This is topic Strong FXPS boost circuit in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Dave Macaulay (Member # 813) on 02-26-2002, 03:11 PM:
I'm trying to run a 7k FXPS at low current (3-4kW ... another story...) and the boost voltage gets too low, as this voltage varies according to the taps used - and the pulse ignitor needs a lot of voltage. At the required lamp current the ignitor operation is unreliable, with reliable ignition the current is way hot.
Has anyone got a way to increase this voltage? I've added extra windings to other brands of rectifier, but I don't have one of these here to check if that is possible. I expect to go out and look at one tomorrow morning, but if anyone has done it and can give me ideas it would be greatly appreciated!
BTW, the drawing in the manual has some glaring errors, so I'm not trusting it much. Parts would blow up good if it was wired as drawn, so I have to check some details on a working unit. The backwards main diodes are obvious, but what limits the zener current? Humbug.
Posted by Gordon McLeod (Member # 33) on 02-26-2002, 05:26 PM:
Kniesly makes a boost supply board that is basically a 110-110 v isolation transformer that has a half wave rectifier output (i usually put in a full bridge) this is parreleled to the output filter cap
It is controlled by the same relay board that they use in the auto ignitor but with a 56v zenier
Posted by Ken Layton (Member # 133) on 02-27-2002, 01:09 AM:
What make and model lamphouse is this power supply being used with?
Posted by Paul G. Thompson (Member # 655) on 02-27-2002, 01:13 AM:
Spark gap setting OK? Is the Zener OK? Zeners are cheap. I would just replace it with something Gordon mentioned....I had a very unreliable igniter in one of my Super Lumex's. When I inspected it, there was enough room for a bumblebee to walk through the gap. I reset the gap, and it fires every time now. 
Posted by Pete Naples (Member # 761) on 02-27-2002, 03:57 AM:
I've been through this, but the opposite way around ie the rectifier was giving me way too much OCV, and the resultant enormous inrush current was destroying bulbs in 400 hours! I feel that 300 V DC is possibly a little excessive!On the boost transformer there are some wires ( I forget how many ) sticking out, these are taps. They are described in the book somewhere. It tells you only to connect to a specific pair, but I found that if you experiment with other pairs ( they aren't marked at all ) you can raise or lower the OCV. I had this problem with Strong FXPS, I assume that the primary transformers are wound for US line voltage, (380v?) and ours at 415 causes higher OCV?
Posted by Richard Fowler (Member # 893) on 02-27-2002, 06:41 AM:
The power in the U.S. is generally 208 - 230 VAC.
Richard Fowler
TVP-Theatre & Video Products Inc. www.tvpmiami.com
Posted by Dave Macaulay (Member # 813) on 02-27-2002, 07:57 AM:
Thanks for the ideas.
I'm going out to have a good look at one now. I don't want to add an additional boost transformer but it is an option. I'll see if the 208 3ph ones have boost taps - maybe this is only on 380/415 models?
The DC pulse ignitor isn't the problem - we've swapped between a few units and all are the same, working perfectly at "too high" current and badly at "OK" current for the smaller lamp.
Posted by Pete Naples (Member # 761) on 02-27-2002, 04:34 PM:
OK so you guys have something in the order of half of our phase to phase voltage? Assuming the transformers are the same, it's little surprise that I have to play around with those taps when I install one of these rectifiers!
The book I have for them makes no distinction between US/Euro models, other than that ours have a 240-110v transformer to drive the lamphouse fans etc. (That transformer is no end of trouble too, but that's another story!)