LM723 adjustable bench PSU not working

[eccerr0r]

Re: LM723 adjustable bench PSU not working

I tested the chip that I thought was dead in a reference design... it works despite its behavior is different than another 723 I had (by another manufacturer)!
WTF? Maybe these really are indestructible *shrug*. My test circuit must be bad or differential between the +/- is over 5 volts, though it too didn't destroy it...

Tested three of them in the jig, they seem to regulate OK, weird...

[eccerr0r]

Re: LM723 adjustable bench PSU not working

Hmm... I dug up all the µA723/LM723/MC1723's I could find ... they all behave differently? Weird. Need to see if I can hack up a test jig and toss the broken ones if there are any (some are untested pulls...)

[Dannyx]

Re: LM723 adjustable bench PSU not working

I think I just either killed a LM723 or have a dead LM723 in my hands. I'm not sure if I tried feeding in the entire 12V+ output voltage back to the negative input of the error amplifier or not, but now with a voltage divider there, it seems stuck at 0.9V...

That's when I read the datasheet: absolute maximum input is 8.5 volts....

so I might have killed it... One dead LM723!

And here I was thinking those things are virtually indestructible

[eccerr0r]

Re: LM723 adjustable bench PSU not working

I think I just either killed a LM723 or have a dead LM723 in my hands. I'm not sure if I tried feeding in the entire 12V+ output voltage back to the negative input of the error amplifier or not, but now with a voltage divider there, it seems stuck at 0.9V...

That's when I read the datasheet: absolute maximum input is 8.5 volts....

so I might have killed it... One dead LM723!

[Dannyx]

Re: LM723 adjustable bench PSU not working

is the lenovo the yellow rectangle?
http://www.ebay.co.uk/itm/253074640200

Yeah, I said "square"....facepalm....rectangle is what I meant and yes that's the one

[stj]

Re: LM723 adjustable bench PSU not working

Sh!t, I SO WANT THOSE I actually have half that kit - bought it a while back from my electronics store, but a "refill" would definitely be handy. Only downside is that I don't see a square Lenovo power jack. I found that separately in my country but was fairly pricey for a piece of wire with two jacks either end so I let it slide for now. Deffo getting those you linked to

is the lenovo the yellow rectangle?
http://www.ebay.co.uk/itm/253074640200

[stj]

Re: LM723 adjustable bench PSU not working

here is a review:
http://lygte-info.dk/review/Power%20DPS5015%20UK.html

and a review of one that can boost!
http://lygte-info.dk/review/Power%20DPH3205%20UK.html

great site btw, here is the index page:
http://lygte-info.dk/

[eccerr0r]

Re: LM723 adjustable bench PSU not working

Dang now you're making me thinking about getting one or buying the guts for one, alas I already have a 0-18V 15A analog PSU (CC/CV, crappy regulation (overshoot/undershoots like mad) as it's SCR based, but works with fairly high efficiency nevertheless - does not really get hot.)

*sigh*

[Dannyx]

Re: LM723 adjustable bench PSU not working

That said browsing Aliexpress I found this bunch of test leads I might just go for

Sh!t, I SO WANT THOSE I actually have half that kit - bought it a while back from my electronics store, but a "refill" would definitely be handy. Only downside is that I don't see a square Lenovo power jack. I found that separately in my country but was fairly pricey for a piece of wire with two jacks either end so I let it slide for now. Deffo getting those you linked to

[Per Hansson]

Re: LM723 adjustable bench PSU not working

I was instantly reminded of Dave from EEV and how he'd probably throw it right in the trash and call it a complete piece of junk....which actually gives me a great idea for an EEVBlog video suggestion: Dave reviewing one of these China supplies....we all know what the outcome would be, but hey, for the money you can't really beat it

I would not say that at all.
I bought a Elfa branded 5A 30v bench PSU a few months back: RND Lab 320-KD3005D
I absolutely love it because it's compact so fits nicely in my van and of quality steel construction.
Yet it costs well below $100
I choose it over the more advanced programmable version since I simply have no need for that functionality.

