Author Topic: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown  (Read 55572 times)

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Offline blueskull

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #100 on: December 11, 2015, 12:30:08 pm »
As for the rust, coating the steel after it has been cut and bent to shape would cure this issue. However, the shoddy wiring, the problems with the output connections and the low quality components mean that there is no way I would recommend this product to anybody. Spacing decent quality connectors 19mm apart is not a difficult task.

This is not rust, its metal oxide. Must have fallen out from some leaky MOSFET.    ;D

Despite it is a joke, MOSFET does not use metal oxide, at least the power ones don't. HKMG ones does.
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Offline stranger

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #101 on: December 11, 2015, 09:56:22 pm »
Regarding the connector pitch on the PSU, Siglent and others might want to read this. Most instruments with dual banana plug connections follow the well established convention of using a 0.75inch mounting pitch.

Why?  As has been suggested it allows dual plugs to be used such as:

http://www.abbatron.com/products/28-dual-instrument-test-adapters

or

http://www.digikey.co.uk/product-search/en/connectors-interconnects/banana-and-tip-connectors-jacks-plugs/1441927?k=dual%20banana%20plug

I use these for both multimeter leads and PSU connections when I need to make frequent connections. For meters when doing 4 wire Kelvin measurements it speeds connections and cuts errors. My standard low voltage multimeter leads long ago had their plugs chopped and were permanently wired into a dual plug.

All my PSU and instruments of various USA, UK and Chinese brands meet the 0.75inch pitch standard which may go back 50 years, it becomes very noticeable when something does not, Japanese expression "A nail that sticks out will be hammered".
 

Offline Fungus

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #102 on: December 11, 2015, 10:59:44 pm »
Regarding the connector pitch on the PSU, Siglent and others might want to read this. Most instruments with dual banana plug connections follow the well established convention of using a 0.75inch mounting pitch.

All my PSU and instruments of various USA, UK and Chinese brands meet the 0.75inch pitch standard which may go back 50 years, it becomes very noticeable when something does not, Japanese expression "A nail that sticks out will be hammered".

Question is: How can somebody in charge of designing a PSU NOT know that.  :palm:
 

Offline Macbeth

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #103 on: December 11, 2015, 11:24:10 pm »
The worst of it is all the references to Master and Slave plastered on the front. How on earth do they think they could get any western universities or schools labs kitted out with this blatant racist triggering? Not safe space friendly at all. Even the hard disk manufacturers stopped with that racist stuff back in the IDE days when they renamed Master and Slave to Primary and Secondary. (Where's mojo to back me up on this one?)  :palm:
 

Offline Rasz

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #104 on: December 12, 2015, 12:42:27 am »
Regarding the connector pitch on the PSU, Siglent and others might want to read this. Most instruments with dual banana plug connections follow the well established convention of using a 0.75inch mounting pitch.

All my PSU and instruments of various USA, UK and Chinese brands meet the 0.75inch pitch standard which may go back 50 years, it becomes very noticeable when something does not, Japanese expression "A nail that sticks out will be hammered".
Question is: How can somebody in charge of designing a PSU NOT know that.  :palm:

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Online Kleinstein

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #105 on: December 12, 2015, 02:36:20 am »
At least the supply is consistant: ther terminals are a little to large and a little to far appart.

So maybe there are dual 4.2 mm plugs somewhere in china.

At least for europe the terminals have an additonal problem: they are not compatible with safty plugs (those with a fixed tube). So this supply does seem to comply with EU standards for lab equipment. If we are lucky there is a EU versions with better terminals.
 

Offline Zbig

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #106 on: December 12, 2015, 06:20:33 am »
Even the hard disk manufacturers stopped with that racist stuff back in the IDE days when they renamed Master and Slave to Primary and Secondary. (Where's mojo to back me up on this one?)  :palm:

Not exactly. There were two channels: Primary and Secondary, each of them supporting up to two devices on a single cable: a Master and a Slave, for a total of four devices. So you had a "Primary Master", "Primary Slave", "Secondary Master" and "Secondary Slave" in a maxed-out configuration.
 

