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Old 19th Jan 2019, 1:53 pm   #1
qualityten
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Default Weller W TCP50 soldering iron capacitor question

I have a Weller WTCP50 soldering iron, which has suddenly stopped working. It's been working well for the last six months since I replaced the magnetic switch with an original Weller part.

The PSU is okay, and 26vac is reaching the heating element, but is not returning via the 0.01uF 400v capacitor. I've tried replacing the capacitor, but it still does not work. However if I short out the capacitor, it heats up as normal.

I don't understand the function of the capacitor, beyond guessing that it suppresses the on-off spark of the switch. Is the capacitor essential for for the safe working of the iron, or can I remove it and still use it safely?

Or is the correct repair located elsewhere in the circuit?
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Old 19th Jan 2019, 2:01 pm   #2
Sean Williams
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Default Re: Weller W TCP50 soldering iron capacitor question

If you short out the 0.01uf cap you are effectively bypassing the Magnastat temperature control.

This would tell me that there is a problem with the Magnastat.
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Old 19th Jan 2019, 2:14 pm   #3
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Default Re: Weller W TCP50 soldering iron capacitor question

Thank you for your quick reply. Is the magnastat the same part as the magnetic switch?

If so, is it just bad luck that a new part would fail after 6 months? I use the iron for an hour or two about 3 times a week, I.e. not heavily.
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Old 19th Jan 2019, 3:04 pm   #4
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Default Re: Weller W TCP50 soldering iron capacitor question

Yup, thats the same part - it may not have failed - the thermostatic switch contacts may be pitted or dirty - if this is the case, you might be able to clean them
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Old 19th Jan 2019, 3:37 pm   #5
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Default Re: Weller W TCP50 soldering iron capacitor question

Thanks for confirming this Sean. I did that with the same part before I replaced it. Very fiddly. I wonder if the contacts are more subject to corrosion in a damp garage?

I'll use my old Oryx in the meantime, but these Wellers are such a pleasure to use.
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Old 19th Jan 2019, 4:12 pm   #6
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Default Re: Weller W TCP50 soldering iron capacitor question

Update: I've successfully cleaned the contacts and am back in business. It's clicking away nicely again. Thank you for your advice Sean.
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Old 19th Jan 2019, 6:40 pm   #7
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Default Re: Weller W TCP50 soldering iron capacitor question

Quote:
Originally Posted by qualityten View Post
Thanks for confirming this Sean. I did that with the same part before I replaced it. Very fiddly. I wonder if the contacts are more subject to corrosion in a damp garage?
More than likely! Subjectively I always thought the Magnastat switch was more reliable on the older 240V version. More volts to blow away crud and less current to switch.
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Old 25th Jan 2019, 5:09 pm   #8
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Default Re: Weller W TCP50 soldering iron capacitor question

Hi,
My Weller keeps working thanks to the "thermostat" principle.
When I saw it working 8 hours a day, 40 hours a week, I decided to buy one. Just the iron, the transformer is na alternative one.
The principle is the Curie point. Under a certain temperature, the magnet atracts and closes the contact (yes, the capacitor is to absorb the sparks of the 50w switching). When it reaches the trip point, when the stength of the sping is bigger than the temporarily magnetic force lost dued to heating, it opens. Then cools down to the point the magnetic force come back, pulling back to ON position, and so forth.
You can clean the contacts some times before it wears out definetivelly. So far it's the best Iron that I know. Cheers.
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