Film-Tech Forum ARCHIVE: Lamp doesn't strike

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Posted by Antonio Marcheselli (Member # 373) on 06-13-2002, 03:45 PM:

We are always searching what is causing continuing stops on our Vic 5 consolle.
A colleague of mine noted that, after the stop, the lamp won't strike. He has to try many times.
Can be a security switch, or something similar that is preventing the lamp to strike? I was thinking that if a security switch is preventing the lamp to strike, the lamp should not TRY to strike but should stays dead, do you agree?

Suggestions, please!!!

Bye
Antonio

Posted by Andy Muirhead (Member # 712) on 06-13-2002, 05:58 PM:

When a xenon bulb is hot, it will require a higher voltage to strike than if it is cold. Some rectifiers are great and will re-strike a hot bulb immediately, while others are not so great. I have two that will re-strike a hot bulb perfectly, and two that require the bulb to be cooled for 10-15 minute before they will succesfully re-strike.

This may have something to do with why you can't re-strike immediately, although probably has nothing to do with why the bulb is going in the first place.

I don't know anything about Vic-5's, so that's all i can offer!

Posted by Gordon McLeod (Member # 33) on 06-13-2002, 07:55 PM:

I would tend to be looking at the powersupply for the automation(control system) as if it is cutting out would esxplain why the projector and lamp are cutting out

Posted by Will Kutler (Member # 770) on 06-13-2002, 11:18 PM:

I Just finished servicing a theatre with a similar problem. Vic 4 w/Super Lume-X and Strong High Reactance Single Phase Rectifier (1600 Watt System).

Problem: Xenon shut down during operation...

What was the fix? I have to look up the resistor and capacitor numbers again, but several RF Suppression Caps in the lamphouse were fried. These caps also tied another circuit to ground via a bus.

Also, in the power supply, there were a few bad diodes w/bad connections!

Sorry, but the part nos have skipped my memory and I need to edit later...

Posted by Antonio Marcheselli (Member # 373) on 06-14-2002, 05:19 PM:

Thanks for your replies!

I've found a faulty switch that perhaps has caused all the stops.
However I had just today the same difficult starting the xenon after 2 min. stop.

Since our rectifier never had these problems we think that there should be a problem.

Also, We've noticed the following:

1. The amperometer is not fixed, it is "shaking" about 2/4 amps.
2. The lamp has 1 month and is too black. The last one became too black in the same manner.

We are going to change the diodes, then we will check the current with an oscilloscope to see where is the problem.

If you have other ideas... The rectifiers is made by IREM

Bye!

Antonio

Posted by Rick Long (Member # 213) on 06-14-2002, 05:48 PM:

A couple of quick thoughts on this.

Re; the lamp stopping after it has struck, perhaps a micro-switch in the STOP timer may be loose in its mounting or faulty. Have had this a few times. The lamp cannot strike, even with the lamp switch on manual until the switch makes contact again.

With our first sets of Cinemeccanica consoles many years ago, we had difficulty in striking bulbs. We beleive this was due to the points in the spark gap being exactly that - POINTS!. The corona effect allowed the charge to leak off to early. Whether that was the case or not, ignition was dramatically improved by removing the centre electrode, and filing the end electrodes to a rounded point (an aperture file works well for this). The points were set to about the thickness of a dime apart.

Good luck!

Posted by Wes Hughes (Member # 981) on 06-14-2002, 07:43 PM:

If you have a bouncing ammeter you most likely have one or more leaking or shorted diodes.

That would explaing the blackening and short lamp life. AC Ripple is murder to a short-arc xenon.

Posted by Antonio Marcheselli (Member # 373) on 06-15-2002, 04:45 PM:

Thanks for your replies.

I'm going to buy a new set of diodes.
Can I buy them in electric shops (industrial electric shops) os should I have to order them directly to IREM?

Bye
Antonio

Posted by Richard Fowler (Member # 893) on 06-15-2002, 06:43 PM:

Most IREMS use a 42HFR( arrow pointing toward the lead )diode with an attached lead. It is better to go a 60 amp version and possibly changing them all to insure better life...if available, you should use a silicon heat compound prior to installing the diode(s) to the heat sink. Diodes are fairly inexpensive but do get the model with the welded lead since some people with then try to attach the lead with a poor solder job and create more future work.
Richard Fowler
TVP-Theatre & Video Products Inc. www.tvpmiami.com

Posted by Antonio Marcheselli (Member # 373) on 06-16-2002, 05:55 AM:

Thanks Richard,

IREM told me that my rectifier requires 72 HAR 40.
Seems that my rectifier has 72 HFR 100. What is the difference?

Thanks for the tips, will be precious!

Antonio

Posted by Steve Guttag (Member # 268) on 06-16-2002, 10:40 AM:

In International Rectifier ease....

The first digit is the current
The second digit is the lead
The next two letters indicate series
The third letter (if any) is the "R" for reverse
The last numbers is the Peak Inverse voltage (x10).

Thus, a 72HFR100 would be a 70amp diode with a red covered attached lead, a reverse diode (red), and has a PIV of 1000 volts.

A 70HFR100 is the same thing without the lead.
A 71HFR100 is the same thing but with a bare attached lead.

IREM tends to use "HAR" series which has a different breakdown. The "A" stands for "avalanche."

IREM tends to "design" their stuff such that the components are running just about at spec with no headroom. This is true of the diodes, contactors and wires.

