Faulty Power Supply

That's going to be difficult to do without a schematic or even just a brand amd model number. In case someone here has the same or similar unit so that he can walk you right through the procedures.

But, to give you a starting point, I'd suggest you check the potentiometer used for varying the voltage (that is, if it uses a potentiometer. You didn't give enough info in your post). Then, check the output transistor or transistors. They may be shorted. After that, check everything else .

To make life easier on you, I'd either:

• send it back to the manufacturer (if it's under warranty)
• take it to a service shop

150 Amps, eh? That's big. Biggest I've ever handled is 40 Amps, and it's not adjustable. Well, it is adjustable, but only for fine tuning. It's a 24Vdc power supply and the adjustment only does +/- 1 volt.

Is it really 150Amps? Not 150mA? 'cuz that is big. You could weld with that.

Shucks! I was gonna suggest that he use it for a welder and buy another power supply, but you beat me to it. 'Course, he'd have to limit his welding to 3/8" plate with 1/4" rods . . .

I bought a Sorenson 20 Volt / 80 Amp variable DC supply once, and that wasn't the highest power model they had, either.

I would guess Mbhele is off-line and hasn't had time to tell us what kind he's got, 'cause they're about 7-8 hours ahead of where I am, and I'm planning to be drinking beer less than 5 hours from now.

I don't know what type PS he's got, but some of the people around here have big power supplies made by Miller, a welder manufacturer.

Some old, old, old, big power supplies I have run into are "variable reluctance" types, which controls current to a fixed load (thereby affecting the terminal voltage) by varying the reluctance of interleaved iron laminations (transformer core) by separating them up to the point of complete separation, but I suspect that ain't what he's got.

It's sounds like you've popped the voltage regulator. Imagine that there is a voltage regulator chip, or circuit, in there that gets 40V as an input and outputs a variable voltage. If the voltage regulator dies, then the raw 40V input will be on the output. I would take it apart and see what sort of chips you have on the inside. If there is a 3 or 5 legged device connected to a largish heatsink (chunk of metal) then that is probably your regulator. Find the number on it and you can get a replacement. (Google the part number, or try Jameco or Digikey)

It's also possible that you have a switching regulator instead of a linear one. In this case, the device attached to the heatsink would be a transistor or MOSFET switch. Find the number on it and replace it.

There may be other damage as well, but these components are the most likely culprits.

Also, while you've got the box open, look for any broken wires or PCB etches - many supplies use sense lines to monitor the output voltage. If the sense line becomes open, then the power supply will tend to put out it's maximum voltage all the time.

If you have a voltmeter, try tracing the input voltage through the power supply to get an idea of how it's laid out. Typically there will be an AC input stage, which may be a transformer, followed by a diode rectifier bridge. Then there will be the voltage regulator circuit, which is either a single 3 or 5 pin device (linear) or a larger IC and a transistor switch. The larger device is the switch mode controller chip - these are often 14-16 pins. There may be some protection circuitry in the form of linear comparator chips that monitor the output and/or input voltages and currents. If it's a switcher, there will be some kind of inductor connected to the switch. It's possible that there is no input transformer and the power supply uses a transformer connected to the transistor switch for both the switching inductor, and to provide isolation from the AC lines.

Also, google the manufacturer and part number and see if you cam locate a manual. Try ebay as well. The manual may include the schematic.

Lastly, it's possible that if you have a switching regulator it's in the form of a module - something bigger than a single IC. If that's the case, you can't get to what's inside and you'll have to replace the whole thing.

Have fun, and take notes.

Its a big power regulator. we can find it on market. #2 Bhank's analysis is quite right. I think it would be also a switch power. There are lots of control chip inside now but most of early chip will be 494, 3524, 3892 etc. the output are almost mosfet connected by bridge H type.from your description. I tink the control system is good, because if its hurted by hv or hc, the output will be zero. if its really switch power, mostly there would be sample part. for example tl431 or resemble parts. no feedback signal convey to IC input, so that the control pulse will be max duty, say 50%. so you should according to #2 description step by step, you will find the fault location. maybe a filter capacitor parallel sample resistor brokenout, or some parts last followed it was hurted. but if you are not familiar the circuit, you'd better ask other for help. otherwise you will make large fault if you hvnt a diagram, the best way for you is sent a pic on the net, so that most of us can give a complete analysis to repair it.

bill is right that miller is fa famous welding mahine manufacturer, and olts our pipe manufacturer is using its products especially auto welder. the welder can be 150A, 360A, 400A etc. but their open voltage will be up to 60 -- 120 v and close volt will be less 20 or 10 vot. they are current type power. I suggest he send out pic on net or ask elelctrc engineer for help.

Pls. check the potentiometer(s) for voltage adjustment. If this is open then this could result in complete rectified un-regulated DC voltage appearing on the output side. Most probably there are power transistors in the power supply. If even one of the transistors has shorted, then also this could happen. If this is the case, then the problem is much bigger since you need to then check as to why that failed. There could be a problem in the control circuit.

We manufacture DC regulated power supplies and therefore can provide you with troubleshooting tips.

Ashok Toshniwal, Bangalore, India

way oversimplifyed but.

Switches

Power

Timing

Data.

THE trouble shooting key. Check any fuses first before takeing anything apart.

I would start by unpluging the thing.

omberdonk,

Check any fuses first before takeing anything apart.

