STAR LU3204-00 low cost digital soldering station – review and teardown
This station is a low cost (about 50 euros) digital soldering station.
It was bought when we had to set-up one additional workbench for a visiting engineer, and now it stays in my home lab.
It's a Chinese OEM product, that I've seen sold under different brands and case color.
Mine is black , labeled STAR electronics (Italy), model LU3204-00, but in the UK you can buy it from Maplin, model N16CH:
http://www.maplin.co.uk/48w-lcd-display-solder-station-98133A similar model (with the same display and electronic, but without presets, is sold by Velleman :
http://www.vellemanusa.com/us/enu/product/view/?id=522851and by others (RS sells one with it's label for a very higher price).
Once I found the manufacturer, a reputable Chinese company, but I've lost the name and the site's address.
The station body is rather small, fitted with anti-slip feet, and has a clear LCD display (12 mm digits) showing both actual and set temperatures, complete with operation indicators:
HEAT when heating, WAIT if temperature is some degree lower or higher than the set point, °C or °F.
The mains cable is fixed to the unit, and the exit is not on the rear, but on left side, making it really uncomfortable on the bench, so I promptly opened the case and installed an IEC power inlet on the rear and, at the same time, wired a green power ON LED (you can see two red/black wires in the photos) because you can tell the station is on only by looking at the LCD, and after the first day of use I forget it on for one week…
(I believe having seen a similar one with an illuminated LCD, but I'm not sure)
Actual use is really intuitive: a button for C/F selection, two buttons (UP and DOWN) to change the set-point, three (almost un-useful) buttons for preset temperatures (200 – 300 - 400 °C).
There is an internal buzzer that alerts if the unit is switched on without a stylus connected, but remains silent if the heater is open…
The stylus is a 48W, low voltage (24V), not too big and really comfortable to hold. The cable is about 110 cm long, rather flexible (it's shorter and stiffer than my Weller's, but the price is about 70% lower).
The supplied tip is a conical one, rather small, but other tips are available, at about 3-4 euro a piece. The tip is made of magnetic metal (maybe iron) coated with a grayish finish and with a tinned point.
The heater of the supplied stylus died after about 2 weeks, and I discovered that the heater was a special order spare part (at least for my supplier) , but I got a new stylus for about 10 euros.
Removing the tip of the first stylus showed a cylindrical "gasket" made of sheet metal, and a lot of metallic "dust" that was released by the tip (see photo).
Don't know, but I fear that these tips will have a very short life, by corroding themselves from the inside.
The stylus holder "feel" was "cheap": made from plastic, with only a sheet metal shield to protect the hot stylus, it was sliding all over the bench top, making difficult to insert the stylus.
I could have changed it with another, but decided to modify it adding an U-shaped piece of aluminum riveted to the underside, fitted with 4 anti-slip feet.
When I disassembled the main unit, I checked the wiring, and found it to be neat, well made and complying with safety regulations.
Tip and stylus connector are grounded to the mains cable ground.
There is a fuse holder on the rear panel.
The power transformer is of adequate size, incorporating a thermal fuse, and does not becomes too hot in actual use.
The controller board is dual side, using mostly SMD parts.
The bigger chip is one HOLTEK HT1621B (LCD driver)
Next to it one ATMEL AT89C2051 8 bit microcontroller, and the smaller two are one ATMEL 24C024 (I believe it's an EEPROM, but I'm not sure: could not find it in ATMEL site), and one LM358 dual op-amp.
The board shows some signs of "afterthought", like a tantalum cap added "on the air".
In use, the low power of the stylus was detected only at first start-up, needing about 65 seconds to reach 300 °C. A moderate (10 °C) overshoot was noted, but only at start-up.
The tip temperature was displayed accurately, with only 3-4 °C of error, but only at steady state. The sensor is far form the tip, so you can cool the tip (by touching the wet sponge), and the real temp is shown decreasing only after many seconds of delay.
I don't understand why the temperature control algorithm is limited to a simple ON/OFF: with that microcontroller it is possible to write the code for a more efficient type of control (I don't ask for a PID, but at least a PD).
By summing up: a nice, decently made unit, manufactured to good quality and safety standards, that operates correctly , for it's price.
I tested it in our small production environment, and I found that the productivity (number of good joints per hour that can be made) of this tool is comparable to one of our older Weller units. I could even solder some SMD parts.
For hobby or semi-pro work, it could be a bargain…