Hello,
I bought a couple of these on/off switches:
I use one in an amplifier build as on/off switch. I wire the hot wire from the 220V mains to this switch. After a couple of on/off cycles, the switch breaks and remains 'on' regardless of its position (there is current flowing even when the switch is on 'off' position). Now this might be a single defective switch, but I have replaced it 3 times already and every time the same problem occurs - after a couple of cycles, the switch remains always 'on'.
Am I using this switch correctly?
Is is due to a bad batch of switches?
I bought a couple of these on/off switches:
I use one in an amplifier build as on/off switch. I wire the hot wire from the 220V mains to this switch. After a couple of on/off cycles, the switch breaks and remains 'on' regardless of its position (there is current flowing even when the switch is on 'off' position). Now this might be a single defective switch, but I have replaced it 3 times already and every time the same problem occurs - after a couple of cycles, the switch remains always 'on'.
Am I using this switch correctly?
Is is due to a bad batch of switches?
It must be a piece of junk. This can be very dangerous.
Throw away any remaining of those switches and buy something different.
Throw away any remaining of those switches and buy something different.
I have been using the same switches (from parts express)
never failed
but I hate those screw wire contacts, always gets loose, so I solder the wire on it
never failed
but I hate those screw wire contacts, always gets loose, so I solder the wire on it
Even with a legitimate product, there might be issues related to the type of load: typically, some types of high-inrush loads will weld together some contact materials.
When a detailed datasheet is available, you can figure out the best contact option for a given duty (AC1, etc.)
When a detailed datasheet is available, you can figure out the best contact option for a given duty (AC1, etc.)
How much capacitance in the power supply? How much DC voltage?
What's the DC resistance in the circuit to the capacitors including the transformer?
I agree; a switch rated for 250V probably should withstand that. Nevertheless, one version of that switch had a 15A limit, which could easily be exceeded when closing the contacts.
I have an (admittedly old) switch from a Carver receiver, and it has a film capacitor (Panasonic 1uF? .1uF?) soldered to the switch terminals, effectively in parallel with the switch. Perhaps that would help soften the blow when the switch is flipped.
Kind regards,
Drew
I have an (admittedly old) switch from a Carver receiver, and it has a film capacitor (Panasonic 1uF? .1uF?) soldered to the switch terminals, effectively in parallel with the switch. Perhaps that would help soften the blow when the switch is flipped.
Kind regards,
Drew
Wire a snubber capacitor (an X2 rated part) across the switch contacts... and you'll probably find they last longer. The problem will be arcing when the switch is toggled, due to the inductive load of the transformer primary coupled with the high inrush current of the supply capacitors charging.
I don´t think you have an electrical problem but a mechanical one, suspect you are overtightening the mounting nut.
That is a 15A switch!!!!! and you are NOT turning ON-OFF, say, a 15 HP motor in an elevator or a similar brutal load.
And solder those wires, avoid those terminal screws like the pest they are.
That, or yours belong to a very poorly assembled batch.
That is a 15A switch!!!!! and you are NOT turning ON-OFF, say, a 15 HP motor in an elevator or a similar brutal load.
And solder those wires, avoid those terminal screws like the pest they are.
That, or yours belong to a very poorly assembled batch.
Possibly Chinese, and those may be wildly rated, don't trust them more than 3 Amps.
Buy a good brand, solder (or use crimped lugs), the wires, and put a snubber.
MOVs work as snubbers too.
I leave my amps on, and use the wall switch, find it easier than having to wear out odd switches (hard to get) and hard to replace.
5A ordinary wall switch, no issues so far. Feeds a multi socket box.
Computer, monitor, amp, all together, pulling a little over 1 A in total...well below max. rating.
Buy a good brand, solder (or use crimped lugs), the wires, and put a snubber.
MOVs work as snubbers too.
I leave my amps on, and use the wall switch, find it easier than having to wear out odd switches (hard to get) and hard to replace.
5A ordinary wall switch, no issues so far. Feeds a multi socket box.
Computer, monitor, amp, all together, pulling a little over 1 A in total...well below max. rating.
IF SMPS powered, which I am most certain you have, turning that unprotected unsnubbered wall switch will create quite the spark.
While built-in SMPS power switches expect that and are snubbered , MOVed, etc. at Factory.
While built-in SMPS power switches expect that and are snubbered , MOVed, etc. at Factory.
The fact is.... most DIY'ers do not have the education or experience in order to do a properly designed project.
Lacking the important fundamentals is like driving a car blindfolded.
Lacking the important fundamentals is like driving a car blindfolded.
I've seen a data sheet for similar looking switches (which give no clue to inductive load ratings) but they do mention that the body of the switch must be (and their words) 'Compulsorily Grounded'.
There are only two possibilities really.
