Film-Tech Forum ARCHIVE: Strong rectifier

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Posted by Bruce McNaughton (Member # 2691) on 02-28-2018, 04:09 PM:

I have a Strong rectifier which was mated to a Strong Lumex lamp house with a 3K bulb. It was supposedly 'hard wired' to that lamphouse. They work perfectly well together.

I now want it to run other lamps in a Kinoton lamp house. 1600W, 2000W. The rectifier has an electronic control which adjusts the DC amperage once the (3K)lamp is alight so it will certainly run lower wattage lamps.

The problem that I have is that the unloaded voltage from the rectifier reads 225VDC.

All of my reading tells me that this should be in the range of 120-170VDC so I am afraid to connect it up to the Kinoton in case of damage to the striking circuit.

There is no adjustment available to lower this DC voltage.

The model is 6280109. Ballantyne/Strong won't respond to my request for a manual. Manuals for models close to this model do not relate to my unit.

I have thought that the 225VDC could be a 'false' reading and once connected (loaded) may well drop to something within the correct range...

Any experience from members would be very appreciated.

Posted by Sam D. Chavez (Member # 1841) on 02-28-2018, 05:44 PM:

There was a circuit to lower the output voltage of the switch so you could get older Lumex to strike.

You should write to ric.sanjurjo@btn-inc.com, and tell him of your concern. I think he's still there.

Don't use my name. Lol

Posted by Peter Hall (Member # 695) on 03-03-2018, 12:37 PM:

I hope that this helps. I wouldnt worry about the 225V open cct voltage (vs the stated max of 190v). The IREM switchers had much the same and they worked fine with Kinoton lamphouses. If your Kinoton ignitor is a Kinoton (sits under the lamp) then expect it to fail whatever you do now that it is 10 or 15 years old. The IREM ignitors in earlier Kinotons were far better.

This is the mod we used to use to get Strong lamphouses to auto-strike with horrid UK made TandR rectifiers (straight out of the fork-lift factory, open cct voltage around 65VDC). I dont think it will help in this case - Sam, I guess you are talking about a DC boost mod in the rectifier ?

"Super Lumex mod to auto strike with lower rectifier voltage

First check open circuit and running DC voltage from the rectifier. Open cct voltage should be >70V (>95V on IREM or switch mode). Run voltage should be <25V. DO NOT modify if running voltage is above 30V.

Replace VR201, 1N5369 51v(or could be IN5374 75v or 1N5377 91v) with 1N5366, 39v, RS 3149164

Lamp should now auto strike when switched to AUTO."

Posted by Sean McKinnon (Member # 612) on 03-05-2018, 11:07 AM:

Are you referring to the open circuit (no load) DC voltage or the voltage for the contactor circuit?

Posted by Mark Gulbrandsen (Member # 72) on 03-06-2018, 12:06 PM:

Peter is referring to the zener diodes on the ignitor auto ignite control board in the lampenhousen.

Mark

Posted by Bruce McNaughton (Member # 2691) on 03-08-2018, 09:46 PM:

Although Ballantyne/Strong have not answered any of my requests for assistance, Sam's contact did reply. He cited a "charge pump" which apparently boosts the output DC voltage and can be modified to reduce it... That's where the help ended because he could not send a circuit and communication has ceased.

Posted by Sean McKinnon (Member # 612) on 03-09-2018, 11:57 AM:

Sorry I was addressing the Original Poster Bruce. I was unclear if he was talking about the output DC voltage or the voltage from the lampenhaus to close the contactor.

I can see from his last post that he is indeed talking about the output DC.

Posted by Mark Gulbrandsen (Member # 72) on 03-09-2018, 12:40 PM:

Yep, many rectifiers have a seperate HIgh Voltage "Start Circuit" SOme rectifiers like Irem have an integral Start Winding on the main transformer. Switching supplies have to because of their nature have a seperate high voltage start circuit that's usually diode isolated from the lower voltage higher current run circuit.

