Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

[ljnash]

Hi all, this is my first post so please go gentle on me!

I very recently picked up a Panasonic TH-46PZ81B (46" plasma 2008 vintage) with a known fault (10 blinks of the red power light after pressing the front power button) that I hope to repair so that I can give it to my sister. My sister is still using a 28" CRT in 2017! I'm hoping my sis gets a new TV and I get the satisfaction of bringing a plasma back to life!

I was hoping that the cause of this 10 blink SOS would be the TEA1611T chip on either the MC201 or MC301 located on the P(MAIN)-Board. This diagnosis seems to be wide spread across the internet and the chap selling the TV had even highlighted this as a likely cause. However, having purchased a couple of new IC's and fitted them along with new 1uF 0603 caps the fault remains unchanged.

At that point I did what I should have done in the first place which was to try to get hold of a service manual and to investigate the problem properly.

I've not been able to find a service manual for this specific TV but I have found one for the TH-46PZ81FV which seems to share the same P(MAIN)-Board (EXT2MM704MGH) and one for a TH-58PZ850AZ which seems to share similar PA and A-Boards. I've also found a couple of helpful threads on this very forum:

https://www.badcaps.net/forum/showpo...84&postcount=7
https://www.badcaps.net/forum/showthread.php?t=36706
11th Generation Full High Definition Plasma Display Training

With these resources in hand I set about trying to determine what was and wasn't working on the TV.

According to both service manuals the 10 blink SOS indicates one of the following errors: Sub 5V SOS; Main 3.3V SOS; DTV 9V SOS; or Tuner Power SOS.

What I've found so far:

• When the front power button is pressed the 15V F_STBY (15V standby supply originating from the P(MAIN)-Board) was being correctly generated (so MC301 was working!). The 15V generated does seem a little high, measured at 15.9V
• This in turn was feeding the PA-Board which generates both SUB 5V and DTV9V (SUB9V) measured from test points TPS5 and TPS9 on the PA-Board
• Also as long as the front power switch is left in the ON position (latched in) there is 5V present on the STBY5V line of P7(Pin 5)
• This would appear to leave Main 3.3V and 'Tuner Power' (I'm still not exactly sure what this one is)
• On the A-Board Sub 3.3V is present during the brief period after pressing the main TV power button before the unit shuts down
• 3.3V (STB3.3V) is present at connector A1
• The schematics I have show that Main 3.3V is simply a switched output from Sub 3.3V (Q5693 PMOS switch driven by a BJT which is controlled by IC1100)
• Main 3.3V is not present. The reason, IC1100 is not asserting the TV_MAIN_ON line
• I really need some experianced help!

Now I'm in a sort of 'chicken and egg' situation. I don't know whether there is a fault with IC1100 (seems unlikely, fingers crossed!) or if there is some other condition that is not being met preventing IC1100 aserting the TV_MAIN_ON line which in turn is preventing Main 3.3V being present causing the test to be failed.

One of the posts mentioned above talks about Vsus initially being present as well as the standby 15V. Vsus is controlled by MC201 on the P(MAIN)-Board and is definately not being generated. From measurements (although I've been struggling with this) it appears the optoisolator device acting as the ON/OFF switch for MC201 is intentionally driving MC201 into its OFF state at start-up (which suggests Vsus is not initially ment to be present, unless of cause this is a fault!).

The training document above (google docs) manages not to cover the PZ81 (even though I'm sure its from the same year as the PZ80 and PZ85) which is a shame because it does give a sequential work through of the power up sequence (page 13 seems the best sort of fit but doesn't mention Main 3.3V).

As you can probably tell I'm pretty well stuck (especially without the correct service manual).

Can anyone shed light on the correct sequence of rail power-ups for this unit and on 'what depends on what' for the TV to initially correctly enter the standby state?

Any advice welcomed.

[Moreno83]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

Hi , welcome to the forum!

I repaired many of these PZ85 with that famous PS , but never this model.
Have you tried freezing the 2 small boards to see if the tv turns on? You sure all the solder connections are ok? Especially the small capacitors , those pads are really tiny.

You already posted the correct SM for this tv? These boards are also used in other models so im pretty sure this SM will do the trick.
SM says its the A board but it can be the A board mis diagnosing the error. ( blink pattern isn't always correct ).

[tom66]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

I had a difficult 10 blink fault on a PZ70 that may be related. It was caused by a fault in the VSUS circuit. When the PSU detected a VSUS fault it turned off the 15V supply which triggers a 10 blink code.

