Power Supply 17IPS16-3

[steffen55]

Hi all,

please could you help me with some basic troubleshooting hints for a Vestel 17IPS16-3 power supply from an LCD TV.

The power supply seems to have no output at all. I can measure a voltage of ~325V at the primary side of TR800 but no voltage at all at the secondary side. Looks like it's shorted.

Are there any inputs to locate or at least to isolate the fault?

Thanks!!

[PowerAmpFreak]

Re: Power Supply 17IPS16-3

It appears the SMPS recieve proper rectified mains. I assume TR800 is the main SMPS transformer, right?
Either the SMPS has problems to start, like a dried start-up electrolyte (use to be 10-220uF cap close to the switch controller, like UC3842, 3843 and so on)
Either the SMPS does start, but has one or more of the outputs shorted.
In this case, the supply use to enter "hick-up" mode and a sound is heard from the supply.
I don't know a thing about the relevant SMPS in this post, but this is just general advice to get a "dead" SMPS up.

[steffen55]

Re: Power Supply 17IPS16-3

Thanks a lot for your response! Regarding your questions:
- yes, TR800 is the main transformer
- removed all the electrolyte capacitors right now and will remeasure them tomorrow
- there is no sound from the SMPS
Is there any possibility to measure the cirquits to isolate the problem?

attached the schematics of the SMPS

[tom66]

Re: Power Supply 17IPS16-3

See if you get a good Vcc on IC805. Measure with your COM terminal connected to the negative end of any of the main input caps.