troubleshooting a tv power supply

R!f@@

Joined Apr 2, 2009
9,918
Really. U have only the bridge soldered and the fuse blew?
Disconnect and discharge the cap and check the fuse again
 

Thread Starter

johndoe45

Joined Jan 30, 2010
364
yep. sparked as soon as i put it in. but lasted a little.

just used the continuity test and it blew.

discharged and checked already
 

R!f@@

Joined Apr 2, 2009
9,918
OK Then
If the fuse blew then there is two explanation, or three may be.
Desolder the bridge and check again for leakage.
Need to confirm the 4 diodes are OK
second ..how is the filter cap, is it bulging from the top.
Can you check it or show it.
third remove the MOV for now. see the attached pic or it may be a cap. remove it and show me
 

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Thread Starter

johndoe45

Joined Jan 30, 2010
364
the filter cap is fine. when i use capacitor setting it gives me the rating on the capacitor. no bulging. and where is the mov?
and how do i check for leakage on the bridge. diode testing again?

i've seen plenty of bulging capacitors on the net so i should know. will take pictures tomorrow. completely dark outside and camera sucks with house lighting.
 

Thread Starter

johndoe45

Joined Jan 30, 2010
364
it is a cap. tested it before
on board it says CN7 so that means it is a capacitor just to verify. can check post 13 to see the number on top side (CN7). little dark but can see number

on the capacitor itself it says

CNR
1 0D471K

girlfriend nagging me to go to Target. so will be back and desolder bridge, cap, and whatever else you suggest.
thanks for the help once again.
 
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R!f@@

Joined Apr 2, 2009
9,918
Hmm OK.. Then the bridge is faulty.
There is nothing else to load the mains with the FET removed.
A leaky diode in the bridge may be the culprit.
Can you get another bridge. May be from a PC PSU or TV board, they will do fine for most of the time.
Don't try to replace it with low voltage diodes ok.
 

Thread Starter

johndoe45

Joined Jan 30, 2010
364
now on diode. can i probe it from the top to isolate it from the circuit and get an accurate test or does it NEED to be desoldered?

Rectifier
KBP206
 

Thread Starter

johndoe45

Joined Jan 30, 2010
364
ok. well will do that when i get back.

on the other side there is another FET right? did i need to desolder that one cause the blue wire could carry the voltage across to the other side and something faulty from there could cause fuse to blow?
 

Thread Starter

johndoe45

Joined Jan 30, 2010
364
alright leaving to Target. let me know what you want me to do when i get back before i go to bed. going to radioshack tomorrow to get new rectifier. said they have two.
 

R!f@@

Joined Apr 2, 2009
9,918
before replacing the bridge you need to put a fuse and power the board, the fuse should not blow, if it does, then you have faulty line filter caps.
You should get AC voltage at the bridge terminals.
See if you can get AC line voltage at the bridge middle 2 pin pads.

wait...

Show me the original fuse first
 
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R!f@@

Joined Apr 2, 2009
9,918
:confused::confused::confused:
There is a problem.....
Tell me is that a new board or an old one.
Something is missing here.
You need to clear this up.
 

Thread Starter

johndoe45

Joined Jan 30, 2010
364
i don't know if it is technically old. its on a tv that was like two or three years old probably.
picture of fuse is on post #1. it is square thing next to inductor. it is labeled but forgot to use black color font. the fuse was shattered. if shook it, could here the pieces.

well the board was fully functional and i accidentally touched board when power was on. thought my friend had turned it off already. so i have no idea where i touched. therefore, this is not a practical tv problem i wouldn't think. not like overusing the tv and blowing some capacitors.
 
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