TH-42PZ70BA 10 bllinks not intermittent

[tom66]

Panasonic TH-42PZ70BA.

Think I've narrowed it down to DG board.
- P board is working +15V, freeze spray on MC modules makes no difference.
- Have +15V, +9V and +5V from PA board.
- Have all sub and main voltages on DG board.
- MICOM is getting all status voltages OK (pin 114 is low (AG_SOS) except at turn off, pins 66, 67, 34, 30, 27 all >2.7V)
- Fans spin for a second before relay clicks out.
- VSUS hits +215V, VDA -does not rise- to +75V, stays under 1V. Panel isolated, it still does not rise (panel not shorted thankfully!)
- AG_SOS (for SOS10) rises to +3V but this appears to occur after the relay clicks - as a quick test I jumpered it to ground through my DMM (@5.6mA reading) and SOS10 still occurred. So I don't think this is causing the problem or if it is, it is indicative of other faults across the board.

I figure the VDA only turned on after TV has completed boot, but would appreciate if someone can confirm if VDA is active before or after fans turn.

Otherwise, I suspect bad DG board though would like to be certain, it is really odd if the DG board seems to have no error inputs but still

Anyone have one of these open willing to do a few quick checks?

[tw2005]

Re: TH-42PZ70BA 10 bllinks not intermittent

Are you using any training guides with this one? If D3 was disconnected and the panel fired up would that help you ?

[tom66]

Re: TH-42PZ70BA 10 bllinks not intermittent

I'll try that later- should go full white right?

[tom66]

Re: TH-42PZ70BA 10 bllinks not intermittent

What training guide are you using? My TV does not have DG3. It only has a DG board, no H board for additional video inputs. Power rails +5V and 4off +9V generated on the PA board.

[tom66]

Re: TH-42PZ70BA 10 bllinks not intermittent

NVM, found DG3, in plain sight 10 blinks but no fans spinning with it out.

[tw2005]

Re: TH-42PZ70BA 10 bllinks not intermittent

panasonic_th-42pz700u_th-50pz700u_th-58pz700u_th-50pz750u_th-58pz750u_10th_generation_hd_plasma_training

10th gen, suggests removing D3 helps determine if sos10 is SC or SS.

But it was a longshot and not sure if it applies to this.

By disconnecting D3 on the D board, the panel can be forced to automatically turn ON. This duplicates the same effect that the “Power STB/Panel VCC On” command has on the CPU of the D board. (“Power STB On VCC” is normally output from the DG board when the power is turned on.
•
When D3 is disconnected, the base of Q9044 on the D board is no longer grounded by Q4014 on the DG board. As a result of this, Q9044 is turned on grounding the base of Q9046 to turn it off. When Q9046 is off, the “chip enable” pin of the 3.3V regulator IC9011 goes high, allowing for “reset” and 3.3V to be output to the CPU IC9003 on the D board.
•
When IC9003 receives the 3.3V and the reset pulse, it outputs the “Main ON” command (3.2V) to the power supply. The power supply turns on when it receives this voltage and it outputs the Vda, P+15V, P+5V, and Vsus voltages to turn on the “Panel Drive Circuit” without having to turn on the “Signal Switching/Processing/CPU” circuit. When the “Panel Drive Circuit” is on, the LEDs on the Scan and Sustain board light up to indicate that this circuit is on.
•
This could be useful when troubleshooting a “No Power” condition. It could also help to determine if the SC board or the SS board are the cause of a 10 blinks condition.
•
Do not let the TV run for more than 30 seconds when D3 is disconnected.

[tom66]

Re: TH-42PZ70BA 10 bllinks not intermittent

I've used that. Same result. Any flowcharts for this model? I'm getting no panel fire up (LEDs on SC/SS do not glow) AND 10 blinks with that out.

Thinking since D board controls power LED that it could be a bad D board instead. I have a PZ80 D board but almost certainly incompatible.

[tw2005]

Re: TH-42PZ70BA 10 bllinks not intermittent

I've used that. Same result. Any flowcharts for this model? I'm getting no panel fire up (LEDs on SC/SS do not glow) AND 10 blinks with that out.

Thinking since D board controls power LED that it could be a bad D board instead. I have a PZ80 D board but almost certainly incompatible.

I've got nothing. It was a struggle to find that. Sorry.

[tom66]

Re: TH-42PZ70BA 10 bllinks not intermittent

Thanks for your help. Tomorrow, I'm going to try jumpering PANEL STBY ON to a 5V source through a resistor and see if I can get it to fire up.

Heavy beasts, these! I thought PZ80s were heavy but these weigh a ton! I'm fixing this TV for a friend, got it cheap on eBay. Figured I might get lucky with the common P board issue (which affects PZ70 too), but no such luck at the moment.

This is actually only my second PZ70, most Panasonic plasmas I've worked on were PZ80s. I think the Panasonic TH-42PZ70BA, first one, was my "virgin" plasma - I hadn't done plasmas up to then, only LCDs. And it worked out pretty sweet (7 blinks SC board fault )

[tom66]

Re: TH-42PZ70BA 10 bllinks not intermittent

Ordered a DG board. Will update if it fixes the problem; I'm only about 90% sure it will, because the checks didn't show anything obviously wrong, I am guessing it is a fault with the sub micom, as that is what triggers 10 blink code. Perhaps corrupted software/eeprom can also trigger 10 blinks. I wish Panasonic would provide full flowcharts for each blink code source.