[ljnash]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

Hi Moreno and tom,

Thank you both for your replies.

@Moreno, I haven't tried freezing the TEA1611 chips on the MC201 and MC301 boards as I skipped ahead and just replaced them both with new IC's. I de-soldered the two boards and took them into work on the weekend to do the soldering under a microscope (as you say they're pretty small parts!). I'll try and get hold of some freeze spray to see if the replacement part on the MC201 board is acting up. I'll also look at the board again to double check.

@tom, I'm interested to hear about your trouble with a Vsus fault as I know my board isn't generating a Vsus voltage (controlled by the MC201 board). As I mentioned it doesn't seem the MC701 board is instructing the MC201 to turn ON (but it seems quite difficult to tell when the optoisolator is engaged). Do you happen to know when the Vsus is meant to be generated? Is it supposed to happen at the same time as the 15V F_STBY?

If Vsus is meant to be there early in the power-up sequence that might explain why the A-board isn't switching on the Main 3.3V supply.

[tom66]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

It might be related to a thermal fuse issue or a fault with the UVP/OVP circuit, but I'm not sure at all

[Agent24]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

Is it just me or do the large brown capacitors near the 'scope probe look bulgy?

[tom66]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

They often do, but they are usually OK

[ljnash]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

Hi all,
Just wanted to post an update, unfortunately I'm not really making any progress!

I still really need input from someone that knows what the correct power-up sequence is for this model of TV.

I made the decision to pay for a copy of the exact service manual for this TV just to be sure the board schematics I was following were correct. I've attached the manual so that others in the forum can more easily get hold of it. Hopefully it may prove useful to someone (had to zip it to make it small enough to upload).

I managed to pick-up a second hand P(MAIN) board from eBay which was described as faulty. I'd hoped it may have a different fault to my existing board and between the two that I could track down the faults. But as luck has it they both appear to behave exactly the same!

I decided to try focusing on the Optoisolators controlled by MC701 which seems to control all of the power supplies on the P(MAIN) board.

• PC201 = VSUS Fault indication
• PC202 = VSUS ON
• PC301 = 15V Standby Fault Indicator
• PC302 = Mutil rail ON (15V and Vda)
• PC401 = Vda ON
• PC501 = Bias ON (not sure about this one)

I've gone back over some of the measurements I'd made and I've found:

• PC301, PC302 and PC501 all have a 1V drop across the input diode meaning they are being turned on immediately after pressing the on switch but are then disabled as the fault is detected.
• PC201, PC202 and PC401 have 0V across them at all times.

• PC201 looks like it is not meant to be on in standby (as it is supplied from 5V (provided by MC451) which is not turned on by MC701. As this Optoisolator is responsible for sensing a VSUS fault it appear that VSUS is not enabled in standby. There is a 5V standby rail so this assumption seems sensible, doesn't it?
• PC202 is responsible for enabling VSUS, so clearly MC701 doesn't believe it should be switched on at this point.
• PC301 is responsible for reporting an error with 15V standby. On both my boards this is ON. I'm not sure what the logic is meant to be here but it looks like ON allows VAUX on the TEA1611T chip to be supplied with power and hence turn/stay ON.
• PC401 is responsible for enabling Vda, so again MC701 doesn't believe it should be switched on at this point.

The fault sensing circuitry seems really odd on this board, to me at least. Utilising an "Optoisolator" and "Adjustable Output Shunt Regulator" to detect a fault.

Looking at the 1431T datasheet (Adj. Voltage Reg) I briefly thought I may have an answer to my issue. It seemed that IC352 should be outputting 15V hence keeping PC301 OFF (even though this didn't seem to make sense given what I have said above). However, after replacing IC352 with a Ti TL431CLPE3 I found I still have the same output. So all I achieved was confirmation that I have no idea how this part of the circuit is meant to behave!

Still not really making any sense of this but would anyone like to comment on the following possibilities:

Perhaps PC301 should be OFF if the 15V output is working correctly?

Is an F_STBY voltage of 15.9V too high (perhaps my replacement TEA1611T chips are also faulty)?

Looks like VSUS should be OFF in standby?

[freakaftr8]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

I've repaired about ten of these. The TEA1611 IC's I have never found to be actually faulty but on my first repair I replaced them anyway. There is a possibility that you could have a thermal fuse issue on the primary Transformers. Panasonic's were known to blow these open.

