Author Topic: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown  (Read 102700 times)

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Offline SeanB

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #125 on: December 14, 2015, 06:52:52 pm »
I see what looks like a nylon spacer with a moulded rim to ensure the washer nut is kept centred and right away from the mounting disc.  I suspect this spacer will have a cylindrical protrusion at the rear, separating the bolt shaft and any other metalwork.  In short, there is no shorted turn.

Yup, you're right! But it would be still an interesting experiment to find out what the impact (in numbers) of a shorted turn in the middle of the toroid would be.

low voltage high current 1 turn transformer?
primary overheat, insulation breakdown, etc = electroboom?

About 10 seconds after turn on the metal will be hot enough to start melting the outer insulation, and after around 20 seconds the transformer will do an impressive arcing smoke emitting death as the primary windings short together from the inner insulation overheating and melting off. Followed by either a fuse blowing, the mains breaker tripping or the input primary wires burning out.

Generally something to avoid if you can. If it is a higher than 500VA toroid it might only do all thin in under 1 second, leaving the smoking remains and a red hot metal chassis as well.

If the case is aluminium it might just melt out the bolt as well with the flames and arc, and if you are lucky the anodising will provide insulation so nothing happens for a while till the oxide is punctured for some reason.
 

Online Fungus

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #126 on: December 14, 2015, 08:32:41 pm »
About 10 seconds after turn on the metal will be hot enough to start melting the outer insulation, and after around 20 seconds the transformer will do an impressive arcing smoke emitting death as the primary windings short together from the inner insulation overheating and melting off. Followed by either a fuse blowing, the mains breaker tripping or the input primary wires burning out.

Generally something to avoid if you can. If it is a higher than 500VA toroid it might only do all thin in under 1 second, leaving the smoking remains and a red hot metal chassis as well.

If the case is aluminium it might just melt out the bolt as well with the flames and arc, and if you are lucky the anodising will provide insulation so nothing happens for a while till the oxide is punctured for some reason.

With a bit of luck you can even get a second degree burn on your hands when you grab it to try pull the plug.    :-DD

 

Offline HKJ

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #127 on: December 14, 2015, 08:38:42 pm »
The recessed safty conectors are useful (and in the EU required for a lab supply that deserves it's name) for low voltages too.
Its not about isolation of the connectors itself, but compatibitly with new safety plugs with a fixed insulation tube.

You can get binding post that works with the shrouded banana plugs. I have that on nearly all my power supplies.
 

Online tautech

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #128 on: December 14, 2015, 08:47:03 pm »
The recessed safty conectors are useful (and in the EU required for a lab supply that deserves it's name) for low voltages too.
Its not about isolation of the connectors itself, but compatibitly with new safety plugs with a fixed insulation tube.

You can get binding post that works with the shrouded banana plugs. I have that on nearly all my power supplies.
I'm after some of those, link please?
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Offline HKJ

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #129 on: December 14, 2015, 08:51:07 pm »
I'm after some of those, link please?

I do not know where you can buy them, but Keithley and TTi uses them.
 

Online Fungus

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Online tautech

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #131 on: December 14, 2015, 09:08:08 pm »
I'm after some of those, link please?

I do not know where you can buy them

http://www.ebay.com/sch/i.html?_nkw=banana+shrouded+test++socket
Sorry, no.
4 mm banana shrouded socket to binding post.

Edit
And with X hole
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Offline c4757p

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #132 on: December 14, 2015, 09:15:15 pm »
The recessed safty conectors are useful (and in the EU required for a lab supply that deserves it's name) for low voltages too.
Its not about isolation of the connectors itself, but compatibitly with new safety plugs with a fixed insulation tube.

So even if the supply is low voltage this alows you to use the better cables as well and thus no more need to have the unsafe old style banana plugs or the plugs with movable shield.

I cut the shrouds off my cables, because they're useless. Then they fit in any banana jack. Shame we all can't just stop selling shit to the EU until they learn not to be so up themselves with regulations.
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Online Monkeh

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #133 on: December 14, 2015, 10:48:53 pm »
The recessed safty conectors are useful (and in the EU required for a lab supply that deserves it's name) for low voltages too.
Its not about isolation of the connectors itself, but compatibitly with new safety plugs with a fixed insulation tube.

So even if the supply is low voltage this alows you to use the better cables as well and thus no more need to have the unsafe old style banana plugs or the plugs with movable shield.

I cut the shrouds off my cables, because they're useless. Then they fit in any banana jack. Shame we all can't just stop selling shit to the EU until they learn not to be so up themselves with regulations.

Shame we all can't just stop selling shit to the US until they learn to play better with others.
 

Offline John Coloccia

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #134 on: December 14, 2015, 11:49:04 pm »
The recessed safty conectors are useful (and in the EU required for a lab supply that deserves it's name) for low voltages too.
Its not about isolation of the connectors itself, but compatibitly with new safety plugs with a fixed insulation tube.

So even if the supply is low voltage this alows you to use the better cables as well and thus no more need to have the unsafe old style banana plugs or the plugs with movable shield.

I cut the shrouds off my cables, because they're useless. Then they fit in any banana jack. Shame we all can't just stop selling shit to the EU until they learn not to be so up themselves with regulations.

Shame we all can't just stop selling shit to the US until they learn to play better with others.

I don't know what I'd do without all that British lab equipment.  ::)

Shrouded connectors on a power supply are a fail, because all that will happen is people will create workarounds which will be far less safe than regular binding posts. No reason you can't have both, which is clearly the safest and sanest path forward in the actual real world, not the make believe world of the bureaucrat.
 

Offline Tothwolf

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #135 on: December 15, 2015, 05:52:30 am »
I cut the shrouds off my cables, because they're useless. Then they fit in any banana jack. Shame we all can't just stop selling shit to the EU until they learn not to be so up themselves with regulations.

