8mm Forum: Bulb keeps blowing

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Posted by Rick Schleicher (Member # 5633) on October 31, 2016, 12:02 AM:

Hello,

New to this forum [Smile]

I have our family Regal K-109 projector and movie camera along with 30 movies. My issue is the projector keeps blowing the bulb. Old bulb blew in about 1 sec. Bought 2 more and the second bulb blew in about 5 seconds. Not ready to install the second bulb until I find the problem.

At $15.00 each, I need a solution

Thoughts?
Rick

Posted by Janice Glesser (Member # 2758) on October 31, 2016, 02:20 AM:

Welcome Rick. I can think of a few reasons a bulb will blow. The K109 takes a 120V 750W bulb...You should measure the voltage of the house outlet to check for spikes. Then check for bad wiring in the lamp holder. The wiring is very old on these machines. The power switch could also be faulty. Make sure the bulb is well seated in the holder. It is always possible that the second bulb was also bad. This happened to me recently. I thought it was the projector causing the lamp to burn out... and I too was afraid to put in another bulb. However the next bulb worked fine. If you don't find anything electrically suspicious you will have to try the third bulb.

Posted by Steve Klare (Member # 12) on October 31, 2016, 04:09 PM:

Most of the time we see something like this, it's because somebody is driving the bulb with way too much voltage, but with a 120V bulb, how can that be?

Let's say you had a projector with a 120V bulb set up for North America, and you plug it in in Europe. Your 120V is now maybe 250 and of course you've created a very expensive photo flash!

Let's say you do the same in reverse: you plug your European projector in in San Diego and your 120V has now become less than 60! You'd be lucky to get any light at all! (It would certainly last a long time...)

I'm with Janice here, you need that voltage measurement.

Posted by Andrew Woodcock (Member # 3260) on October 31, 2016, 06:19 PM:

Beyond that, poor contacts in heavy current lamp circuits is all too often the main offender in my experiences.
Even at this voltage this is still a 6 & 1/4 amp circuit (approx).
750w is a serious amount of wattage for a projector lamp and these are old machines, often with very old joints, insulating blocks and wiring.

Posted by Rick Schleicher (Member # 5633) on October 31, 2016, 09:04 PM:

Well, the outlet reads 118.8-119.2. Initially it was 119.1 and slowly went up and down as noted over 30 seconds, never spiked or went above 119.2

As for seating the bulb, I was able to insert and give about 1/8th twist or maybe a bit more, how much more should it go? Will it go to a stop?

I'll start looking at wiring this weekend

Since I am not electrically inclined, do you have recommendations for someone to service it if need be?

Thanks in advance
Rick

Posted by Mathew James (Member # 4581) on October 31, 2016, 09:04 PM:

750W? Gulp...
There goes the hydro bill [Smile]

Posted by Maurice Leakey (Member # 916) on November 01, 2016, 03:30 AM:

Rick
The DDB lamp has a medium pre-focus base and should be turned 90 degrees clockwise after inserting in the lamp holder.
The two fins are differently shaped which only allows insertion the correct way.

Posted by Janice Glesser (Member # 2758) on November 01, 2016, 12:30 PM:

The original bulb that came with the Keystone K-109 projector was a 15V max bulb. This obviously would blow rapidly if connected to a 118 - 120v outlet. The correct bulb should be a DDB 750W 120V - 125v 25 hr.

JUST A THOUGHT...

You might try using a variable voltage regulator to lower the AC voltage a bit going to the projector. To see if that helps.

Here are two I use...the one on the left I purchased off Ebay and the one on the right I made using a common dimmer switch.

Posted by Rick Schleicher (Member # 5633) on November 03, 2016, 08:52 PM:

Well good news

I couldn't see anything wrong with the wiring. Cleaned all the lenses, film gate... and installed a new bulb, this time I made sure it was fully seated 1/4 turn to the stop, unlike the last time I only went 1/8 turn cuz I couldn't tell if that was it or not.

And.... everything works great, even watched a Popeye cartoon

All's well in this 8mm land

Thanks everyone
Rick

Posted by Janice Glesser (Member # 2758) on November 03, 2016, 09:59 PM:

Nice work Rick. Sounds like you are in business. There's also a good chance the second bulb was defective.

Enjoy your films!

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