Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

[tom66]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

You could try applying a current limited 5V source to the area, then using freeze spray to locate which components get hot. I've used this before on a T-con board.

[smartjohn]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

No, I realize the pain involved, but I'm up for the challenge! I am thinking about ChipQuick solder for any large pin count IC removal. It looks to be a better way. I have not looked at the cost yet so maybe I should reserve my decision until i price it!

IC501 and IC521 look to be the FET Drivers on mine. M81707FP Mitsubishi chips for both. I don't see any bad resistance on these initially. Did you find shorts on any of yours in circuit?

[smartjohn]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

So Tom, you're saying just hang a 5V supply on the 5V_F_A (orB) outputs (w/respect to GND) and set the limit to say 100 milliamps?? Then check for the hot spots? (by seeing which freeze spray spots evaporate first?) Sounds brilliant to me...!

[tw2005]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

IC501 and IC521 look to be the FET Drivers on mine. M81707FP Mitsubishi chips for both. I don't see any bad resistance on these initially. Did you find shorts on any of yours in circuit?

IC771 [/QUOTE]Vin to com is about 2.1 Ohms, Vout to com I am getting 6.3 ohms...QUOTE]

If Vin to GND = 2.1ohms then IC16501 Vcc (pin 11) to Gnd(pin 15) also = 2.1ohms on a 15V line = over 7 amps drawn.

Have a look at the schematic and see if you agree, I would treat that as bad but is it the V reg or the driver. I'll suggest driver. If you take out the REG and tests good then both input side and output side of that cct has issues. That's my theory

[tom66]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

So Tom, you're saying just hang a 5V supply on the 5V_F_A (orB) outputs (w/respect to GND) and set the limit to say 100 milliamps?? Then check for the hot spots? (by seeing which freeze spray spots evaporate first?) Sounds brilliant to me...!

I think the outputs of those regs are floating, so it'd best to put the 5V source across e.g. the regulator's input or output capacitor. I've used amps, but I was working on a power circuit. If the short circuit is on the order of a few ohms, then 100mA should be fine.

[smartjohn]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

I didn't have access to a regulated 5V supply, so I built one from an old ATX computer supply! It's actually not to bad for free.. I am going to use a large resistor to limit current. I found another major issue: diode D725 is a dead short. This would short the 5V_F_A and 5V_F_B outputs together. These both feed the buffer boards and I'm guessing a large backrush of current and/or too high a voltage from some failure on the buffer boards may have killed D725. This this is a super small, one of the smallest SMD diodes I have seen!

I also received my $5 ea SU / SD boards but I will not test these until the SC board is completely healthy! I plan to replace D725 and then re-check all other previous resistance readings next.

[tw2005]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

I didn't have access to a regulated 5V supply, so I built one from an old ATX computer supply! It's actually not to bad for free.. I am going to use a large resistor to limit current. I found another major issue: diode D725 is a dead short. This would short the 5V_F_A and 5V_F_B outputs together. These both feed the buffer boards and I'm guessing a large backrush of current and/or too high a voltage from some failure on the buffer boards may have killed D725. This this is a super small, one of the smallest SMD diodes I have seen!

I also received my $5 ea SU / SD boards but I will not test these until the SC board is completely healthy! I plan to replace D725 and then re-check all other previous resistance readings next.

You should resistance check those buffer boards first in case you've received bad ones. Just received more bad parts myself from FLATTVPARTS in the UK. Both SD/SU supplied dead short and I even went to the trouble of asking them if they test their buffers!

I had a win and succeeded in rebuilding 2 of my TNPA5081 SC boards.

[tom66]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Yes... no one tests these buffers.

And the newer buffers get damaged when the TV Is plugged in while cracked.

So I would advise anyone who harvests these parts to check if the TV has been powered up, and not to power it up themselves. A cracked screen isn't ever going to work, so I don't know why someone would bother.

[smartjohn]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

So back on my trek, D725 checked OK out of ckt... so I went with tom66's trick and boosted 5V into the outputs of IC725, IC725 one at a time. I played around with current resistors and finally settled on 2ohm 10watt which was giving me around 500mA. Bingo! IC564 gave me an Ouch! to the touch after about 5min of current. It's the only thing on the whole board that was getting hot that I could tell. I was hanging my 5V input on the output of IC725 (the 5V_F_B supply). This looks to be a Schmitt inverter, TC7SH14FU. Now off to go parts shopping again!

[tw2005]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

So back on my trek, D725 checked OK out of ckt... so I went with tom66's trick and boosted 5V into the outputs of IC725, IC725 one at a time. I played around with current resistors and finally settled on 2ohm 10watt which was giving me around 500mA. Bingo! IC564 gave me an Ouch! to the touch after about 5min of current. It's the only thing on the whole board that was getting hot that I could tell. I was hanging my 5V input on the output of IC725 (the 5V_F_B supply). This looks to be a Schmitt inverter, TC7SH14FU. Now off to go parts shopping again!

So you removed IC564 and confirmed short across pins 3 & 5 and rechecked the 5v regs again?

