EEVblog #404 - Korad PSU Followup

[Michal]

I am from Poland, that is in Europe.  So that wouldn't be the best solution for me to buy something in the Australian market.

Please give me some info if there is a sticker with printed version number of the PSU shown in EEVblog #404. If not, please write so. That would help me buy the newer one.

Hmm....

All ours are modified stock. Plus all our stock has been tested by us for short circuit test and a ramp up to full load test.

How to understand that. TRIO is modifying these PSU's and I won't buy one in the European market or what?

I'm confused now.

[HackedFridgeMagnet]

It seems Trio is upgrading all its existing stock to the new version.
Other distributors in other parts of the world may not be doing this, you will have to ask them or Korad directly.
Any stickers on the Korad boxes that Trio are selling probably wont help you identify old versions from upgraded versions.
You will probably need to see or see photos of inside the box to be sure.

[Michal]

So is the upgrade TRIO's own project? Or they've got KORAD's spare parts to replace? Anyway, that's really unusual situation.

[EEVblog]

So the upgrade is TRIO's own project? Or they've got spare parts to replace? Anyway, that's really unusual situation.

No, it's an official board set sent from Korad, after they investigated the issue and (it seems) fixed it.
They sent the new boards Trio because they complained that they got dud supplies.
Whether or not Korad will actively do the same with other suppliers and ship them boards too, I don't know, you'll have to ask them.
And I can't imagine every supplier being willing to strip the things down and refit boards themselves. Trio are doing this off their own bat.
It is most likely that all existing stock out there is the old batch.
But I would like to think that any new stock coming from Korad is the new design.
Also, we don't know if any 110V versions have the same issue.

Dave.

[alm]

My take on it is that the service from Korad sucks, even Trio Smartcal had problems getting anything out of them. They're much more likely to listen to Trio than to a random consumer, however, since they represent a much larger sales volume. I would be hesitant to buy Korad products without a good distributor to handle any issues for me. Support might very well be non-existent.

[EEVblog]

My take on it is that the service from Korad sucks, even Trio Smartcal had problems getting anything out of them. They're much more likely to listen to Trio than to a random consumer, however, since they represent a much larger sales volume. I would be hesitant to buy Korad products without a good distributor to handle any issues for me. Support might very well be non-existent.

Well, when you buy from a reputable distributor, then that's what you are paying extra for, that extra piece of mind. They are the ones that will usually fix any issues for you, regardless of how good/bad the manufacturer or product might be. Some dealers for example offer their own extra warranty, and if it fails outside the manufacturers warranty (or they have trouble getting the manufacturer to support the warranty) then they are the ones that eat it.

Dave.

[alm]

But in the case of a reputable manufacturer like Fluke, you can always go back to the original manufacturer if the distributor is unable/unwilling to help you. In the case of Korad, the distributor might be your only hope. I would be much more willing to buy a Fluke DMM from a distributor with lousy support than a Korad power supply.

People used to say about 3Com network interface cards that no where you found it, even if you picked it out of the garbage, if it didn't work you could send it to 3Com and they'll give you a working one. With that kind of manufacturer support, who needs distributors?

[EEVblog]

But in the case of a reputable manufacturer like Fluke, you can always go back to the original manufacturer if the distributor is unable/unwilling to help you. In the case of Korad, the distributor might be your only hope. I would be much more willing to buy a Fluke DMM from a distributor with lousy support than a Korad power supply.

People used to say about 3Com network interface cards that no where you found it, even if you picked it out of the garbage, if it didn't work you could send it to 3Com and they'll give you a working one. With that kind of manufacturer support, who needs distributors?

A local dealer will often give you instant service, and local of course. i.e. if it fails, you walk back in the door and they will likely just give you a new one instantly (or a loaner), and they are left to sort out the details, not you.
Few manufacturers are going to offer that kind of service, and they usually aren't local. Good luck if you are overseas without a local manufacturers office...

Dave.

[alm]

If the equipment is sufficiently complex, then the only thing the dealer can do is to sit on the equipment for an extra week before sending it off to the manufacturer. Best case is that you get it back just as fast as if you'd have shipped it yourself, and you save on shipping costs. Worst case is that they attempt to replicate an intermittent problem, fail, and send it back to you as 'fixed'. The fasted way to deal with this is to include a note to the effect of 'please send this directly to the manufacturer referencing technical bulletin #'.

If the manufacturer is unwilling to help, then a good dealer might give you a replacement or (partial) refund. If the manufacturer is unresponsive, then the dealer might do the screaming and calling several times per day work for you. That's when a good dealer is important.

[Michal]

I sent email to my local distributor, hotair.pl. I hope they're fixing these PSU's to. Or maybe they have the new ones from Korad on the stock.

[Bored@Work]

A local dealer will often give you instant service, and local of course. i.e. if it fails, you walk back in the door and they will likely just give you a new one instantly (or a loaner), and they are left to sort out the details, not you.

Local dealers have the nasty habit of going out of business, especially in the current economic climate.

Even if they are still around, here local dealers have a very special local habit, letting you jump through all sorts of hoops before they even consider lifting a finger. Irrespective of what the contract says, what the law says and what warranty they promised, typically there first response is to point to the manufacturer and then go silent.

Dealing with the middle man is a pain here. And that's why direct manufacturer support is a must for me. And that is why I don't have much good to say about the likes of Rigol, Hantek, Uni-T or even GW-Instek. No, I don't care if they have a walk-in repair center at the other side of the word, a service phone number for China or instant support in the US.