'Always a good idea to check those. However, I've yet to see a fuse blow that will cause a circuit to raise it's output voltage instead of cutting it out completely. That would not be the first thing I would check.

Thanks for repplies.

PS name is DELTA elektronika ZIERIKZEE made in HOLLAND.

Sirial no. is 1200 S 24.

I cant see the Voltage regulator. Maybe its because Iam not familier with this components.

Any way i tried to insert pictures of this PS.

I aslo use a Sorensen PS which give 20V @ 150A

Holy jeebus!

The switches are those three things bolted to the metal on the far left of the second photo. Start there. They look to be connected in parallel to the output bus - you can see the etch through the board going to the output lugs.

What kind of test equipment do you have?

Also - check those remote sense lines - they must be connected!

Those are Output Diodes in Parallel.

What kind of test equipment do you have

Fluke 85 Multimeter.

Can't see the V-Regulator.

hmmm - then you should be able to trace from the diodes back to the switch. The etch should be large enough to see, or you can ohm it out. What are those four TO-220's bolted to the central metal rail on the left in the bottom picture?

The switch should be near the toroid - but you have 3 of them. I'd bet that the smallest one is just a filter choke. The board with the blue pot on it must be the regulator board. Are there any components underneath?

You can download the manual at:

http://www.elgar.com/products/DCS/downloads/DCS-E_3kW_Operation_Manual_M362295-01_RevB.pdf

It looks like it covers the theory of operation pretty well.

In the back of the manual there is a link for schematics. It doesn't work, of course, but if you contact them directly, I'm sure they'll give you a link to the schematics. Have your serial number handy.

If you get a link to the schematic and want to share it with me, I'd be happy to go through the schematic with you.

See what more information can do?

I was googling for a schematic or the manufacturer but couldn't find it. 'Should've started with the manual like bhankiii did. Good work.

Have you had any luck with checking the things we've been suggesting? That thing is a lot more complicated than the usual regulators I've been working with but I'd still start with the potentiometers. It's the easiest to check and can cause the symptom you've just described.

Thank you!!!......Thank you!!!.......Very much guys for your effort and expensive time. It was the potentiometer. I was afreid to take it off the bord.

Now both my power supplies are working. But steel need more information in troubleshooting power supplys and common components used to build PS.

I have lots and lots of High current Old PS to repeir on my spear time.

Thanks again.....

Keep up with the GOOD WORK.

It was that blue potentiometer next to the Caps on the left of the second picture.

YAY!!

These days you can almost always find some good info online. The best place to start is the manufacturer.

Good luck.

I have lots and lots of High current Old PS to repeir on my spear time

Dang! I should have asked for a consultation fee!

Good luck. If all those power supplies have the same problem, you'll make lots and lots of money.

Dear Vulcan

on 17-03-08, I had posted a reply mentioning our friend to check the potentiometer for voltage adjustment & that is where the problem was, as acknowledged. Even I should ask for consultation fees!!!!!

Cheers

Ashok Toshniwal, Bangalore, India

Dear Friend

Nice to know that your power supply is now up and going. Thanks for acknowledging as well. I had anticipated that that could be the problem and one of our friends on the forum thought it was "way too simple". Wisely it is said, "greatest truths are simplest".

For any further clarifications, pls. feel free and hope you are able to fix up all your other power supplies as well.

With good wishes & kind regards

Ashok Toshniwal, Bangalore, India

My reply:

I am too late to add some info for the PS as the problem is already resolved, but I can add points about Regulated Supplies from my 30 years in service of Electronics as Service Engr:

1. In early days of 50s Voltage Tapped Suplies came-up, used by Battery-charging shops

and welders. These were & are still in bulk use.

Mbhele's message was as simple that PS is giving Full- uncotr0olled output, So the Control-circuitry was the culprit.

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Hi every one. I have a regulated ( variable output voltage ) power supply with a maximum Output Voltage of 24 volts @ 150Amps. Now the PS output voltage is nolonger variable, when you turn it on it just go up to 40 volts.

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2. Then came the adapters for Transistorised radios [and a little later with Compact Cassett players].

These were & are in use [hundreds Gadgets added].

a. These are Simple Stepp-down transformer rectified with a single Diode or at the most a bridge-rectfier [as chagers for like MobileTel].

b. With addition of Filter Capacitors for Radio etc

c. With addition of dicrete V. Reg [now 3-pin reg are favourites as are simple in design & service]

3. Lager PSs for Labs:

a. Conventional & simple as in para 2 b. & c above

b. Presisin quality, using advanced Electric &Electronic Tech. This is the field I will impart my experience with collegues.

4. Normally low-power & Fixed Voltage PSs use concept of para 2 abve.

Medium-power & above have come-up with Switch-Mode to save bulk of Power Transformer. But mostly as Fixed Voltage [though may be multi-outputs] like PC PSs & Bench PSs for labs.

5. Variable-Voltage Hi-powers are using various Systems like:

a. Phase-Controlled, PWM [Pulse-width-Modulation control] &

Fixed-Voltage Regulation having a Pre regulator to vary the output Voltage.

A Vaiac [Variable Transformer]controlled by Voltage-Control Knob + Fixed Voltage Reg in series

Hi All,

Starting at the manufacturer is indeed the best thing to do. We, the Dellta Elektronika customer support team are always willing to help you. Just send an email to support@delta-elektronika.nl

Best regrards

Delta Elektronika