Re: 820-01041 MBP 15" '18 Schematics/bv request
Thanks!
rvanpruissen
Member
Last Activity: 05-09-2023, 12:55 PM
Joined: 03-17-2013
Location: Eindhoven
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Re: STB3.3v = 0.4V on Panasonic p42v10
"Fires up" indeed, sorry habit from laptop repairs
This was indeed a recycled board from a seller who claims it's working. Maybe it isn't...
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Re: STB3.3v = 0.4V on Panasonic p42v10
Hey guys, in the meantime I've bought a new signal board. Unfortunately it still doesn't work, but some things have changed. Now when I turn on the TV I hear the relays clicking and the backlight turns on. However, theres nothing on the screen (no OSD), I have 13 blinks and the TV shuts itself down.
I've had some time to cool down and gather some courage to start over again. Any ideas where to start? Cheers. Rick.Leave a comment:
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Re: STB3.3v = 0.4V on Panasonic p42v10
Thanks guys. I might try removing the IC in the weekend. I guess the worst that could happen is that I gain some experience in removing IC's
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Re: STB3.3v = 0.4V on Panasonic p42v10
Could the short also be on one of the 100 connection of IC1100 I didn't 'disconnect'? Or is it unlikely there's an internal connection between the 4 IVDD STB3.3V connections and the rest of the connections.
Any suggestions on where to check next? IC1100 is indeed difficult (impossible?) to find (and replace).Leave a comment:
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Re: STB3.3v = 0.4V on Panasonic p42v10
Ok guys. So after removing L1100 I've isolated the problem to the STB3.3V supply to IC1100, see attached image. The caps indicated in yellow are the ones I've removed so far and still there's only 4.2ohm resistance between this part of the STB3.3V line and ground.
Any brilliant ideas for the next step or should I assume IC1100 is shorted? I'm thinking maybe the crystal's capacitors on the right, or even further down the lines coming from IC1100.
Please help this electronics noob on his epic journey...
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Re: STB3.3v = 0.4V on Panasonic p42v10
Thanks budm. A bit out of my league though I have no reason to think this diode is bad, so I'll focus on the STB3.3v line first.
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Re: STB3.3v = 0.4V on Panasonic p42v10
Crap. Just took a look at the schematic and D503 is parallel to a transformer, so thats what I'm measuring. Any particular reason to believe it's D503 TVRepairNoobie? Otherwise I won't try to get it out of the board. Thanks again!Leave a comment:
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Re: STB3.3v = 0.4V on Panasonic p42v10
Thanks guys! I'm baffled to see that D503 measures open both ways, using the diode tester on my multimeter. Could this be the source of the problems? Or am I doing something wrong (sorry, sometimes I'm missing some basic electronics skills )
To fix the A-board, I think I'll go with Neelix' plan to remove L5480 first and test whether IC5480 itself is shorted to ground, or the short is somewhere in the rail. Not sure about when though, bit busy now.
Keep em coming please!Leave a comment:
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Re: STB3.3v = 0.4V on Panasonic p42v10
There's a regulator on the A-board (IC5480) which supplies the STB3.3V, based on the STB5V. I've included some pictures:
[LIST][*]409: Overview[*]408: A-board component side[*]412: Close-up of IC5480[*]413: A-board foil side[*]414: Close-up of IC1100 which is should be powered by STB3.3V (among others[/LIST]
Meanwhile, I've found out that when I disconnect A3 connector (to D-board) and leave the rest plugged in, the TV powers up: relays click, backlight is on but still no standby light. At this point, STB3.3V becomes 0,67V (less...Leave a comment:
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STB3.3v = 0.4V on Panasonic p42v10
Hi guys,
Recently I've been given a faulty Panasonic p42v10. The symptoms are as follows:
[LIST][*] No response when on power[*] No standby LED[*] No relay clicks[/LIST]
After some research, I found out that:
[LIST][*] STB5V rail is measuring 4.5V (just within tolerance?)[*] STB3.3V rail measures 0.4V. [*] STB3.3V has a resistance to ground of 4.2ohm with no cables connected to the board (A-board).[/LIST]
At this point I'm not sure how to proceed as there are many components connected to the STB3.3V rail, all of which could be shorting to ground.
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Re: New Members - please post your introductions here
Hi, I'm Rick. I've used this forum several times for component level repair of (mainly) laptops. My background is in mechanical engineering but as a hobby I've been trying to teach myself some electronics skills. For now I'm using the experience on this forum to help me fix stuff. I hope I'll be able to help someone myself sometime soon.Leave a comment:
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