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Panasonic TH-46PZ850u Bad MC201 Capacitor "Fixed"    
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COlt Hero



Joined: 22 Aug 2010
Posts: 12
Location: USA

PostPosted: Mon Oct 27, 2014 12:27 pm    Post subject: Panasonic TH-46PZ850u Bad MC201 Capacitor "Fixed" Reply with quote

OK - It appears I've "fixed" my Panasonic TH-PZ46850U Plasma with the 10-blink problem. I just ended up removing that bad (microscopic) capacitor on MC201 (in place .. I did *not* remove the power supply board). When I powered the set up and it worked, I decided to leave well enough alone.

To get the bad cap out, I first bent the tiny MC201 sub-board on the power supply board to the left until it was perfectly perpendicular with the power supply main board. For some reason, it came from the factory bent about 30 degrees to the right of perpendicular, and with other capacitors nearby, I didn't think I could get the soldering iron in there successfully without damaging something else. Next, I put the TV on the floor standing on its left side. I did this because now the tiny MC201 sub-board would be sitting horizontal (parallel to the floor), which made it easier to work on. Next, I put a dab of solder on the cap's outer-edge connection (don't ask my why, but NorCal did this before removing his cap - maybe it spreads out the heat load from the iron???). Then I put a 90-degree angle pick on the back edge of the tiny bad cap and applied pulling pressure toward me, while also applying the 15-watt soldering iron to the cap to break it free. With the capacitor removed, the set came up and ran fine this past weekend.

Why does the set run with the capacitor removed?? Beats me. My guess is the circuit prefers an open connection here and the cap failed closed?? I dunno. Will I eventually install the replacement capacitor? I have it, but I don't think I will install it. WAY too small of a soldering job and I think I'd just end up causing another problem. If the problem comes back, it'll probably be the same capacitor failing on the MC301 board. Then I'll do the freeze test again to confirm, and remove that cap, too!
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kuhurdler



Joined: 28 Dec 2006
Posts: 2847
Location: Overland Park, KS

PostPosted: Wed Oct 29, 2014 12:27 pm    Post subject: Reply with quote

Thanks for posting back.

This is the same model TV i have in my family room. Best picture I have come across so far.
COlt Hero



Joined: 22 Aug 2010
Posts: 12
Location: USA

PostPosted: Tue Nov 04, 2014 12:02 pm    Post subject: Reply with quote

My picture seems to look better now (after removing the cap), but then again - maybe it's just that I got used to watching my nearly-20-year-old 27" JVC CRT for two months.

Someone here at work, more savvy with electronics, theorized that the cap was merely a 'filter' that wasn't absolutely necessary (??). I'm a software guy, and I know I've run into unnecessary logic over the years. This cap removal made me wonder if the same problem exists in hardware (unnecessary or redundant components on circuit boards).
kuhurdler



Joined: 28 Dec 2006
Posts: 2847
Location: Overland Park, KS

PostPosted: Wed Nov 05, 2014 1:55 pm    Post subject: Reply with quote

It's pretty common design practice to put a capacitor on the power input of active ICs/modules. It prevents a lot of issues with the chip doing unexpected things due to noisy power.
I would never argue that it's unnecessary, but agree that you may get away without using it.
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