If anyone needs Strong switchers (compact only) repaired I still do repair them quite often around here. I get them from all over the country. My price is roughly about half of what the factory charges. I used to get 6 to 8 a month, now it's down to about one every other month... mostly from follow spots. I can no repair the suitcase style switchers are many of the semiconductors are obsolete.

Mark

Posted by Bruce McNaughton (Member # 2691) on 03-09-2018, 03:28 PM:

Mark, given that you are some 10,000 miles from me and that sending the Strong unit to you would cost far more than it is worth, is there any help that you can offer by way of pointing me to the area of the circuit that can be modified to lower the DC output?

Posted by Mark Gulbrandsen (Member # 72) on 03-09-2018, 04:48 PM:

Bruce,

I never had to modify any of their rectifiers... ever. I just changed the appropriate Zener on the auto-ignite board in the lamphouse for the amount of no-load dc voltage present. What lamphouse are you using this on? I am also not familiar with the Kinoton arrangement for auto-strike, but bet it's something along the lines of what Strong did. Peter Hall, I think was on the right track...

Mark

Posted by Steve Guttag (Member # 268) on 03-10-2018, 11:48 AM:

I've run numerous Strong switchers with Kinoton lamphouses with both DC and traditional igniters without incident. There was a modification on the last generation Ignition board with solder pad to change its trigger voltage to use with low-boost rectifiers like the older IREMs (they normally couldn't get above 85VDC.

Once the threshold is met, the igniter is going to start to do its thing and once the lamp is lit, the voltage is going to drop. The only potential harm is if the high voltage stays that way for a protracted period of time but then again, if that is the case, the coil and spark gap are going to be destroyed by over use too. Christie won on that one by having the ability to stop the auto ignition if it got too hot (bi-metal).

You would need to know what generation Kinoton lamphouse you have to know what igniter circuit is in use and if you are REALLY still bothered by it, put an appropriate zener in line with the feed to the igniter board to drop the voltage to your desired range.

Posted by Bruce McNaughton (Member # 2691) on 03-10-2018, 08:36 PM:

Steve

The Kinoton lamp houses that I plan to use are the small 2K units made in 1987. They strike beautifully with a Xebex rectifier which delivers 80 odd amps. So I guess that I should drop the input to somewhere near that voltage. Can you suggest the appropriate zener value? I am electronically illiterate but I have enough talent to add a component...

Posted by Mark Gulbrandsen (Member # 72) on 03-10-2018, 09:59 PM:

quote: Steve Guttag
There was a modification on the last generation Ignition board with solder pad to change its trigger voltage to use with low-boost rectifiers like the older IREMs (they normally couldn't get above 85VDC.

I had problems with those older IREM's not igniting 3kw and larger lamps. Its just insufficient no load DC for most lamps that size. I ended up installing an external 150VDC boost box that Neumade used to make and that solved the problem.

Mark

Posted by Dave Macaulay (Member # 813) on 03-10-2018, 09:59 PM:

They're talking about the zener on the Strong lamphouse auto-ignite board... this gets effectively subtracted from the open circuit rectifier voltage to close the strike relay: so with a 24V relay and 120V open circuit voltage they used around a 95V zener. The zner voltage was changed for different rectifiers, switchers usually have higher OC voltages.
Things got different for the pulse ignitors, best to leave them out of this.
I'm not sure what circuit Kinoton uses for their auto ignite. An AC ignitor will need a voltage sensing circuit. Regardless, when the lamp DC voltage gets above a certain level the ignitor goes on. Trigger voltage is adjusted to allow the rectifier to start fully and be ready to strike a lamp, Strong lamphouses set for passive rectifiers would have issues with switchers because they would run the ignitor before the rectifier was really ready to go.
You need to look into the autostart circuit and understand it before you start fiddling with different zeners.
Note that Strong rectifier control circuits are designed for Strong lamphouses and some mods are needed to get them working - with their safety cutouts functional - on European lamphouses.
Be very careful, that 100V+ DC voltage is rather dangerous.