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Durst M707 color - What electric circuitry should be inside ?
Hello,
About 1,5 years ago, I purchased a second-hand Durst M707 color enlarger. After a (more or less) monthly printing session, I had a 'meltdown' last weekend ... When opening the head of the enlarge, I found a) the wires connected to the lamp were brazed to some kind of connecting plate and b) the wires from the cable entering the enlarger were bolted to that same plate. Apparently, the tin connecting the wires coming from the lamp had melted, and the wires had come loose. This made me start considering wether there should be some kind of overheating-protection in the enlarger-head, as the temperature can become very high (as my old chemistry books tell me tin melts @ a temperature of 231.9°C). Since there's nothing to be found except for a few wires connected to each other I wonder : 1. What was originally in there. 2. If the state of my enlarger more or less ressembles the original state, can I make an improvement so that the enlarger only needs some cooling down instead of opening and fixing it when the temperature gets too high. 3. Would it be a good idea to build in a small fan in the enlarger-head (as I've heard when using a laborator @ school). Since the enlarger came with a 12 V transfo, I could maybe use a fan similar to those used in computers (which would be my first step into the digital era ;-) ) ... Thx, Philippe |
#2
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Durst M707 color - What electric circuitry should be inside ?
"Philippe Lauwers" wrote
About 1,5 years ago, I purchased a second-hand Durst M707 color enlarger. After a (more or less) monthly printing session, I had a 'meltdown' last weekend ...a) the wires connected to the lamp were brazed Durst designs there enlargers rather well, so it is hard to imagine the enlarger getting as hot as you describe. Be sure, though, that the right lamp is being used in the enlarger. It may be made for a 50W and have a 100W installed, which would lead to big time overheating. Or, there may have been a short in the lamp wiring and the 10-20 amps the transformer can supply (for a short time) was enough to melt the solder joints. But "brazed" -- or do you mean soldered? Brazing is half way between a weld and solder and I doubt you melted a brazed joint - the aluminum housing would have to melt first (IIRC). Solder is the stuff radios and circuit boards are put together with. Around the house it is a soft wire made of 60% lead and 40% tin. Apparently, the tin connecting the wires coming from the lamp had melted, and the wires had come loose. That _is_ pretty hot, in any case. This made me start considering whether there should be some kind of overheating-protection in the enlarger-head, Besides the solder melting, you mean... There are thermal cut-off switches: http://www.thermtrol.com/products.htm I am sure you have something just like them in the eu. The usual application is to have a self-resetting disc thermostat in series with one or two thermal cutoffs. An old coffee maker will yield both the thermostat and the cut-off(s). 3. Would it be a good idea to build in a small fan in the enlarger-head If it really runs that hot, yes. Most small computer fans run on 5VDC, the enlarger transformer provides 12VAC so you would need to build in a power supply circuit. OTOH, you may want to have the fan run all the time, this is the normal way air-cooled equipment works. A small 'wall wart' 5VDC power supply would run the fan and most folks have a box full of the things from old electronic gadgets and the like. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ |
#3
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Durst M707 color - What electric circuitry should be inside ?
Typically, in appliances where heat / current is an issue, crimped
connectors (and brazing) are used to prevent "de-soldering" although as another poster indicate, its hard to imagine that an enlarger draw enough current to cause this but maybe in combination with the heat from the bulb. "Nicholas O. Lindan" wrote in message ink.net... "Philippe Lauwers" wrote About 1,5 years ago, I purchased a second-hand Durst M707 color enlarger. After a (more or less) monthly printing session, I had a 'meltdown' last weekend ...a) the wires connected to the lamp were brazed Durst designs there enlargers rather well, so it is hard to imagine the enlarger getting as hot as you describe. Be sure, though, that the right lamp is being used in the enlarger. It may be made for a 50W and have a 100W installed, which would lead to big time overheating. Or, there may have been a short in the lamp wiring and the 10-20 amps the transformer can supply (for a short time) was enough to melt the solder joints. But "brazed" -- or do you mean soldered? Brazing is half way between a weld and solder and I doubt you melted a brazed joint - the aluminum housing would have to melt first (IIRC). Solder is the stuff radios and circuit boards are put together with. Around the house it is a soft wire made of 60% lead and 40% tin. Apparently, the tin connecting the wires coming from the lamp had melted, and the wires had come loose. That _is_ pretty hot, in any case. This made me start considering whether there should be some kind of overheating-protection in the enlarger-head, Besides the solder melting, you mean... There are thermal cut-off switches: http://www.thermtrol.com/products.htm I am sure you have something just like them in the eu. The usual application is to have a self-resetting disc thermostat in series with one or two thermal cutoffs. An old coffee maker will yield both the thermostat and the cut-off(s). 3. Would it be a good idea to build in a small fan in the enlarger-head If it really runs that hot, yes. Most small computer fans run on 5VDC, the enlarger transformer provides 12VAC so you would need to build in a power supply circuit. OTOH, you may want to have the fan run all the time, this is the normal way air-cooled equipment works. A small 'wall wart' 5VDC power supply would run the fan and most folks have a box full of the things from old electronic gadgets and the like. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ |
#4
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Durst M707 color - What electric circuitry should be inside ?
