Hey guys,
I just had an amp stop working on me today. Totally dead. It worked fine yesterday.
Turns out the power switch wouldn't pass any power to the to the transformer, so I took it out, and sure enough - no conductivity on either side (it's a DPST type).
It has X capacitors across the terminals, and I tried removing those. Now the switch works just fine! How can this be? It's wired as follows:
Now, I want to replace these X caps, but I only have X2 capacitors, and I'm not sure they're even the same value (more like 33 nF). Can I use that anyway?
Thanks guys. 🙂
I just had an amp stop working on me today. Totally dead. It worked fine yesterday.
Turns out the power switch wouldn't pass any power to the to the transformer, so I took it out, and sure enough - no conductivity on either side (it's a DPST type).
It has X capacitors across the terminals, and I tried removing those. Now the switch works just fine! How can this be? It's wired as follows:
Now, I want to replace these X caps, but I only have X2 capacitors, and I'm not sure they're even the same value (more like 33 nF). Can I use that anyway?
Thanks guys. 🙂
The switch has possibly a poor contact internally. The capacitors will be fine unless physically damaged. 33n class X will be OK. They are only there to stop the interference generated when switching the power off. Too high a capacitor value and the mains won't switch off properly due to the AC flowing through the capacitors.
I looked inside the switch and it looks brand new. No blackening as can usually be seen in these, and the contact surfaces are shiny.
The X capacitors in there are old Rifa parts, and they have some obvious internal cracks, but the values measured on my meter are correct (about 24-25 nF).
What is the difference between X and X2 capacitors? I cannot find any clear info on that on the net.
The X capacitors in there are old Rifa parts, and they have some obvious internal cracks, but the values measured on my meter are correct (about 24-25 nF).
What is the difference between X and X2 capacitors? I cannot find any clear info on that on the net.
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See http://www.illinoiscapacitor.com/pdf/Papers/EMI_RFI_suppression_capacitors.pdf. It was the 6th answer when I Googled; maybe you stopped reading after 5?
For Mains rated capacitors I am only familiar with the X1, X2, Y1, Y2 versions.
X2 and Y2 are rated for use on single phase domestic supplies upto 254Vac
X1 and Y1 are higher rated and I think they are suitable for 3 phase commercial/industrial supplies upto 440Vac.
I have no information about X rated capacitors.
Was there a standard that pre-dated what we currently use?
X2 and Y2 are rated for use on single phase domestic supplies upto 254Vac
X1 and Y1 are higher rated and I think they are suitable for 3 phase commercial/industrial supplies upto 440Vac.
I have no information about X rated capacitors.
Was there a standard that pre-dated what we currently use?
Saw this over in the Vendors Bizarre:
CW2C-10A-T from: http://connexelectronic.com
But there are many vendors with similar gadgets. Caps and "hum bucking" coils on the output side with power switch and fuse. (Considered a "laboratory quality" type, but the price ain't bad. 😉 )
An externally hosted image should be here but it was not working when we last tested it.
CW2C-10A-T from: http://connexelectronic.com
But there are many vendors with similar gadgets. Caps and "hum bucking" coils on the output side with power switch and fuse. (Considered a "laboratory quality" type, but the price ain't bad. 😉 )
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probably a wonky switch, heating the lead with the soldering iron fixed it, might want to replace the switch.
Hum-bucking usually refers to a method of winding the coils inside electric guitar "pickups". (This article on Wikipedia) says more.
MJ: Yes, correct, and usually two coils in a circuit that effectively rejection of common mode noise, electronic and mechanical noise ...
The "cute" name has everything to do with the coils and their relationship to themselves and the applied circuit, in these cases, as a filter of power line and extraneous LF "hum" ... and can apply to a laundry list of "hum" rejection techniques.it
The "cute" name has everything to do with the coils and their relationship to themselves and the applied circuit, in these cases, as a filter of power line and extraneous LF "hum" ... and can apply to a laundry list of "hum" rejection techniques.it
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I don't think a power line filter is designed to filter out "hum" - it is meant to pass "hum" and stop RF. For a mains PSU input "hum" is good; "hum" is your power source!
The reason a common-mode choke is used is not because it has superior noise reduction properties (it hasn't - it doesn't touch differential-mode noise), but because it avoids saturating the ferrite core so the choke can be much smaller and cheaper than a pair of ordinary chokes.
The "cute" name is simply wrong and misleading.
The reason a common-mode choke is used is not because it has superior noise reduction properties (it hasn't - it doesn't touch differential-mode noise), but because it avoids saturating the ferrite core so the choke can be much smaller and cheaper than a pair of ordinary chokes.
The "cute" name is simply wrong and misleading.
OK, fine, don't use the "cute" name
... Playing semantic games is not my forte'.You are of course correct, the power line filtering is meant to be a low pass filter, allowing all of the energy below ~~ 200 Hertz through to the transformer, but "roll off" and filter the "common mode" noise and RF above ~~ 1K Hertz and more (depending on the design).
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So using '"hum bucking" as a "cute" description for a common-mode RF choke was just a temporary lapse from your usual precise use of language - I am pleased to hear this.FastEddy said:
The typical mains filter that most would ever come across is related to EMI specs, and so filter attenuation characteristic is pretty much outside the audio range of frequencies.
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