Offline Zbig

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #107 on: December 12, 2015, 06:37:19 am »
Isn't it that the main justification for a standard-spaced terminals on a PSU is the ability to use a shorting bar for parallel serial/symmetrical connection? On Siglent, you don't do that as there are internal relays for that.
« Last Edit: December 12, 2015, 07:03:53 am by Zbig »
 

Offline blueskull

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #108 on: December 12, 2015, 06:42:24 am »
Good to see there are still people remember master and slave configurations. I thought no one ever remembered the IDE thing anymore.
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Offline jnissen

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #109 on: December 12, 2015, 07:22:48 am »
Mmmm,

 - Deceptive Corporate practices
 - Non standard width banana plugs
 - Crap quality banana plugs
 - Shit caps

Seriously, those banana plugs?  Entire instrument is a complete fail.


 :palm:


100% agree!
 

Online Messtechniker

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #110 on: December 12, 2015, 10:23:41 pm »
Thanks, Dave, for the teardown of the Siglent SPD 3303X. As far as I’m concerned
there is no need for a full review of this thing at the moment. I admit, I was for a
while thinking about buying it, but after these results ….  :palm:
This would have been my first purchase of semi-serious kit made in China.
I will now forget it for the next 10 years or so.

I’m looking now at the Hameg HMC 8043. I know, quite a different animal also price wise.

Yours - Messtechniker
Agilent 34465A, Hameg HMO1022, R&S HMC 8043, Voltcraft VC 940 and M-Audio Audiophile 192
 

Offline mjt

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #111 on: December 13, 2015, 06:05:05 am »
So if there's only one AD7792 and the three outputs are isolated, how are they coupling the signal to get 5 digit precision?

I'm not an electronics expert, but I thought to get good linearity through an optoisolator you need the type with two matched photodiodes (so you can do feedback) which the pc817 isn't.

Or am I missing something? Do they have an ADC for each channel, or some feedback arrangement that doesn't need both photodiodes to be in the same package, or something?
 

Offline Macbeth

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #112 on: December 13, 2015, 07:25:46 am »
I’m looking now at the Hameg HMC 8043. I know, quite a different animal also price wise.

Yours - Messtechniker
The only real gamechanger I found (without an actual review of how it really performs) are the binding posts. Now I know the Rigol DP832 also had an issue with a batch of them with binding posts being the other way - too narrow. Perhaps this is a bad sample? The non standard spacing would be an issue if it had sense terminals that you use standard spaced shorting bars on I guess. Surely nobody uses those fixed space banana to BNC converters on PSUs?

The Hameg is an instant fail because, like my Tenma 72-83xx PSUs it uses those recessed "safety" banana sockets. That is utter fail on a low voltage PSU.
 

Offline Smokey

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #113 on: December 13, 2015, 11:27:43 am »
 

Offline c4757p

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #114 on: December 13, 2015, 11:39:59 am »
Surely nobody uses those fixed space banana to BNC converters on PSUs?

I do. It's nicer to have one (thin) coax on the bench than two leads - especially when it's more than one. And why wouldn't I? That's a "standard" I thought no power supply maker would be dumb enough to go against... :palm:
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Online Monkeh

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #115 on: December 13, 2015, 01:15:48 pm »
Surely nobody uses those fixed space banana to BNC converters on PSUs?

I use a lot of double banana plugs.
 

Offline Macbeth

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #116 on: December 13, 2015, 02:17:00 pm »
Guess I'm wrong? I never would have thought of powering stuff up using a BNC RG58 cable and no doubt another BNC at the other end to whatever convertor going into the DC input of DUT, but it takes all sorts...?

