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1 hour ago, andyr said:

 

What you say is all true, Alan ... but not many people are going to listen to you - coz, after all, stuff "made in China by no-name manufacturers" costs a lot less than stuff made in Oz.  :thumb:

 

(Perhaps you should change your SNA-name to "Cassandra"?  :) )

 

Andy

 

 

What people spend their money on is of no concern to me mate.  I just have a low level of sympathy for them when they get scammed with an amplifier that delivers half the output power the maker claims it's supposed to or is equipped with a transformer that's well below the required VA rating and with a 220v primary instead of a 240v primary which experiences a meltdown or blows up. ?  Likewise for other bits of kit with outrageous claims 

 

We live in a disposable society Andy.  People aren't interested in real quality. What they want is lots of "gold" plated plastic bling.  Things aren't built to last because in order maximise profits most manufacturers aren't going to use high quality parts, instead opting for components that hopefully last just beyond the warranty period (if even any warranty is offered).  

 

The difference between the layperson and someone working in the electronics industry is those working in the industry know the difference between the quality of components and can generally spot a fake Nichicon electrolytic capacitor by sight alone.

 

Unfortunately there will always be a faction of people who will dismiss well established scientific evidence and facts in favour of pseudo science because it serves their narrative.  

 

Cheers,

Alan R.

   

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Absolutely.  The Australian made units have to pass electrical certification and safety test before they can be legally sold here in Australia.  Exactly the reason why some bits of hifi kit aren't ret

I suggest a full kettle is an appropriate load.   I predict the diodes will get red hot (which is why I use a 35a, metal-cased diode bridge - bolted to the bottom panel of the case, for heat

There's a reason why the ones made in Oz cost more than the ones sold by AliExpress.   Andy  

18 hours ago, Leinster Lad said:

Here is my circuit as far as I can tell ?

image.jpg

 

I think there's an error in the reverse engineering.  The two 2200uF capacitors appear to be effectively across the mains and not in parallel with the diode arrays in a series configuration with the output, that is in series with the load .  Also they are in aiding (+-+-) not opposing (+--+) polarities.

 

Cheers,

Alan R.

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O

I've mentioned the polarity of the caps a couple of times now.

 

The two electros, near as I can tell, (which is a bit hard because of the double sided board and black  lacquered tracks) , both visually and metered, are wired as per my mud map diagram.

 

Pretty sure.  One leg of the cap bank is direct to the input active trace.

 The other end of the cap bank is connected to neutral input leg via one bank of diodes.

The X2 cap is connected the same but opposite. (to neutral input trace and then to active thru the diode bank on the active input trace)

 

So it is a bit more complex than the very simple circuit reference earlier.

 

Whether it works or not I have no idea, and after all, it is not going to be powering the Queens pacemaker!

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1 hour ago, Leinster Lad said:

O

I've mentioned the polarity of the caps a couple of times now.

 

The two electros, near as I can tell, (which is a bit hard because of the double sided board and black  lacquered tracks) , both visually and metered, are wired as per my mud map diagram.

 

Pretty sure.  One leg of the cap bank is direct to the input active trace.

 The other end of the cap bank is connected to neutral input leg via one bank of diodes.

The X2 cap is connected the same but opposite. (to neutral input trace and then to active thru the diode bank on the active input trace)

 

So it is a bit more complex than the very simple circuit reference earlier.

 

Whether it works or not I have no idea, and after all, it is not going to be powering the Queens pacemaker!

 

I'm not doubting you mate.  Just the circuit makes no sense whatsoever.  

 

Cheers,

Alan R.

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I can't see how it's connected on top of the board but below how it's connected at the bottom of the board (at least what I can see from the picture), each pair of diodes is connected in opposite direction with joint in the middle (square)

 

LL, can you confirm and maybe mark how are the caps connected from the top? 

 

1190596371_DCblocker.jpg.e3a092f33b2f4beda4f278bd0e1c628f.jpg

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As you can see from the pics, the top layer is really difficult to see.

 

Cannot see where the tracks for the electros are on top of the board.

 

As i've ordered replacement caps and diodes, i'll pop them out later. Should make the top tracks more visible.

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4 minutes ago, Leinster Lad said:

As i've ordered replacement caps and diodes, i'll pop them out later. Should make the top tracks more visible.

 

yeah, I think we need to see how it's connected otherwise it would be kind of weird 

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not quite correct,  the neutral line is direct to output (not thru any diodes)

 

The common point of the diodes in the neutral are only connected to one cap and the resistor

 

 

also with a 1 meg resistor tying the negative legs of the caps together

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Ah ok, I thought from the picture that each side is connected to the AC terminals

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3 hours ago, Leinster Lad said:

Bigger diodes and caps fitted. Now to soak test. 

image.jpg

Not convinced, here, bigger is better. I do like these modules though.

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? so when the original diodes and caps were sighted right here that they were probs inadequate, ie, diodes rated at 3 amps would be too small.  Caps were too small and not high enough ESR.

 

Should I not have bothered?

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Diodes are now 600 prv @  30 amp (325 amp surge) ON semi

Caps are now 7300uF 0.019 ohm  ESR  and   6800 mAh ripple  Nichicon

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7 hours ago, Leinster Lad said:

? so when the original diodes and caps were sighted right here that they were probs inadequate, ie, diodes rated at 3 amps would be too small.  Caps were too small and not high enough ESR.

 

Should I not have bothered?

 

If you were pulling more than 3A, then the original diodes would be inadequate IMHO and IME most likely to fail prematurely.

Nothing wrong with using large value capacitors with a lower ESR.  Firstly they will have a lower loss and dissipation and the Nichicons are a good choice, and secondly they will most likely last longer than the "no name" types.  

 

The point of the whole exercise is does the unit effectively block any d.c. content present on the mains? 

 

IME, most Chinese designed devices have overly inflated specifications and at best achieve about 50% of whatever they are rated at.  With this board sporting its original components, a claim of 10A continuous current delivery using 3A diodes is overly optimistic.

 

Cheers,

Alan

 

 

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Been holding my tongue on this one.

But since it involves mains electricity, I'll add my 2 cents worth.

 

I'm with Alan on this. The schematic (as drawn) is NQR for a proper dc blocking arrangement.

Power up at your own risk, but don't expect the function to be up to par with other units, even with the up-rated components.

You may also find that those caps may not last the distance either because of their placement in the circuit.

 

Good luck Leinster Lad.

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