Repairing 12v power supply

[Deeler]

Hi u all.

new to forum.

I got a 12v power supply thats not working correctly . i will explain circuit briefly. 220v ac goes in to a little transformer mark as l1 on circuit board(0.6X35T lc). Before that i measure 220v ac. after that i measure the same V. then it goes through a reculator(pbl 406). measuring than 320V DC.Then it goes through a couple of Caps rated 100uf 400vdc. Then it comes to my problem . 12 pole Transformer(Rp1100-5s lc 0016). don't know how the hell to measure it then. I am sure that, that transformer is not working properly. were can i get an replacement? I think panasonic vcr's have an simuler transformer on its power supply.....

Any Help please, and could any one explain to me what thats little transformer mark as L1 does..

 

[Nigel Goodwin]

It's a switchmode PSU, not a conventional one, you shouldn't be touching it if you don't understand it.

L1 will be a simple bifilar wound RF filter choke

 

[ecerfoglio]

.......and could any one explain to me what thats little transformer mark as L1 does..

L1 is not a transformer but an inductor (or two inductors wound on the same magnetic core). It is just a filter to reduce the interference that your power supply may generate.

...then it goes through a reculator(pbl 406).....

This seems to be a rectifier, which along with the filter capacitors converts 220 VAC into a DC voltage of its peak value (310V aprox.)

....Then it comes to my problem . 12 pole Transformer(Rp1100-5s lc 0016). don't know how the hell to measure it then. I am sure that, that transformer is not working properly....

That seems to be the "real" power supply or DC-DC converter.

As Nigel posted while I was writing this, BE CAREFULL with line voltage. If you don't know how the circuit works, and you don't know how to work SAFELLY arround it it's better (and safer ) to stay away from it.

 

[Deeler]

Nigel thanks for reply

That PSU that you are talking about are mark on the board as T1. Does'nt that stands for transformer? If it is what you say it is, is there a way to measure it, that it is in working condition?

 

[Nigel Goodwin]

Assuming it's a switchmode supply, failure of the transformer would be incredibly rare - it's mostly the electronics that fails.

 

[Hero999]

Check the following:

The electrolytics haven't gone high ESR.

The input bridge rectifier works.

The transistors that switch the transformer work.

The above three faults are very common, I'd even recommend replacing all the electrolytics as a matter of course.

 

[Deeler]

Check the following:

The electrolytics haven't gone high ESR.

The input bridge rectifier works.

The transistors that switch the transformer work.

The above three faults are very common, I'd even recommend replacing all the electrolytics as a matter of course.

Thanks For replying. i will check that.