Philips 42PFL7662d/12 sound, no picture. Backlight failure

[lenny_mc]

Hi,

First post here. what brilliant forum!! Turned on the TV yesterday, had sound, no picture. This had happened a couple of times in the past, but the picture had allways come back after fully unplugging the TV. yesterday the picture didnt come back. Some googling pointed me in the direction of this forum, and from reading this forum I was able to diagnose that the backlight is not coming on for whatever reason. Some more googling suggested that the inverter boards (one master, one slave) can give problems on this particular model TV with modification kits available. I took the boards off the TV and had a good look at them, and it looks like 3 of the four caps are bulging. (im waiting on my camera to charge before posting pictures) Could this be the cause of the problem? They are samwah caps. I can order good quality replacements handy enough, so im going to start with replacing these before trying anything else. Ill keep this thread up to date.

repair kits seem readily available, but given my limited soldering experience id like to try the caps first as they look easiest!!

Ive not done anything like this before, so any help would be appreciated!! Im based in Ireland, with 220 v mains. I also bought a new TV yesterday, so am not in any rush to resolve this, but it would be nice to fix it up and have it in the den!!

Thanks for looking,
Lenny

[drpj23]

Re: Philips 42PFL7662d/12 sound, no picture. Backlight failure

They definitely well could be, and are at least a problem you would have to take care of before moving on.

Replace all 4 (or more if more on other inverter board). Panasonic FM/FR/FC seems popular here

Make sure the caps are installed correctly i.e. polarity matches.

What kind of inverters are they? (pics and part number)

[lenny_mc]

Re: Philips 42PFL7662d/12 sound, no picture. Backlight failure

Thanks drpj23


I replaced the four caps (after checking the polarity) with panasonic caps but still have the same issue. No backlight.

i put a meter on the positive terminal on each of the caps before i changed them and they all showed 23.8 v. I put the meter on after changing the caps and all show 23.8 v

There is another user here with another user who looks like he is having the same issues as me. As noted in his thread, there are repair kits available, so it does look like there is a known problem with the boards. I have found someone on ebay who can repair the failed board for about 50 euro so I might go with that.

Pictures of the bad caps in situ





The board part numbers are - Master - 6632L-0470A, slave - 6632L-0471A

This is an example of a repair kit (i have no affiliation to this ebay seller)

I have found a couple of instances of damage to the big chip (is that the IC?) but I dont have any damage like that on any chips.

anyway, thanks for looking. ill keep you updated if I find anything else.

[drpj23]

Re: Philips 42PFL7662d/12 sound, no picture. Backlight failure

Ok, yes I have actually had these before in a Vizio.

Usually the caps, that IC, and the four FETs on each board go bad.

You can replace the parts but they'll fail again in the future but here is the modification document if you want to go for it.

Otherwise, there are updated inverters on ebay you can purchase usually under $50.
If you go that route, they may not fit like the previous ones so if there was shielding over the originals then it will not fit with the new ones but that is OK.
The holes should line up though (not all will be used though)

[lenny_mc]

Re: Philips 42PFL7662d/12 sound, no picture. Backlight failure

thanks drpj23. i dont think my soldering would be up to that level, so I think ill just buy two new boards. Including shipping and buying the boards, it works out about the same as buying the repair kit and modifications.

At least Ill still get to keep the tv (hopefully) and wont have to dump it!!

Ill let you know how I get on.

[daphney]

Re: Philips 42PFL7662d/12 sound, no picture. Backlight failure

i no this is an old thread but i have just got 1 of these tvs with same fault i have found all parts & ordered seperately except the tvs 33v diode is this suitable SMAJ33A-E3/5A ?
or can some1 tell me wat i need please
many thnx as always

[dick_barton]

Re: Philips 42PFL7662d/12 sound, no picture. Backlight failure

Here's some more information with full parts list.

https://cdn.badcaps-static.com/pdfs/...5e1a3051db.pdf

[daphney]

Re: Philips 42PFL7662d/12 sound, no picture. Backlight failure

i have ordered that already & resistor &caps that are listed in inverter mod pdf above just unsure what to get for this part...
STEP 3.5
Solder zenerdiode (TVS) on PNEL-T707A and PNEL-T708A:
-Solder zenerdiode TVS (33 V)on red indicated position.

thanks for help & info as always