Electronics > Projects, Designs, and Technical Stuff
Silicone lead for soldering iron -- recommendations?
werediver:
--- Quote from: Gyro on September 03, 2020, 09:55:04 pm ---I resolved the tip grounding issue on my TS100 by bridging C26 on the PCB (schematic attached). This connects the Tip to the outer barrel of the supply connector.
--- End quote ---
I'd strongly recommend against doing so. This may be suitable for the power supply you are normally using with your TS100 (if you ground the negative DC output), but that renders your TS100 harmfully incompatible with other power supplies, like the cheap 19 VDC bricks often used to power TS100 (I use such more often than not).
The cheap 19 VDC bricks may not use the ground lead internally at all (that was the case with my unit). Due to some capacitive coupling the DC outputs may have half the mains AC on them (capable of supplying only small current via a capacitive divider).
Now, if the circuit you're working with is grounded (intentionally or not), which is a good way to protect it from ESD, you're "powering" it with that high AC voltage via the soldering iron tip, which can easily damage active components.
TS100 tip is normally isolated from the supply lines and should only be directly connected to ground.
werediver:
--- Quote from: ebastler on September 03, 2020, 09:20:02 pm ---@werediver -- nice idea with the ground lead routed through the outer tubing. I need to check whether the notebook supply I have earmarked has a grounded output, and come up with a solution one way or the other.
--- End quote ---
I usually use a cheap 19 VDC brick power supply that came in a bundle together with my TS100. That brick does not use the ground lead internally at all. I had to open it and just use the ground lead to arrange a ground outlet on it (without grounding any of the output DC lines).
TS100 tip is normally isolated from the supply lines and I'd recommend to only connect it directly to ground (well, some people would want a few megaohms of resistance to the ground, but that's not the industry standard).
Gyro:
--- Quote from: werediver on September 04, 2020, 07:44:36 am ---
--- Quote from: Gyro on September 03, 2020, 09:55:04 pm ---I resolved the tip grounding issue on my TS100 by bridging C26 on the PCB (schematic attached). This connects the Tip to the outer barrel of the supply connector.
--- End quote ---
I'd strongly recommend against doing so. This may be suitable for the power supply you are normally using with your TS100 (if you ground the negative DC output), but that renders your TS100 harmfully incompatible with other power supplies, like the cheap 19 VDC bricks often used to power TS100 (I use such more often than not).
The cheap 19 VDC bricks may not use the ground lead internally at all (that was the case with my unit). Due to some capacitive coupling the DC outputs may have half the mains AC on them (capable of supplying only small current via a capacitive divider).
Now, if the circuit you're working with is grounded (intentionally or not), which is a good way to protect it from ESD, you're "powering" it with that high AC voltage via the soldering iron tip, which can easily damage active components.
TS100 tip is normally isolated from the supply lines and should only be directly connected to ground.
--- End quote ---
Yes, I am well aware of Y cap current leakage - I would (and did) only use a grounded negative, decent quality PSU, an old IBM/Lenovo in my case. Second-hand high quality brand laptop bricks on ebay are almost always preferable to the cheap no-name stuff with dubious safety clearances that is sold these days. I avoid them unless I can internally inspect them for quality and layout. With a grounded output PSU, bridging C26 is a convenient way of being able to quickly plug and unplug without having to undo the grounding screw - useful in my case where I seem to quite often switch between mains brick and battery pack. As I said previously, your implementation will result in a lower noise tip ground, even with a grounded output PSU.
You're right, I should have made that clear for less experienced readers, however ebastler is aware of the potential Y cap leakage issue. Some have actually reported stability issues then running the TS100 with particularly leaky / noisy floating output PSUs and a separately grounded tip... https://www.eevblog.com/forum/reviews/ts100-doesn_t-function-properly-when-earthed/
werediver:
--- Quote from: Gyro on September 04, 2020, 09:49:25 am ---Some have actually reported stability issues then running the TS100 with particularly leaky / noisy floating output PSUs and a separately grounded tip... https://www.eevblog.com/forum/reviews/ts100-doesn_t-function-properly-when-earthed/
--- End quote ---
That's curious, thank you for mentioning. Luckily, I have no such issues with my setup either because of a better grounding, or because of a less noisy / leaky supply. Still, good to be aware of a potential fault mode of the tool I use.
NiHaoMike:
Instead of jumpering across the capacitor, add a 100k-1M resistor in parallel.
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