Samsung UN55ES7100 Blinking front light and no backlight - clicking

[R_J]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

Almost all the schematics I have seen that are similar feed QS801 transistor which acts as a voltage regulator/switch with about 20~25 volts, the input is the collector, output is the emitter and what acts as the reference is the base (which is also turned on/off by the opto), and almost all of them use a 15 volt zener diode as a reference diode from base to P-GND. so supplying the input with 13 volts you will not get enough voltage out to run the pfc ic.

[budm]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

almost all the schematics i have seen that are similar feed qs801 transistor which acts as a voltage regulator/switch with about 20~25 volts, the input is the collector, output is the emitter and what acts as the reference is the base (which is also turned on/off by the opto), and almost all of them use a 15 volt zener diode as a reference diode from base to p-gnd. So supplying the input with 13 volts you will not get enough voltage out to run the pfc ic.

+10

[jason123]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

Does that mean the Zener is bad? it's not fully turned on? or is the transistor bad??

Can you share a schematic possibly that i can go through node at a time to see where the failure is? Thanks R_J

[R_J]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

No it means the voltage being supplied is too low, the 15 volt zener won't start to conduct untill it sees at least 15 volts, you are supplying 13
here is a similar schematic
If you have a 47µf for cs805, replace it same with cs802 10µf

[budm]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

BN44-00523B schematic may be close enough to REV A board.
B uses SPC7011f for PFC IC. You need to check the board layout and compare it to the schematic.

[jason123]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

So i replaced them with brand new caps 10 and 47 uF @50V, and now the on voltage has dropped from 13.1 to 12.55 V
Does that make sense?

[budm]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

How about the Voltage on cap CS802, does it change a lot too?

[jason123]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

13.1 to 12.55V was referring to voltage on JP810 before and after replacement of caps.
Would you like me to measure voltages on the caps directly?

[budm]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

13.1 to 12.55V was referring to voltage on JP810 before and after replacement of caps.
Would you like me to measure voltages on the caps directly?

That is the Voltage for CS805, I like to see if the Voltage on CS802 (for running the stby SMPS IC) acting the same as CS805 or not.

[jason123]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

CS802 is reading 9.62V with TV on or off

[budm]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

That seems low to keep the stby IC running, but at least it is not changing like the one on CS805 for running the PFC IC.
I wonder if DS806 for the PFC IC power supply may be leaky: https://www.badcaps.net/forum/attach...3&d=1559233792

[jason123]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

Just got the ShopJimmy repair kit... they sent the wrong pfc chip (through hole instead of surface mount package)
I replaced DP808 and ICM801. TV IS WORKING! Not sure which IC did the job.

Thank budm and the rest for the help.
Special Thanks to R_J: though I made few stupid mistakes in the reporting you were very kind and helpful!

Side question...this TV has annoying light on both sides; from either angel of viewing you can actually see the leds... is that normal?

[budm]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

Good to hear, at this point you should take those Voltage measurement for future reference.

[jason123]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

Voltage went up to 15.4v when TV is on (up from 13.x V)

[budm]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

At JP810? I thought you were getting about 17V when TV is off and then it drops down to 13v when TV is on.

[jason123]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

Yes, now when TV is on, it doesn't drop as much. It goes to 15.4v, enough to turn PFC chip on from what I learned

[jason123]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

Any comment on the edge light? Is this normal?

[budm]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

I see that on my edge lit LG also.

[budm]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

Yes, now when TV is on, it doesn't drop as much. It goes to 15.4v, enough to turn PFC chip on from what I learned

I expect higher than that on JP810 since that Voltage needs to feed the 15 Voltage regulator section to be able to get 15V out of the regulator circuit, the input has to be higher than the output to have head room for regulation.

[jason123]

Re: Samsung UN55ES7100 Blinking front light and no backlight - clicking

It's been running for few hours... hopefully I didn't button it up too soon