Inexive (Vestel) TV constantly blinking after plugging in

[unimatrix93]

Hello everyone, I have a constantly blinking Inexive LED TV.
Display is: VES390UNVA-2D-N01
Mainboard: 17MB97
PSU: 17IPS71

The TV power led start blinking constantly right after plugging it in, I tried to update via USB but did not help.

[unimatrix93]

I did some measurements on the PSU and C20 and the other two 400V filter caps has only 320V total.
Also there is a rithmical clicking noise from the PSU, like it tries to turn on.
I checked on PWM IC FAN6300A and VDD is only 5V, and HV goes from 0 to around 175V following the ticking noise pattern.

[nomoresonys]

Check for bad solder joints on bottom of powerboard.

[unimatrix93]

Check for bad solder joints on bottom of powerboard.

I already did with microscope.

I measure the connector on the PSU:

ST_BY: 0V
BL: 0V
PWM: 3.3V
5V_STBY: 0V
12VCC: 12V
I measured these while the mainboard is connected.

[unimatrix93]

Check for bad solder joints on bottom of powerboard.

I already did with microscope.

I measure the connector on the PSU:

ST_BY: 0V
BL: 0V
PWM: 3.3V
5V_STBY: 0V
12VCC: 12V
I measured these while the mainboard is connected.

[nomoresonys]

Unhook powerboard from mainboard and retest standby, need standby or tv will not work. Post at least some good clear pictures of the powerboard, front and back.

[unimatrix93]

Unhook powerboard from mainboard and retest standby, need standby or tv will not work. Post at least some good clear pictures of the powerboard, front and back.

With the MB disconnected:
STBY: 0V
BL: 0V
PWM: 1V
5V: 0V
12V: 11.7V

[Diah]

yours measurements had error how could you have VCC 12V and other 0 ?
this PSU known problem with caps 560uf 35V

[unimatrix93]

yours measurements had error how could you have VCC 12V and other 0 ?
this PSU known problem with caps 560uf 35V

I rechecked the connector voltages and I get the same results. Negative probe on the ground pins of the connector.
I measure 520nf capacity for the cap and It has 25V when I plug in the PSU and slowly rising to 29V.

[unimatrix93]

yours measurements had error how could you have VCC 12V and other 0 ?
this PSU known problem with caps 560uf 35V

PXL_20250328_101130849.mp4

This what I measre on the FAN6300 IC VDD and HV pin - negative probe on the filter cap's negative leg.

[Diah]

we cant see any things.. dont use video photos enough.... change the 560 cap

[nomoresonys]

I rechecked the connector voltages and I get the same results. Negative probe on the ground pins of the connector.
I measure 520nf capacity for the cap and It has 25V when I plug in the PSU and slowly rising to 29V.

Is that a typo, 520nf is a lot different than 520uf. one uf equals 1000nf.

[unimatrix93]

Is that a typo, 520nf is a lot different than 520uf. one uf equals 1000nf.

Yes, it's a typo. Also, I removed the cap from the board and I measure 504uF on it. I ordered a replacement for it, hope that will be the culprit.

[unimatrix93]

Found something weird, based on the schematic R1 should be 4.7Mohm while I measure 7.9Mohm on it removed from the circuit.

[unimatrix93]

we cant see any things.. dont use video photos enough.... change the 560 cap

I replaced the cap with a new one, capacity is 560, low-ESR.

Same symptom, 5V in missing. only 12v and 3.3v PWM.