FNIRSI DWS-200 - Page 1
Forum section: electronics / general

author: Electro Fan
author_rank: Super Contributor
timestamp: December 25, 2024, 11:12:09 pm
content: FNIRSI DWS-200Recent review; not super extensive (doesn't answer all the usual questions) but the product looks like it has potential.review:company product info:https://www.fnirsi.com/products/dws-200Looks like several reviews out there… more info:And another:

author: Hydrawerk
author_rank: Super Contributor
timestamp: December 26, 2024, 12:37:12 am
content: Not compatible with original JBC handpieces.

author: thm_w
author_rank: Super Contributor
timestamp: December 27, 2024, 08:37:12 pm
content: https://www.eevblog.com/forum/reviews/fnirsi-dws-200-200w-doubt/Quotehttps://www.reddit.com/r/soldering/comments/1fjrdtc/fnirsi_dws200_f245/

author: Electro Fan
author_rank: Super Contributor
timestamp: December 27, 2024, 11:43:24 pm
content: What are the best test procedures to determine if a soldering station is properly wired so as to avoid resistance, leakage, grounding issues, etc.? Any step by step test procedures published anywhere? Thx

author: thm_w
author_rank: Super Contributor
timestamp: December 27, 2024, 11:58:49 pm
content: Measure tip resistance to earth of power socket on station.Measure AC voltage on tip wrt earth with iron powered on.Can check the power lead and power socket outlet is properly earthed while you are at it.https://www.esda.org/assets/News/OpenForumHandtoolsPrass08-1.pdfhttps://www.descoindustries.com/pdf/TB-4011.pdf

author: das_strobel
author_rank: Contributor
timestamp: January 09, 2025, 02:55:10 pm
content: Youtuber Defpom (who is also active in this forum if I'm not mistaken) has done the modification to earth the tip:https://youtu.be/EZl3pdQ2PIoEven the solder pads are there. The space is just empty.I just received this station yesterday and I like it very much. I didn't do the modification yet. What do the experts that are around here think?

author: thm_w
author_rank: Super Contributor
timestamp: January 09, 2025, 10:23:20 pm
content: Quote from: das_strobel on January 09, 2025, 02:55:10 pmDo the modification unless you like soldering parts and not being sure if they will work after the fact.

author: ExaLab
author_rank: Regular Contributor
timestamp: April 22, 2025, 05:37:07 pm
content: This soldering station can irreparably damage most devices sensitive to static charges (and not only...).Suppressing the LF ac component (at 50 or 60Hz) conducted to the soldering tip by the SMPS transformer bridge capacitance (and the EMI capacitor in parallel to it) might not be enough.Below, some suggestions on how I limited (by more than 10dB) all the HF components as well:1. Input PE Decoupling/Limiting ResistorInput Power Earth has been decoupled with a 330Ω 2W metal film wired resistor. It has been connected to the -24V reference of the power supply.Purpose of this resistor (which as general rule should be zero) is to limit the stilus current in case the tip accidentally comes into contact with a live component.This will avoid damage to the soldering station.A secondimportant role of this resistoris to limit the pulse current injected by the tip of the stylus when it comes into contact with components related to GND. In fact, the high currents injected to the tip for its heating cause a potential imbalance of about 1.5 volts between the tip and the reference ground. The 330Ω resistor will limit this current to a maximum of 4.5mA.In parallel to this main resistor is placed an auxiliary 220kΩ 0.25W resistor. It is used to ensure adequate temporary control of the tip potential in case the 330 ohm resistor were to be damaged.2. Shielding of the Flyback TransformerA lot of the HF electric noise found at the tip of the soldering iron is mainly due to the magnetic fields radiated by the flyback transformer (which is located very close to the main board).The transformer was shielded with a short-circuited copper strip overlapping the winding.In addition, a copper strip was inserted along the entire perimeter surface of the same.Both shields were connected to the -24V output reference of the power supply.3. 25μH Common Mode InductorTo limit the Common Mode Noise a 25μH inductor was inserted between the power supply board and the main board.4. Equipotential Bonding ConnectorIn order to minimize the noise residues present on the tip of the stylus, a connector dedicated to the equalization of potentials has been made available. The same is electrically connected to the reference ground of the main board through a 1 kΩ decoupling resistor.Also in this case, the purpose of this resistor is to limit to about 1.5mA the current peaks injected by the tip if it is accidentally placed in contact with this equipotential reference.Therefore, if required, to minimize the induced noise, instead to a direct PE bonding use this connector to equalize the potential of the work reference plane.The table below summarizes the results obtained.Notes:• TIP Peak Voltage: very short peak pulses @26kHz (SMPS frequency)• TIP Style: 245 (very similar results for the 210 TIP)• High Energy Peak Voltage: refers to the voltage drop caused by the current flowing through the stylus lead (peaks of about 7 - 8A across a 150 - 190mΩwiring resistance)• High Energy SC Peak Current: refers to the short circuit current due to the 1.5V Peak Voltage. The related current with respect GND is limited by the 330ΩInput Ground Resistor. The Equipotential Bonding Current is limited by the 1KΩ decoupling resistor.

author: lyzanxia
author_rank: Newbie
timestamp: September 30, 2025, 05:33:19 am
content: Sorry for the stupid question, but this all is in addition to bridging the two empty pad's which will ground the tip?Do you maybe have a picture of the 2 resistors connected in parallel for point1?

author: ExaLab
author_rank: Regular Contributor
timestamp: October 02, 2025, 01:47:32 pm
content: Sorry, I don't have an image.If you look closely at the fourth photo, you can see the 330 ohm resistor arranged vertically on the component side (it's wrapped in black heat-shrink tubing).The 220kΩ safety resistor is located on the solder side...For more clarity on the connection method, refer to the drawing below.