General > General Technical Chat
DEADLY WIRING FAULT ; Atten 858D+ Hot Air Rework Station
saturation:
I've completed a 'QC' safety inspection, basic circuit analysis and performance test on the 120V unit I received, and I'm impressed it works so well for something so cheap. Once you get the bugs ironed out, its well worth the $63 I paid.
More later, but here are key items.
I've re-viewed Dave's good video. I'm not sure who cloned who, but there are subtle build difference between WEP/Yihua versus Atten, or it could be these are 120V versus 240V models. If you need 120V, you must buy the 120V unit as the heater is mains powered.
Operation principle:
The unit is basically a mains powered hair dryer, with a "light dimmer" style Triac to adjust temperature to the heater, and the speed knob is a variable resistor that just reduces VDC fed to the fan. A uC receives feedback from the heater sensors to maintain output temperature as dialed in.
Here are the key issues:
WEP units have Yihua labeled PCBs, Dave's Atten had Atten labeled PCBs and used a different uC
"120V" units have different transformers, in my case a 110V/50 Hz labeled one
The heater assembly is for 110V
The heater assembly has a temperature sensor than maintains output temperature once dialed in
The handset interface PCB has some exposed parts that were shorted with solder debris when I received mine, I had to clean it up and cover it with liquid insulator
The power switch was connected to the neutral line, I re-routed it to switch the hot line
The heater shroud is grounded, so are all exposed metal parts
The dialed in temperature needs to be calibrated to properly read output in Celsius
saturation:
The mains plug is hard wired using a snap on strain resist then glued to the chassis, this is different from the Atten 858 unit reviewed by Dave.
The glue is weak. Above it is the fuse holder with a plastic bolt. Initially, the insulated heat shrink blue wire was nearly touching the casing of the transformer. It was repositioned as in the photo, also the other end of the fuse block was bent away from the transformer body. The fuse holder wasn't tightened properly so the assembly eventually spun when the fuse was screwed back in, breaking the glue hold that initially held it to chassis. Simply tightening the plastic bold was enough, and I'll add better glue later.
From the 120V, mains wiring, the blue wire is hot to the fuse, with the output wire going directly to the PCB. The yellow wire is grounded to the transformer mount, the brown wire is neutral headed to the switch block. The hot wire and neutral wire has to be rewired for safety reasons.
You can see the transformer is 110V for the 120V market. The color code for the secondary is labeled GRE but the wire is yellow.
The heat gun has its shroud grounded by a high temperature soldered white woven insulated [ probably glass/silica] wire. The heater is wrapped with mica paper and inserted into the shroud. The yellow wire is the reed switch sensor.
The wiring harness interface PCB. The white woven ground wire on the left is connected to the green ground wire on the right. The yellow reed switch wires on the left are grounded on one end and then to a yellow sense wire on the right. Note, the exposed wires with insulation stripped off; these were shorted by solder debris were later cleaned and the exposed wires covered with liquid tape. The clear and grey wire on the right are connected to the neutral line of mains voltage and are connected to the large pair of red wires on the left. Red and blue wires on the left are thermal sensor wires from the heater and are connected to the same color wires on the right. VDC power for the fan is from the black and brown wires from the right.
The heat gun disassembled. Power to the fan is taken from behind the PCB. The mains wires are the solder points to the far right on the PCB, well separated from the VDC and DC sense wires grouped on the left. The nozzles of this unit are bolted to the gun like a clamp, versus Dave's unit had which were simply inserted.
saturation:
I noticed a manual, FWIW, is not available on pdf anywhere on the net. I scanned the English section as png graphics for reduced size.
Last fault I found, the ground connection from the heat gun to the chassis is not connected because of insulation caused by the paint. Paint has to be stripped off on all screw joints so a proper connection can be made. This also is required to make better connections between the top metal cover and the bottom half, where the ground wire is screwed in.
saturation:
858D temperature calibration. Updated data now inline with Hakko's recommendations.
The heat gun was fixed with a helping hand and a 1000 Celsius K-thermocouple fixed 5mm from the nozzle tip with another helping hand, and the angle adjusted for the maximum temperature transfer. Per Hakko, this produces a fairly cosistent temperature in the 'sweet spot' and minimizes variation of temperature with air speeds.
858 8 5
LED speed speed
120 120 121
150 148 146
200 203 202
300 310 315
400 412 420
480 494 493
858 LED = readout of unit in Celsius
8 speed = #8 fan speed temp in oC
5 speed = #5 fan speed temp in oC
http://www.hakkousa.com/kb/Article.aspx?id=10340&cNode=0T3N5T
SimonIremonger:
I found, indeed, that the casing was not grounded anywhere! Same problem with paint all over the place.
Also, the mains plug didn't comply with BS1363 (shrouded earth pin!) and contained 13A fuse, highly inappropriate for the very thin bundle of strands in the cable...
I changed cables, scraped off paint all of those spots, and added a ground tab using the transformer's connection to the casing, directly to the earth pin on the inlet.
Initial looking at the circuit board suggests, also, that little attention is paid to isolating low and high voltages anywhere. Had anybody noticed this?
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version