Leitz Focomat V35 Problem/Short...Help?

[kauffman v36]

Hi,

At school we have a V35 in amazing cosmetic condition that hasnt been used in god knows how long (sincebefore i started there). So the other day i get in the mood to tinker with it and see if the things works since i know its one of the best enlargers for 35mm. I turn it on, everythings fine, and then poof. Bulb burns out. Shit, wth happened. So my professor and I take out the bulb, see if it was bad, it was obviously burnt so we replaced it with a brand new bulb. Same thing happened, in less time.

This leads me to believe there is a short somewhere in the electric portion of the enlarger, it was through 3 bulbs total and i wasnt willing to waste more since theyre not cheap.

Does anyone have any suggestions or ideas as to where to start to find the short. I know its a leica and yadi yadi ya but a short is a short, honda or mercedes, and can be easily fixed if attacked correctly. I know theres some electric gurus on here that tinker with enlargers 24/7.

Thanks in advance!
Robert

 

[MartinP]

What head is on the thing ?

 

[Mark Fisher]

My guess is that the wiring is fine and the bulbs you are using are the wrong bulbs. Here is the site that will tell you everything you need to know:

http://www.bonavolta.ch/hobby/en/photo/v35.htm

They switched bulbs at some point in production and the earlier one is a bit tough to get. The worst you'll need to do is to check the voltage with a voltmeter and wire in a new bulb holder.....probably a half hour job once you get the holder.

They are great enlargers and well worth the effort of fixing it up.

 

[kauffman v36]

Its the b&w VC MG head on it, NOT the color head. With either of the heads its a diffusion, not a condenser AFAIK. The bulbs are made by philips and are 12V75W but i dnt have one right now so thats all i remember. After looking at the link provided, it does look like the NEWER version of the ligth box and bulb is the one im dealing with.

Some have sent me a PM, thank you. I appreciate all the help.

Some more info, the Enlarger does not use the voltage stabilizer ive seen on ebay and read about a couple times.

Thanks again!

 

[John Koehrer]

The lamp socket may have failed, It's very common in any enlarger that uses halogen lamps. High temps cause them to fail.
75V lamp has to have a power supply somewhere to go from line voltage to 75 so check the V at the socket.

 

[kauffman v36]

check for what exactly John? Ill take apart the enlarger tommorow and find what your talking about but what am i looking for physically?

 

[jerry lebens]

Sounds like you have the correct lamp. Mr Koehrer may be correct, the ceramic sockets do fail from time to time but they're very cheap and easy to replace. Just have a good look at the wiring as it approaches the socket (the little ceramic cube that the lamp plugs in to) and see if there's any burnt or melted insulation on the wiring.
Another thing you might check is that the transformer is switched to the right voltage input. The V35 could be set for either 110v or 240v AC ; there's a two way selector on the transformer chassis and it may be set on the wrong voltage for your area (it's the kind of thing that happens in schools, students will fiddle with things!)

Good luck, it's a great enlarger!

Jerry

 

[kauffman v36]

Alright guys, i went to school today and heres the deal

Enlarger does use the newer type bulb so thats not the issue. the little block that the bulb plugs into is not burnt, have residue, or anything the signifies is being fried. Wires from there through head and through the arm are intact, i did not take apart the base. I put in a new bulb today and it stayed on without losing ligth for about 4 minutes, then it started dieing and within 30 seconds it was dead, the bulb turned black on the inside, like the previous bulbs weve tried.

Were thinking something is over heating in the base, or a short, maybe the resistor?


Any new ideas?

 

[TimVermont]

Find a voltmeter and measure the output at the lamp socket.

 

[RobertV]

Philips 13139 75W is the right HLX bulb.
Check your transformer first because it's a low voltage bulb 12V and the transformer should give 11,5 - 12Volts and just over 6 Amperes.

 

[tkamiya]

The lamp socket has two contacts. Although they may not appear burnt, many times, they have built up enough oxidation that resistance may be higher than should. When this happens, with high current going though, extra heat will build up and the result is - shorter life of bulbs.

Since you say the bulb lasted 4 minutes (meaning a while), I suspect this may be the case. The real fix is to replace the socket. You can try cleaning it but it is often hard to do it completely because of its cramped and near inaccessible configuration.

 

[kauffman v36]

Where would I find a new bulb socket? Is it specific to the v35?

 

[kauffman v36]

to bring back an old thread, weve isolated the problem to the transformer from our tests with a multimeter...anyone can help with replacing or fixing it?

 

[Mark Fisher]

If RobertV's 6+ amps is correct, then you just need to get a transformer with the same ratings (115VAC to 12VAC and at least 7 amps, I presume) and the same connections. The best source for that sort of thing in the States is Digi-Key or Newark Electronics. I suspect you can find a drop in replacement from that at a low price. If the transformer is blown, you need to replace it.