Shame we all can't just stop selling shit to the US until they learn to play better with others.

If it would mean an end to the RoHS silliness outside of the EU then I'm all for it.
 

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #136 on: December 17, 2015, 01:32:51 pm »
Just a quick note to let everyone know that the Siglent engineering team does pay attention to your comments and suggestions. They have informed us that they are addressing the SPD3303X/X-E internal wiring placement & dressing issues pointed out on Dave's video.

Thanks
Steve
 

Offline German_EE

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #137 on: December 17, 2015, 07:31:33 pm »
Fixing that wiring is easy, fixing the front panel issue will probably need a new front panel, one or more new PCBs with the holes 19mm apart and a new supplier of front panel connectors.
Should you find yourself in a chronically leaking boat, energy devoted to changing vessels is likely to be more productive than energy devoted to patching leaks.

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Online Fungus

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #138 on: December 17, 2015, 07:39:06 pm »
Fixing that wiring is easy, fixing the front panel issue will probably need a new front panel, one or more new PCBs with the holes 19mm apart and a new supplier of front panel connectors.

I think they were referring to "internal wiring", ie. the loose mains wires at the side that were being cut by the sharp metal.

I'm not sure what he means by the "dressing issues".
 

Offline nctnico

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #139 on: December 17, 2015, 10:34:13 pm »
Dressing of wires: cable harnesses and / or fixating
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline orin

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #140 on: December 19, 2015, 11:16:12 pm »
Just a quick note to let everyone know that the Siglent engineering team does pay attention to your comments and suggestions. They have informed us that they are addressing the SPD3303X/X-E internal wiring placement & dressing issues pointed out on Dave's video.

Thanks
Steve


They really need to address the binding posts - see attached picture of a SPD3303D as it arrived from Tequipment.  Still haven't heard back from then what they intend to do about it...




 

Offline orin

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #141 on: December 20, 2015, 12:54:13 am »
errrr wait a minute, even the screw thread got torn out?


Broke at the wire hole... the holes that Dave criticized for being too small!

 

Offline Macbeth

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #142 on: December 20, 2015, 01:15:44 am »
errrr wait a minute, even the screw thread got torn out?


Broke at the wire hole... the holes that Dave criticized for being too small!

Not fit for purpose it appears. What are they made of, the cheapest die-cast crap painted over or what?
 

Offline orin

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #143 on: December 20, 2015, 03:10:02 am »
errrr wait a minute, even the screw thread got torn out?


Broke at the wire hole... the holes that Dave criticized for being too small!

Not fit for purpose it appears. What are they made of, the cheapest die-cast crap painted over or what?


No idea about the base metal.  Shiny, so probably plated with something - nickel perhaps?

 

Offline SeanB

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #144 on: December 20, 2015, 04:38:06 am »
Brass, but the wall thickness is so thin that it simply snapped at the thinnest part at the root of the thread, where the wall had the least area in the hole. Basically they are too thin in the wall, and need to be made larger in diameter, along with making the inner hole the correct diameter to fit the standard socket.

Basically the manufacturer took too much brass off, to cut the cost of the material used in the individual item. They probably charged Siglent the cost of the length of brass used to machine the post, adding the cost of the plating as well. The manufacturers gross profit comes from the removed brass as scrap metal to be remelted, probably around $7 per kilo.
 

Offline orin

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #145 on: December 20, 2015, 04:59:02 am »
Brass, but the wall thickness is so thin that it simply snapped at the thinnest part at the root of the thread, where the wall had the least area in the hole. Basically they are too thin in the wall, and need to be made larger in diameter, along with making the inner hole the correct diameter to fit the standard socket.

Basically the manufacturer took too much brass off, to cut the cost of the material used in the individual item. They probably charged Siglent the cost of the length of brass used to machine the post, adding the cost of the plating as well. The manufacturers gross profit comes from the removed brass as scrap metal to be remelted, probably around $7 per kilo.


Make a lot of sense... although now useless as a binding post, the remaining hole is still deep enough to accept a banana plug.  Deep oversized hole = more removed material to scrap.  If the hole wasn't so oversized, the binding post might have survived shipping!

 

Offline madires

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #146 on: December 20, 2015, 01:40:49 pm »
Basically the manufacturer took too much brass off, to cut the cost of the material used in the individual item. They probably charged Siglent the cost of the length of brass used to machine the post, adding the cost of the plating as well. The manufacturers gross profit comes from the removed brass as scrap metal to be remelted, probably around $7 per kilo.

And Siglent just wants to address the mains wiring issue while missing the gorilla at the front door.  :palm:
 

Offline rs20

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #147 on: December 21, 2015, 10:35:11 pm »
Got a 5 mm hole for wire...

Er, how do you tighten down after you've placed the wire through the hole? Or are you supposed to just poke it in there and hope?

It looks more to me like that's supposed to be a right-angle banana jack hole. Sure it's not 4mm?
 

Offline Smokey

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #148 on: December 22, 2015, 01:40:08 am »
Got a 5 mm hole for wire...
Er, how do you tighten down after you've placed the wire through the hole? Or are you supposed to just poke it in there and hope?
It looks more to me like that's supposed to be a right-angle banana jack hole. Sure it's not 4mm?

There is always hope my friend! 
Its just to screw around a little and the wire stick!  ;)
The end holes are 4mm.... so they fit a banana plugg...

But is it RoHS???????:)
 

Offline Circlotron

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #149 on: January 09, 2016, 02:10:54 am »
Not sure if some already mentioned it, but in Australia at least, don't the regulations require that if you can come in contact with the output of a transformer then the primary and secondary have to be segregated as is commonly done with an EI transformer? How does a toroidal measure up in this regard?
 


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