Bought the Fnirsi DWS 200 soldering station. Safe to use although not grounded? - Page 1
Forum section: electronics / beginners

author: shyney
author_rank: Newbie
timestamp: August 31, 2025, 08:01:03 pm
content: I just bought my second soldering station after seeing all the positive reviews on YouTube. Previously, I was using the XYTronic LF-1600 (80W) and occasionally the TS100 soldering iron. I wanted something more powerful.However, I later realized that one review mentioned the soldering tip is not grounded, which could potentially damage electronic components.I'm not an expert in soldering, so I didn’t know that having a grounded station is important. I mainly use my soldering station for electronics repair, such as console chip mod installations, mouse switch replacements, and quadcopter builds (soldering motors to ESCs and receivers to the flight controller, etc.).Is it still safe to use the DWS 200 for the purposes mentioned above, or am I risking damage to any components?

author: Ian.M
author_rank: Super Contributor
timestamp: August 31, 2025, 08:48:40 pm
content: My experience is ungrounded tip solder stations with SMPSUs frequently destroy ESD sensitive components due to their Y capacitor leakage current. Fortunately its trivial to mod this one to ground the tip. See:https://www.eevblog.com/forum/reviews/fnirsi-dws-200/https://www.elektormagazine.com/review/fnirsi-dws-200-soldering-station-review

author: shyney
author_rank: Newbie
timestamp: September 01, 2025, 10:34:48 am
content: Quote from: Ian.M on August 31, 2025, 08:48:40 pmI'm a bit confused because everyone seems to be saying something different about what should be done. Some say you should simply bridge the ground pads with solder, others suggest placing a 2 Ohm or 0 Ohm resistor between them, and yet others recommend using a 1.2 MOhm resistor. Additionally, some people write that if you bridge the ground pads, the thermocouple in the soldering tip no longer works properly and the temperature control constantly overshoots the setpoint. And in the last post from your link, there's a modification described that, as a beginner, I don't even fully understand—it seems quite complex:https://www.eevblog.com/forum/reviews/fnirsi-dws-200/msg5889598/#msg5889598So I'm really confused about what I should do to avoid damaging any components.

author: Ian.M
author_rank: Super Contributor
timestamp: September 01, 2025, 02:22:36 pm
content: First I must state that I don't have this station and nor would I buy one due to the reported issues.The problem is the station and iron have no provision for directly grounding the tip, and the very high heating current when the tip cartridge heater is active causes significant voltage drop across the low-side power return wire in the iron's cord, so if you mod the power supply board to link the pads next to the the ground wire to ground the 0V rail, you've now replaced blowing components due to the Y capacitor leakage current with failure to regulate temperature while the tip is in contact with a grounded part, + grossly excessive injection current to any silicon junction. e.g. at 200W heater power, with a 24V PSU the heater element must draw 8.3A, and even 0.1 ohm of resistance in the iron cord and connector will cause the tip voltage with respect to the 0V rail to considerably exceed the approx 0.7V of a forward biassed silicon PN junction, so risking literally blowing traces off a grounded board by diverting this return current round a ground loop!As such, if you aren't comfortable modding it and/or if the constraint that even after modding, any board or wiring you work on must be fully disconnected, so it is isolated from ground, before using this station to solder on it causes you concern, I would raise a case with the seller that its lack of tip grounding (to comply with commonly accepted industry standards, i.e. ANSI/ESD STM13.1-2000) renders it unfit for purpose, so it should be returned for a full refund.

author: shyney
author_rank: Newbie
timestamp: September 01, 2025, 02:35:54 pm
content: Quote from: Ian.M on September 01, 2025, 02:22:36 pmSo if I bridge the two pins it should be safe to solder to sensitive components like mosfets etc. but I should never solder to something that is connected to mains ground if I understand you correctly? This would fit my purpose since I will never solder to something that is powered or connected to mains ground.

author: Ian.M
author_rank: Super Contributor
timestamp: September 01, 2025, 02:45:30 pm
content: Basically yes, but remember this means you need to *FULLY* disconnect a board before working on it. e.g. you cant safely solder anything inside a PC case unless you fully disconnect all cables to it, and you cant leave your scope probes or other test equipment connected to a board while you quickly change a component. If you think this is ever going to be a problem, return it *NOW*!

author: shyney
author_rank: Newbie
timestamp: September 08, 2025, 07:08:04 pm
content: Thank you very much for all your explanation. I decided to return the station and with the help of you explanations I was able to convince the seller to return it. (official fnirsi store). They also said that they will pass all information to the engineering department although I doubt that they will improve anything in future products.Can you recommend a good soldering station with no voltage leak that has a good variety of soldering tips for normal work and also for smaller smd components that can be purchased for a reasonable price?