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Photo Forum / Film Photography / Darkroom / February 2007Leitz Focomat v35 buzzing
My enlarger head makes a buzzing sound whenever the light's on and the enlargement intensity fluctuates slightly. It's still useable, but every so often a print is a little lighter or darker than expected. I've ascertained the problem isn't in the timer unit, and the bulb is new, so what could it be? Has anybody else had this problem? Thanks... > [Leitz V35] head makes a buzzing sound whenever the light's on and the > enlargement intensity fluctuates slightly. If you are sure the buzzing is in the head the most likely cause is a loose connection. Usually: hissing buzz = loose connection, arcing rattling buzz = loose transformer core, relay or hardware humming buzz = loose transformer coil Is the buzz constant? Happen all the time? What happens if you give the enlarger a slap [like an old TV set]?  SignatureNicholas O. Lindan, Cleveland, Ohio Darkroom Automation: F-Stop Timers, Enlarging Meters http://www.nolindan.com/da/index.htm n o lindan at ix dot netcom dot com >> [Leitz V35] head makes a buzzing sound whenever the >> light's on and the [quoted text clipped - 10 lines] > Is the buzz constant? Happen all the time? What happens > if you give the enlarger a slap [like an old TV set]? Also check the lamp socket. Signature--- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com -- Posted via a free Usenet account from http://www.teranews.com >Also check the lamp socket. Indeed. The screw-in clamp can loosen and has caused buzzing on both my V35s. Slapping the head does nothing, and I have the lamp holder screwed in tight. The buzzing's continuous but gets softer and louder as the bulb is brighter and weaker. I did think of the transformer, but wouldn't the sound be coming from there rather than the head in that case? Or maybe the fluctuating current induces buzzing in the head? >I did think of the transformer, but wouldn't the sound be coming from >there rather than the head in that case? Or maybe the fluctuating >current induces buzzing in the head? The current to the bulb is 12V AC (alternating current) so it is capable of causing buzzing at 50Hz. > Slapping the head does nothing, and I have the lamp holder > screwed in > tight. The buzzing's continuous but gets softer and louder > as the bulb > is brighter and weaker. Check the lamp itself and the condition of the contacts in the holder. If the lamp socket or lamp base are corroded they may have developed intermittant high resistance which may also cause the buzzing. Of course, also check the wiring. A voltmeter will also be helpful in discovering if the output of the transformer is varying around. The source of the buzzing may be difficult to localize. A makeshift stethescope will help. This can be no more than a stick of wood or even a long pencil. Hold one end against you ear and poke the other around where you think the sound is coming from. Sometimes this will locate the source. Its an old auto mechanic's trick. It is possible for the lamp itself to be producing the buzz. Lamps sometimes do this when near the end of their lives. That might also account for the variation in brightness. Signature--- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com -- Posted via a free Usenet account from http://www.teranews.com >It is possible for the lamp itself to be producing the >buzz. Lamps sometimes do this when near the end of their >lives. That might also account for the variation in >brightness. True. To the OP: If there is a variation in brightness, there will also be a significant variation in colour temperature, which could significantly affect results. A new bulb may well effect a cure. Philips 13139, or 6604 if you have the earlier bulb holder. The 6604 is hard to find and expensive. Most Focomat V35 enlargers have been converted to take the later Philips 13139 bulb, which is much easier to find and reasonably priced, for example GBP 11.55 from: http://www.bltdirect.com/products.php?products_Current=7&cat=228 If you remove the protective plate over the rear of the enlarger head, you will find the bulb type clearly marked. |
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