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Electronics => Repair => Topic started by: PoDuck on October 09, 2023, 04:37:50 pm

Title: How to test Hakko 470b heating element
Post by: PoDuck on October 09, 2023, 04:37:50 pm
I acquired a Hakko 470b desoldering station that won't heat up.  I assume that it's got a bad heating element, but I'm not sure, so I tried to test for voltage.  I get no voltage.  My first assumption was that the base that is bad, but after thinking about it for a minute I thought that a failsafe design would rely on the temperature sensor to be operating before heating up the element, which would prevent the base from sending power if the thermocouple is bad.  I don't know enough about the operation of these to know how to test that though.

Am I correct about this type of failsafe, and if so, how do I test that I will get voltage to the heating element if I have a good thermocouple?  In other words, what do I have to do to the thermocouple input to get the base to send voltage to the heating element output?

Thanks
Title: Re: How to test Hakko 470b heating element
Post by: edavid on October 09, 2023, 04:55:44 pm
Open the gun and measure the resistance of the heating element, as described in the manual.
Title: Re: How to test Hakko 470b heating element
Post by: blauerscharik on October 09, 2023, 05:21:39 pm
I had a similar fault once. Iron wouldn't heat up. I measured the resistance of the heating element and it was OL. So I thought hhhm what if I solder a light bulb to those terminals? So I did. The light bulb started glowing and the iron got hot too. I de-soldered the bulb and the iron started working again. Don't know what that was all about.
Title: Re: How to test Hakko 470b heating element
Post by: floobydust on October 09, 2023, 06:27:47 pm
more here: https://www.eevblog.com/forum/repair/hakko-470-471-de-soldering-station-schematic/msg1296987/#msg1296987 (https://www.eevblog.com/forum/repair/hakko-470-471-de-soldering-station-schematic/msg1296987/#msg1296987)
Title: Re: How to test Hakko 470b heating element
Post by: PoDuck on October 09, 2023, 06:45:25 pm
Okay, tested the lead and got ol.  Opened up the gun, and pulled the heating element out, and the wire came apart from the element.  Answers the question.

Thanks.
Title: Re: How to test Hakko 470b heating element
Post by: Miti on October 09, 2023, 11:43:24 pm
Quote from: PoDuck on October 09, 2023, 06:45:25 pm
Okay, tested the lead and got ol.  Opened up the gun, and pulled the heating element out, and the wire came apart from the element.  Answers the question.

Thanks.

Those heating elements are very expensive but don't throw the bad one. I fixed mine and it still works after more than a year. Take a paper clip or some strong steel wire and try to push it in the hole where the heating wire broke. You may touch the broken end. Then you'll have to be creative with how to keep it pushed in the hole while assembling it. Use heat resistant materials like silicone or mica and shove it around the paper clip wire.
Title: Re: How to test Hakko 470b heating element
Post by: PoDuck on October 13, 2023, 03:30:13 pm
There is no hole to put the wire into.  It appears that the connection broke cleanly, and I would have to solder the wire back down with some sort of high temperature solder, which I don't have.  I just went ahead and bought new parts for an 809.