[Michal]

I got answer from hotair.pl. They said this is the old problem with KA3005P an they sold out all their PSU's (new ones). I've got to wait two weeks for new shipment and then buy.

Happy New Year !!!

[Polossatik]

They all came from the same guy in Finland, and ended up between about £150-£170 each including shipping:

http://www.ebay.co.uk/itm/221123189659

He had a whole bunch to sell - I'm guessing a factory closed down, perhaps - and advertised them in batches over the course of the year. Sadly I've not seen any more recently, though it might be worth dropping him a note to ask if there are any more likely to become available. They all worked fine and were accurately calibrated.

just fyi: i contacted the seller and he said when asked if there where more: "Hi , I may get more of them in the near future. I'll check the stock when I get back to Finland, I'm just now abroad."

[UPI]

FYI - Here is what I received from SRA (through Amazon) on December 28th 2012.

It seems to have some but not all updated parts.

The transformer still says 220V and I don't see the "bodge" capacitor. Everything else looks updated.

[george graves]

Look like they are also selling a two unit version with an added 5v 3 amp out.

I  can just see one side blowing up, and you'd be stuck with both on your desk.

[ivan747]

I think they just provided a 240V country, Australia, with 220V transformers. The transistors were already at their maximum ratings and after getting the extra 10-20 volts they failed. American ones should come with a 220/110 volt transformer because they use 110V. Maybe that's why Australian ones have the new power transistor board.

[IanB]

Actually, no. America is a 120 V country as I mentioned above. If you are not getting 120 V out of your receptacles you are being short changed by your power company.

[JackOfVA]

We started out as a 110V country, thanks to Tom Edison. He picked a nice round number, 100V for DC distribution, and then added 10%, 110V total. The first AC systems maintained the 110V DC standard (in VAC RMS, of course), and over time the nominal distribution voltage has crept upward as (a) it permits more efficient use of the distribution network and (b) it allows the power company to sell more electricity.

If one wishes to be more pedantic, Edison's original DC system was actually +/- 110V, with a neutral/ground. But from what I recall reading, only 110V was made available to customers, some got +110V and others -110V and none had 220V DC.

If you look at old equipment nameplates or catalogs, you will see the nominal line voltage stated as 110V (really old), 115V, 117.5V and now 120V. My line voltage used to run 123-124V but after the power company reworked its local distribution network a couple years ago, it's almost always within 1V of 120V.

My UPS power supply has trip points at 135V / 95V, and within that range it will not switch to inverter.

[george graves]

That's interesting....cause house hold outlets are 120 - but if you have a dryer outlet it's usually refereed to as a 220 - not 240.  At least that's what it's called.

[mickpah]

wiki to the rescue again http://en.wikipedia.org/wiki/Mains_electricity_by_country , looks to me that the majority of the world is using 220-240 including China at 220v.
If I was looking looking to market a global product 230v +/- 10 % looks to be a nice fit and a 110V version for those who like big think mains cables and have the money for all the extra copper in the walls

[saturation]

The US is typically 240V or more multiphase AC distributed to customers, however within dwellings 240V are split into 2 branches, each with 120V and converted to single phase.  Large appliances in the US are typically 240V; water heaters, central airconditioners, etc., .

http://en.wikipedia.org/wiki/Mains_electricity#History_of_voltage_and_frequency

[jancumps]

I've got 3-phase + neutral at home. The previous owner had heavy machinery.
I can take 400V  between two phases, and 230V between phase and neutral.

[saturation]

The real difference between 120V and 240V is mostly is in-room wiring, much less how the power company distributes power.  Naturally, the other difference is the line frequency.

The 120V system used in the US  uses smaller diameter wires for room distribution vs say the UK, its typically 14 AWG ~ 2mm^2, compared to UK code which requires 4mm^2.   Although the wire diameters evntually vary depending on distance from the distribution panel and what the appliance its expected to serve, these wires are typical for mains receptacles.

http://en.wikipedia.org/wiki/Electrical_wiring_in_the_United_Kingdom

http://en.wikipedia.org/wiki/Electrical_wiring_(US)

wiki to the rescue again http://en.wikipedia.org/wiki/Mains_electricity_by_country , looks to me that the majority of the world is using 220-240 including China at 220v.
If I was looking looking to market a global product 230v +/- 10 % looks to be a nice fit and a 110V version for those who like big think mains cables and have the money for all the extra copper in the walls

[mickpah]

ahh, as always the devil is in the detail.
 In Australia at least a circuit protected by a circuit beaker can have  20 power outlets , each rated at 10 amps (in practice this is 10 points each with two sockets) protected by a 15A breaker using 2.5 mm² cable. This is subject to  derating factors for how the cable is run but it a good starting point for discussion. I have no idea what the wiring rules are in the US, so will leave that for others.

Can't beat ohms law.
2kW resistive  at 240v = 8.3 amps  , 2kW resistive  at 110v = 18.2 amps , no getting around the fact you need the copper in the walls to carry the load if you don't want voltage drop and heat loss ( fire).

[Monkeh]

The 120V system used in the US  uses smaller diameter wires for room distribution vs say the UK, its typically 14 AWG ~ 2mm^2, compared to UK code which requires 4mm^2.

Please don't talk out your arse. UK 'code' requires nothing of the sort.

120V systems wired in the US manner use far more copper. That's an unavoidable fact.