Film-Tech Forum ARCHIVE: Strong 88001-3 Power Supply Problem

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Posted by Richard Cockrum (Member # 2417) on 05-31-2005, 09:23 PM:

We've finally begun to change over from carbon arc to xenon at our theatre. We got a Xenex II lamphouse and a Strong 88001-3 power supply. This is a one phase 220V unit that is supposed to put out 16-29V at 35-75A. I hooked it all up after diligent perusal of the Xenex II manual here, with a 1000W bulb. I tried to get a manual for the power supply from Strong, but they don't have one. They were able to tell me that the lamphouse control hooks up to numbers 5 and 6 on the terminal block, and the potentiometer is supposed to control the current.

Unfortunately, when I fired it up the meter on the lamphouse was reading 140A cold,which gradually went down to 90A as the units warmed up. Voltage was at 29-30V. Adjusting the pot didn't do anything to decrease the current. The lamp did light.

I then put in a 1600W bulb that I had in a Eprad Universal 47000 that we got when we bought the Xenex. The same thing happened.

My question, does anyone know if there is some other way to adjust the output of one of these power supplies, or is there something wrong with it. All help appreciated.

Posted by Mark Gulbrandsen (Member # 72) on 05-31-2005, 09:53 PM:

Its possible that you have the pot in wrong or that you have the wrong pot. That model number doesn't quite jive my memory so other than that.......
If this is an early switcher then you will want to read this disappointing Strong bulletin....
Sorry, It Can't Be Repaired Anymore.......

Of this is an old Strong SCR regulated power supply, it is still unrepairable. These were boatanchors. I suggest that you return it to whom ever sold it to you. The Kneisley should be ok though.

Mark

Posted by Richard Cockrum (Member # 2417) on 05-31-2005, 10:07 PM:

Thanks, Mark. No, its not a switching power supply. I'd say its an SCR regulated supply. It's a boat anchor as far as weight goes, at least.

The pot was in it when I got it. I haven't replaced anything. I just got it hooked up today. Fortunately, if it is bad, it was free, or rather a trade for a Kneisley 3 phase supply that I got with the Xenex II. We don't have 3 phase in the building, and I don't want to have to put it in.

I take it you're saying the power supply is bad, then?

Posted by Steve Guttag (Member # 268) on 05-31-2005, 10:11 PM:

Psssst...If you check the FS/Wanted section...we have four Kneisley single-phase 1600 watt rectifiers for sale...cheap with almost zero hours on them (less than 12). Sorry for the cross plug but it does seem to apply for this thread.

link

Posted by Mark Gulbrandsen (Member # 72) on 05-31-2005, 10:16 PM:

Definately look into getting one of Steve's units then. He is close enough that shipping it shouldn't be too bad.

Mark

Posted by Richard Cockrum (Member # 2417) on 05-31-2005, 10:23 PM:

Thanks for the link, Steve. I'll be in touch.

In the meantime, if anyone has anything else on the Strong...

Posted by Brad Allen (Member # 470) on 06-01-2005, 10:17 AM:

Meter on the Xenex II could be fibbing to you as well. Get a clamp on meter and check the amps.

Posted by Mark Gulbrandsen (Member # 72) on 06-01-2005, 07:49 PM:

Brad is right on that one, they are a bit notorious. When they fail I usually replace them with a higher quality Simpson meter or equivelent. One way to possibly tell of the rectifier is working and the meter is bad is if the intensity of the lamp varies when you run that pot up and down. Don't leave that thing it for very long though until you are darn sure what current its operating at.

Mark

Posted by Richard Cockrum (Member # 2417) on 06-01-2005, 09:14 PM:

Thanks Brad and Mark. It's good to know these meters can fib. I'll have to find someone with a clamp-on for DC, though. I haven't got one.

I checked the pot with a DMM. It went from 0 - 500 ohms as I rotated it, so it seems to be working okay. Again, though, I didn't see any change in the light. I tried putting in another pot, also. With both pots, I couldn't see any change in the light's behavior and any setting.

I ran the lamphouse for about half an hour tonight with the pot set at its minimum. As it warmed up, the current gradually went down to 70A on the meter, and the voltage stabilized after about 10 minutes at 25V. This is with a 1600W bulb in.

Any other hints appreciated. In the meantime, I contacted Steve about his power supplies.

Rick

Posted by Michael Schaffer (Member # 1204) on 06-02-2005, 04:32 AM:

You can get a good clamp adapter for AC and DC current measurement (plugs into the mulitmeter) for a little more than $100, for instance from Fluke. Sure, that is money too, but money very well spent considering how many problems and loss of performance can be caused by not having a current meter at all, especially when dealing with unreliable lamphouse meters.

Posted by Gordon McLeod (Member # 33) on 06-02-2005, 10:03 AM:

That rectifier often was designed for use with two pots one on the back of the old Lumex lamphouse and a second one on the rectifier
often they will not regulate without both
Also one of the SCR may be shorted
When they work they are a good rectifier when they don't....... [Frown]

Posted by Richard Cockrum (Member # 2417) on 06-02-2005, 11:45 AM:

Thanks, Gordon. I looked at the Lumex manual here on Film-Tech. It showed that the pot goes between leads 32, 33, and 34 in the power supply, and specifies that this is for an 88000 series supply. Unfortunately, it doesn't say the size of pot to use. But I'll put one in tonight and try it out.

Rick

Posted by Richard Cockrum (Member # 2417) on 06-02-2005, 07:45 PM:

Gordon, you are, as the motto under your picture says, a Film God. I put a 10K pot on the control lines of the power supply, set the original pot to its halfway point, and it worked. I have full control (as far as I can tell) over the output of the power supply. When I left the theatre tonight it was running a 1600W bulb at 22V and 65A. I could turn it up or down.

To all who had suggestions, thank you.

Rick

Posted by Steve Guttag (Member # 268) on 06-03-2005, 10:11 AM:

Gord,

Why do I think that both pots were 500-ohm types? The one in the rectifier set the range (or upper limit) and the one on the lamphouse was the one that allowed one to fine tune the current.

Richard, I checked and we do have an 88001-3 manual in our collection...when time permits, I'll send it to Brad for posting.

Posted by Gordon McLeod (Member # 33) on 06-03-2005, 10:54 AM:

I believe they were both the same value but I can't remember nor find the book on it
I have never been able to find the schematics for the regulator boards and I believe one of the chips on it is discontinued

Posted by Richard Cockrum (Member # 2417) on 06-03-2005, 11:50 AM:

I checked the setting on the pot I hooked up. For the 22V 65A it's at just over 3K-ohms (for what its worth). The 10K pot was just what I had, and the Lume-X manuals didn't give a value for the pot.

Steve, I emailed about one of the rectifiers you had. I'm still interested if you still have them. And the manual for the Strong will be helpful when you get the time. Right now I'm good. It's on to the next project - getting a double mut in the booth and a projector out.

Rick
rickc@rdcsoft.com

Posted by Steve Guttag (Member # 268) on 06-03-2005, 04:01 PM:

Richard,

There have been several inquiries to the rectifiers and they are on a first come, first serve basis. It does appear that your current regulator rectifiers are working though.

Gord, I think the pot values were the same too and that the rectifier pot is 500 or so...though I can believe that they might have played with the values over the years.

I might even have schematics to the boards somewhere. Time has been so tight and these would definately be scan jobs that take a bit of time. I have sent a few manuals that I needed in PDF form Brad's way as of late though.