LF501EM5F No Power, Chirping/Beeping Transformer

[Microbot118]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

C3214 is shorted on these main boards its underneath L3201 above the black ribbon connector. It took me 5 hours and a hot air gun but finally cleared the short from P-ON+21V to ground. Hopefully nobody else has to go through that, I can still hear the diode check beep in my sleep. Sets will power on now, I haven't found a replacement yet but will keep you posted.

Put small like sized cap from part graveyard in place of C3214 and is working perfect again.

+1 on C3214. I have a model LF551EM5 that wouldn't power up, power supply board chirped when plugged in. Sure enough C3214 was shorted. Different main board than OP but similar layout. Swapped with a cap from a junk samsung phone main board and it's back in action.

[akk944]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Microbot,

Did you remove C3214 to check for the short... any way to check it without removing it? I still have this TV sitting in my living room.

[Microbot118]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Microbot,

Did you remove C3214 to check for the short... any way to check it without removing it? I still have this TV sitting in my living room.

I tested it in place as a preliminary check. It read 0 ohms, but as Bud mentioned earlier there are other caps parallel to this one. If one reads short they all read short until the culprit is removed.

Once I removed c3214, I verified that it was short off the board and the other remaining caps read correctly in circuit.

If you are new to (de)soldering I would highly recommend getting some flux and braid, and clean well with isopropyl alcohol before plugging it back in.

[akk944]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

I tested it in place as a preliminary check. It read 0 ohms, but as Bud mentioned earlier there are other caps parallel to this one. If one reads short they all read short until the culprit is removed.

Once I removed c3214, I verified that it was short off the board and the other remaining caps read correctly in circuit.

If you are new to (de)soldering I would highly recommend getting some flux and braid, and clean well with isopropyl alcohol before plugging it back in.

Okay! I got it the C3214 cap out. Now I am getting some resistance off this cap off the board.. does that matter?

C3208 which is still on the board and in parallel with the C3214 I removed was previously coming up with no resistance. Now it has some resistance on a higher setting of my multimeter. What other troubleshooting can I do to confirm and where can I source a replacement cap from?

Thanks!

[Microbot118]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Okay! I got it the C3214 cap out. Now I am getting some resistance off this cap off the board.. does that matter?
C3208 which is still on the board and in parallel with the C3214 I removed was previously coming up with no resistance. Now it has some resistance on a higher setting of my multimeter. What other troubleshooting can I do to confirm and where can I source a replacement cap from?

Thanks!

Sorry for the late reply, just turned notifications on so I should be more punctual.

It's hard to say definitively if the resistance on the removed c3214 matters, but if parallel caps are no longer shorted it looks like progress to me. If you want to check that the short is really gone, the easiest way would be to clean the board to get any residual flux removed, then measure the resistance between the 2 unoccupied pads from c3214.

Rather than trying to source a new cap, I really just found a visually similar looking cap with approximately the same footprint from a junk board and it worked.

However, this was a free tv for me so there was no risk involved. I'm not sure what your situation is but I wouldn't recommend this method if this is for a customer or something.

[jason123]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

C3214 is shorted on these main boards its underneath L3201 above the black ribbon connector. It took me 5 hours and a hot air gun but finally cleared the short from P-ON+21V to ground. Hopefully nobody else has to go through that, I can still hear the diode check beep in my sleep. Sets will power on now, I haven't found a replacement yet but will keep you posted.

Put small like sized cap from part graveyard in place of C3214 and is working perfect again.

You saved me hours of troubleshooting. Replaced the cap and the TV fired right up. Thank you very much!