Problem with Weller soldering iron

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Deadly Sones

Deadly Sones

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Joined 2011
#1
The last few days, I noticed my soldering iron has been acting up. When I turn it on (cold) the power light flashes, instead of staying illuminated until it gets to temperature. Seems to take a long time and the temperatures don't seem right. Very seldom will it pulse to maintain the temp. Just stays off or pulses on and off, the stays off again for awhile.

Any ideas of the cause? Maybe replacing the iron, or could it be within the controller?

http://vid1047.photobucket.com/albums/b475/deadlysones/MVI_2403_zpse2b666b9.mp4
 
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#2
Soldering Iron

Hi I had a similar issue with a different but similar brand. There was a frayed connection in the cord as it went into the base unit. The wire in question went to the temperature sensor in the iron. It became intermittent and would act just like you describe. Of course you might have a heating element going bad as well. I would check continuity first before replacing any parts.
 
#6
O.K. The iron station is a WES51. So far I took the PES51 (actual iron) apart and didn't see any problems with the wiring but isolated the wires anyway. That didn't work. Next, I bought a brand new PES51 (just the iron and cord) from Digikey. It even came with a tip (although I have many).... still no power light or heat at all..... :headbash:

Guess it's time to take apart the controller and see if I can find any issues. 🙁

Which capacitors in particular would you be speaking of Kiriakos? This WES51 is only about 1 year old and I haven't even really used it much over the last few months.
 
#9
Its a little over a year old. and I just took it apart so might have voided the warranty.

I've been through the service manual and all the checks check out fine. It have 28vac across the red and yellow wires.

Things I did notice is one small smd diode is reading .048v in both directions on diode check. Pretty sure that shouldn't be. Also when checking resistance between legs 1 and 3 of the BTA12 I only get 70 ohms. Not sure if that should be higher or not.

I'm thinking I should pull the BTA12 and test out of circuit or else just buy another one and def replace that one diode. I'm not sure what diode to order for it though.

Thanks for the help,
 

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#11
I think that diode may actually be an inductor. Bat12 is an SCR. The 8 pin microchip device is likely a microcontroller telling the scr when to fire. You need to reverse engineer the circuit to figure out how it operates to test it. Let me know if you need any resistance or voltage readings from mine.
 
#16
That 8 pin thru hole I.C. in the first pic doesn't seem to be soldered in very well, IMO. Those top traces are depending on the thru hole connection. Maybe some resistance or opens in those connections?

After further review, none of the thru hole connections look good to me.. Cheepskates! Reflow them all and check that pot. It looks like a wire wound and could be intermittent.
 
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#17
It's a pretty small circuit. Looks like a voltage regulator, an op amp and a micro-controller. You should be able to trace the main circuits and figure it out. The regulator likely feeds 5 volts to the micro-controller. The op amp might be buffering the output to trigger the SCR. Did you try resetting the lockout with a magnet?
 
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