Panasonic TH-42PZ85E --> Completely dead!

[tom66]

Re: Panasonic TH-42PZ85E --> Completely dead!

Seems ok, in circuit measurements are difficult to do.

[Moreno83]

Re: Panasonic TH-42PZ85E --> Completely dead!

Hmm ok. Its to easy to just swap the PB. Im curious where the fault is so I'm not giving up

[Moreno83]

Re: Panasonic TH-42PZ85E --> Completely dead!

Tom , what about removing the 701 module and take some close up pictures? I still got the freeze spray so if you have any suggestions…I'm willing to try anything and if i fix this tv I'm definitely gonna keep this tv and send you some beer money

[tom66]

Re: Panasonic TH-42PZ85E --> Completely dead!

Well, if 701 is found to be defective, I do have that board on my scrap PSU.
(It's missing AC detect module and MC201/MC301)

I don't think pictures will be that useful, the board will have a custom microcontroller on it, programmed with custom firmware, so very little repair could be done on it.

[Moreno83]

Re: Panasonic TH-42PZ85E --> Completely dead!

That would be nice but also a guess.
I was just reading through your thread ( TH-42PZ80B ) and just googling for the fault "10 blink without power button " i find a repair set for the MC201/301 which is suggesting the removal/replacing of the 1uf cap.

I know you mentioned MC201/301 are not in the picture at this moment but in different situations its critical for starting up.
Tomorrow ill desolder the 701 for inspection under microscope , maybe resolder the controller?

[tom66]

Re: Panasonic TH-42PZ85E --> Completely dead!

Ok, so the thing you should understand about PSUs is most of them have stages. This one in particular has many stages of operation.

S0 - Standby output not active, PSU plugged in. This is the case of the power supply being plugged in but the main power switch not being depressed. It will be in S0 in case of a fault with 5V standby, AC detect or others.

S1 - Standby output active, main outputs not active. This is where the power supply normally is in when the standby LED is lit. It is also where the power supply will be immediately switched to in case of a fault condition.

S2 - Standby output active and 15V output active. Prior to entering this state the relays will click. The 15V output should then become active. If it does NOT, then the MAIN BOARD (A BOARD) will trigger a fault condition - the power light will blink 10 times. This mode is entered as soon as the TV is plugged in on most of these models and then is stopped about 30 seconds later. Note that since the A board on your set is not powered up by the PSU it never sends the command to enter S2 so you will not get the initial relay clicks. If you did get 3 clicks from the PSU and 10 blinks, you would have MC201/MC301 fault (I always forget which one does 15V and which does Vsus but I always replace both caps at the same time.) If you get 2 clicks then a delay, the set has successfully passed its 15V power on stage.

S3 - Standby, main & Vsus output active. This mode is the final stage before the panel is primed, then sustained, which means it should shortly start producing an image. If a fault occurs at this stage the power light will blink one of the following codes:

... 2 blinks = Complete Vsus failure (**) P board fault or Vsus shorted (SC/SS fault)
... 4 blinks = P board fault, other code, usually Vsus overvoltage or problem with other supply rail, or possibly PFC circuit fault (unconfirmed)
... 6/8 blinks = Low Vsus causing SC/SS fault trap (partial/pink image may also appear briefly, or for some minutes before tripping this code)

(**) This codes for 15V failure (which would sound like a 15V problem right??)... however the trap here is when the PSU encounters a Vsus fault it will immediately jump back to S1... this causes the set's D board to detect a 15V fault which immediately makes it jump back to 2 blinks code. Very confusing, has got me before...

When you power up the A board using your 5V supply it is immediately trying to jump from S1 to S2. This trips a fault, because it tells the P board to turn on the supply rails but it does not comply and the low voltage rails (3.3V, 5V, etc.) generated on the A board do not appear. This trips a SOS10 code (which codes for failure of 3.3V, 5V, and 9V supplies, IIRC.)

[Moreno83]

Re: Panasonic TH-42PZ85E --> Completely dead!

