TCL - L50E3020FS not turning on

[Amraks]

Re: TCL - L50E3020FS not turning on

I think I have narrowed it down to being that chip(U401) and But I also thought we might have some bad resistors along the LVCC line but they are testing to near their respected values.

Diodes Tested around the circuit
D401 = Good
D403 = Good
D404 = Good

So checking on the VCC line
R412/2R7 = 3.0 Ohms (good)
R409 /100R = 100.3 Ohms (good)
D402(Zenor Diode going back to ground)= Good
R305 4R7 = 5.0 ohms
*R314 4R7 (not really necessary as it goes into another chips VCC supply which turns on fine and powering its chip, ready signal then switches a transistor enabling power supply for pin 7(Lvcc) on u401 ) = 5.0 ohms

Tested at
R305 = 17.0v (Good)
Pin 7 tested off d401 = 16.0v


Also I have removed u401 from circuit while testing.

I would say this FSFR1700XS is faulty.

[Amraks]

Re: TCL - L50E3020FS not turning on

Thanks all that helped on this TV
A new FSFR1700XS has bought back the voltages and the tv is now working.

[maxvalutech]

Re: TCL - L50E3020FS not turning on

Nice to see a conclusion post as so many fade into the ether leaving one wondering what happened.

[Amraks]

Re: TCL - L50E3020FS not turning on

I like to finish what I started and hopeful someone else benefits from this.
Schematics and data sheets helped a lot to understand that 24vdc circuit that was having trouble firing.
enjoying working on LED TV Power supply problems now days now I kinda know more of what I am looking at.

I think I might get back to Plasma Power Supplies, I have 2 Plasma's I have been putting on the back burner for awhile now.

[Amraks]

Re: TCL - L50E3020FS not turning on

Managed to get another one of these TV's

no ps-on this time

Main filter caps voltage is 324v this time so the other PFC is mising.

both these are open circuit replaced them as they had holes blown in them, I powered on tv and got some new holes in the same components I replaced. all diodes look fine.
R201 = 4R7
R201 = 4R7

I am trying to figure out where to look next.

[dick_barton]

Re: TCL - L50E3020FS not turning on

Got some new holes in what? R201 & R202. If so then check the resistance between pin 1 & pin 6,7,8 of FSL206MR for short circuit internal mosfet.

[Amraks]

Re: TCL - L50E3020FS not turning on

Yes r201 and r202 both have nice holes in them again lol.

FSL206MR
Pin 6 427.3 ohms
Pin 7 427.2 ohms
Pin 8 427.1 ohms

[dick_barton]

Re: TCL - L50E3020FS not turning on

Not a dead short circuit but a very very low reading. Pins 6,7,8 are all connected together internally. I would have expected it to read Kohms while still in circuit.
I would remove it and test between pin 1 and Pin 6 (or 7 or 8.)

[Amraks]

Re: TCL - L50E3020FS not turning on

out of circuit readings

Pin 6 0.680 k
Pin 7 0.680 k
Pin 8 0.681k

[dick_barton]

Re: TCL - L50E3020FS not turning on

I would replace the IC.
With the set off you could also check between the pin1 to pins 6-7-8 on the board (with the IC removed) to make certain there is no low resistance and also the components around it for any damage.

[Amraks]

Re: TCL - L50E3020FS not turning on

pin 1 to pins 6-7-8 no low readings.
no damage except for them 2 resistors which where acting like a fuse.

bit of a back story on the tv
person was watching tv for 4 hours and turned it off into standby mode and 2 - 4 mins later he heard 4 - 5 pops.

[Andrew F. Ali]

Re: TCL - L50E3020FS not turning on

I would replace the FSL206MR. to start with.

[Amraks]

Re: TCL - L50E3020FS not turning on

replaced all these components tv is powering up and shutting down properly.

[Amraks]

Re: TCL - L50E3020FS not turning on

Hey Ended up with another one of these Sets again in fact this one been here twice but none of the above on what I have fixed in the past.
Previous fault was it would turn off back light once it had a channel or input.
I fixed this by resetting tv holding vol - ch + while powering on lasted a few months.

New fault
will flash loading logo and then it will switch off back lights
Here are the voltages
1. 23.90v
2. 23.90v
3. 0v Gnd
4. 23.90v
5. 0v Gnd
6. 0v Gnd
7. 3.25v STB
8. 0V A_DIM
9. 0v Gnd
10. 0v P_On
11. 0.895v P_Dim
12. 3.26V BL_On

Are we looking at dead backlights this time?

[budm]

Re: TCL - L50E3020FS not turning on

Are you sure P_ON is 0V?
BTW, can we see the pictures of the whole backside of the TV showing all the board?

[Amraks]

Re: TCL - L50E3020FS not turning on

Hey Budm hope all is well.

(P_ON is mV plugged in and unplugged) disregard metering error.

[Amraks]

Re: TCL - L50E3020FS not turning on

Here are the photos you requested

[Amraks]

Re: TCL - L50E3020FS not turning on

Hey There P_On is at 3.2v
Just tried my other meter the probe was a bit more fatter and made contact with the pin.

[budm]

Re: TCL - L50E3020FS not turning on

Hey There P_On is at 3.2v
Just tried my other meter the probe was a bit more fatter and made contact with the pin.

OK.
The P-DIM is <1V, so check the Voltage on the P-DIM aging when turning on the TV to see how high it jumps up to and then wait 5 seconds to see what it settle down to.
Your pictures are not clear, I need to see the pictures of the LED driver board since we need to do some Voltage testing on that LED driver board too.

[Amraks]

Re: TCL - L50E3020FS not turning on

P_dim jumps to 4.94v