Cost pressures...?
primary winding=fuse if anything goes south downstream; you just have to be willing to replace the $$$$ transformer instead of a .$ fuse.
I find it actually more disturbing that there is no insulation whatsoever on the solder connections that carry line voltage to protect from consequences when accidentally touching with meters, tools, hands, etc.
It seems these kinds of shortcuts become more and more common, especially since most stuff nowadays just gets kicked to the curb when it breaks, instead of being repaired. Because new is cheaper.... NOT.
primary winding=fuse if anything goes south downstream; you just have to be willing to replace the $$$$ transformer instead of a .$ fuse.
I find it actually more disturbing that there is no insulation whatsoever on the solder connections that carry line voltage to protect from consequences when accidentally touching with meters, tools, hands, etc.
It seems these kinds of shortcuts become more and more common, especially since most stuff nowadays just gets kicked to the curb when it breaks, instead of being repaired. Because new is cheaper.... NOT.
I can honestly say that I've never seen a consumer product that was so dangerously designed as this in all of my years of popping covers.
And there is no mains fuse underneath on the hot pcb, I checked.
I promptly double checked to see if it was unplugged and put the cover straight back on, no way I'm going to be working on this unit.
And this isn't a hack or something that has been put on afterwoods, the soldered joints look original.
And there is no mains fuse underneath on the hot pcb, I checked.
I promptly double checked to see if it was unplugged and put the cover straight back on, no way I'm going to be working on this unit.
And this isn't a hack or something that has been put on afterwoods, the soldered joints look original.
Yeah I know.. I've seen it too mostly in VCR's, but this one is sticking right up at the top of the chassis, usually you find it somewhere hidden or out of the way..
Maybe I'm overacting a little bit but yeah... its not nice to see a big nasty active and neutral line sticking up like that.
In the pioneer you've got 3 points of contact on a pcb thats high up in the air that could potentially kill you.
This is an inch off the roof of the cover.
This is what its like in a sherwood:
Maybe I'm overacting a little bit but yeah... its not nice to see a big nasty active and neutral line sticking up like that.
In the pioneer you've got 3 points of contact on a pcb thats high up in the air that could potentially kill you.
This is an inch off the roof of the cover.
This is what its like in a sherwood:
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Ahh so its one of those jobs.
anyway I've moved onto a Nikko ND-390 II now...
http://www.diyaudio.com/forums/anal...-390-ii-anyone-got-schematic.html#post3304052
anyway I've moved onto a Nikko ND-390 II now...
http://www.diyaudio.com/forums/anal...-390-ii-anyone-got-schematic.html#post3304052
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Unfortunately I see it being done today, all the time, as in Fender guitar amps (and many others)
Yes, they *do* use a primary fuse, but they mount *everything* on a big fweekin' PCB: Preamp, Power Amp, PSU (so far, so good) but also the mains fuse, and sometimes different mains taps (say, 120/240 windings and such) IN THE SAME big fweekin' PCB.
Of course, using 0.01 cent exposed fuse clips, and much worse, tracks and pads on same PCB.
So you unmount it to take a couple measurements (it's still "floating" over the metallic chassis, because it's hooked to the transformer), and you have to be 24/7 aware of that dangerous area, try to avoid it touching the chassis , etc.
At least the example shown above "stays where it is", you can work quite a few inches away on other PCB or whatever and/or cover it with tape or glue, but the Fender dangerous spot moves around during servicing, and the big PCB, being still tied to some wiring, has a mind of its own about where it wants to stay or move to.
I always slide a couple thick magazines between the chassis and the danger PCB zone, but it's a clunky solution at best.
Sometimes I disconnect the PCB mounted live fuse and momentarily add an external one, properly taped around like a mummy, while servicing lasts.
Oh well.
Yes, they *do* use a primary fuse, but they mount *everything* on a big fweekin' PCB: Preamp, Power Amp, PSU (so far, so good) but also the mains fuse, and sometimes different mains taps (say, 120/240 windings and such) IN THE SAME big fweekin' PCB.
Of course, using 0.01 cent exposed fuse clips, and much worse, tracks and pads on same PCB.
So you unmount it to take a couple measurements (it's still "floating" over the metallic chassis, because it's hooked to the transformer), and you have to be 24/7 aware of that dangerous area, try to avoid it touching the chassis , etc.
At least the example shown above "stays where it is", you can work quite a few inches away on other PCB or whatever and/or cover it with tape or glue, but the Fender dangerous spot moves around during servicing, and the big PCB, being still tied to some wiring, has a mind of its own about where it wants to stay or move to.
I always slide a couple thick magazines between the chassis and the danger PCB zone, but it's a clunky solution at best.
Sometimes I disconnect the PCB mounted live fuse and momentarily add an external one, properly taped around like a mummy, while servicing lasts.
Oh well.
Yes, but even so, the design is poor (just to put it mildly).
Plus there is a *BIG* contradiction ... or call it double standards ... literally.
UL/CSA/TÜV/SEMKO/IEC/etc. rules have a very elaborate set of rules as to how dangerous voltages must be treated inside Electronic stuff, going to the extreme of stating "NO live voltage must be "touchable" inside, period" (I'm paraphrasing).
To the extreme of stating insulating caps or thermo contracting tubes must be used over all live terminals, creep distance between contacts, insulating "walls" between power switch terminals and so on.
So much so that Fender amps use different power switches for USA or Europe markets (they even show them on schematics), not because of line voltage but because of line safety regulations ... yet they leave exposed fuses, connection pads and as I said, pads and tracks of the SAME PCB .
I really don't know how they get approved and allowed to stamp the Safety conformity seals in the back panels.
Plus there is a *BIG* contradiction ... or call it double standards ... literally.
UL/CSA/TÜV/SEMKO/IEC/etc. rules have a very elaborate set of rules as to how dangerous voltages must be treated inside Electronic stuff, going to the extreme of stating "NO live voltage must be "touchable" inside, period" (I'm paraphrasing).
To the extreme of stating insulating caps or thermo contracting tubes must be used over all live terminals, creep distance between contacts, insulating "walls" between power switch terminals and so on.
So much so that Fender amps use different power switches for USA or Europe markets (they even show them on schematics), not because of line voltage but because of line safety regulations ... yet they leave exposed fuses, connection pads and as I said, pads and tracks of the SAME PCB .
I really don't know how they get approved and allowed to stamp the Safety conformity seals in the back panels.
I wonder. We are worried about the mains connections being exposed to the technician. I won't get into the other aspects. Yet open a tube amp and all the 500v conncetions and other B+ connections are exposed. If we are worried that a service technician will hurt himself touching the mains with his tools, we should be thinking about sealing the chassis so he can't open it, if he is that lacking in skills.
The power switch in those Fender amps is accessible to the outside world. All the stuff on the pc board is not. As to "all on the same board", look at any SMPS. For safety approvals, they need to have a certain amount of space between primary and secondary circuits. Being on the same board is not the issue.
The power switch in those Fender amps is accessible to the outside world. All the stuff on the pc board is not. As to "all on the same board", look at any SMPS. For safety approvals, they need to have a certain amount of space between primary and secondary circuits. Being on the same board is not the issue.
A lot of electronics have switch mode PSU units with rectified mains across the reservoir capacitors. Think of all of the pics of the DCX2496 you have seen on this site. How many have insulated the reservoir capacitor top in the PSU? In the UK that cap has over 330VDC exposed and that baby BITES! (as my brother found out when he touched it - he nearly threw up!)
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