Bad power supply

[simba368]

Looking for a power supply for a proscan 32" tv model # plded3273a-e cant seem to locate board has a burnt coil board number is ayo68c-1sf22-b i have several with the same problem attached is a picture of the board any help or thoughts of a possible repair solution would be greatly appreciated thanks mike

[selldoor]

Re: Bad power supply

Are you sure the coil is burnt out? - has it shorted out and blown the fuse?

[simba368]

Re: Bad power supply

i dont see a fuse and yes the coil is burnt thanks

[simba368]

Re: Bad power supply

Are you sure the coil is burnt out? - has it shorted out and blown the fuse?

dont see a fuse coil is burnt you upper right corner

[selldoor]

Re: Bad power supply

Well I cant tell from your pictures - is it the one labelled L1

[simba368]

Re: Bad power supply

Well I cant tell from your pictures - is it the one labelled L1

yes l1 on all boards

[selldoor]

Re: Bad power supply

OK I cant find much on these sets- have you removed one of the inductors - can you see
anything on it that might identify it. Is it just a single coil with two legs or does it have 4.
If there s nothing to identify it and no schematic, you may be down to guesswork!!.
There are some guys on here who might just know what you need.
If it is just a single coil then my suggestion would be to measure it width outside diameter inside diameter wire diameter and see if you can find something similar eg
http://www.ebay.com/itm/10piece-Toro...item43bb184939.

You may be able to calculate the inductance needed by uncoiling one- see here
http://www.ehow.com/how_6026538_calc...ance-coil.html

I suppose the other question is what caused them to burn out?

by the way the fuse on the board is a small red oblong one under the plastic square
bottomleft on your picture

[budm]

Re: Bad power supply

Can I see good clear pictures of the bottom side of the board? That looks like to be common mode choke for AC line filter.
The fuse is the rectangular box close to the AC input connector.
Dose the coil test out to be open circuit?

[matt2oo5]

Re: Bad power supply

Please I m having the same issues, any help will be appreciated

[selldoor]

Re: Bad power supply

Please I m having the same issues, any help will be appreciated

Well - have you measured the coil? - tried to calculate the values?
posted the picture of the back of the board as Budm asked?

[simba368]

Re: Bad power supply

Can I see good clear pictures of the bottom side of the board? That looks like to be common mode choke for AC line filter.
The fuse is the rectangular box close to the AC input connector.
Dose the coil test out to be open circuit?

hi have been really busy thanks for the input the coils are not open and the fuse tests cl i have attached some new pics thanks mike

[selldoor]

Re: Bad power supply

Ok - The L1 doesnt actually looked burnt though it does have a hot spot on the back -its meant to have black stuff on it.

Have you marked one leg of the L1 on the back of the board- Is the solder joint on it good? if not that could cause it to overheat- remove old solder clean trace and resolder.
Have you been testing some diodes the solder on a couple looks odd.
D17 ?

Have you done any testing on the boards - voltage on Big Cap

[budm]

Re: Bad power supply

OK, I thought you are talking about the common mode choke on the bottom left of the picture in post one, now I see you are talking about the L1 on the top right. It is part of the pi filer after the out put of the rectifier, must be a lot of current draw by the load to cause the wire to heat up that much or due to bad filter cap since the inductor will represent high impedance to high frequency AC but low resistance to dc, if the filter caps are bad then there will be lots of high frequency AC which the coil will try to block so it will heat up, it is expecting to see small amount of AC ripple if the filter caps are good.

[ploof]

Re: Bad power supply

Did you ever find out what the problem was ? I have the same problem but my coil is really fried. would you have any direction on the fix, parts replacement or part #'s

thanks

[paulstef]

Re: Bad power supply

The solution is here. https://www.badcaps.net/forum/showthread.php?t=43429

You can use a lot of different inductors but you will need a scope to make sure it doesn't saturate. I also recommend lowering the LED current.

FET and LED controller you get from digikey and aliexpress, respectively.

[paulstef]

Re: Bad power supply

I made a video on how to repair this board: https://www.youtube.com/watch?v=GrfSmtzFjCc

[Ltank]

Re: Bad power supply

Coils usually can short between windings that change the XL on that type you can normally count how many turns are shorted.
If all else fails remove the coil, count the turns and note the spacing between the windings, measure the coil winding diameter then get another coil wire of same wire size and rewind it.

[ploof]

Re: Bad power supply

Wow nice video so since i am a little limited in elctrical calculation if i was to order the core and resistors would you be able to give me what i am looking for as in specs for the resistors and core i would order them on ebay and attempt to fix my tv it was brand new bought over a year ago but only used a couple douzen of times.

Ploof

[ploof]

Re: Bad power supply

sorry if i ask a lot of question but if i understand i would just need to change the coil and add 2 resistors? or do I need to also change the fet and led controller I really want to fix this tv

[paulstef]

Re: Bad power supply

sorry if i ask a lot of question but if i understand i would just need to change the coil and add 2 resistors? or do I need to also change the fet and led controller I really want to fix this tv

Check the FET first. Do a diode test from gate to source. If it's short you will need to replace the FET and probably the controller too. Or do a diode test from source to drain which should have a voltage drop of about 0.4V or 0.5V

As for the core, a few turns , say 10, on one of the yellow cores I took from other boards work great.

The resistors you only need to change if you want to lower the LED current.
It's not mandatory, but I think inductor core and LEDs too may last longer.

Sorry I'm not sure either what you would have to buy on ebay because I do not know the exact specs of the core. But when I put "yellow powder iron core toroid" in ebay search it comes up with several results. I would chose a bigger one than the one that was in there.

Ideally you would need an oscilloscope to measure if the waveform looks good. But it also works without checking it. If the core saturates but is so big that heat doesn't damage it's the FET that is more likely to blow up.