Panasonic TCP42S30 SN Board reflow-Help out a noob!

[tom66]

Re: Panasonic TCP42S30 SN Board reflow-Help out a noob!

One thing I did when I repaired my U30B (this model is identical except it has smart features) was install a light bulb in series with the SN board power connector. Alastair suggested this and I do recommend it for first power ups of repaired boards. The idea with this is, if the worst happens and there's a short on the board, the bulb will limit the current - acting as a resistor - and give you a handy indication by lighting up. This SHOULD limit any damage, perhaps it will even save the responsible part, if it's just a soldering fault or such!

Of course, having the bulb in does cause the Vsus at the SN board to drop, and so can affect the picture, but as long as nothing goes pop, you should be good to remove it completely.

I used a 150W bulb, which was enough for most ordinary TV to not affect the picture, the bulb intensity would vary with the picture. A 60W bulb was too low to start the TV most of the time. If full white or very bright scenes came up, it would trip SOS 6 (and the picture would look awful.) But, otherwise the TV worked fine with a bulb.

This is using a 230V AC lightbulb on a 200V DC circuit (note that 200VDC = 200VAC for a bulb, due to RMS...)

[WHaThEFLuX]

Re: Panasonic TCP42S30 SN Board reflow-Help out a noob!

I just might try that......with everything on the board I powered it up and it behaved as if Q441 and D481 were still lifted, grey flash and ERC 6 blinks.....does that mean I soldered IC502/Q531 incorrectly?

[WHaThEFLuX]

Re: Panasonic TCP42S30 SN Board reflow-Help out a noob!

?

[tom66]

Re: Panasonic TCP42S30 SN Board reflow-Help out a noob!

Yes possibly. That is what mine did when those parts were not properly in.

[WHaThEFLuX]

Re: Panasonic TCP42S30 SN Board reflow-Help out a noob!

Everything looks ok, could solder be shorting two pins of the IC since they're so close together?

[tom66]

Re: Panasonic TCP42S30 SN Board reflow-Help out a noob!

Have you checked under a loupe/magnifier to see if the pins are properly reflowed?
Also, are the parts on the right way?

[WHaThEFLuX]

Re: Panasonic TCP42S30 SN Board reflow-Help out a noob!

they're in the right way, the solder looks sloppy but there's space in between the pins, idk, maybe I'll lift it and try again.....

[WHaThEFLuX]

Re: Panasonic TCP42S30 SN Board reflow-Help out a noob!

Not sure how exactly, but I finally have a working set!

After contemplating taking a sledge hammer to the panel and really "fixing" it for good, I decided to go over everything one more time.

Finding absolutely nothing wrong is certainly discouraging, so I started thinking of abstract things to try. I lifted the new IC502 off the board and replaced it with the original one, so I had new DG302s, a new Q531, and the old IC502.

The old Q531 must have been bad and the new IC502 must have been a dud because when I powered it up low and behold I got the no signal box on the screen!

The ERC caps on the SC board buzz pretty loudly, about twice as loud as the ones on the SS board, but I'm not complaining, the picture quality is great and better than I expected.

I'd like to thank tom66 and tw2005 for their help, advice, and input, without them I would've never gotten anywhere with this set......you guys are awesome!!!

[tw2005]

Re: Panasonic TCP42S30 SN Board reflow-Help out a noob!

Not sure how exactly, but I finally have a working set!

After contemplating taking a sledge hammer to the panel and really "fixing" it for good, I decided to go over everything one more time.

Finding absolutely nothing wrong is certainly discouraging, so I started thinking of abstract things to try. I lifted the new IC502 off the board and replaced it with the original one, so I had new DG302s, a new Q531, and the old IC502.

The old Q531 must have been bad and the new IC502 must have been a dud because when I powered it up low and behold I got the no signal box on the screen!

The ERC caps on the SC board buzz pretty loudly, about twice as loud as the ones on the SS board, but I'm not complaining, the picture quality is great and better than I expected.

Did you a flux pen at all/ One thing I found makes a world of difference to neatness and how the solder flows was adding flux.

I'd like to thank tom66 and tw2005 for their help, advice, and input, without them I would've never gotten anywhere with this set......you guys are awesome!!!

top effort for a noob! Are all the screws in and tight? i would not have expected it to be buzzing too loud

[tom66]

Re: Panasonic TCP42S30 SN Board reflow-Help out a noob!

Nice fix. My set hardly buzzed at all so I'd be careful to check screws as tw suggests...

[WHaThEFLuX]

Re: Panasonic TCP42S30 SN Board reflow-Help out a noob!

I did use flux towards the end, it made everything flow really well. The board contact points on IC502 were really messy once I lifted it, so I used the flux and a fine tip on the iron to even them out, even though they were so small it was surprisingly easy. I must say the flux is very sticky, I'd end up shifting it out of place because it kept sticking to my tweezers! The screws are in as tight as I'm comfortable making them, if I put my ear next to the board it's the ERC caps themselves that are humming, wondering if something got slightly damaged when I popped the ERC cct, who knows.

Anyways, here she is in all her glory!

[tw2005]

Re: Panasonic TCP42S30 SN Board reflow-Help out a noob!

I did use flux towards the end, it made everything flow really well. The board contact points on IC502 were really messy once I lifted it, so I used the flux and a fine tip on the iron to even them out, even though they were so small it was surprisingly easy. I must say the flux is very sticky, I'd end up shifting it out of place because it kept sticking to my tweezers! The screws are in as tight as I'm comfortable making them, if I put my ear next to the board it's the ERC caps themselves that are humming, wondering if something got slightly damaged when I popped the ERC cct, who knows.

Anyways, here she is in all her glory!

[ATTACH]107474[/ATTACH]

LOL, I was wondering where my flux pen line went . Into the quote.

Now , when you describe buzzing caps as pretty loud and then come back and say "if I put my ear next to the board" it's not quite the same description.

Sounds normal if you have to get your ears close to the board to hear a buzz.

[WHaThEFLuX]

Re: Panasonic TCP42S30 SN Board reflow-Help out a noob!

I only put my ear up to it to locate exactly where it was coming from.......As a reference, I have to put the volume up to about 60 to hear the audio clearly over the buzzing. If there was a scene with no music and just dialogue, you would easily be distracted by it. I'll be connecting it to a system so it's really no big deal, I just wanted to be sure that something wasn't actually wrong.