Panasonic TH-42PZ70BA 7 blink code

[flocko]

Picked this up yesterday had 7 blink code, now i have the back off pulled the plugs from Sc and SS to try to find the fault, now with all plugs back in except Sc 20 i get a flashing green to a standing green light and all the fans are running. so is this the same fault that has come up before with the transistors on this board or something else.

[tom66]

Re: Panasonic TH-42PZ70BA 7 blink code

Sounds like the common 2N3995 failure.

[flocko]

Re: Panasonic TH-42PZ70BA 7 blink code

i hope so, but i could not remember any one saying that when they pulled Sc 20 out it went on to power up, anyway will pull the board and start lifting them legs and testing thanks Tom

[johnboy1313]

Re: Panasonic TH-42PZ70BA 7 blink code

i hope so, but i could not remember any one saying that when they pulled Sc 20 out it went on to power up, anyway will pull the board and start lifting them legs and testing thanks Tom

I don't know the differences in the models, but maybe it's like my TH-42PZ77U with the 7-blinks, check this out.

https://www.badcaps.net/forum/showthread.php?t=24894

My set did power on with SC20 disconnected.

[flocko]

Re: Panasonic TH-42PZ70BA 7 blink code

Hi johnboy just lifted all 14 legs on the row of fets found the dead one Q653 the second from last and the other end to the dead one on yours. so need to put in an order for two 5N2307 just in case, thanks

[johnboy1313]

Re: Panasonic TH-42PZ70BA 7 blink code

Awesome

[flocko]

Re: Panasonic TH-42PZ70BA 7 blink code

Hi the 5N2307 came though the door this morning and has been fitted, and we now have a working set. i will keep my eye open for more of these panasonic plasmas as i now have a spare 5N2307.My thanks go to Tom and Johnboy for all your help regards Flocko

[BrianWicks]

Re: Panasonic TH-42PZ70BA 7 blink code

I have the 7 blink problem on my plasma tv. I have isolated the problem to the su board. With the su disconnected from the sc board the tv stays on and the display works on the bottom half of the screen. I checked the ribbons' from the display to ground to see if the panel is shorted and all ribbons are open. The sc board was checked on another tv and it is OK. Do you think I should replace both the su and sd boards or will the su fix the problem? Is there any way of testing the su board out of the tv? I would not like to ruin a new board if something else is wrong. Tried a supposed to be good SU card and still 7 blinks. Panasonic TH-42PZ77U.

[baggyboy]

Re: Panasonic TH-42PZ70BA 7 blink code

Hi, I'm new to all this so any help would be appreciated please. I've got an 8yr old TH-42PZ70BA. It was repaired under warranty in it's 1st year due to the 7 blinks. Same problem again. Is it the 5N2307 fet? I used a digital meter and got the following readings:

Q641- 215
Q642- 222
Q643- 215
Q644- 208
Q645- 150
Q646- 215

Q695- 1058
Q696- 1047

Q648- 823
Q649- 818
Q651- 812
Q652- 819
Q653- 817
Q654- 829

I'm suspecting Q645 is faulty and needs replacing. I'd be grateful for any advice please. Also any reputable sellers for the part in UK please. Thanks!!

[flocko]

Re: Panasonic TH-42PZ70BA 7 blink code

Hi You can see if it is the SC shorted by removing the SC20 plug and powering set on, the fans should run with a green led showing on the front, testing the SC should be done with the board removed you need to lift one leg of each mosfet ,then test with meter set to low ohms (200) test between the tab (north) and each leg+ across legs, any showing low ohms(short) should be replaced, mosfets 5N2307 you can pickup from eBay for under £2.00 Hope this is of help Flocko

[baggyboy]

Re: Panasonic TH-42PZ70BA 7 blink code

Thanks for your reply! Tried pulling out SC20 connector, not budging! I'm afraid that I will snap something. To remove the SC board do I have to remove SU and SD boards completely together with the flexible cables on the side? That's what it says in the manual. To remove the SD board do I have to remove the AV unit which lies above it? Also when checking the FETs (once SC board removed) by "lifting one leg" does this involve desoldering one leg on each of 14 FETs to check for shorts.

[flocko]

Re: Panasonic TH-42PZ70BA 7 blink code

the SC20 plug needs to be pinched to lift its tab, then it will release,take care when removing the white plug from the buffers as this can get damaged, the buffers can remain in place for now just remove the screws holding the SC board then it can be removed from the buffer sockets by pulling apart,and yes you will need to lift one leg of each mosfet to test, read though the link in post 4 above for more info

[baggyboy]

Re: Panasonic TH-42PZ70BA 7 blink code

Thanks for your advice Flocko! Here goes...fingers crossed!

[baggyboy]

Re: Panasonic TH-42PZ70BA 7 blink code

Screws off, 2 white connectors off by prising towards you. Now tried prising the SC board from the buffer boards but not enough room due to the silver cylindrical rollers which take the wall bracket screws inhibiting further movement. Just need to get the 4 black connectors on SC board to come away from the buffers. Any tips before I start removing the AV and the SU and SD boards!

[flocko]

Re: Panasonic TH-42PZ70BA 7 blink code

To be honest.you will need to do whatever it takes to remove the SC, a long time has passed from the last one of theses I worked on, did you try running the set with SC20 unplugged

[baggyboy]

Re: Panasonic TH-42PZ70BA 7 blink code

Yes. Moved the SC20 connector away with needle nosed pliers. Powered TV up. Fans working and LED remained on green light..no blinking reds! It's just the AV unit in the way of the SD connectors. I hoping it's not too much hassle removing the AV unit..will consult the engineers manual.

[baggyboy]

Re: Panasonic TH-42PZ70BA 7 blink code

An update. Lifted a leg off each FET and it confirmed the faulty one was Q645 (as in post 9) above. Is it necessary to lift a leg off the FETs? I originally placed the negative lead on the S and postive lead marked G on the board. Removing the faulty FET took a lot of heat using a gas soldering iron directly as a mini blow torch. Also soldering the new FET was difficult due to the solder drying up quickly on the base of the FET....but eventually managed it! TV is now back up and running!!! Thanks guys.

In future any tips regarding the removing and soldering the FET? Solder air guns any good?? Solder paste maybe instead of solder wire?

[flocko]

Re: Panasonic TH-42PZ70BA 7 blink code

For this type of work I use an old chisel tip 60w soldering iron,lift the legs first,then by running new solder on the tab wait for the component to come free and lift off, tin the back of the new part and use flux on the pad, heat tab until you see solder run out from under the component.Glad you were able to get your set up and running and happy to help