Film-Tech Forum ARCHIVE: Smoking Strong Switcher Rectifier

This is topic Smoking Strong Switcher Rectifier in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=005190

Posted by Rick McCluney (Member # 642) on 08-09-2003, 09:55 PM:

In my experience when a switcher rectifier goes out it goes out and you have to replace it. I have encountered one now that on 2 occasions starts to smoke, but the lamp continues to stay lit.The first time it happened was Wednesday night. The second time was this afternoon. I haven't witnessed this but I have been told that the smoke comes out of the top (it is positioned so that the fan intake and exhaust are at the bottom). The model number is 6280005. Any input that anyone has to offer would be greatly appreciated.

Thanks,
Rick

Posted by Josh Jones (Member # 447) on 08-09-2003, 10:41 PM:

In a situation like this I would check for the obvious, shorts across the output of the supply, wiring that is inadequite for the job (too small), stuff along those lines. Also I would AFTER LOCKING OUT THE SUPPLY BREAKER, AND SHORTING THE CAPACITORS, measure the resistance across the lamp output terminals and look for a very high resistance(several thousand ohms). If there is a low resistance, like under a thousand or even a hundred, something is going out of tolerance, like a bleeder resistor, or a capacitor is drying up or developing a fault. Also, if this is a switching power supply, check that all the venitlation ports are clear and not obstructed by dust, dirt, or other debritus. If you are allowed inside, vacuum off all the heatsinks and other objects that appear as if they would get hot, or are near a ventilation source. also inspect components for signs of overheating, such as disscoloration and other signs of failure. That is what I would do.

Good luck,

Josh

Posted by Rick Long (Member # 213) on 08-10-2003, 12:53 AM:

62-80005 is a 3KW switching rectifier, old-style hardwire type. These have given me few problems. They were used in many an X-90 console I have come across (with 2500W bulb).

Maybe the guy at the factory who had to rebuild this forgot to wipe off the oil after drilling and tapping the screws for the newer power-output transistors, explaining the smoke.

My rule of thumb with these is, if it works don't fix it.

(Still, couldn't hurt to check the integrity of the D.C. connections).

[ 08-10-2003, 08:59 AM: Message edited by: Rick Long ]

Posted by Andrew Duggan (Member # 1302) on 08-10-2003, 01:14 AM:

I've had similar issues in the past. I don't recall ever having a rectifier begin smoking, but have certainly dealt with alarming burning smells coming out of them. However, when checking it out, nothing has been electrically amiss. Do you have any spots inside that are charred, or any place where smoke has left any kind of residue or anything?

I'd just chime in the same advice, check all your connections for any unwanted resistance, check out your capacitors (please avoid shocking yourself to death during this step. Thanks.) and basically go through the full circuit with your meter, connection-by-connection from the breaker box to the bulb. If there's a problem along the way, you'll find it.

If you're concerned about ventilation to the top of the unit, you could always add more exhaust fans! (I know what you're saying... "Oh, Andrew that's your answer for EVERYTHING! Just add more fans, just add more fans....you sound like a broken record.")

Posted by Paul G. Thompson (Member # 655) on 08-10-2003, 01:20 AM:

Check the blowers to make sure they are not clogged. And yes...if you can, check the security of the junction block and other components. I had one smoke. It was caused by loose terminations on the junction block for the Xenon lamp cables.

Also, send it to a "No Smoking Seminar." That's where I'll be headed for in a couple of days. I slipped. [uhoh]

Posted by Chris Hipp (Member # 1788) on 08-10-2003, 01:34 AM:

I had one that was smoking about a week ago. In my case the quick connect plug going into the power supply had heated and melted. I could smell the electrical burn for a couple of day before it went out. I think it was caused by the positive lead cable not being securely tightened.

Posted by Bruce McGee (Member # 131) on 08-10-2003, 07:35 AM:

Check all connections. Also, look for loose plastic, etc. that might have fallen on the circuit board. One of my Eiki xenons smoked when I got it. The problem was a ball point pen cap that was laying on a large wirewound resistor in the power supply. I was thrilled with this finding, as I got the whole machine for the cost of shipping.

If something is overheating, you should be able to see it.

Posted by Bruce Hansen (Member # 281) on 08-10-2003, 11:52 AM:

If there is oil dripping into it, onto a hot heatsink, from the projector, that can cause smoke.

As above, check all connections.

Posted by Gordon McLeod (Member # 33) on 08-10-2003, 11:57 AM:

I have had several of the older ones where the DC terminal melted
During the meltdown the unit kept running but some fould smoke came outThere appears to be an issue with them self loosening over time mybe due to the highfreq of the switcher

Posted by Ken Layton (Member # 133) on 08-10-2003, 12:07 PM:

Gordon's right. I've seen several of the old switchers that had the white DC terminal strip melt and burn. The wire clamping screws were loose! You should also check for a physically leaking electrolytic capacitor.

Posted by Alan Gilbertson (Member # 242) on 08-10-2003, 02:46 PM:

I'm with Ken, I had the same thing happen 2 weeks ago. The leads from the lamp had aluminum wire instead of copper and they came loose and melted the square D connector (which you can get from Granger)

Posted by Gordon McLeod (Member # 33) on 08-10-2003, 04:05 PM:

That is not alluminum wire but tinned copper

Posted by Chris Hipp (Member # 1788) on 08-10-2003, 04:27 PM:

If you are running a high wattage bulb then it may be a good idea to just not use the plastic plug. Just connect the wires directly.
If you need to replace the plug, I found one at home depot for about $30 whereas Grainger wanted almost $80, who knows how much strong would want.

Posted by Rick McCluney (Member # 642) on 08-10-2003, 09:07 PM:

Thanks for all the input. Loose connections sounds like
the most likely culprit here.The rectifier was installed at least a year ago by a newbie tech. I'll let you know what the problem is when I get a chance to check it out. By the way it is only running a 1600 watt bulb in a Super Lumex.

Thanks,
Rick

Posted by Rick Long (Member # 213) on 08-11-2003, 11:16 AM:

One more thing you might want to check. The contactor is bypassed by three 5-ohm 100-watt resistors. This is necessary to keep from blowing the breaker each time the rectifier is turned on due to a heavy inrush current being drawn by the large filter capacitor.

Some of these resistors were a variable type with a moveable slider, and occasionally, the slider comes loose, and burns.

The resistors are easily seen by removing the cover.

Posted by Rick McCluney (Member # 642) on 08-11-2003, 08:17 PM:

Sure enough it was the white Square D terminal block which had melted on one side. I should have thought of a loose connection, but I had not encountered the problem before in a switcher and only once before in a Strong Highlite console.

Rick

Posted by Gordon McLeod (Member # 33) on 08-11-2003, 09:17 PM:

It is a good idea with all high current equipment to check the tightness of electrical connections monthly

Posted by Phil Hill (Member # 371) on 08-11-2003, 09:47 PM:

Rick: Thanks for posting a follow-up after the problem was traced down. [beer]

It should be a rule and not just a common courtesty to post a follow-up after a solution has been discovered to a "help-wanted-technical" post.

It helps us ALL!

>>> Phil

Posted by Michael Schaffer (Member # 1204) on 08-12-2003, 05:34 AM:

quote:
It is a good idea with all high current equipment to check the tightness of electrical connections monthly

Under current?

Posted by Rick Long (Member # 213) on 08-12-2003, 01:33 PM:

Following up on Phil's comment, thank you for posting the solution.