Thomson 40FW3263 No power

[piernov]

Hi,
Thomson 40FW3263 which doesn't power on.
No power at all on the power supply output, no voltages in secondary.
No voltages on primary side of transformers.
Nothing looks burnt or shorted in the primary side.

I pinpointed the issue down to FSL206MR which does turn on (getting 7.8V on the VCC pin) but doesn't switch.

• 7.8V on VCC
• 0V on Feedback
• 120Vrms on Startup
• 320V on Drain

410ohm between feedback and ground pins (both ways). I think the IC is bad, I will try to replace it and see how it goes.

Sorry for the blurry pictures, I didn't manage to take better pictures than that…

The FSL206MR is the small 8 pin DIP between the big capacitor and the small transformer.

[budm]

Re: Thomson 40FW3263 No power

What do you have on LINE SENSE pin?
Per app notes the FB is control by OPTO, what resistance do you get on FB pin if OPTO is not connected.

[piernov]

Re: Thomson 40FW3263 No power

Line sense is tied to ground (same trace).
The feedback pin resistance to ground is mostly affected by the FSL206MR. If I disconnect this IC, I get 0.6V in one direction and OL in the other in diode mode. I can still try to disconnect the optocoupler, but I'll do that tomorrow.

[dick_barton]

Re: Thomson 40FW3263 No power

Have you checked the electrolytic capacitor on pin 6. It says that pin 5 supplies the initial current to charge the capacitor connected to VCC (pin 2) and when it reaches 8V the transformer supply takes over.

[piernov]

Re: Thomson 40FW3263 No power

Completely forgot about this TV until I received the replacement IC…
Well, indeed it was the FSL206MR which was dead. The new one measures 5.7-5.9Mohm between feedback and ground.
The TV now works perfectly fine again.