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In this video, I test out the new hot air rework station I just got to solder my Mini esp32 S3 boards. I dissect the hot air gun, encountering an Australian plug and a couple of interesting quirks inside the control PCB. I attempt to understand the circuit, welcome your thoughts on the build quality, and then solder on a new, hopefully safer, UK-compliant plug. Post-assembly, I apply way too much solder paste thanks to these tricky solder syringes, before setting the station to 300 degrees C for some hands-on rework. After some trials, I successfully fix some solder bridges with my soldering iron and behold, everything is connected and it works! It's just another blink sketch, but hey, it's confirmed – The new hot air station works!

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[0:00] I ordered a hot air rework station a
[0:02] while back and it’s just arrived I’ve
[0:04] been soldering up some of my Mini esp32
[0:06] S3 boards from PCB way and I’ve been
[0:08] using my mini hot plate but if you
[0:10] watched the previous video you’ll know
[0:12] there are some issues with this as we’ve
[0:14] got components on the bottom of the
[0:15] board so why not try it out with the hot
[0:17] air station I had three recommendations
[0:20] from my fellow makers this one is a bit
[0:22] of a classic and has been covered in
[0:24] detail by eev Block in the past there is
[0:27] a newer version that looks pretty good
[0:28] as well and in hindsight it might have
[0:30] been better as I could have easily
[0:32] swapped this cable for a UK one but in
[0:35] the end I went with this one as
[0:36] everything is integrated into the hot
[0:38] air gun itself let’s see what we’ve
[0:40] actually got in the Box well we’ve got
[0:42] instructions it might actually be worth
[0:45] reading these for a change we’ve got an
[0:47] Australian plug which is interesting I
[0:49] don’t see any sign in the fuse but maybe
[0:51] Australian plugs don’t have them let me
[0:53] know in the comments and we’ve got this
[0:56] very non-uk standards compliant UK
[0:58] adapter the Earth pin should be
[1:00] completely bare with no insulation
[1:02] and we’ve got a spare heating element
[1:05] there’s a bunch of nozzles I’ll have to
[1:07] do some youtubing to understand what
[1:09] these are for
[1:10] let’s get this thing opened up and see
[1:12] what’s inside
[1:14] disassembly is pretty easy we just
[1:16] unscrew this end cap and the device
[1:18] comes apart
[1:19] unscrewing the cable clip gives us good
[1:22] access to the control PCB
[1:24] there’s a couple of things that
[1:25] immediately jump out to me the Earth
[1:27] wire has just been stepped off so I
[1:30] guess our dodgy adapter is completely
[1:32] fine
[1:32] the Live Wire is pretty close to this
[1:34] screw but that might not matter as the
[1:36] screw doesn’t really seem to be
[1:37] connected to anything but it’s something
[1:39] to watch out for when I resolder this
[1:41] I’m also slightly confused by this
[1:43] unpopulated capacitor there seems to be
[1:45] some legs sticking out but I can’t see
[1:47] any component on the other side of the
[1:48] board very curious
[1:50] let’s see what we can work out about the
[1:52] circuit feel free to chip in with a
[1:54] comment if you can add any extra
[1:56] information
[1:57] these two wires are for the fan and are
[1:59] switched by this mjd122 powered
[2:01] Darlington resistor
[2:03] the heating element is connected here
[2:05] and here this white IC here is a ct3041
[2:09] which is a zero Crossing photo track
[2:11] optocoupler
[2:13] so our heating element is driven from
[2:14] domains and the power is controlled by
[2:16] the photo track
[2:18] over here we’ve got what looked like the
[2:19] components of a switch mode power supply
[2:21] flipping the board over this chunky
[2:24] thing is an npn transistor it might be
[2:26] the switch for the switching power
[2:27] supply but I’m not entirely sure I can
[2:29] see an ee prom which means this must be
[2:31] the microcontroller I’m not sure what it
[2:33] is there’s no markings but it feels like
[2:35] a safe bet that’s what it is there is
[2:37] some interesting power control going on
[2:39] as when you plug in the device the
[2:40] control side of things Powers up and
[2:42] then when you turn the switch it starts
[2:44] shooting and blowing air if it’s above
[2:46] 100 degrees C then when you turn it off
[2:48] the fan keeps blowing until it’s cooled
[2:50] down quite a nice safety feature 100
[2:52] degrees will still cause a nasty burn
[2:54] but it hopefully won’t set anything on
[2:56] fire
[2:57] this power electronic stuff is really
[2:58] not my thing so I’ll be interested in
[3:00] what you all think of the build quality
[3:02] there do seem to be lots of slots cut
[3:04] into the board to provide isolation so
[3:06] I’ve desolded the main cable let’s get a
[3:08] new one soldered on
[3:10] the only thing I’m not really happy
[3:12] about is the two wires soldered onto the
[3:14] same pad
[3:15] the cable I’m using has a standard UK
[3:18] compliant plug and it’s got a nice 3 amp
[3:20] fuse so hopefully it’s a bit safer
[3:22] however I’m not sure what to do with the
[3:24] Earth wire I guess ideally it should be
[3:26] connected to the metal part of the gun
[3:28] let me know what you think for now I’ll
[3:30] just tape it off
[3:31] my assembly is pretty straightforward we
[3:34] just screw the PCB back into its place
[3:36] and then clamp the cable down
[3:39] [Music]
[4:19] thank you
[4:34] well that was quite traumatic but we got
[4:36] there in the end
[4:38] now as usual I’ve got way too much
[4:40] solder post on the board I don’t know
[4:42] about you but I find these solder
[4:44] syringes really hard to use maybe I
[4:46] should invest in some of these to get my
[4:47] grip strength up but it’s really
[4:49] difficult to squeeze the post out I’ve
[4:51] set the temperature to 300 degrees C and
[4:54] I’m running with maximum airflow one
[4:56] thing that’s nice is the air is pulled
[4:58] through over the PCB so the component
[5:00] should all be cooled by the airflow I
[5:02] wasn’t sure which nozzle to use so I
[5:04] just picked one that seemed sensible it
[5:07] takes a bit of time but eventually the
[5:08] solder starts to melt and we can go
[5:10] around all the edges of the board
[5:13] [Music]
[5:23] there’s a couple of solder Bridges it’s
[5:25] hard to get this right without a stencil
[5:27] but we can easily fix these with a
[5:28] soldering iron close inspection shows
[5:31] that everything’s folded up and it
[5:32] doesn’t look too bad there’s a few pads
[5:34] where there’s way too much solder but
[5:36] everything is connected and I feel like
[5:38] this should work
[5:44] so does it work of course it does is
[5:47] another blink sketch I’m really sorry
[5:50] foreign
[5:59] [Music]

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Chris Greening


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A collection of slightly mad projects, instructive/educational videos, and generally interesting stuff. Building projects around the Arduino and ESP32 platforms - we'll be exploring AI, Computer Vision, Audio, 3D Printing - it may get a bit eclectic...

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