Delta Elektronika ES 030-10 CC problem [SOLVED]

[JacquesBBB]

I  found a Delta Elektronika ES 030-10  SMPS  from my favorite dumpster.

Its a nice unit that was reviewed in
https://www.eevblog.com/forum/testgear/delta-elektronika-es030-10-power-supply-review-teardown-and-tests/msg800910/#msg800910
but  mine is not working properly, as otherwise it would not have been in the dumpster, but it looks like
a unit that worth  to be repaired.

- The voltage seems to work fine from 0 to 31 V, although
there is a strong ripple signal at the oscilloscope.


But the main problem is in the CC  setting. The CC  pot is totally unresponsive, and the display stays always to the same value (1.58), whatever is  the real  current value. I made the test here with a 22 R resistor so the  current value
at the meter are the right ones.





Does anybody can give me some direction for  repairing this unit ?
Thanks

[Floyo]

Its probably a good idea to contact Delta, their support is top notch, and they will probably have a good idea what might be wrong and will almost certainly be willing to help in some way. http://www.delta-elektronika.nl/en/contact/company-details.html , the support address is the one you want.

Next to that you can of course start troubleshooting. Seeing as the current meter always displays 1.58A regardless of load, this would suggest an issue with the sensing circuitry, not the potentiometer etc.
The shape of the ripple is also weird, the converter should be switching at 100Khz, which is about the time between the ripples, but not quite. On my unit that ripple is sinusoidal, and also spot on 100Khz. Since the supply runs of a crystal timebase it should be pretty precise. Also the amplitude of the ripple is way to high.

But, the first rule of troubleshooting is "measure voltages", so start by checking the auxiliary supply that feeds the regulation circuitry. See if the voltages on the ribbon cable are ok, if they have lots of ripple etc. Those voltages are generated by a small flyback converter situated close by the main filter cap.

Also, don't forget to check the simple things, the pots inside the unit, the programming switches on the rear etc. There are also some things you can measure on the programming connector, There is an Imonitor output, see if that also thinks 1.58A is being measured by the shunt regardless of load. The reference voltage is also present there, see if that is within spec just to be sure

http://www.delta-elektronika.nl/upload/dts_es300.pdf you can find the pinout here.

All the ICs used are fairly standard types, so finding datasheets is no issue.

[JacquesBBB]

Thanks for your advices !

Do you have  the ES 030-10 schematics ?  I found  the ES 030-05 one on http://elektrotanya.com/
but not the ES 030-10.

I have indeed looked to the rear connector, and made a few measures there, but I will have to check again.

[Floyo]

I do have the schematic, but I'm not sure if sharing it is ok, so you will have to contact Delta for that.

Another thing I wondered, that screenshot of the ripple, at which conditions was that taken e.g. output voltage and load. Also, does the output ripple change a lot when loading the supply down, and how do you probe the output? Lead inductance can really mess with measurements, the connection that is visible in my review thread is a decent way to go, otherwise just try to keep all wires as short as possible to rule out any errors due to probing.

Right now its not really clear to me if the CV output is totally fine or if something fishy is going on, so figuring that it is important. The ripple should be pretty low, as per the datasheet spec. The relevant waveforms can be found in the review, those were all taken at full output voltage.

[Kjelt]

Yes contact Delta, they sent you the schematic, they can also repair it for you against costs. Beautiful psu, definitely worth repairing.
I had my 0-300V, 5A a similar issue, these psu  seem to have a problem of reverse sinking. In my case it was only one opamp that was damaged, replacing it fixed it 100%. 

[JacquesBBB]

I have  found the problem with the ripple. It was because I had remove the shielding   in order  to
have access to everything. With the  cover put back, I get a much  better response, that is now in agreement with the datasheet. (18mV pp).

I had my 0-300V, 5A a similar issue, these psu  seem to have a problem of reverse sinking. In my case it was only one opamp that was damaged, replacing it fixed it 100%. 

I  am suspecting something of the sort, and check the OP177, but it seems OK (V+ ~ V-) .
Which Opamp did you change ?

