This is topic ORC troubleshooting (was Looking for some ORC manuals) in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Paul Mayer (Member # 355) on 02-12-2001, 12:32 AM:
The RPS-2500 I've been working on is beginning to get to me. At first, I couldn't get the fans to run, let alone get it to strike. So while waiting for the schematics to arrive (thank you again Paul Thompson!), I cleaned up the #1 power supply and did some general tightening, treated the connector with Cramolin and replaced a few suspect crimps. Nothing special, didn't replace anything.Now the fans ran upon power-up as they're supposed to, but the #1 lamp wouldn't auto-strike (at first). Manually struck it, then shut it down. Subsequent auto-strikes worked, but then the lamp would shut itself down after about seven minutes of operation. None of these symptoms occured when I connected this power supply to the #2 lamp, so I began to suspect #1 lamp instead of #1 power supply. Ran out of time at that point, so called it a weekend.
Now today, I fired up everything again to confirm symptoms--was planning to swap ignitor cards to see if the symptoms moved with the cards. But now the #1 lamp and supply are running just fine. Auto-strike worked, and the lamp stayed lit for a half-hour test. D'oh! 
Can't troubleshoot it if it don't stay broke! 
Of course Murphy says if I try to use it in its present state on a real money show, the thing'll cack at five minutes to curtain. Ain't (electrical) intermittants fun?!
Posted by Paul G. Thompson (Member # 655) on 02-12-2001, 10:14 PM:
Paul, there was a post I thought I sent. But now I don't see it. What I said in that post is you might have a flakey bulb.
Posted by John Eickhof (Member # 323) on 02-12-2001, 10:36 PM:
Did you check the internal air flow switch in the lamphouse on the squirrel cage blower? Sometimes these get stuck with dirt and are sluggish thus delaying PS & ignition. Also, the 'auto strike ' sensitivity may be set too high for the unit to attempt to strike as the power supply voltage is not ramping up fast enough (possible bad filter caps or blocking diode)Good luck!------------------
John Eickhof President, Chief Slave
Northwest Theatre Equipment Co., Inc.
P.O.Box 258
Wendell, ID. 83355-0258
208-536-5489
email: jeickhof@nteequip.com
Posted by John Eickhof (Member # 323) on 02-12-2001, 10:40 PM:
I forgot to mention the 'seven minute' shut down....This is most likely the 'temp' sensor safety switch on the rectifier bridge heat sink, it could be that when cleaning, you
bumped the wires (they are in slip-on terminals) on the 'clixon' switch, thus it is sensing an over heat situation and opening the control circuit after a while...Make sure all connections are tight and the fans are moving a LOT of air! (These old beasts are very 'TEMPERTURE-MENTAL'!------------------
John Eickhof President, Chief Slave
Northwest Theatre Equipment Co., Inc.
P.O.Box 258
Wendell, ID. 83355-0258
208-536-5489
email: jeickhof@nteequip.com
Posted by Paul G. Thompson (Member # 655) on 02-12-2001, 11:56 PM:
John, not only that - they are nothing short of a pile of junk that have served its purpose. If all those regulator transistors are shot, it is almost as cheap to get another used power supply. Seems to me, if I recall correctly, those things were about 30 bucks a pop. I am not sure if they are available any more. As far back as 1980 when I was a service rep, obtaining those little boogers was difficult.
Posted by Paul G. Thompson (Member # 655) on 02-12-2001, 11:59 PM:
oops - double post. I am not sure how that happened. I must have double-clicked my moose. 
Posted by Mark Gulbrandsen (Member # 72) on 02-13-2001, 01:50 PM:
NTE has the transistors available and yes, they are around 30 bucks! The fortunate thing is that all of them RARELY blow at once. Most ORC's that I have repaired have only needed a couple at most, plus perhaps new driver transistors. The good thing is that when one or two short they pass all the current taking the load off of the others. The reason that they are so hard to get is because they are germanium transistors. The driver transistors are the silicon variety though.
With Model 1000's I always rebuild them with higher rated diodes and SCR's. These days one can get higher rated devices in the same case style as the old ones that will fit right in place of the old version. Also if you replace the electrolytics on the driver and regulator PC boards every 4 years or so they will be more stable as the proximity of the caps to the heat causes them to dry up quicker than normal. I have a number of the model 1000's in rental that we use on dailies jobs which have piled up tens of thousands of hours and they never even burp! The other secret is to provide enough cooling,and don't use more than a 750 watt lamp in them, at least for long periods.
Mark @ GTS
Posted by John Eickhof (Member # 323) on 02-13-2001, 03:12 PM:
I stock the regulator transistors, Mark is correct, I have never had to replace all of them! Usually two or three are enough to render the unit inoperable. Keeping the airway clear and the proper shroud around the heatsink helps these immensely! I always threatened to experiment with replacing the transistors with some beefy SCRs but as few of these that are still operating did not justify the effort. When examining the regulators, the ones with blown 20 amp fuses are the bad ones! But it is always wise to test the others for opens!------------------
John Eickhof President, Chief Slave
Northwest Theatre Equipment Co., Inc.
P.O.Box 258
Wendell, ID. 83355-0258
208-536-5489
email: jeickhof@nteequip.com
Posted by Mark Gulbrandsen (Member # 72) on 02-13-2001, 04:44 PM:
I always thought that they could be replaced with silicon transistors with a few minor changes on the driver card to compensate for the higher bias that silicon semis require, Alas its like John said, there are not enough around to make it worthwhile. Plus, Who has the time?
Mark @ GTS
Posted by Paul Mayer (Member # 355) on 02-16-2001, 10:54 PM:
Thanks for the additional tips guys! I'm building road boxes this weekend, but next weekend I'll be back on the ORCs.And a big "thank you" to John Eickhof for coming through with a copy of the manual! Brad, if you're watching this thread I'll get some PDF scans made from this manual and send them to you for the manual collection.
Again, thank you all.