LF501EM5F No Power, Chirping/Beeping Transformer

[martystv]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

I have a Magnavox 46me313v/f7. I checked c3214 and sure enough it was shorted and fixed the problem Good Call. Also Budman I took your advise and got the LED Tester from SJ and it has already been a big help. It's pretty cool. Thank you both for the good advice!

[Shane711]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

I was about to give up on this but I think I found the problem. I have this power board and no TV to test it in because someone sent it to me hoping I could fix it. Board number BA3AU0F0102_2. I wasn't sure if the board was bad but I read this whole thread and it didn't help me much on this issue but I finally found D614 to be shorted. I have another board I am going to swap out the diode from but I will need to buy some new ones. I can not tell what this diode is. It is only marked "BR"

I also suspect IC601 which I found to be FA5640 Switching Power Supply Control.

The person said his TV was hit by lightning and he replaced the main board. I am going to swap out these parts and retest the board. Hopefully I have fixed the problem and I can send this board back and be done with it.

[Shane711]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

OK, so here is the follow up. After removing the diode D614 is was not shorted. But after replacing IC601 the short was gone. Then I tested the board and I got my voltages up and running so the board is fixed. Seems like the cause was IC601 and it was shorted making me to think the diode D614 was shorted.

Also if anyone attempts to remove IC601 it is glued to the board. I removed mine with my mini heat gun but the board pop corned and the IC popped up off the board. If someone knows a better way to remove a glued down IC I would like to be educated.

This board is now being boxed up and shipped back to its owner

[CapLeaker]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

easy. cut the traces of the IC with a knife, put a little heat on it and pull the IC off or carefully lift it with a flat screwdriver. Then remove the cut off legs that are soldered to the pads with your soldering iron and fresh solder. Done.
I have to admit, that I didn't see any IC601 go bad on those Emerson's yet.
If D614 would have been shorted, you would have more trouble back on the primary side. However, it is a very good Idea to replace D614 with a better diode to prevent a bad outcome later.

[Shane711]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

OK, so in order to replace D614 with a better diode I need to know what the original is and then I would get one with a higher amp rating, right? I have no idea what it is.

And if I read your post I would understand that is to cut the traces on the board but I think you meant to cut the legs of the IC and then remove the IC and remove the legs from the board with a soldering iron. Yes, this is a good way to do it but for sure that IC will be trash after that ordeal. But I guess it is the best way and has to be done.

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

This may help:
TFZGTR27B, it is there to clamp the Voltage on the VCC pin from over Voltage.
You can go with 1W instead.

[Shane711]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Would this be the correct part number for the 1 Watt Diode? DZ2W27000L

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

DZ2W27000L has bigger footprint so you need to find way to fit into the old footprint.

[Shane711]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Are you saying it is bigger in size? That shouldn't be too hard. But I rather have one that would fit in the spot, not sure how to find it I guess. I expect it would be a little bigger.

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

If you look at the spec sheet of both diode, you can see the dimension spec.

[CapLeaker]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

OK, so in order to replace D614 with a better diode I need to know what the original is and then I would get one with a higher amp rating, right? I have no idea what it is.

And if I read your post I would understand that is to cut the traces on the board but I think you meant to cut the legs of the IC and then remove the IC and remove the legs from the board with a soldering iron. Yes, this is a good way to do it but for sure that IC will be trash after that ordeal. But I guess it is the best way and has to be done.

YES, I meant the legs off the IC, not the traces. Sorry, I was in a hurry to write this post.

If Kaboom would read this, he would be blastin me again.

[Baron7]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

same symptom I fix change main board and work

[fcisolutions]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

C3214 is a 270 Pico cap btw.

So I too have the same tv. Did you ever get a replacement part?

[fcisolutions]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

I have a Magnavox 46me313v/f7. I checked c3214 and sure enough it was shorted and fixed the problem Good Call. Also Budman I took your advise and got the LED Tester from SJ and it has already been a big help. It's pretty cool. Thank you both for the good advice!

Hey @martystv I have the same issue although C3214 and was trying to not only find a replacement cap but need help with polarity.

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

C3214 is the MLCC (Multi Layer Ceramic Capacitor) brown rectangular shape SMD cap, right? So there is no polarity for that cap.

[JDC]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Confirmed: c3214 on main board replaced, TV works fine now.

[DrDigitalKC]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

C3214 is a 270 Pico cap btw.

I have this exact TV with the same chirping sound when plugged in.
I replaced a blown power supply about 8 months ago.
I've scoped out this power supply and cant find any bad components. I unplugged the ribbon cable from the main board to the power supply board and the chirping stopped. I'm certain the main board is the issue.

It seems to have been confirmed by you all that the problem lies with the C3214 cap on this main board.

The value is a 270pf...
What is the voltage?
I see several different ones available the most common being 50v.
I would guess that a 16v would do for this application.
Anyone have any idea or link to a good replacement part?

[Shane711]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Go 1 step up on the voltage. Do not use the same voltage or the cap may go bad again. If it had a 16v use a 25v or higher. The voltage just means how many volts it can handle before it fails so the higher the voltage the stronger the cap.

[DrDigitalKC]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Go 1 step up on the voltage. Do not use the same voltage or the cap may go bad again. If it had a 16v use a 25v or higher. The voltage just means how many volts it can handle before it fails so the higher the voltage the stronger the cap.

This is good info... however I need to know the original value of said cap. I do not have, nor could I find the schematics for this board.
and yes, I did plan on upgrading the voltage tolerance.

[DrDigitalKC]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

UPDATE:
Fix confirmed.
Changing cap C3214 fixed the issue.

Original symptom:
The tv started "chirping" in cycles every couple of seconds on would not power on.

I have confirmed it is a blown cap on the main board location C3214.
Another tech here confirmed it as a 270pf cap, however voltage is not yet identified.
We ended up scrapping out a similar but smaller Emerson tv with a broken panel but similar main board. it had the same layout. I transferred C3214 from one board to another, and my LF501EM5F has life again!

We need to figure out the voltage of either the original or an acceptable replacement so we can either link to a replacement part or at least narrow it down for our next fellow tech to run across this issue.