1/ The switch is unsuitable for the load you are trying to switch. Failure within 2 on/off cycles that you mention suggest something else. A 15A switch should survive switching pretty much anything we discuss in these pages for many more cycles than that, even if it is unsuitable.
2/ The switch is not what it appears in terms of quality and/or is a fake.
What are you switching with it?
There are only two possibilities really.
1/ The switch is unsuitable for the load you are trying to switch. Failure within 2 on/off cycles that you mention suggest something else. A 15A switch should survive switching pretty much anything we discuss in these pages for many more cycles than that, even if it is unsuitable.
2/ The switch is not what it appears in terms of quality and/or is a fake.
What are you switching with it?
I put a 275V / 20 mm MOV across my house mains supply. Phase to Neutral, years ago.
My entire house is snubbered, I have found less arcing wear on everything in the house.
🙂
The extension board for the PC / monitor / amp has a smaller 14 mm MOV in it as well.
The PC SMPS does have NTC, and only some units of those have the snubbers, most have links for reasons of cost cutting.
So I did my own work around for the problem.
What power switch?
That is just a 5V standby to ground triggered from front panel momentary action switch, and that starts the SMPS, shut down can be as usual by OS or pressing the same button for a few seconds.
The power cord is direct, most SMPS do not have a switch, that went out of the computers in the Pentium III era in 2002 or so.
Front panel main switch also went with the PC-XT supply, the PC-AT supplies do not nave it.
I have to first start the mains supply to the board, from the wall switch, then press the Power button on my PC, and that starts the machine.
So there is no switch on/off (load) arc, the SMPS starts when I tell it to.
Maybe you were thinking of something else when you posted.
My entire house is snubbered, I have found less arcing wear on everything in the house.
🙂
The extension board for the PC / monitor / amp has a smaller 14 mm MOV in it as well.
The PC SMPS does have NTC, and only some units of those have the snubbers, most have links for reasons of cost cutting.
So I did my own work around for the problem.
What power switch?
That is just a 5V standby to ground triggered from front panel momentary action switch, and that starts the SMPS, shut down can be as usual by OS or pressing the same button for a few seconds.
The power cord is direct, most SMPS do not have a switch, that went out of the computers in the Pentium III era in 2002 or so.
Front panel main switch also went with the PC-XT supply, the PC-AT supplies do not nave it.
I have to first start the mains supply to the board, from the wall switch, then press the Power button on my PC, and that starts the machine.
So there is no switch on/off (load) arc, the SMPS starts when I tell it to.
Maybe you were thinking of something else when you posted.
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I've had a batch of cheap miniature switches that were junk - guess what, from eBay... They jammed or felt rough and half of them were quickly completely broken. Absolutely no quality control...
And all this, as well as many other products, is the result of outsourcing of course.
Junk IMO.
I have had similar issues with a China hot-air blower. The blower itself is still (somehow) functional but the ON/OFF switch has been changed multiple times. I guess this is due to the inductive kickback that happens while turning off.
However, if the quality control is so bad, then touching the metallic rocker to operate the switch could even become a safety issue, as both terminals would be live as the switch is always conducting current.
I wouldn't recommend any snubber / capacitor / MOV etc. as these would increase the off-state leakage of the switch. If the load is heavy, use an MCB for ON/OFF, as has been done in the equipment (picture) below.
https://5.imimg.com/data5/SELLER/De...1691329/dc-regulated-power-supply-500x500.png
However, if the quality control is so bad, then touching the metallic rocker to operate the switch could even become a safety issue, as both terminals would be live as the switch is always conducting current.
I wouldn't recommend any snubber / capacitor / MOV etc. as these would increase the off-state leakage of the switch. If the load is heavy, use an MCB for ON/OFF, as has been done in the equipment (picture) below.
https://5.imimg.com/data5/SELLER/De...1691329/dc-regulated-power-supply-500x500.png
I disassembled one of the defective switches and did not find any visible trace of welding on the contacts at least.
As member JMFahey guessed, there is indeed a 300W SMPS power supply connected (and a 3e TPA3255 amplifier board downstream).
I placed another similar switch from another batch and made sure the nut was not overtightened. It's still working so far but I am definitely looking into either snubbering properly that switch after reading all your comments.
Would an MCB in this case satisfy the snubbering requirements of the SMPS power supply?
Thank you all for sharing your knowledge and experience on this topic so far, it has been a very educative read.
As member JMFahey guessed, there is indeed a 300W SMPS power supply connected (and a 3e TPA3255 amplifier board downstream).
I placed another similar switch from another batch and made sure the nut was not overtightened. It's still working so far but I am definitely looking into either snubbering properly that switch after reading all your comments.
Would an MCB in this case satisfy the snubbering requirements of the SMPS power supply?
Thank you all for sharing your knowledge and experience on this topic so far, it has been a very educative read.