should read around +100 Volts DC. The power supply side (main supply) should read +40 Volts or so. Since the lamp is not lit at this time the main supply is not regulating and at its maximum voltage. The key here is the lamp side of the diode must be at a higher voltage than the main power supply side. If these voltages are present at about these levels the diode diode may have failed open. To test this, turn the power off, discharge everything to ground (!!!), and measure across the diode with an ohm meter. Readings should be different when you reverse the meter leads. If this blocking diode checks good and you don't get about 35 - 40 volts on the main supply side you have a main supply/regulator problem. Hope this makes sense.  |  IP: Logged Bill Duelly Film Handler Posts: 92 From: Roselle Park, NJ Registered: Feb 2006 posted 07-05-2012 06:43 PM                     Pete, thanks for the info. One side is 40 v but the other reads about 225v  |  IP: Logged Pete Lawrence Expert Film Handler Posts: 192 From: Middleburg, PA Registered: Aug 1999 posted 07-05-2012 08:11 PM                     The two voltage readings sound fine. Normally the higher of the two wouldn't get much above 130 Volts and only for a short time. At that voltage the relay would close, fire the igniter, and light the bulb. Once the bulb conducts the DC voltage across it is about 27 to 30 volts or so. So it looks like the blocking diode may be open. You can check that with an ohm meter as I described above. Make sure both sides of the diode are discharged to ground first. Do the low voltage side first then the high voltage side, then repeat. If you short the high voltage side first you could pull a big current spike through the diode (if it's still good) and damage it. I usually use some low value resistor (25 Ohms or so), NOT a screw driver, to discharge power supplies. After your sure everything is discharged you can make your resistance measurement. You may have to disconnect one side of the diode to get an accurate meter reading. Just take off the mounting nut and separate the wires from the diode. It's not necessary to unsolder anything. Remember where all the washers were when it comes time to re-connect it. I'll bet the diode is open, but it's still possible the main supply has a problem.  |  IP: Logged Bill Duelly Film Handler Posts: 92 From: Roselle Park, NJ Registered: Feb 2006 posted 07-06-2012 08:50 AM                     Havent had a chance to test that diode for resistance yet, but i ordered a replacement before the weekend started. Just as an fyi, the one there is designated IN 2131A. And i've been told that te replacement for that now is: NTE 6026  |  IP: Logged Bill Duelly Film Handler Posts: 92 From: Roselle Park, NJ Registered: Feb 2006 posted 07-06-2012 03:22 PM                     Ok, disconnected the diode from the wires Open in one direction 135k ohms in the other.  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 07-06-2012 11:19 PM                     Yep that's a classic open diode. Be sure to use heat sink compound when replacing it and don't overtorque the stud/nut.  |  IP: Logged Bill Duelly Film Handler Posts: 92 From: Roselle Park, NJ Registered: Feb 2006 posted 07-07-2012 12:11 PM                     Am i mistaken that isnt that what diodes are supposed to do? Block current in one direction (open) and a lower resistance (135k in this case) to allow flow in the other?  |  IP: Logged Pete Lawrence Expert Film Handler Posts: 192 From: Middleburg, PA Registered: Aug 1999 posted 07-07-2012 12:21 PM                     It seems this problem is contagious. Now my M1000 won't light either. The same blocking diode we have been discussing has literally fallen apart in mine. I opened the top cover to take a couple of measurements just to see if the wires had to be disconnected for a clean good/bad reading. The solder-on anode lead could be easily moved. Well that's wrong! Turns out the seal between the anode and the case has shattered. So it's time for a new blocking diode. I ordered a couple diodes with somewhat higher specs as a replacement. It's been suggested in other discussions of this lamp house that the ratings of the OEM part are marginal, and I agree. I don't like NTE replacement parts as they simply take someone else's product and put it in their plastic bag. And they double or triple the price of the part. Bill, you mentioned something in your first post that I didn't catch at the time. "I turn it on and the spark gap