I have 2 of these PSUs in a chassis , each powering a channel of Abraxalito' s class D amp.
Stacked on top for packaging. I initially removed the cover from the lower one for air flow and cooling reasons. Not that they get particularly hot.
Been fine for a couple weeks then came to switch it on ( mains switched with a latching push button) recently and got a healthy pop from inside the case. Couldn't really tell what, but it all seemed to be working. It's done it a few more times and got to a point where the switch wouldn't switch it off so I assumed something in the inrush had fused the switch shut.
Thought I better had look into this and have just taken the lid off, and off the offending PSU. It would seem to have eaten up the ICL on what I assume is the main 240v in. Not exactly a big load from this class D amp. And the switch seems to have 'recovered'!
Any thoughts on this?. Shall I just replace it? What sort of value and do I uprate it.? It all still works but a shower of sparks on start up isn't so family friendly! The PSU states 100 to 240vac and I'm pretty sure I'm around 245 a lot of the time, but I doubt this is the cause.
Stacked on top for packaging. I initially removed the cover from the lower one for air flow and cooling reasons. Not that they get particularly hot.
Been fine for a couple weeks then came to switch it on ( mains switched with a latching push button) recently and got a healthy pop from inside the case. Couldn't really tell what, but it all seemed to be working. It's done it a few more times and got to a point where the switch wouldn't switch it off so I assumed something in the inrush had fused the switch shut.
Thought I better had look into this and have just taken the lid off, and off the offending PSU. It would seem to have eaten up the ICL on what I assume is the main 240v in. Not exactly a big load from this class D amp. And the switch seems to have 'recovered'!
Any thoughts on this?. Shall I just replace it? What sort of value and do I uprate it.? It all still works but a shower of sparks on start up isn't so family friendly! The PSU states 100 to 240vac and I'm pretty sure I'm around 245 a lot of the time, but I doubt this is the cause.
Attachments
Probably means nothing but the faulty upper PSU is the one that I've pinched 240v from for the 'on' indicator illumination in the switch
The switch is certainly zapped if it was refusing to switch off. It may appear to be working now but the contacts will be shot and could be intermittent and arc. Make sure any mains switch is suitably rated for the expected inrush currents.
I can't tell from the pictures but is that part definitely a thermistor and in series with the incoming supply? or is it across the supply in which case it would be a VDR.
I can't tell from the pictures but is that part definitely a thermistor and in series with the incoming supply? or is it across the supply in which case it would be a VDR.
Those switches are notoriously high in contact resistance and they are plain unreliable. Nice looks and rotten innards. Not all but very often. Sometimes even steel contacts are used, I had a few stainless steel versions ("porn models") measuring 40 Ohms resistance. They are totally unsuitable for mains voltage operation. If you open them you sometimes are very glad your casings are connected to PE. Also check the contacts in that blue socket with a magnet 🙂 There exist good ones from the same country at a different price but if you want reliability you need Bulgin or Marquardt. Marquardt 1835 practically never fail. Switches used in industrial devices usually still are old fashioned good quality. Aliexpress/Ebay/Taobao switches generally are a waste of materials, time and money.
BTW it is mandatory for safety to switch mains voltage L and N with a double pole switch at least 250V 10A rated preferably with faston connectors 4.8 or 6.3 mm. Some of these don't win beauty contests so finding a nice one may be a challenge. They won't let you down however and they are safe.
Possibly this one was leaking or high ohmic. Since the power switch is single pole the mains voltage could have been "pulsing" the PSU's.
* Please replace the ICL's in both PSUs for a known good brand/type.
BTW it is mandatory for safety to switch mains voltage L and N with a double pole switch at least 250V 10A rated preferably with faston connectors 4.8 or 6.3 mm. Some of these don't win beauty contests so finding a nice one may be a challenge. They won't let you down however and they are safe.
Possibly this one was leaking or high ohmic. Since the power switch is single pole the mains voltage could have been "pulsing" the PSU's.
* Please replace the ICL's in both PSUs for a known good brand/type.
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Thanks JP we overlapped in replying. Indeed I have had one of these switches in a SMPS powered class A amp for some time with no issues but maybe it was from a different supplier. Shall tear down this bad switch to have a look.
Could the switch have caused the ICL issue then?
Could the switch have caused the ICL issue then?
IMHO yes. Please read post #5 in detail if you like safety/reliability. These are like many parts today nice looking garbage from China. Buy European quality before the factories close down I would advise. The west outsources production of switches but the metallurgic knowledge went out of the door together with the retired workers.
To keep using these is simply gambling. How many times we have had EU made mains switches fail in the last decades? And how many times do we experience this today?
To keep using these is simply gambling. How many times we have had EU made mains switches fail in the last decades? And how many times do we experience this today?
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Seem copper colored (!) contacts so that is a plus 🙂 Not the required alloy probably (well, for sure) and too tiny because of the ball like other contact causing pitting. Are the other conducting parts all plated steel I guess? Apparently they use various materials in the same models/series of switches so stuff becomes batch dependent. What is the current rating of this one? 220V 5A like usual? The real rotten ones have no contact ratings except for the power on LED. Why? The customer will return the switch when the LED fails directly because of user error.
"All that", yes but yet we buy it based on looks and connect it to mains. And now a second time. As long as the LED shines blue....
"All that", yes but yet we buy it based on looks and connect it to mains. And now a second time. As long as the LED shines blue....
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The only ferrous material was the spring and the little linkage.
Potentially 3A rating if I'm looking at a like for like item listing. Maybe here is my issue seeing as the SMPS are 2.5A each. But I assume this is worst case at max output .
Potentially 3A rating if I'm looking at a like for like item listing. Maybe here is my issue seeing as the SMPS are 2.5A each. But I assume this is worst case at max output .
Switches arc at opening not closing. That is why you place a capacitor over the opening contacts so it will extinguish (quench) an arc as it absorbs the energy.
EDIT: The arc point is clearly visible on the contact. It will arc if unprotected even if rated at 1000A
EDIT: The arc point is clearly visible on the contact. It will arc if unprotected even if rated at 1000A
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