LF501EM5F No Power, Chirping/Beeping Transformer

[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

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.

[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 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

[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.

[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!

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

@CityWideTVTech! Iam working on the same tv you mentioned with the c3214 cap! I've replaced the cap from another model with the same main board and still getting the little chirp when plugged in! I even removed the cap and just jumped the two points! What am I missing/doing wrong? BTW Iam new to TV repair!

So you jumps the two legs of the filter cap together? if so you may have caused more damages to the circuits.
Did you check to see if the cap shows low resistance before you replace the cap? May be the shorts is not in that power supply section. you need to check the resistance of all the Voltage output pins and GND to see if any one of them show very low resistance when all the boards are connected to gether.

[SLK001]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

I even removed the cap and just jumped the two points! What am I missing/doing wrong? BTW Iam new to TV repair!

Sounds like you're new to electronics, too. You NEVER jumper a capacitor. Look at your schematic and see what you probably destroyed.

[CornerCreekTech]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

@CityWideTVTech! Iam working on the same tv you mentioned with the c3214 cap! I've replaced the cap from another model with the same main board and still getting the little chirp when plugged in! I even removed the cap and just jumped the two points! What am I missing/doing wrong? BTW Iam new to TV repair!

[citywidetvtech]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

C3214 is a 270 Pico cap btw.

[citywidetvtech]

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.

[martystv]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

I didn't know they had that. Looks pretty cool. I did take the panel apart and all led's are working.

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

LED tester or good variable power supply with current limitter would have help without taking the panel apart.
I.E.
http://www.shopjimmy.com/sid-gj2c-le...ght-tester.htm

[martystv]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

thanks for your help budm!! I will open the screen this weekend and check out the led's.

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Well, at least we learn something about this version of the power supply and main board, the 3.3VDC standby Voltage is generated by the main board which gets the 8V from the power supply during the standby mode.

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Ha Ya what a deal. I have a friend that picked it up from the curb and asked me if I could get it running for him. And of coarse you always dream of the easy bad cap issues, But that never seems to be the case for me. Ha Ha. So I told him I would take it to the shack and look at it. I'm thinking the main board went bad first with a shorted ceramic cap on the 3.3 vdc voltage regulator circut, and then it made it to the curb and in the process I think it was dropped or damaged or who knows. So that the deal. Thanks for asking.

[stj]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

smashed screen wont effect the protection circuit.

so you have a smashed screen, bad mainboard and bad led's?
sounds like an un-natural combination - did someone sell you that tv?????

if you fix or bodge the led issue to get the tv running, and verify it sort-of works,
you can sell the boards.
if you take out the led strips you can sell the working ones.

or you can scrap the mainboard and glass, mod the psu to keep the leds on and use it as a workshop lamp.

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Well that was a waist of time and resources!!!! Couldn't see this one until the back light came on. My Protect3 voltage was .87 also.
Thanks again budm

[shadetreetrader11]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

I'm having a heck of a time figuring out what to jump where to get the back light on.

[budm]

Re: LF501EM5F No Power, Chirping/Beeping Transformer

Normal will be 2~3V range, so you do have LED problem same as the OP in the other thread.