sizzles/sparks. I had a brief flash from the bulb but nothing after that." What should happen is about 3 to 5 seconds after you throw the main switch the igniter should fire with a quick snap and the lamp should flash on very briefly as the boost supply dumps it's charge through the lamp. This ignition attempt (flash) should repeat every 3 to 5 seconds if the lamp fails to light normally. There should be no "sizzles". In reply to your last post, the 135K Ohm reading in the forward direction seems high. But it's very dependent on the type of meter. Many newer digital meters have an actual diode test position where you can read the forward voltage drop of the diode. A much better test. But even that isn't conclusive as your meter is using about 1 mA to test a diode that normally passes many amps.  |  IP: Logged Bill Duelly Film Handler Posts: 92 From: Roselle Park, NJ Registered: Feb 2006 posted 07-07-2012 03:50 PM                     Does someone know what the correct distance is for the spark gap on this? I know I had kept the paper that came with this replacement piece, but alas waters from Irene washed it away.  |  IP: Logged Bill Duelly Film Handler Posts: 92 From: Roselle Park, NJ Registered: Feb 2006 posted 07-07-2012 06:24 PM                     Am i mistaken that isnt that what diodes are supposed to do? Block current in one direction (open) and a lower resistance (135k in this case) to allow flow in the other?  |  IP: Logged Tony Bandiera Jr Film God Posts: 3067 From: Moreland Idaho Registered: Apr 2004 posted 07-07-2012 09:02 PM                     No Bill you are not mistaken. The 135k ohms is way too high, it should be low (around 30-40 ohms IIRC) in the "forward bias" direction.  |  IP: Logged Pete Lawrence Expert Film Handler Posts: 192 From: Middleburg, PA Registered: Aug 1999 posted 07-08-2012 02:10 PM                     I can't help you with the spark gap distance as the ones in my lamps are in a little sealed glass tube. The glass is clouded over and I cant see the actual gap. With regard to measuring diodes with an ohmmeter... When you try to use an instrument designed to measure parts that obey Ohm's law (like resistors) on components that don't obey Ohm's law (diodes and other semiconductors) you get inaccurate and/or false readings. The only way to accurately test semiconductors is with a curve tracer that can apply full rated voltage and current to the device under test. There are other simple tests that can be done, like run 40 amps through the diode and measure the forward voltage drop for instance. But that doesn't give a complete picture. A simple ohmmeter can check for some failures, like dead shorts or opens with some confidence. But in other cases your meter will lie to you. For example, the 135K Ohm measurement you got in the forward direction would imply (using Ohm's law, E=I*R) that it would require 5,400,000 volts to get 40 Amps to flow through that diode. We know that's wrong. Even Tony's 30 Ohms would require 1,200 Volts for 40 Amps to flow. That value is also wrong. Basically what I'm saying is you can't trust your ohmmeter to give correct readings in all cases. The bad diode I have checked fine using my digital meter. It even checked good when I set up a 15 Volt DC power supply and a light bulb to see if it would pass current in the forward direction and block in the reverse direction. My error here is the light bulb only drew around 20 mA not 40 Amps. When I cut open the diode case I found the silicon diode chip pretty much splattered around the inside of the package. But under low current and voltage it would still act like a diode. Hope this explanation helps some.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 07-08-2012 02:53 PM                        Old timers in the Altec Service days used a switch leg to a 100 watt light bulb. Nothing and full brightness are wrong; dim bulb is correct. Louis  |  IP: Logged Ian Parfrey Phenomenal Film Handler Posts: 1049 From: Imbil Australia 26 deg 27' 42.66" S 152 deg 42' 23.40" E Registered: Feb 2009 posted 07-09-2012 01:00 PM                     I had one of these units before with a similar problem. This was rectified by removing the glass spark gap, throwing it away and installing a Kinoton adjustable spark gap. Bingo! Problem fixed. It may also be worthwhile doing a re-cap of the supply. These lamphouses are getting on in years and the supply gets baked fairly easily.  |  IP: Logged

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