Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

sansui san2701 lcd power supply

Status
Not open for further replies.

Repair-me

New Member
Hi all. currently trying to get a basic power supply running again., its just your mains to 12 volt dc & 24 volt dc output. Nothing special.

Now this particular TV is known to have bad caps, they all end up leaking everywhere over the casing. Ive replaced all the caps in the psu because that was the first issue standing in my way. And it still wouldn't work, now im only focusing on the bottom half of the psu as that’s the 12volt line that runs the standby circuit. Anyway so I replaced the switching diodes next to the transformer. Still no go, then I replaced the mains transistor prior to transformer, and still no go, the voltage in the 12v caps hits 1v. And you can hear a ticking noise. Anyway im thinking it’s possibly the pwm surface mounted controller circled in blue. Just wanted know some professional opinions?
**broken link removed**
.
**broken link removed**
.
**broken link removed**
 

sheldonstv

New Member
if it is ticking you may have a fault on the primary side due to hi esr capacitors-you may have a sc on any of yr smps outputs(shorted diodes etc-it could even be no start up due to oc resistors-.........
 

Repair-me

New Member
if it is ticking you may have a fault on the primary side due to hi esr capacitors-you may have a sc on any of yr smps outputs(shorted diodes etc-it could even be no start up due to oc resistors-.........

thanks for helping. not many people actually reply to assistance here. :)

well after the transformer, all the diodes and caps where changed. and when i put 12dc from another ps, the caps hold charge, thats how i know there's nothing shorting on the output side(cold side). im sure its on the (hot side) prior to the transformer. there are 2 big resistors which connect to the transformer, one gives resistance on my multimeter, the other has no resistance so either its high up there in ohms., or its burnt on the inside, the colours look like either:

68k resistor.
blue, gray, orange, gold

or

6.8k
blue, gray, red, gold

hard to tell the colours

this is a picture of it. but in the picture it looks orange and not red. different story in person

**broken link removed**

and if you look at the board for the yellow circle this is where it was connected to. im sure its meant to have resistance which it has none.

**broken link removed**
.

**broken link removed**

should i try a new 6.8 or 68k first?
 

sheldonstv

New Member
ok that is a 68k resistor,what type of meter are you using???i have several but the main one i use is an auto ranging digital meter.....but that does look like a 68k resistor-make sure you use the correct replacement wattage wise.....
 

Repair-me

New Member
lol human error., my multimeter has a hold button, and it was on, so when i came to measure that resistor. it showed nothing. anyhow now it shows its a 68k. so that isn't the problem. i mean if its not on the cold side, and there isn't much parts on the hot side. could it be the transformer? it ticks and only produces have the required voltage out of the dc side?
 
Status
Not open for further replies.

Latest threads

Top