Thx for the explanation , its funny i was just reading a thread about over voltage.

"Under normal condition, pin 114 of the main CPU (IC1103) is low. When a short circuit or an over-voltage condition occurs, the SOS detect circuit is triggered making pin 114 high. When pin 114 goes high, the TV shuts down and the power LED blinks 10 times."

Is this also true for my tv? Was just searching for MC701 repair and found this.

[tom66]

Re: Panasonic TH-42PZ85E --> Completely dead!

IC1103 is another processor on the A board or D board (can't remember which)
Your set is never leaving "S1" so focus on that problem for now. By forcing it to skip to step S2, you are tripping the fault detection.

[Moreno83]

Re: Panasonic TH-42PZ85E --> Completely dead!

You are right , I'm still in stage 1.
What did you do with your set that had this problem? Is it still catching dust somewhere?

Ps , when jumping pin 13 to pin 9 i hear a clicking sound around D551. Something in that area is clicking. Sounds like a old clock that you rewind

[Moreno83]

Re: Panasonic TH-42PZ85E --> Completely dead!

Also , D504. What do you measure if you measure that diode?

I get a short on both sides in circuit. All other diodes are measuring ok but this diode is different

[Alastair E]

Re: Panasonic TH-42PZ85E --> Completely dead!

Also , D504. What do you measure if you measure that diode?

I get a short on both sides in circuit. All other diodes are measuring ok but this diode is different

You could always check the schematic--See if there's an inductor or resistor across it....
Or even pull one end and re-test!

[Moreno83]

Re: Panasonic TH-42PZ85E --> Completely dead!

Thx for the reply! I already removed it before and it measured "OL" on both sides. Found a thread by someone asking the same but he never mentioned again and fixed the tv so i guess the diode is fine…..
Its getting late so ill remove 1 leg tomorrow and test it again.

[tom66]

Re: Panasonic TH-42PZ85E --> Completely dead!

What did you do with your set that had this problem? Is it still catching dust somewhere?

I fixed it. Someone was nice enough to send me a scrap PSU with MC501 still on it. I took that off and replaced it. I will send you that PSU onwards, minus MC501, MC201 and MC301 (which are already missing.)

Your fault is completely different though, as you have AC detect signal whereas I did not (although the end symptom, dead no standby, was the same.)

[Moreno83]

Re: Panasonic TH-42PZ85E --> Completely dead!

Wow nice!
I just unsoldered 701, will look at the module under microscope to see if i can find something

[tom66]

Re: Panasonic TH-42PZ85E --> Completely dead!

I had that one for over a year. It was so intermittent that I gave it to a friend, it worked fine for almost 12 months, I moved it into my room and it stopped working again. Replaced that module and it worked perfectly. It was a strange one.

I'll try checking that other pin on my set, on the scope.

[Moreno83]

Re: Panasonic TH-42PZ85E --> Completely dead!

701 looks fine under the microscope
I also replced the 470 cap next to it but nothing has changed.
Cant i jump that cpu command? Some device needs the 5v...

[tom66]

Re: Panasonic TH-42PZ85E --> Completely dead!

If you jumper the CPU command, you risk damaging the plasma panel module if you bring up the supplies in the wrong order. For example if you bring up the 5V before Vda, you will permanently destroy the plasma panel. So short answer is no.

[Moreno83]

Re: Panasonic TH-42PZ85E --> Completely dead!

Hmm ok! Just brainstorming hehe

[Moreno83]

Re: Panasonic TH-42PZ85E --> Completely dead!

D504 is 170v is that ok?
Ps, i would like to buy your mc701 module if Thats ok? Maybe the cpu is dead...

[tom66]

Re: Panasonic TH-42PZ85E --> Completely dead!

PM me, I'll have to check with the post office on the price to Netherlands but it's yours for postage cost.

My set has about 2V at AC_VIN.

I also have a sine clock at bottom outermost (with module installed in board and in TV) of 6 pin silver device on MC701 module. 8MHz. Perhaps worth comparing to yours? This indicates the CPU is running.