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A Dimmer, A Transformer, and a Soldering Iron... Please Help!

A Dimmer, A Transformer, and a Soldering Iron... Please Help!

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  #1  
Old 06-16-06, 08:27 PM
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A Dimmer, A Transformer, and a Soldering Iron... Please Help!

Hello Everybody,
I have a soldering iron that heats to 900 degrees, it has NO variable setting, just 900 or off. I need to re-flow solder on a PCB board that goes in my washing machine*. I keep reading that 900-F (can't find the 'degree' symbol) is much too high. I am a brand new solderer and don't want to take any chances. Is there a way, using the above mentioned items, that I can make my soldering iron 'dimmable'? If I can, how do I configure these things? Which goes to the wall and what wires do I connect? I posted pictures at the link below so you can see what I have to work with. I am really trying to learn basic electric work and really appreciate any help (detailed help, that is!) anyone can offer.
By the way, the Transformer is 120V in and 30V out, the soldering iron is 25W, and the dimmer is the regular incandescent type 600W 120V.
May you be happy and well,

Jess

Here are pictures http://pg.photos.yahoo.com/ph/go_kit...A5hCFBymnFMXis

*Funny thing, it is the same problem as seen here, using the same exact fuse. Bet it's a Kenmore frontloading machine! Seems to be the way they go. http://forum.doityourself.com/showth...&highlight=pcb
 
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  #2  
Old 06-16-06, 08:32 PM
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Originally Posted by EG13
Hello Everybody,
I have a soldering iron that heats to 900 degrees, it has NO variable setting, just 900 or off. I need to re-flow solder on a PCB board that goes in my washing machine*. May you be happy and well
Jess
Go to Radio Shack and get a smaller iron. They are cheap. IF you don't you can damage the componebts on the board.
 
  #3  
Old 06-16-06, 08:36 PM
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I am literally "in the sticks" with no electronics stores anywhere near by. I will be making a trip next week but wish I could wear clean clothes! Is there any way to make this work?
 
  #4  
Old 06-17-06, 05:07 AM
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First: no reason you could not use that dimmer to lower the heat of the iron. The transformer does not look from the pic like it would have a 25 watt rating, but 30 volts would be too little anyway.

What parts on that board do you need to "reflow"? I see a lot of delicate components, and I would not give you a high chance of success. If it a connection on something big like the choke or relays or one of the plug connectors, then forget about the dinmmer.....just do it. With the dimmer, you will not have any idea how many watts are going to the iron. If you let the temp be too low, then it will just struggle a long time to get the joint up to temp, and time is your enemy because heat will migrate farther from the joint the longer the heat is applied.
 
  #5  
Old 06-17-06, 05:09 AM
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1) If you are new to soldering, then you are asking for trouble here. You need to _practise_ with the soldering iron first. You need to be able to judge when the joint is fully flowed without sitting the soldering iron too long in one place and excessively heating components around the joint.

While I am certain that there is such a thing as 'too hot', you run a bigger risk of overheating and damaging components with a soldering iron that is too cold. The reason is that the joint itself limits the temperature by melting, but heat is constantly flowing away from the joint to the surroundings. The faster the joint is heated up to melting, the _less_ heat that gets to the surrounding components. Of course, if the joint is fully molten, and you simply leave the soldering iron in place, then the hotter iron will heat the surroundings more -- this is why you need to learn to judge if the joint is properly reflowed.

2) In addition to the soldering iron, you will need a good flux agent, and stuff to keep the soldering iron tip clean and 'tinned'. This assists the heat transfer from tip to joint; a dirty tip has the same problem as too low a temperature, you get slow heat transfer, slow melting, and more heat carried to the surroundings.

3) Some soldering irons are simple resistive heaters. Powering such a soldering iron with an ordinary incandescent dimmer will reduce the power output. But since the relationship between temperature and power is quite non-linear, you will have no way of knowing what tip temperature you get,.

Other soldering irons have built in temperature regulation, something like a thermostat. These irons will keep the same temperature even as you reduce the power in, until the power in is not enough to maintain the setpoint. These will be even harder to control for temperature.

I suggest that you find a circuit board that you don't care about, a wet sponge for tip cleaning (don't use this for anything else, remember that lead is quite toxic), and simply use the soldering iron that you have to practise, with no attempt to reduce the temperature.

-Jon
 
  #6  
Old 06-17-06, 07:23 AM
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Just a note:

To use a "degree" symbol, on a Win XP machine, go to:

Start> All programs> Accessories> System Tools> Character Map

Find the character you want to use, double click on it, the click "copy". Now you can paste this character into the text you are writing.

212°

There is another way using the "Alt" key. You can hold down Alt and hit 0146. On a laptop this can be a pain as the "num lock" is not usually on.
Alt Key Symbols
 
  #7  
Old 06-17-06, 07:43 AM
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Originally Posted by Speedy Petey

There is another way using the "Alt" key. You can hold down Alt and hit 0146. On a laptop this can be a pain as the "num lock" is not usually on.
Alt Key Symbols
WOW, that link is worth ¥1,000,000. (or $8681.309 American)
 
  #8  
Old 06-17-06, 08:05 AM
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See, I'm good for something.
 
  #9  
Old 06-25-06, 01:56 PM
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Man, You guys are awesome!

wareagle – Thanks for the quick action!

594tough – Thanks for the heads-up!

winnie – This was just awesome of you to provide. I’ll add it to
my soldering info. for future reference.

Speedy Petey – I needed that, thanks!

Nap – Ha Ha!

I am always amazed when people I don't even know are so helpful. I don't have much to contribute yet, but when I learn I will share with others just like you all did with me. You guys are real cool.

With mucho appreciation,
Jessie
 
  #10  
Old 06-25-06, 02:04 PM
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Check this out!

I found this cool project and made one....and it even works! That's not always a given with me!

With the important information you provided I think I will be able to get this job done. Then, I will have clean clothes and all will be right with the world. Well, one thing will. Same difference!

Take care.

Jessie
 
  #11  
Old 06-25-06, 03:25 PM
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Speedey: I don't know if this varies by machine, or what:


Alt 0146 = (blank)
Alt 0186 = º
Alt 0187 = »
Alt 0188 = ¼
Alt 0189 = ½
Alt 0190 = ¾

eMachine, XP home
 
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