For 3KW and below rectifiers, 85 amp diodes will do. There is no point in keeping all the various sizes. I generally recommend a high PIV...800 - 1600...depending on what is available (it is amazing how that fluctuates with some suppliers). Nowadays, I don't seem to be having any trouble getting over 1000PIV. The higher PIV will protect them against spikes, to some degree.

As to the leads, they are harder to find and cost more. I have made up leads that I attached with screws/nuts to standard diodes for those rectifiers that so need them. I don't like the preattached leads since some rectifiers (ie the LP associates and it's MANY copies) tend to need about 1/2" more lead than the preattached ones give you. Therefore, the leads are under stress. Whereas we make our leads, they are crimped and soldered, never had one fail.

Steve

------------------
"Old projectionists never die, they just changeover!"

Posted by Antonio Marcheselli (Member # 373) on 06-16-2002, 05:47 PM:

Steve,

Thanks for all the info!

Antonio

Posted by Stan Gunn (Member # 554) on 06-16-2002, 06:08 PM:

Antonio
also check the capacators and the switching relay assembly
it is not unkown for the relay to fail. causeing high inrush current to the lamp, or not switch the cap back into circuit.
This will cause hard stricking and premature lamp failure.

------------------
KALEE FOREVER. CARBON ARC, THE ONLY LIGHT FOR THE STARS!
ALL PARTS FOR VICTOR AND KALART VICTOR 16MM PROJECTORS.SERVICE TO 35 AND 16MM PROJECTION EQUIPMENT.
35MM sprockets made to order.

Posted by Antonio Marcheselli (Member # 373) on 06-18-2002, 12:00 PM:

Steve, I went just today searching diodes...

We have a 110A rectifier with a 3k lamp.

If I've correctly undertood your instrucions better diodes would be

82HAR100, right?

P.S. A bit OT: "lamp doesn't strike" or "lamp don't strike"?

Bye
Antonio

Posted by John Hawkinson (Member # 1135) on 06-18-2002, 08:17 PM:

"Lamp does not strike," which can be contracted to "Lamp doesn't strike," is correct.

"Lamp don't strike" would be "Lamp do not strike," which is incorrect, since "lamp" is singular, and "do" is the plural form. Either that, or it's an imperative, meaning, "Lamp! Do not strike!"; few people go around ordering their lamps like that, though ;-)

--jhawk

Posted by Richard Fowler (Member # 893) on 06-18-2002, 09:34 PM:

82HAR100 would be fine......

Posted by Antonio Marcheselli (Member # 373) on 06-19-2002, 04:56 AM:

Thanks john, I just need to read again my english grammar book!!

Thanks Richard!

Antonio

Posted by Steve Guttag (Member # 268) on 06-19-2002, 06:29 AM:

Richard,

What does IREM supply on their 3KW rectifiers? The 82HAR100 would be an 80 amp diode. Even 85 amp diodes run pretty damn hot on 3KW. If it's an IREM, it wouldn't surprise me since they ALWAYS play things close to failure on their specs. When they go, I always put in an 85 amp diode, leaded or non (with an attached lead).

Personally, I feed that rectifier companies should switch to the next package size up from the DO-5 when they hit the 3KW systems...go for a 150K series (150 amp, like on a 4K-7K system)

Steve

------------------
"Old projectionists never die, they just changeover!"

Posted by Antonio Marcheselli (Member # 373) on 06-19-2002, 06:36 PM:

Steve,

Actually our 110A IREM rectifier has 72A diodes.
Now we have a 3000W lamp, but we had a 4000W since 1 year ago. Try to imagine that rectifier at 130A...

When Diodes failed, Cinemeccanica just replace them, noone noted that the rectifier was out of range. Cancelled shows, blowed lamps...

BTW, I saw the lamp: in the upper portion there is a well defined dark zone, like a ink blob (but not so dark!).

Bye
Antonio

Posted by Richard Fowler (Member # 893) on 06-19-2002, 08:05 PM:

What model IREM do you have? does your model have the additional filter choke? We stock the 72amp version as a generic replacement for the IREM since most of the ones we see in our region either use 42amp or 60amp units. Cost is always a factor even though a few lost shows this is a moot point. The larger stud size diode recommended by Steve costs 3 to 4 times more than the type used in an IREM but the failure rate on a properly sized heat sink would be minimal......Some people may rag out Kneisley rectifiers but in the scores of units we have installed I can remember only replacing 2 - 3 diodes, which are DO-8 type with the larger stud vs the smaller DO-5 style as found on most IREMS.
Richard Fowler
TVP-Theatre & Video Products Inc.

Posted by Antonio Marcheselli (Member # 373) on 06-20-2002, 12:43 PM:

First a question: I found HFR diodes, seems that HAR are no longer available. Can I surely install HFR on my IREM?

Our rectifier is G3-X131DM

When the theater was opened the temperature in the booth and in the projector was pretty high. We lost many shows for lamp and diodes failure. Now temperature is under control but since we are going to change the diodes and since we have only one projector...

82HFR120 costs about 7$ each. Our "official" supplier sell 72HFR100 to us at 17$ each...

Bye
Antonio

Posted by Antonio Marcheselli (Member # 373) on 08-07-2002, 09:37 AM:

Steve,

I found 87HFR120

what means this "7"? Will be good for our rectifier?

Bye
Antonio