Film-Tech Forum ARCHIVE: Strong switcher problem

This is topic Strong switcher problem in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Jack Ondracek (Member # 1466) on 01-04-2003, 10:21 PM:

I'm suspecting the answer to this might be "send it to the factory", but here goes:

A couple of years ago, I bought an Ultra 80 with a 7kW supply (model 6284001), an absolute blowtorch that made my largest drive-in screen blindingly bright and made me a true believer in the virtues of water cooling [Cool]

. Late last year, I reopened an indoor quad that had an X-60D with the same model switcher. Both lamphouses work fine with their respective power supplies.

I eventually decided the X-60 had to have a new reflector (ha!)... For expediency's sake, I brought in my Ultra-80 & hooked it up to the power supply that was already there. The lamp would not strike automatically, but would if you tripped the manual strike.

It turns out that the no-load voltage on the supply serving the X-60 is quite a bit lower than the one that came with the '80, though both are the same model. To make the '80 work automatically, I had to bring in the supply that came with it.

So.... the obvious question, since the manual says nothing about it and isn't particularly detailed: Is the no-load voltage adjustable or tapped?... or is there a problem with the supply. If the latter, is there anything I can do locally (I am conversant in component level repairs), or do I need to send it in to get it fixed?

Jack

Posted by Gordon McLeod (Member # 33) on 01-04-2003, 11:15 PM:

What no load are you getting If it is only slightly lower change the zenier diode on the auto strike board in the lamphouse to a slightly lower voltage one

Posted by Jack Ondracek (Member # 1466) on 01-04-2003, 11:36 PM:

Yah... I figured someone would ask! [Wink]

I'll have to check it again, Gordon... and the problem one is disconnected now. I think it was along the lines of around 50 volts lower than the other, though.

The thought of lower voltage zeners did occur... but I'm curious why two supplies of the same model should be that much different.

Posted by Gordon McLeod (Member # 33) on 01-05-2003, 01:03 AM:

10-20volts I could see 50 volts no way it would put it below the threshold of supplying enough inrush current to establish the arc
short awnser send in in for repair

Posted by Ken Layton (Member # 133) on 01-05-2003, 01:33 AM:

The manual says "no load should be 120 to 140 volts DC. If lower consult factory".

Posted by Jack Ondracek (Member # 1466) on 01-05-2003, 02:01 AM:

Sounds about right. If memory serves [Confused]

I think it was running about 100 volts, and the other is around 150.

Posted by Gordon McLeod (Member # 33) on 01-05-2003, 11:49 AM:

Lamps should still light well at 100v (The original spec was 60volts back when) Changing the zenier will make the autostrike work

Posted by Jack Ondracek (Member # 1466) on 01-05-2003, 06:41 PM:

quote:
from Gordon:
Changing the zenier will make the autostrike work

Yah... and the supply does work fine otherwise. But..... why two identical supplies should have different voltages has me pretty curious. [Confused]

Posted by Tristan Lane (Member # 1169) on 01-06-2003, 01:57 AM:

Depending on the type of switcher, there is an adjustment potentiometer on the rectifer for voltage. It is usually located on the access panel to the DC and lamphouse wiring terminations. It is covered by a plastic plug. Maybe this is the cause of the voltage differences in the two rectifiers.

Tristan

Posted by Pat Moore (Member # 380) on 01-06-2003, 07:39 AM:

Hi Jack; I'm far from a Switcher expert but I believe they should develop the same open circuit voltage. In my experience Switchers always got >120VDC when they were working right. It might be something simple, but you'd have to talk with one of the guys in-house to find out what to check. Might be that you need to send it in to us and we'll make that as painless as possible. Give us a call and we'll guide you through.

Pat