Australia's Science Forum

Hi everyone,

We have quite a few transformers/power packs that need repairing. Does anyone know how much it costs to have one repaired and who does the repairs??

Thanks.

have you checked the fuses?
We took ours to an electrician who repaired them - just a normal electrician

Any idea how much it cost? I have one that is reading high on the voltmeters (ie dial says x, voltmeter says x+y). Last time I had a broken but potentially fixable powerpack I asked our maintenance/ groundsman who sid they weren't worth the cost. Not sure how accurate that is

First check the fuses..then
we have one lab tech in thie area who is a whiz with this sort of stuff, so first we ask him
If that is no good then we take ours to a local electrician who is prepared to do them - and not all are prepared to do small items. We get a quote first before going ahead.

dumb question, but where are the fuses situated, and do they look like the ones in microscopes?
Sorry, I'm not a particularly electrically gifted, but I know enough that I don't want to hit a capacitor and end up in the next edition of Darwin Awards.

Where is NSW are you?

Now the voltage output is only a rough indication because it changes with the load you put on it.
Give me a word picture or make and I'll answer some of your questions

Ocker - you know who I meant in my post!!!

O that guy Sunray!

Well, I'd simply been hooking the powerpacks up to a DC voltmeter, and testing/reading the voltage as I turned the dial to 2V, 4V, etc. All the other voltmeters were reading correct to about half a volt, but this one was reading 14v when the dial was turned to 12V. The type is ST907A 220/240V input, AC 50/60Hz, total load 5 amp http://www.chemtalk.com.au/viewtopic.php?f=26&t=451/Online%20Stor ... d=13996150 It looks a lot like this. I can't seem to embed the image.

Everything is working OK!
It's possible for the output to be up to 16V on 12v setting with no load
It's a function of the smoothing capacitors in the output the value is 12v RMS (root mean squared) ( 0.707 of peak) but it's possible to go up to peak value

Sorry I meant to say all the other powerpacks were reading correct to half a volt, but I think you got my gist. Thanks Ocker, you're a man of many talents.

The others have better quality smoothing, but nothing wrong with it.

geeeee .. I never check mine like that.. if they WORk is all i am interested in.

So my HOD has decided that our dead power packs are not worth fixing and to get rid of them. Can I just chuck them in a bin or do they need to be disposed of in a particular way?

Save them for me, I can often make one good from two crook especially the older type can all be fixed they are of basic construction the later type constructed on production line are too hard to apart to be worth it but a lot of goodies can be salvaged

P M me to let me know where you are, if not too far I will collect

We have several that are either tripping out, or clicking when we use them. They are all IEC Cat No. 2633-001. Does anyone know if they are worth repairing or should we just throw them out & buy new ones? Our physics teacher has said that they're not worth the cost of repairing.
TIA
Mel

Melded
I've had two do that . One was shorted rectifier diodes and the other shorted OVP zener diodes.

You can buy the bits from IEC . Being a TV tech I found it no biggy to fix but you will need a good soldering iron and solder sucker .......and about an hour.

But we are probably not allowed to

Your Physics teachers probably right in that if you had to pay to get them repaired it would certainly be more than half the cost of a replacement

Yes you are right the amount of work to separate the two boards makes them not worth it, if paying labor costs, the older type were easy to repair,and better quality components.
Such is life.

Ocker, what's the brand and model number of that which you describe as needing to separate the two boards? I can work out which one you are referring to.
Harv