I meant soldered. Life isn't always easy without a dictionnary @ hand ;-)
"Nicholas O. Lindan" schreef in bericht ink.net... "Philippe Lauwers" wrote About 1,5 years ago, I purchased a second-hand Durst M707 color enlarger. After a (more or less) monthly printing session, I had a 'meltdown' last weekend ...a) the wires connected to the lamp were brazed Durst designs there enlargers rather well, so it is hard to imagine the enlarger getting as hot as you describe. Be sure, though, that the right lamp is being used in the enlarger. It may be made for a 50W and have a 100W installed, which would lead to big time overheating. Or, there may have been a short in the lamp wiring and the 10-20 amps the transformer can supply (for a short time) was enough to melt the solder joints. But "brazed" -- or do you mean soldered? Brazing is half way between a weld and solder and I doubt you melted a brazed joint - the aluminum housing would have to melt first (IIRC). Solder is the stuff radios and circuit boards are put together with. Around the house it is a soft wire made of 60% lead and 40% tin. Apparently, the tin connecting the wires coming from the lamp had melted, and the wires had come loose. That _is_ pretty hot, in any case. This made me start considering whether there should be some kind of overheating-protection in the enlarger-head, Besides the solder melting, you mean... There are thermal cut-off switches: http://www.thermtrol.com/products.htm I am sure you have something just like them in the eu. The usual application is to have a self-resetting disc thermostat in series with one or two thermal cutoffs. An old coffee maker will yield both the thermostat and the cut-off(s). 3. Would it be a good idea to build in a small fan in the enlarger-head If it really runs that hot, yes. Most small computer fans run on 5VDC, the enlarger transformer provides 12VAC so you would need to build in a power supply circuit. OTOH, you may want to have the fan run all the time, this is the normal way air-cooled equipment works. A small 'wall wart' 5VDC power supply would run the fan and most folks have a box full of the things from old electronic gadgets and the like. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ |
#5
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Durst M707 color - What electric circuitry should be inside ?
Have Nick run down to Electronic Surplus on Broadway and 55th and get you
some inexpensive Teflon wire. "Philippe Lauwers" wrote in message i.nl... Hello, About 1,5 years ago, I purchased a second-hand Durst M707 color enlarger. After a (more or less) monthly printing session, I had a 'meltdown' last weekend ... When opening the head of the enlarge, I found a) the wires connected to the lamp were brazed to some kind of connecting plate and b) the wires from the cable entering the enlarger were bolted to that same plate. Apparently, the tin connecting the wires coming from the lamp had melted, and the wires had come loose. This made me start considering wether there should be some kind of overheating-protection in the enlarger-head, as the temperature can become very high (as my old chemistry books tell me tin melts @ a temperature of 231.9°C). Since there's nothing to be found except for a few wires connected to each other I wonder : 1. What was originally in there. 2. If the state of my enlarger more or less ressembles the original state, can I make an improvement so that the enlarger only needs some cooling down instead of opening and fixing it when the temperature gets too high. 3. Would it be a good idea to build in a small fan in the enlarger-head (as I've heard when using a laborator @ school). Since the enlarger came with a 12 V transfo, I could maybe use a fan similar to those used in computers (which would be my first step into the digital era ;-) ) ... Thx, Philippe |
#6
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Durst M707 color - What electric circuitry should be inside ?
Or a miscontact in some of the wires, and due to the high current (12V
bulb), lots of heath. Jorge "Budwich" wrote in e.rogers.com: Typically, in appliances where heat / current is an issue, crimped connectors (and brazing) are used to prevent "de-soldering" although as another poster indicate, its hard to imagine that an enlarger draw enough current to cause this but maybe in combination with the heat from the bulb. |
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