I managed to remove these much easier using 2 soldering irons.

Also check out Q743 & Q810 around that inverter.

next to SC20 can you measure resistance TP82 to gnd and also across C563

Before you rush off and order a TC7SH14FU, check the physical size. On mine it's a TC7SH14F which is larger than the FU. The panasonic part number for yours and mine are the same and it's just under 3mm wide which also matches the TC7SH14F in the datasheet. Note the chamfered edges on the FU. The F is not.

There's 4 of these on your SC board

[tw2005]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

If you have trouble finding these as it appears they're no longer in production Texas Instruments lists these as compatible SN74AHC1G14DBV. The DBV refers to the case, what follows this ignore as from what I can tell they're all the same. I got my HA from china.

[smartjohn]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Thanks for the data cross ref. Looks like the TC7SH14F replacement might be the DCK version, since pins center to center are .65mm on both. I'll double check mine before ordering. Still need to check the other active parts in the vicinity. As for checking buffers, what pins do you check for resistance / shorts? What should i see on a good one?

[tw2005]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

TC7SH14F has 0.95 center, DBV is the correct one for this. DCK will be the FU equivalent. I have both TC7SH14F & SN74AHC1G14DBV in front of me and are exact match.

In the service manual, Go to pg35, 10.5 block diagram 4/4. You'll see the SC and SD/SU layout.

Connector SU41 pins 2,4,8 SD42 3,5,8,9 2,4,6 SD46 1

on my boards which are different model, VSCN_F 220K, VFO 1.8-2Mohms, 5V_F over 4Mohms, SCNR_PRO over 5Mohms.
All measured with respect to the ground plate. You may have to switch the blk/red probes around to get a steady reading.

You can also in diode mode check gnd plate to all thebuffer output pins, you should not see any shorts. I see 0.7 on my meter.

[smartjohn]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

I am having 2nd thoughts on D725 and may just replace it. The reverse resistance was a little low ~150K in my opinion. Only problem is I can't find it's real part#. The SMD marking is "1_B" but that doesn't show up anywhere i am looking. Any thoughts ? This thing is REALLY small (approx. 2.1mm).

[tom66]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

150k ohm sounds fine to me... was that in circuit? Many small schottkies are very leaky.

[tw2005]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

I am having 2nd thoughts on D725 and may just replace it. The reverse resistance was a little low ~150K in my opinion. Only problem is I can't find it's real part#. The SMD marking is "1_B" but that doesn't show up anywhere i am looking. Any thoughts ? This thing is REALLY small (approx. 2.1mm).

If you have the manual, you have the part number. Try google and it will literally be staring you in the face and as a bonus the marking 1B matches in the datasheet as well.

[smartjohn]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Got it! Part# is MA2J111, 80V, silicon switching diode. And yes, datasheet states SMD code is 1B. This part is now discontinued but has been replaced by DA2J101. Both are Panasonic parts. The 150k was out of ckt. I will probably hold off on this one as I have alreday sent my Newark electonics order in and don't fell like paying another $10 buck for shipping until I have some other parts on my list.

Also, IC564 did confirm a short across pins 3 -5 out of ckt.

[smartjohn]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

next to SC20 can you measure resistance TP82 to gnd and also across C563

With IC564 removed (waiting for new parts) TP82 to gnd is about 4.4K.

Across C563 measures approx. 153K after it settles.

[freakaftr8]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Hey gentleman.

So here I am browsing the forums and amazingly I am having the same similar issue with my tc-54ps1 utilizing the same ysus sc board except all the components mentioned in this thread test good. I'm getting the 7 blink and when I disconnect the sc from the circuit 6 blinks and hear a wuick fireup on the ss board. So ysus defiantly has an issue. I have ohmed uou the su and sd board and all chips are in spec at around 5.5 m ohms
So I'm kind of in the same boat. All the inverters on the sc
Board seem fine and getting voltage at sc2. Interestingly I'm getting a momentary voltage at the screw lugs of the buffers so vscan is trying to come up as well as all the other voltages on the sc board at the test points. I have tried the one buffer board at a time with no success. Any ideas?
Thanks

[freakaftr8]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Hey gentleman.

So here I am browsing the forums and amazingly I am having the same similar issue with my tc-54ps1 utilizing the same ysus sc board except all the components mentioned in this thread test good. I'm getting the 7 blink and when I disconnect the sc from the circuit 6 blinks and hear a wuick fireup on the ss board. So ysus defiantly has an issue. I have ohmed uou the su and sd board and all chips are in spec at around 5.5 m ohms
So I'm kind of in the same boat. All the inverters on the sc
Board seem fine and getting voltage at sc2. Interestingly I'm getting a momentary voltage at the screw lugs of the buffers so vscan is trying to come up as well as all the other voltages on the sc board at the test points. I have tried the one buffer board at a time with no success. Any ideas?
Thanks

Found something interesting not sure if this will help or not but on pin 1 and 5 of ic773 is shorted both ways. Could someone verify if this is correct? Thanks and hope this helps add into this tnpa4844 board debunking