[vinceroger69]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

https://www.youtube.com/watch?v=qQ_iLxx3Fj4
Transformer test/fix for 10 blink
did you put the two boards back in the correct locations? as they are slightly diffrent

[ljnash]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

Thank you both for your replies.

@freakaftr8, I've double checked the transformer fuse, which looking at the schematics only appears to be present in transformer T201 (VSUS transformer). I measured on the top side of the board between R251 and R252 and measure ~0 ohms for both of my P(MAIN) boards. So the fuses look ok.

@vinceroger69, I've checked the MC201 and MC301 boards to see if they were the wrong way around. I was very careful not to mix them up myself but that doesn't mean someone hadn't removed them before I got hold of the TV! I found an image on a German website (attached) that indicates that they are the correct way around.

Anymore ideas? Do either of you guys know what the power-up sequence is meant to be for this board? With the TV in standby, could either of you tell me which of the supplies should be enabled? Should Vsus, Vda or 5Vc be generated before the TV is switched from standby to the ON state?

[tn245]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

I had a PZ70 with 10 blinks. Did a similar amount of chasing around as you have and in the end found it was just a connector (DG board I think) that wasn't seated properly. Worth checking if you haven't already.

[ljnash]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

Thanks for the suggestion. I've just gone round unplugging and re-seating connectors but no joy I'm afraid.

I did notice something interesting however as a result, when I press the power button on the front of the TV I though it would first go into standby and then power on with the remote (Panasonic's tend to do this unless you push the power button in quickly). This set however appears to be trying to turn on immediately (rapid green flashing light before red flashing error code), so my initial assumptions weren't quite correct.

Not sure this changes much as I still really need to know what the rail power-up sequence is meant to be. So far I have 15V F_STBY, SUB 5V, DTV9V and Sub 3.3V.

[ljnash]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

Hi all,

Does anyone one else have any suggestions before I give up on this repair.

Without further information about power up sequences I don't see that I'm going to be able to get the bottom of this fault.

[tw2005]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

Try this. unplug power, then disconnect A5 and A7. plug the cord in and apply power, TV should turn on by itself with white screen.

If it does that may point to the A board, but not a series I'm experienced on.

I've got a 42PZ80 and P7 auto turns on, greyed display, the fans are running and the sustains boards too are on, removing the LVDS cable A5 then produces white screen.

[tw2005]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

Try this. unplug power, then disconnect A5 and A7. plug the cord in and apply power, TV should turn on by itself with white screen.

If it does that may point to the A board, but not a series I'm experienced on.

I've got a 42PZ80 and P7 auto turns on, greyed display, the fans are running and the sustains boards too are on, removing the LVDS cable A5 then produces white screen.

I noted too that actually the front switch on the PZ80 had to be depressed to turn it on still, but no front LED with A7 removed

[ljnash]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

Hi tw2005,

Thank you for the reply and the power point presentation it's appreciated.

I tried disconnecting A5 and A7 but that just resulted in an even quicker shutdown of the P-board.

I decided to spend some time reading over the presentation (pages 22 to 29 in particular) and I believe I may have a new lead.

According to "Power Supply Sequence (6/8)" on page 27 the D board is meant to assert Panel ON/OFF to instruct MC701 to generate VSUS, Vda, 15V and 5V drives. From the circuit diagrams I have that would be connector D25 (routing to P25) pin 11. I'd noticed previously that "PANEL_ON" wasn't being asserted (driven high in this case) but without knowing the sequence of events I didn't know if that was important.

As everything else in the sequence seems to be ok up to that point it might be a failed D board. I've gambled another £10 on a "tested working" board from eBay to try swapping out. It's just a shame Panasonic located it behind the A-board, with such a big TV you wouldn't have thought they'd end up being short on space!

Thank you again and I'll let you know how I get on.

[tw2005]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

Hi tw2005,

Thank you for the reply and the power point presentation it's appreciated.

I tried disconnecting A5 and A7 but that just resulted in an even quicker shutdown of the P-board.

I decided to spend some time reading over the presentation (pages 22 to 29 in particular) and I believe I may have a new lead.

According to "Power Supply Sequence (6/8)" on page 27 the D board is meant to assert Panel ON/OFF to instruct MC701 to generate VSUS, Vda, 15V and 5V drives. From the circuit diagrams I have that would be connector D25 (routing to P25) pin 11. I'd noticed previously that "PANEL_ON" wasn't being asserted (driven high in this case) but without knowing the sequence of events I didn't know if that was important.

