8mm Forum: Bell and howell 552 problems (mostly exciter lamp)

This is topic Bell and howell 552 problems (mostly exciter lamp) in forum 16mm Forum at 8mm Forum.

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Posted by Young He (Member # 7064) on October 11, 2019, 09:06 PM:

Hello all,

I recently bought a bell and howell 552 for a decent price, and managed to get it to mostly work without problems. The forward, reverse, lamp, still, and sound work for the most part without too many problems, but the exciter lamp does not light. I could get the lamp to turn on with an external power source, but it doesn't light in the projector.

All the tubes appear to light (I can't see if the tube with the shield lights) and the sound works (I used a flashlight as a botched fix to test the sound), but the exciter doesn't light. The two cables going to the lamp appear to be shorted together, but I'm not sure if it's intentional.

Is there a common problem with B&H exciter lamps, and if so, is there a fix that will probably resolve the issue?

There are other problems such as what seems like excessive noise when the volume is turned up, the main drive belt slipping when the projector is started, and the film sometimes getting stuck and accordion-folding in the projector, so I would really appreciate some help with that, but they're minor problems compared to the exciter lamp flat out not working.

I've already tried the service manual and searched online, but I can't figure out the problem.

Thanks for any help.

Posted by Maurice Leakey (Member # 916) on October 12, 2019, 11:35 AM:

Young
I have a similar model which is a 535, this has valves, but is a manual thread.
On my model the exciter lamp only operates when the amplifier is on (and warmed up) and the projector is running.
Your comment about the exciter lamp wiring does sound if it needs further examining.

Posted by Young He (Member # 7064) on October 12, 2019, 08:30 PM:

Hi Maurice,

Thanks for the reply. I believe I had the amplifier turned on when I tried testing the bulb, but I will try again soon.

Also, if it isn't too much to ask, what is the voltage of the pins when the exciter lamp isn't connected?

Posted by Maurice Leakey (Member # 916) on October 13, 2019, 02:45 AM:

Young
The 552 uses the BAK exciter lamp. 4volts, 0.75amps.
https://www.replacementlightbulbs.com/lampbak.html

Posted by Young He (Member # 7064) on October 13, 2019, 01:28 PM:

Thanks, but I was wondering what the voltage was when the lamp was disconnected. I probed it the other day and it read 13vac, but was 0 volts when the lamp was connected. The exciter lamp recently broke out of the blue (I might have moved it around too much?) so it would be helpful to see if there's a difference when the lamp is connected vs disconnected when it's working properly so I can test until I get a new one.

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