150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

[barryra]

I work on tv's off & on & have repaired about 100 TVs over the years. I opened up the back of a Philips 47pfl7403d/f7 and saw that the large 150uf at 450 wv was totally expanded and blown wide.

I'm just curious if any of you have seen this often.? I don't see any any other blown capacitors but I may change some of them in their surrounding area. Also do you think there is any other issues I should check out before I order parts? Thank you

I asked on the AVS forum but have not seen any replies.

[mariushm]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

It can happen... lightning strikes, power phases being shorted in such a way that you'd get 300v+ in the device, active pfc circuits breaking and sending high voltage in those caps...

[barryra]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

Thanks for the reply. Do you think the tv should work after I replace those 2 150uf caps or should I replace all caps?

[Andrew F. Ali]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

These caps are filters in the rectifier circuit and they can fail, after all it they are man-made and active in circuit. I would suggest you test the bridge rect and the switching transistor/s also.

[JohnCT]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

I work on tv's off & on & have repaired about 100 TVs over the years. I opened up the back of a Philips 47pfl7403d/f7 and saw that the large 150uf at 450 wv was totally expanded and blown wide.

I'm just curious if any of you have seen this often.? I don't see any any other blown capacitors but I may change some of them in their surrounding area. Also do you think there is any other issues I should check out before I order parts? Thank you

I asked on the AVS forum but have not seen any replies.

Yep, I've seen about a dozen or more. Several were from bad house wiring (open neutral doubling input voltage), but most were just runaway high ESR. These supplies run 24/7, and when they start getting hot, you can get a thermal runaway. The hotter they get, the worse the ESR gets and they may even get electrically leaky. Once the vent opens, they spew and vent themselves out. You'll find the cap weighs about a quarter what a good one of the same size weighs.

John

[arenat]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

An open resistor in the voltage sense of the PFC could be the issue .

[barryra]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

An open resistor in the voltage sense of the PFC could be the issue .

I'm a little ashamed to show my novice but can you tell me where this/these resistors are located?

Thank you very much.

[budm]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

I'm a little ashamed to show my novice but can you tell me where this/these resistors are located?

Thank you very much.

You need to upload good clear straight shot pictures of the whole top and bottom side of the board to be able to locate the feedback resistor network.

[barryra]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

Thanks budm... I took 4 pictures.

[budm]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

Need pictures of the bottom side of the board because they will be SMD type resistors connected in series in the PFC feedback section..

[nomoresonys]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

http://www.shopjimmy.com/philips-272...pply-unit.htm# Pics. of power supply if that's the one.

[barryra]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

Need pictures of the bottom side of the board because they will be SMD type resistors connected in series in the PFC feedback section..

Hopefully... All that's needed are the capacitors replaced... thanks for checking the board out.

[JohnCT]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

Hopefully... All that's needed are the capacitors replaced... thanks for checking the board out.

Well over 99 percent that all you need is a new cap(s).

AFAIK, most if not all pfc controller ICs will shutdown with overcurrent detection, the type that happens when the pfc capacitor is over volted.

John

[barryra]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

Well over 99 percent that all you need is a new cap(s).

AFAIK, most if not all pfc controller ICs will shutdown with overcurrent detection, the type that happens when the pfc capacitor is over volted.

John

So... I me need to change more than the capacitors since the larger capacitors were blown? Thanks

[JohnCT]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

So... I me need to change more than the capacitors since the larger capacitors were blown? Thanks

Not sure of your question.

If the pfc filter is vented and dried out, just change it. Change any other electrolytic caps on the primary side that check high ESR or show signs of venting (values between 2.2 to 47 ~ 50v for instance). Otherwise, just change the pfc cap and go.

John

[barryra]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

Not sure of your question.

If the pfc filter is vented and dried out, just change it. Change any other electrolytic caps on the primary side that check high ESR or show signs of venting (values between 2.2 to 47 ~ 50v for instance). Otherwise, just change the pfc cap and go.

John

Okay, I'll do that. The capacitors arrived today from Digikey... I live about 2 hours away so the parts get here in 1 day. Thanks for your help! I really appreciate it.

[budm]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

Leave the meter probes on the cap's legs then turn on the TV and see how high the Voltage goes up to, make sure you will able o unplug the cord in case the Voltage goes over 400VDC.

[tvtimmy]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

I have seen the bottoms of the caps blow out. Almost tear the leads out of the board.

[barryra]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

I am having a difficult time melting the solder on this board. Is there some type of coating on top? I'm using a Hako soldering iron at 750.

[tvtimmy]

Re: 150uf at 450 wv Large Capacitor Blown - I've Never Seen This... Have you?

Hot air or a real soldering jron? If its real just melt some new lead free solder on it and then reheat each leg and pull them out with a wiggle.