Panasonic TC-P42S30 6-Blink SOS at Powerup

[Randy_I]

Hi,

I've got a Panasonic TC-P42S30 set that is showing the six blink SOS code at power-on. Thanks to great tips from others on this forum I have a copy of the service manual and have also read through the awesome description of Plasma set operation.

I'm comfortable with electronics and through-hole soldering, new to Plasma set fault location and pretty lame at anything but basic SMD installation. I've got a reliable Fluke 87 DMM for measurements, and a 100MHz dual trace scope available if needed.

Vsus voltage looks good for a few seconds until the system goes into safe mode. I tried disconnecting Vsus at SN2, and also the ribbon connector at SN20. That changed the SOS code to 8 blinks. I'm not sure whether that indicates another fault hidden behind the first one, or just the system complaining about not having the SN board attached. The Panasonic service manual is a little ambiguous about assigning the six blink SOS code, it lists SN board and then seems to hedge their bets a bit with references to the SS. Reading the service manual and schematic it seems like the six blink code is related to the energy recovery portion of the circuit. I hadn't realized how much energy is being managed in one of these beasts until I read the Plasma set theory of operation post. (Once again, awesome job of communicating a complex technical operation in accessible terms!)

From what little I know of the theory and schematic, it seems that the SN, SS, PDP and power supply all interact rather strongly. Right now I suspect a short on the 15v line of the SN board, and will pull the board to do better testing on the bench.

If I do find and fix faults on the SN board, should I also check the SS and power supply before putting the SN board back in operation? I'd hate to simply recreate an SN board fault by not addressing all of the failed components in the overall system.

One more question of those who have gone before me down this path - how do I get the blasted connections along the edge of the screen out of the SN board sockets?

I know to lift the locking bar, which seems to move just fine. Where I'm perhaps overly cautious is in handling those ribbon cables. They seem stuck down. There is almost no clearance for my big fingers when the board is still mounted on the chassis, and I'm reluctant to hang the board by those cables during a removal operation. Likewise the idea of even padded needle-nose pliers isn't very appealing. (Figure I have at least some chance to repair an SN board, but if the cables going to the PDP get damaged the game is over.)

Whatever the outcome I'll post additional info as I find it in hopes it can help others. This forum is a very valuable resource, I'd like to do my part to say thanks and pass it forward.

Thanks!

Randy

[tw2005]

Re: Panasonic TC-P42S30 6-Blink SOS at Powerup

I'd avoid using anything mechanical on those ribbons. people have torn those ribbons and the copper traces are fine.

They do wedge in, I grab them either side with 2 fingers and pop them out pulling dead straight in the opposite direction they insert. Maybe a gentle up/down wiggle at the same time. They will pop out once that wedge is broken so brute force should be avoided, all in the wrists.

[Randy_I]

Re: Panasonic TC-P42S30 6-Blink SOS at Powerup

Pleasure to meet you!

Thanks for the clear insight, I have a much better sense of what to expect. You have a talent for clearly communicating information. I've learned a lot from your answers to other Panasonic owners.

I think the trick for me will be grasping the outer edges with my ponderous fingers. The clearance between connectors / frame is pretty tight.

I currently have the set in a vertical position on its stand. Would you recommend this bit of surgery be done with the unit face down on a protected surface? Seems like it would be safer but I'm new to plasma and not sure how literally to take the "always upright" notices.

Thanks again!

Randy

[tw2005]

Re: Panasonic TC-P42S30 6-Blink SOS at Powerup

Either, it's what ever your the most comfortable with. I've done both ways. If the tv is laid down on something dead flat eg table with a towel laid out at least that should be a nice height.

There's more strength in the panel being vertical, laying it dow especially if heavyhanded or applying pressure on it from beheind with the back off may crack it plus you have the weight of the panel itself.

Not 100% sure about your model but pretty sure Panasonic ditched the glass at the front so the galss you see is the PDP.

That's how my 2010 FHD is.

I've always worked on these flat most of the time and transported them on 6 inch thick foam face down never broken one. (sealed roads)

Thanks for the comp , I try my best but there's guys better at it than I. everyone contributes here, based on their merits.

Edit: once you get the ribbons out, subsequent times should be easier but your next challenge will be inserting them 100% straight and all the way in. It's a feel thing, very hard to describe. If you think, i damage the ribbon the PDP is toast , for me, that usually forces me to go about carefully.

[Randy_I]

Re: Panasonic TC-P42S30 6-Blink SOS at Powerup

Hi,

Managed to get the ribbons out with no casualties, laying it flat made a big difference. (Easier to concentrate on cables when not worrying about tipping the set over!)

SN board is on the bench, component checks seem to indicate that Q401, Q402, Q421, Q422, D401, and D421 are fine. Those just happen to be the active devices provided in the "board repair kit" I purchased, so obviously I have a different failure mode than the one the kit addresses. Yay.

Does this information increase the probability that the fault is on the SC board instead, or did Panasonic generously provide us with multiple common failure modes for the SN?

All the best,

Randy

[tw2005]

Re: Panasonic TC-P42S30 6-Blink SOS at Powerup

Hi,

Managed to get the ribbons out with no casualties, laying it flat made a big difference. (Easier to concentrate on cables when not worrying about tipping the set over!)

SN board is on the bench, component checks seem to indicate that Q401, Q402, Q421, Q422, D401, and D421 are fine. Those just happen to be the active devices provided in the "board repair kit" I purchased, so obviously I have a different failure mode than the one the kit addresses. Yay.

Does this information increase the probability that the fault is on the SC board instead, or did Panasonic generously provide us with multiple common failure modes for the SN?

All the best,

Randy

Most of the posts I've seen are the SN board goes dead short and usually causes a solid LED, no blink.

You could check the resistance on the 5V & 15v lines on the SN and see if that reveals anything.

I'd also check every IGBT for short, not just the common ones supplied in the kit. eg q660,661 etc

You may have to put this board back in and try some board isolation steps or voltage checks.

Unfortunately the schematics are impossible for me to enlarge for me to read. Too low a resolution and search does not work in these pdfs within that so makes it hard to follow.

Maybe someone with eagle eyes can read them better.