Hi this is a medion laptop that runs of battery power but will not charge a battery. On the photo charger socket bottom and just above in middle of pic there is a small oblong peace on charging circuit. I think this has failed can some one tell me what it is and can i replace it thanks.

 

PF501? Possibly a fuse as it's directly in line with the power input as far as I can tell. What does it read on ohms?

The photo could be better?

 

PF501? Possibly a fuse as it's directly in line with the power input as far as I can tell. What does it read on ohms?

The photo could be better?

PF501? Possibly a fuse as it's directly in line with the power input as far as I can tell. What does it read on ohms?

The photo could be better?

I just tested voltage on one side i had 19 volts the other side 0. On a different board i had 19 volts both sides i looks possible to replace but don't no what it is thanks for reply

 

I agree with Paul above, it looks like a surface mount Poly Fuse. See http://www.littelfuse.com/~/media/e...e_ptcs/littelfuse_ptc_lorho_datasheet.pdf.pdf
Those are supposed to reset on their own. If the fuse is permanently bad, you may need to see if something is shorted on the 0 volt side.

 

If it's open then there is probably a reason for that. I'd measure the resistance from the output (that reads 0) to GND. You might have short somewhere

EDIT: well just saw that roderick said the same thing

 

Ok thanks for the replies ill have a look tomorrow

 

Ok finally got round to checking this it looks like the thing to the right of the poly fuse could be the problem. A small round thing that bridges across from positive to negative just above charger scoket.
So does anyone no what this is and what it does.

 

Looks like it has a cathode mark on it and a diode silk screened under it...

BR
Dennis

 

Agreed; looks like a diode. Is the mark under your arrow 'PD501'? A meter check should show higher resistance one way than the other. The 'D' in PD502 suggests that's a diode too.

 

Yes its PD501 could this fail and cause a short. And why does it bridge the charging circuit looks like it goes across positive and negative from charger socket.

 

It may be a reverse voltage protection diode. That would protect the mother board from an external source having the wrong polarity. If one was connected, it may have resulted in a shorted diode. I did that once connecting a rechargeable battery to my bench top power supply. The reverse polarity diode protected the power supply from the battery current by conducting, then shorting.

 

Thanks for replies after testing on meter there is no resistance so it's blown. Does any one no best place to get a replacement here in the uk and what spec I need

 

PD502 looks like a regulator to me.

Looking at the Pletter501 and Pletter502 etc I would think that these are simply taken from bins marked with this scheme without regard to component type for assembly by unskilled labour.
That is they take whatever they find in bin PA501 and put it in location PA501 on the board etc.
There will probably be other letters identifying other parts of the board.

PD501 will be a 5amp 50 or 100 volt diode if the diode idea is correct.
Two things to check

dl324 pointed to a silk screen character. Is that a diode and is that the correct way round for reverse protection?

 

If it was, indeed a diode, and connected the non-conducting way across the output, then maybe you could simply remove it, and see if the assembly came back to life? Afterwards, you could then decide what kind of protection to put in.

 

Why would it be connected the non conducting way?

I think the idea was a series connected diode to protect against reverse connection of the power supply.

A parallel connected diode could have been connected as sacrificial protection against overvoltage, but I doubt it.
In any event the component is non conducting now and if it was connected so it was non conducting in normal service how could removing it make any difference?

 

The OP said it bridges between the Pos and Neg just above the charger socket (re... post #7), therefore it would protect against a reverse polarity input. Not too uncommon form of protection.

Also, the OP said it shows no resistance. Clarification is needed as to the meaning of "no resistance"? Does that mean short or open to him?

 

I'm with studiot.

Why put a diode across the supply that will probably be destroyed by reverse connection of the DC supply? Does it not make sense to put a suitable diode in series with the positive supply. it protects against reverse connection and doesn't get damaged in the process?

 

Hi Paulktreg,

Does it not make sense to put a suitable diode in series with the positive supply. it protects against reverse connection and doesn't get damaged in the process?

If I was protecting against an incorrect power supply being used, I'd add a few more diodes and make the input independent of polarity. But that would add extra cost and it adds up if you plan to ship a lot of units...

 

Besides all of the above, a series diode would prevent needed repair. Design engineers, now days, seem to go out of their way to insure DIY repair is very difficult, if not impossible. Automobile repair often requires "special" tools to even gain access to the problem Or one bolt will be mounted behind some other part requiring major disassembly just to make an otherwise minor repair. I think they must teach this in school now.

 

What model # is it, and does it require a 150 watt 4 pin ac adapter?

Apparently these are fairly high end laptops, so I would expect good design.

Just curious...