[tom66]

Re: TH-42PZ70BA 10 bllinks not intermittent

New DG did not fix problem.
Time to see why that Vda is never coming up - anyone able to measure for me?
Am going to trace power board, could be something to do with that.
I still think it's a fault with the main board in some way but perhaps could be D board, as that controls the power LED.

[tw2005]

Re: TH-42PZ70BA 10 bllinks not intermittent

New DG did not fix problem.
Time to see why that Vda is never coming up - anyone able to measure for me?
Am going to trace power board, could be something to do with that.
I still think it's a fault with the main board in some way but perhaps could be D board, as that controls the power LED.

All I can help you with is from a 2010 X20, Vda ramps up straight away (within a sec) and is on at the same time as Vsus.

I had the ERC cable removed between the SS/SC and when SOS kicked in,, relay click and both removed.

I reckon it would be the same for any model.

[tw2005]

Re: TH-42PZ70BA 10 bllinks not intermittent

Is MC301 marked Vda/STB control in the schematic?

Any chance you got unlucky with the freeze.

Or MC401?

edit: so you have 15V , Vsus, so I guess MC401, D401

[tom66]

Re: TH-42PZ70BA 10 bllinks not intermittent

I'm going to check a few things tomorrow, primarily the Vda before the switch which should always be active. From memory, PZ80s use a buck converter to step down unregulated Vda (~100V) to the required 75V(-2V/+1V)... This converter can be turned off. The converter works off the 15V transformer. This might be different for PZ70s but they still have only two transformers so who knows.

Vda power requirements are around 0.1 amps idle, rising to 1.2 amps with complex images (as tested on PZ80) -- oddly Vda doesn't really vary with panel brightness but rather the complexity of the image (the more transitions in brightness) as the Vda is primarily charging the panel capacitance / wall charge and the more frequently it changes the more power will be used. One of the fields for plasma display research was reducing these transitions to as few as possible, hence one of the reasons for the unusual subfield numbering they now use (e.x. 1,1,3,7,15,19,22,... rather than 1,2,4,8,16...)

It's important that the panel 5V be present before Vda is (or the panel COFs will fry...), so if there's an issue with D board detecting the P+5V it should shut off... however, that SHOULD cause a 5 blink code... But... if the Vda is never rising, perhaps the D or P board shuts off the 15V (killing P+5V in the process) and this causes the 10 blinks I'm getting.

To be honest, this would be my first Va/Vda failure on a plasma... of all the parts of a PSU, it seems to be the most reliable!

Recently I've been working with some VFD modules (vacuum fluroscent display) and they have the same power sequencing issue: they have COG (chip on glass) which requires 5V to be present before the 40V anode/grid supply. Or the COG will fry.

This is all assuming the DG I got from flattvparts is OK.

[tw2005]

Re: TH-42PZ70BA 10 bllinks not intermittent

The schematic I was looking at was PZ700, ETX2MM681MFS which I'm hoping is real close to yours.

[tom66]

Re: TH-42PZ70BA 10 bllinks not intermittent

Well, I'm getting stumped.

Thought I might be on to something with Vda, but the power board micom never toggles the Vda_on signal. So of course, Vda does not turn on.

Thought the SOS10 pulse generated by PA on shutdown might be a fault, but it occurs after the relay clicks off, so I don't think it is (just an artefact of the normal boot procedure.) I checked with a scope.

Going to check some other things on this DG... but not sure where else to go from there.

Could be a bad DG, but what's the chance of two obscure DG board faults? I'm thinking it's running close to zero.

[tom66]

Re: TH-42PZ70BA 10 bllinks not intermittent

Hmm, it might NOT be the main board (DG)

Reason is, was just checking TV_MAIN_ON, TV_SUB_ON etc... and these signals stay high AFTER the relay clicks. Usefully, my scope picks up a little noise spike from relays disengaging and I can see this... These signals are not adulterated by the D board either, they are DG-only.

So surely it can only be the P board. Then a little memory, back to this video:
http://www.youtube.com/watch?v=qQ_iLxx3Fj4

On the PZ80s, Vsus_DET failure leads to 2 blinks.
On these, it may well lead to 10 blinks.

Both 10 & 2 will detect the 15V fault (which occurs after Vsus failure), I guess it's a matter of which wins first. Which is odd - I wonder if Panasonic have a priority system for simultaneous errors? Which is shown in the case of two signals at once?

Going to check that Vsus_DET signal now. And maybe I'll get lucky .

Sometimes, Panasonic error codes cause more trouble than they're worth.

[tom66]

Re: TH-42PZ70BA 10 bllinks not intermittent

...hmm, only 0.03V on VSUS_DET...

[tom66]

Re: TH-42PZ70BA 10 bllinks not intermittent

Here's TV SUB ON showing it staying high AFTER the relay clicks. The spike in the high portion is the relay(s) disengaging, causing a small electrical arc. This wideband rf spike interferes slightly with the scope ground lead.... One type of useful interference... The noise/other interference on the signal is due to deliberately poor grounding (to make spike more visible.)

Clearly showing the DG board diligently attempting to remain functional after the relay clicks out, telling me DG is not causing the fault.

Hmm...

Apologies for the photo, as I can't find a memory stick to directly extract an image of my scope waveform.

[tom66]

Re: TH-42PZ70BA 10 bllinks not intermittent

Fixed it was that thermal fuse.