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Cool Tools: Desoldering Station - 110V - Review

Scoring

Product Performed to Expectations: 10
Specifications were sufficient to design with: 10
Demo Software was of good quality: 10
Product was easy to use: 8
Support materials were available: 8
The price to performance ratio was good: 10
TotalScore: 56 / 60
  • RoadTest: Cool Tools: Desoldering Station - 110V
  • Evaluation Type: Workshop Tools
  • Was everything in the box required?: Yes
  • Comparable Products/Other parts you considered: Aoyue 474A++, Hakko 32TU99
  • What were the biggest problems encountered?: The manual is not of very good quality, and is missing important use and care information.

  • Detailed Review:

    ABSTRACT

     

    The Tenma 21-19700 desoldering station is a quality tool, and a good value. It can’t do everything, but it excels at the tasks it can handle. The manual leaves a lot to be desired, and is probably the weakest part of the package.

     

    FIRST IMPRESSIONS

     

    The station arrived packed in a single plain brown carton. The carton wasn’t particularly heavy cardboard, was crushed at the corners, and was ripped at one corner. Sturdier cardboard would seem to be in order for the outer carton. The peripheral parts and accessories were packed in plastic bags inside the main carton, while the base unit was inside a plastic bag and surrounded by two additional molded cardboard trays. The manual was inside the carton as well.

    Opened carton

     

    The accessory pouch was nice to have, and includes a cleaning tool, a small hand drill for really tough cleaning jobs, a tube of silicone grease, and an assortment of spare parts: six filter sponges, one spring, one filter barrel cap, and two desoldering nozzles. Part numbers for the spares are not indicated in the manual, but some do appear listed at the bottom of the product page on newark.com.

     

    The manual is not very good; it includes pictures of all the parts and some useful exploded-view diagrams, but it is decidedly lacking in important details. For example, the indicator light on the front is on constantly when the unit is heating up to the target temperature, then starts flashing when the unit achieves the target temperature. I know this because I observed the behavior of the unit while testing it, but this fact does not appear anywhere in the manual. There is no indication in the manual of what temperature ranges correspond to the numerical settings printed around the front-panel knob. The cleaning instructions are a helpful start, but they are incomplete. The instructions do not indicate what the user should do with the included silicone grease; I deduced eventually that it is best suited to application on the inside tip of the filter spring.

    All package contents

     

    The construction of the unit seems sturdy. There is a screw on the bottom that must be removed prior to use (it secures the pump during shipping); this fact is mentioned in the manual, and again on a sticker that covers the IEC power cord inlet. The electrical cable and vacuum line running between the handpiece and the base unit are bundled together into a harness using small plastic clips. Both the vacuum tubing and the wire insulation are heat resistant, displaying no melting, warping, or discoloration after being touched with the heated tip of the desoldering tool.

     

    TESTING - First set

     

    Materials: Wire (14ga and 24ga stranded), 60/40 solder, FR4 scrap, 2-layer and 4-layer PCBs, various passive components

     

    Conditions: The heating control on the front of the 21-19700 was set to ‘6.’ The tip attained a temperature of 400°F after heating for one minute.

     

    Test 0: Remove installed parts from PCB

     

    The station performed extremely well, removing five potentiometers having six pins each (two of which were kinked press-fit structural support pins) in about five minutes from switch-on to completion. For each pin, about five seconds of heat-up time were followed by two to three seconds of vacuum time. Kinked structural pins required two passes. The components released with only slight additional heating to the structural pins.

     

    Front of PCB before potentiometer removal

    Back of PCB before potentiometer removal

    Front of PCB after potentiometer removal

    Back of PCB after potentiometer removal

     

    Test 1: Remove solder from ground plane

     

    The station performed fairly well, removing most of the solder in three tries. About five seconds of heat-up time were followed by about three seconds of vacuum time during each try. The copper at the center of the soldered patch has wrinkled/torn some, suggesting that the copper is pulling away from the substrate.

    FR4 before solder removal

    FR4 after solder removal

     

    Test 2: Remove solder from filled PCB through holes

     

    The station performed well removing solder from filled holes in both the two-layer (green) and four-layer (blue) PCBs. About five seconds of heat-up time were followed by about five seconds of vacuum time, then the board was flipped and the process repeated.

    2-layer PCB with filled through hole

    2-layer PCB with cleared through hole

    4-layer PCB with filled through hole

    4-layer PCB with cleared through hole

     

    Test 3: Remove soldered-in through hole components from PCBs

     

    The station was able to release the 1/8W resistor from the four-layer PCB with an assist from some tweezers, but the large copper pours attached to the holes on the two-layer PCB proved to be too much for the station to handle. About five seconds of heat-up time were followed by about five seconds of vacuum time.

    2-layer PCB with resistor attached top before

    2-layer PCB with resistor attached bottom after

    4-layer PCB with resistor attached top before

    4-layer PCB with resistor removed bottom after

     

    Test 4: Remove soldered-in through hole component from milled FR4 blank

     

    The station was able to remove a 1/4W resistor from the milled blank without removing the very small traces from the substrate. About three seconds of heat-up time were followed by about two seconds of vacuum time. The component released with only slight additional heating to each leg.