[Floyo]

Hmm, that looks a lot better indeed, and basically rules out any gross issues to do with power rails, wonky regulation etc. Next up is to check out the current sensing circuitry. The Imon output works from the same 0-5v signal as the panel meters, so its a convenient way to verify/measure the output current externally. the 0-5v from the frontpanel pot can be picked up from one of the legs of the internal/external switch. The centre one carries whichever signal is selected. Your prime suspect is the op177, its configured as a rather standard differential amp. The approximate gain you can work out from the maximum output current, the shunt value and the fact that the output ranges from 0-5 volts that goes to Imon. This wont get you the exact value, but it should be close enough to get an idea if its working ok.

There is also a potentiometer close to the Op177 that trims the offset of that opamp, see if that is in order.  And the other pot in the circuit is the Ical one, which does as the name implies and scales the op177 output voltage.

[Smith]

Some of these older units had non gold plated headers. They tend to give bad readings, like mine did. I cleaned the header, and all is working fine. I should replace it though.

They are really good power supplies, and I like them more than the newer models with smaller displays and their crappy safety bananna connectors.

[JacquesBBB]

I have checked the rear output connector.

Everything with voltage is fine, and I could perfectly tune it with the pots.
On the Imon pin, I have only -0.789 V  whatever is the  current  through my  22 R resistor.

I may try to change the  OP1777  as I should have   one somewhere. In any case, I will put a socket.

[Floyo]

That -0.7 volts sounds suspiciously like a diode clamping the output voltage to a max negative value. Finding that diode and measuring upstream of it might give more insight into what is going on, whether the output is pegged to one of the rails etc. You can also check the output of the OP177 and see where it sits at.
Also measuring the voltage from the + and - input of the OP177 will tell you if the opamp is happy, if they are the same the opamp is ok, if they are significantly different something is wrong.

[JacquesBBB]

Victory !

I changed the OP177G  to a OP177GP I had around,




and everything is working fine now.

 

So thanks for All !  Any hints are always very useful and  you both help me to take the right move.

I still have a small offset  between the  Current and the monitoring pin in the back,  but  this should be easy to fix now.

I am very pleased, especially as this unit was in the trash. It would have been a pity to destroy it. This is one of my best power supply so far, and the fix was  finally  easy. All the unit is very clean.

[Floyo]

Nice , glad it worked out smoothly. Now you have a nice supply that should be good for a long time again. Why whomever threw it out decided to not attempt fixing it is a bit of a mystery, but I guess you shouldn't complain

[Kjelt]

I had the same luck, psu died and some manager decided it was not worth the repaircosts also since they did not need the high voltage with software engineers (dangerous).
  with the fix, exactly the same problem and solution as with my psu though it was an smd opamp different part number, this seems to be this psu design achilles heel, better stock a few spares just in case.

[JacquesBBB]

I have now tuned  the unit, and everything is now spot on !

I got many power supplies of various kind from the dumpster and fixed several of them.
The most surprising case was for a modern classical unit ( 2 x 30 V - 3A + 5V) where the only thing I had to do was to change  the fuse (somewhat hidden).

The delta elektronika is one of the best (if not the best) I have. It is really rewarding to use devices that you have saved from the trash and repaired. Most of my workshop is equipped that way, and I must say that the help from the forum has been extremely precious for these repairs.

[Groschwald]

Hallo an das Forum

Ich habe ein ES 030-10

Ich suche dringend einen Schaltplan zu diesem Netzgerät.

Meins hat den Fehler das es garnix anzeigt.

bis jetzt geprüft alle Sicherungen OK, Gleichrichter OK, bis zum DC Kondensator alles OK. keine weiteren Hilfsspannungen vorhanden.

ich hoffe es kann mir eine weiterhelfen.

[Kjelt]

You can mail the TS of the manufacturer below, be specific, does nothing is not going to do it 
If the PSU is no longer produced they will sent the technical manual.
If it is they sometimes help you in the right direction.
If there is some exotic part failing they will sent you a replacement for COG and sometimes even free per mail.
As a last resort you can always sent it to them for repair.
Try that with some other brand psu 

Technical Support
Delta Elektronika BV
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www.deltapowersupplies.com
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