But yesterday while looking around Youtube I found it's actually made by a Chinese company called Korad and eevblog had looked at it and first failed it.
But the manufacturer did the right thing and fixed the issues reported with it!

EEVblog #314 - Korad KA3005P PSU Teardown
EEVblog #315 - Korad KA3005P Review/FAIL
EEVblog #404 - Korad PSU Followup

The only thing I would do differently is buy the 10A model (which seems to only exist in the programmable version).
But Elfa has not imported that one, and there is an added benefit of having a local service agent of course...

That said browsing Aliexpress I found this bunch of test leads I might just go for

[Dannyx]

Re: LM723 adjustable bench PSU not working

Which PSU did you end up ordering? Was it a DPS5015 (50V 15A) ?

The smaller ones i.e. DPS3005 (30V 5A) everything is in the display module- no second board.

Some of these do not support charging batteries!

Yes, the one that STJ linked to long ago - I believe it's the most "powerful" of the lot.

[redwire]

Re: LM723 adjustable bench PSU not working

Which PSU did you end up ordering? Was it a DPS5015 (50V 15A) ?

The smaller ones i.e. DPS3005 (30V 5A) everything is in the display module- no second board.

Some of these do not support charging batteries!

[Dannyx]

Re: LM723 adjustable bench PSU not working

Just received that PSU module today and it's pretty nifty The most "professional" PSU I've ever owned so far To be honest I thought it looked a bit cheap, but it CAN take it and the build quality is far superior to other things I've seen...sure the caps are no big brand names, the cover for the LCD display flops around slightly and the knob for the pot was not put on straight, but these are just cosmetics. Other than that, no cold joints, no globs of hot glue like you tend to find on stuff like this.

I was instantly reminded of Dave from EEV and how he'd probably throw it right in the trash and call it a complete piece of junk....which actually gives me a great idea for an EEVBlog video suggestion: Dave reviewing one of these China supplies....we all know what the outcome would be, but hey, for the money you can't really beat it

[stj]

Re: LM723 adjustable bench PSU not working

i think the actual maker sells them direct through AE

[Dannyx]

Re: LM723 adjustable bench PSU not working

those psu modules can be noticably cheaper on AliExpress.

Haven't ordered it yet, so I might look it up there as well

[stj]

Re: LM723 adjustable bench PSU not working

those psu modules can be noticably cheaper on AliExpress.

[Dannyx]

Re: LM723 adjustable bench PSU not working

If you're getting it from ebay you have paypal, if you're ordering from AliExpress they have disputes too, and are very helpful if you provide a detailed explanation and photos/video of the issue you are having.

This Banggood deal seems to be trustworthy as well. From you guys' description, it's similar to those other bigger ones like ebay and Ali....

[Th3_uN1Qu3]

Re: LM723 adjustable bench PSU not working

My only real concern is being able to get my money back in the unlikely scenario that something goes haywire....

If you're getting it from ebay you have paypal, if you're ordering from AliExpress they have disputes too, and are very helpful if you provide a detailed explanation and photos/video of the issue you are having.

[Dannyx]

Re: LM723 adjustable bench PSU not working

From what I read online, VAT is 19% here (RO) and is added when the parcel is shipped from outside the EU or when its value is over 10 dollars, both of which apply in the case of that thingy I wanna buy. It's still not terribly expensive so I'm gonna go for it. My only real concern is being able to get my money back in the unlikely scenario that something goes haywire....

[stj]

Re: LM723 adjustable bench PSU not working

that's in Romania i assume,
each country has it's own rules about maximum declaired value before tax is applied.

u.k. is £15 last time i looked - and getting lower every damned year!!
luckily they only check small parcels from china at random - so you usually arent hit.

they put a lot of resources into monitoring stuff from the u.s. though.