    FR4 before resistor removal

    FR4 after resistor removal

     

    Test 5: Remove SMD component from PCB

     

    The station technically removed the 0603 resistor, but the resistor became lodged in the opening of the desoldering tool tip and had to be removed with tweezers. About two seconds of heat-up time were followed by about two seconds of vacuum time; this process was repeated twice on each side of the component. Removing small SMD parts is not a practical application for this tool.

    4-layer PCB with removed SMD resistor

     

    Test 6: Remove wire leads soldered to PCBs

     

    The station performed extremely well releasing 24ga wires soldered to both two-layer and four-layer PCBs. About three seconds of heat-up time were followed by about two seconds of vacuum time.

    2-layer PCB with wire attached top

    2-layer PCB with wire attached bottom

    2-layer PCB with wire removed

    4-layer PCB with wire attached top

    4-layer PCB with wire attached bottom

    4-layer PCB with wire removed

     

    Test 7: Remove wire soldered to connector pin

     

    The station performed extremely well removing a 24ga wire from the post of a JST 5-pin connector. About one second of heat-up time was followed by about one second of vacuum time. The plastic housing of the connector did not warp, melt, or discolor. The pin remains firmly affixed within the connector.

    Wire soldered to JST connector

    Wire removed from JST connector

     

     

    Test 8: Remove wire soldered directly to through hole LED leg

     

    The station performed extremely well removing a 24ga wire from the leg of a yellow 5mm LED. About one second of heat-up time was followed by about one second of vacuum time. The plastic housing of the LED did not warp, melt, or discolor. The diode remains intact, and illuminates as expected.

    LED with wire attached

    LED illuminated after wire removal

     

    Test 9: Remove cold solder joint from PCB/component interface

     

    The station performed extremely well repairing a cold solder joint from the interface between a PCB and a 1/4W resistor. About two seconds of heat-up time were followed by about one second of vacuum time. In addition to removing the cold joint, the remaining solder flowed around the pad and component lead to form a much better joint.

    Cold solder joint before

    Cold solder joint after

     

    Test 10: Disassemble two wires soldered together (24ga)

     

    The station performed extremely well releasing two 24ga wires soldered to one another. About one second of heat-up time was followed by about two seconds of vacuum time.

    24ga wires soldered

    24ga wires separated

     

    Test 11: Disassemble two wires soldered together (14ga)

     

    The station performed acceptably releasing two 14ga wires soldered to one another. About five seconds of heat-up time were followed by about three seconds of vacuum time. This process was repeated twice, once on the exposed end of each of the wires, removing the majority of the excess solder. Slight additional heating was required to release the wires from one another.

    14ga wires soldered

    14ga wires separated

     

    TESTING - Second set

     

    Materials: 60/40 solder, 2-layer and 4-layer PCBs, various passive components

     

    Conditions: The heating control on the front of the 21-19700 was set to ‘8.’ The tip attained a temperature of 460°F after heating for one and a half minutes.

     

    Test 12: Remove soldered-in through hole components from PCBs

     

    The station was able to release the 1/8W resistor from the four-layer PCB with an assist from some tweezers, but the large copper pours attached to the holes on the two-layer PCB were still difficult for the station to handle. The station was able to free one leg of the 1/8W resistor, but I had to resort to coaxing the other leg out by applying additional heat with a soldering iron. About five seconds of heat-up time were followed by about five seconds of vacuum time. This procedure was repeated twice on each leg for the four-layer PCB, and thrice on each leg for the two-layer PCB.

    2-layer PCB with resistor attached bottom before set 2

    2-layer PCB with resistor removed bottom after set 2

    4-layer PCB with resistor attached bottom before set 2

    4-layer PCB with resistor removed bottom after set 2

     

    USE NOTES

     

    The 21-19700 desoldering station is fairly easy to use. The main pitfall awaiting the unprepared is the tendency of the tool to clog. Using proper technique helps immensely with this problem; you should continue to keep the trigger depressed for a second or so after you remove the tool from the work to ensure that all solder has been pulled into the chamber and none remains in the nozzle (Thanks to user mcb1 for the tip in the comments!) There is an indicator on the side of the handpiece that changes from blue to red (only when the trigger is depressed) that indicates a clogged tool. The provided cleaning pin works well to clean the nozzle, which should be done while the tool is hot. After the tool has cooled, it can be disassembled for further cleaning. The spring filter tends to clog; accumulated solder sometimes forms a mass inside the point of the spring, with a small protrusion sticking through to the other side. The easiest way to remove such a mass is to apply heat to the protrusion outside the tip of the spring with a soldering iron while the spring is upright on a heat-resistant surface; the rest of the mass will fall out of the spring. Once the inside tip of the spring filter is clear of solder, apply the included silicone grease to the inside of the spring tip using a q-tip or similar application tool.

    Tool disassembled for cleaning

    Tool with vacuum chamber removed

     

    Final Thoughts

     

    The 21-19700 desoldering station is a simple tool the performs its function well at a reasonable price. It performs far better than similar tools I've used from well-known brands in the solder/rework tool space in some tasks, and though the manual does not give as much information or instruction as it should, the tool is simple enough that one can learn how to use it well fairly quickly.


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