Really the wrong diameter banana sockets are of more concern. And these new EU Elfen Safety PSUs are utter shite. No binding posts at all, shrouded recessed sockets.  :palm:
 

Offline John Coloccia

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #117 on: December 13, 2015, 03:02:26 pm »
I use banana to BNC all the time on a power supply, if only to monitor the voltage on a scope vs some other thing I'm looking at. I power with BNC all the time too. Most of what I do only draws a handful of milliamps...enough to fly to the moon, don't you know.  :) It's pretty ridiculous that they can't get the binding posts and the spacing correct. I've never even given this a second thought on any other equipment I've ever used. It's just how you do it. Baffling, amateur hour kind of nonsense.
 

Offline Tothwolf

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #118 on: December 13, 2015, 03:05:27 pm »
The unprotected mains wiring near sharp metal is inexcusable. How much would a small section of clear PVC tubing really add to the overall cost?

The Rubycon capacitors in this power supply are decent parts. The ZLH series is a long life low ESR part somewhat similar to the Nichicon HE series. Rubycon's YXA series is probably closer to a Nichicon PJ or PS series and are also not bad parts.

While the Lelon capacitors used as main input filters will probably last quite awhile (100Hz or 120Hz), I don't like seeing the smaller Lelon parts on the other boards. Even though 5mm or 6.3mm Lelon parts will probably last the 5 year design life of this instrument, they still aren't the high quality parts I would expect to see in a precision power supply.
« Last Edit: December 13, 2015, 03:09:08 pm by Tothwolf »
 

Offline SL4P

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #119 on: December 13, 2015, 06:06:35 pm »
You mentioned the TO-220 flapping in the breeze...
I also noticed the electrolytics on the front-panel PCB... some were already 'sagging' from vibration / gravity / whatever motivation.
Some white epoxy-snot would fix that for virtually no effort.

Added: the channel-3 switch seems  a bit flimsy - perhaps a pull & slide or other mechanism would be a bit safer - esp as it's directly below the primary controls.
« Last Edit: December 13, 2015, 06:12:16 pm by SL4P »
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Online Messtechniker

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #120 on: December 13, 2015, 07:01:11 pm »
The Hameg is an instant fail because, like my Tenma 72-83xx PSUs it uses those recessed "safety" banana sockets. That is utter fail on a low voltage PSU.

Why this? Just did a 4 wire measurement on a safety banana socket*
with an ordinary banana plug* inserted. Measured 2.5 milliOhms.  8)
What's wrong with that?

*) Used items - laying the the box for ages.
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Offline rs20

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #121 on: December 13, 2015, 10:51:32 pm »
The Hameg is an instant fail because, like my Tenma 72-83xx PSUs it uses those recessed "safety" banana sockets. That is utter fail on a low voltage PSU.

Why this? Just did a 4 wire measurement on a safety banana socket*
with an ordinary banana plug* inserted. Measured 2.5 milliOhms.  8)
What's wrong with that?

Recessed banana sockets are a compromise -- they're less versatile, but you're nominally safe from touching the terminals. If the terminals can't reach a dangerous voltage, then that's a fail, they're less versatile, but __________________.
 

Offline dr.diesel

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #122 on: December 13, 2015, 11:10:36 pm »
I’m looking now at the Hameg HMC 8043. I know, quite a different animal also price wise.

I have one on order.

Surely nobody uses those fixed space banana to BNC converters on PSUs?

I use them all the time as well.

Offline NiHaoMike

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #123 on: December 14, 2015, 05:58:22 am »
Recessed banana sockets are a compromise -- they're less versatile, but you're nominally safe from touching the terminals. If the terminals can't reach a dangerous voltage, then that's a fail, they're less versatile, but __________________.
Could the output be floated at a high voltage? For example, you could use a 15V bench supply to run the gate drive circuit for a motor drive that is running from a mains level supply.
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Offline German_EE

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Re: EEVblog #828 - Siglent SPD3303X precision Lab PSU Teardown
« Reply #124 on: December 14, 2015, 07:40:02 am »
Try it, we'll watch from over here  :popcorn:
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