Looking at the board theres 2 seperate powersuplies 12V & 24V with 2 seperate driver ICs. Surely they both arent faulty? I would have suspected something common to both to be the problem. Before the 2 suplies.

 

again you also have to check if your transformer is in good condition. you know a short in the trans. can cause that especially at the secondary side of the trans.

Who are u?

 

No load, nothing nada.....just open circuit voltage is OK, even a light load cause the voltage to drop, when removed, voltage comes back slooooooooooooooowly.

A load can be anything drawing current. A blown IC, transistor, capacitor etc can all become loads draining current.

A regulator that only "works" no load often means the feedback control circuitry is OK but the power device(s) are blown. They pass enough leakage current to put the output at the right value unloaded but fail anytime any added load is required.

 

Haven't u been reading..
I have changed all the faulty caps in the secondary and this thing is a SMPS.
Would a blown device give no load voltage...

Which planet are u from ?

 

Check the orange poly caps, they have probably gone open (or close to.)

Also measure the ripple on the power supply under load. 300VDC sounds too low, it should be close to ~320VDC in standby and 350 - 400VDC when running.

 

Haven't u been reading..

Which planet are u from ?

The one where I designed power supplies for 30 years. Let me repeat what I said:

A regulator that only "works" no load often means the feedback control circuitry is OK but the power device(s) are blown. They pass enough leakage current to put the output at the right value unloaded but fail anytime any added load is required.

And add this: your post is the electronic equivalent of:

My car doesn't run right, what's wrong with it?

You probably have an off-line switcher designed based around a half bridge topology using dedicated ASICs unique to the manufacturer. When a converter blows and transistor junction get punched, it often puts high voktage onto the low voltage drivers and/or control circuitry. In short, it can blow almost anything or everything. That's why a low wattage power supply is considered a disposable item. Even if you had the schematic, the "repair" procedure is to change every part that could have been hit and that typically costs about 3X what a new replacement P/S does.

 

You probably have an off-line switcher designed based around a half bridge topology using dedicated ASICs unique to the manufacturer. When a converter blows and transistor junction get punched, it often puts high voltage onto the low voltage drivers and/or control circuitry. In short, it can blow almost anything or everything. That's why a low wattage power supply is considered a disposable item. Even if you had the schematic, the "repair" procedure is to change every part that could have been hit and that typically costs about 3X what a new replacement P/S does.

I guess now you make sense to me.

OK then, let me get whirl at all the caps.

 

i have yr manual but cant upload it because the filesize is too big-the pdf limit here is 5mb???the file is 6.1mb

 

i have yr manual but cant upload it because the filesize is too big-the pdf limit here is 5mb???the file is 6.1mb

You can split it here: http://foxyutils.com/splitpdf/
Make sure it's not copyrighted if you want to post it here.

 

and cant split the files eitha..........

 

Sheldons, I have sent u a PM..turn it on if u have not

 

is this yr set??

 

is this yr set??

Does not even come close to what I have..mate
Thanks anyways

 

I worked on a 37PFL7662D/05 which seems to have a similar power supply. Tell me - how many mains filter caps are there (2x100u or 3x100u?)

It had an inverter problem, though. Not PSU. Was an easy fix too...

The 42" version (same as 37", different screen size) has a service manual here. http://www.eserviceinfo.com/download.php?fileid=61885