As everything else in the sequence seems to be ok up to that point it might be a failed D board. I've gambled another £10 on a "tested working" board from eBay to try swapping out. It's just a shame Panasonic located it behind the A-board, with such a big TV you wouldn't have thought they'd end up being short on space!

Thank you again and I'll let you know how I get on.

Good luck with it, can't help much more.

[ljnash]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

Hi tw2005,

Well, I've received my "working" replacement D board but it has obvious damage to one of its inductors. Looks like it should still work electrically but it'll be going back! Did a quick test with this second D board to see if there was any change and unfortunately the TV behaves exactly the same as before.

I've spent the morning getting back into the detail of the schematics as I've found myself looking at the A-Board again.

The A-board is definitely asserting the F_STBY_ON line (Connector P7, Pin 6 from A6) as indicated in your PowerPoint presentation "Power Supply Sequence (4/8)" and the PCF circuit is generating 395V, again in line with the documentation.

Then it comes to the PANEL_ON signal from the D-board which is not asserted until right before the TV shutdown occurs where I briefly see ~3.2V on my multi-meter. On reflection this would appear to suggest that the STB5V to STB3.3V regulation on the D-Board must be working. So I've gone back to thinking that the D-board isn't being given sufficient time to assert the PANEL_ON signal before another board (I'm thinking the A-Board) is telling the P(MAIN) board to shutdown. Also at this point the P(MAIN) board has been told to shutdown anyway so likely wouldn't respond to the PANEL_ON signal anyway.

Going back the circuit and block diagrams for the PZ81B, the 10 TIMES LED SOS is stated to be due to an issue with Sub5V, Main 3.3V, DTV9V or Tuner Power. From my very first post I know that all but Main 3.3V are present and the Main 3.3V is just Sub 3.3V (which is present) switched in by Q5693 on the A-Board in response to the A-Boards TV_MAIN_ON signal being asserted (which it isn't).

So having now gone full circle I'm again wondering when TV_MAIN_ON should be asserted and under what circumstance it's not?

[ljnash]

Re: Panasonic Plasma TH-46PZ81B, 10 Blink SOS (Doesn't appear to be TEA1611T chips)

Good news everybody, another Panasonic Plasma lives again!

Just wanted to share the good news with the forum and take the time to thank everyone who offered me advice over the last 5 months!

I'm still not really sure what the issue was with this TV but after spending some time looking at the F_STBY_15V (which seemed to take quite a while to reach 15V) I decided to take another look at the non-working P(MAIN) board I'd bought off eBay some months ago. I was working under the assumption that perhaps this or another voltage derived from this source was taking longer than the A-Board (or D-Board) liked and hence they were instructing the P(MAIN) board to shutdown.

When I first put this other P(MAIN) board into the TV, back when I first got it, it behaved no differently to the original board so I'd put it to one side. I had a quick poke around looking for any obvious issues (shorted transistors etc...) but didn't see anything really wrong. As I'd still got some new spare TEA1611T chips I decided to change the one on MC301 which looked like it may have gotten hot at some point. I swapped it over into the TV and tried powering on...exactly as before two clicks of the relays followed by both tripping out. Oh well I thought no real loss. Then I wanted to see if any of the supplies from this board came up slowly as well. So I sat with a meter working along looking at various rail voltages turning the TV on and off in quick succession. Then to my absolute amazement I didn't hear a third relay click and the other boards had come to life as well!

Not everything was well at this point as the TV now gave a single Red light blink error code. After a short session of head scratching I noticed that I'd not plugged a cable back into the A-Board (A3) . With that plugged back in I tried turning on again and the TV when back to two relay clicks followed by a third. WTF! So I started turning the TV OFF and ON again in quick succession and the flippin TV only powered up and gave me a picture!

I tried turning it OFF and ON, waiting in between, and I still seemed to be getting instances where the TV would trip out as before.

Anyway, to end the story, I left the TV on whilst I adjusted the VSUS voltage and checked other voltages as per the service manuals instruction. For the last few hours I've been turning the TV on for a reasonable period of time (5 to 30 minutes) and then off again for a similar length and the TV has started behaving itself! Its behaviour when you push the front power button has also now changed, rather than turning straight on it waits to be started with the remote? I've performed a factory reset, so perhaps this has had an effect.

I've put all the screws back in and fitted the back cover and its now been running for the last 2 hours without issue. A little bit more soak testing and I need to find out if it will switch on again tomorrow.

I can then finally pass this on to my poor old sister, bye bye CRT!