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garyfritz
Joined: 08 Apr 2006 Posts: 12026 Location: Fort Collins, CO
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Link Posted: Sun Nov 25, 2018 8:41 pm Post subject: Dead(ish) Panasonic TV |
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I just discovered a previous renter left a 42" TV behind -- apparently because it doesn't work so she dumped it on me.
It looks like it's in good shape, looks like a nice set, but no picture. The splash screen flashes very briefly when it powers up, but after that it's all black. No menus, no nothin'.
It's a Polaroid (!) so probably uber-cheap Chinese crap, but I'd like to keep it out of the scrap heap for a while. Any chance it might be easy to repair?
It's a Polaroid TLX-04243B.
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Curt Palme CRT Tech
Joined: 08 Mar 2006 Posts: 24305 Location: Langley, BC
TV/Projector: All of them!
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Link Posted: Sun Nov 25, 2018 8:50 pm Post subject: |
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If it's an LED TV, then that sounds like one LED section is drawing too much current. The set senses that, and shuts the lamp (LED) power supply down. Ditto if it's a fluorescent tube set.
Some techs apparently open the edge of the LED TV and replace the LED units. I've never done it, and I'll bet you have to nuke 10 sets before you get it down pat.
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HaydnG90
Joined: 22 May 2006 Posts: 1335
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Link Posted: Sun Nov 25, 2018 9:03 pm Post subject: |
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I'd start with replacing the PS board. They are an achilles heal
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Curt Palme CRT Tech
Joined: 08 Mar 2006 Posts: 24305 Location: Langley, BC
TV/Projector: All of them!
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Link Posted: Sun Nov 25, 2018 9:16 pm Post subject: |
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I wouldn't. I've worked on about a dozen, and changed the power supply on a few. That was never the problem. Given also that it's a Polaroid, I wouldn't spend more than $10 on it.
Of course if it's an older set (over say 6 years old), check for bulging caps, and change those. that might bring it back to life.
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HaydnG90
Joined: 22 May 2006 Posts: 1335
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Link Posted: Sun Nov 25, 2018 10:02 pm Post subject: |
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10+year LCD. Does the standby light flash?
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pcheadaches
Joined: 09 Dec 2013 Posts: 62
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Link Posted: Mon Nov 26, 2018 12:10 am Post subject: |
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Open up the back of the tv. On the P/S board you will see a 4 dip switch. Switches 3 and 4 are probably off. Plug in the tv but do not try to turn it on. Slide switch 3 and 4 to on. Then see if tv turns on. If it turns on and stays on put the back, back on and enjoy.
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garyfritz
Joined: 08 Apr 2006 Posts: 12026 Location: Fort Collins, CO
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Link Posted: Mon Nov 26, 2018 1:20 am Post subject: |
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Nope, no flash codes when you turn it on.
Thanks pch, I'll try that when I get a chance.
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AnalogRocks Forum Moderator
Joined: 08 Mar 2006 Posts: 26690 Location: Toronto, Ontario, Canada
TV/Projector: Sony 1252Q, AMPRO 4000G
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Link Posted: Mon Nov 26, 2018 3:08 am Post subject: |
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I fixed a Hemeroid TV one day. 6 Caps and bad solder joints. I left it in the kitchen that night and a pipe broke. Washed all the magic smoke out of it
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CRT.
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garyfritz
Joined: 08 Apr 2006 Posts: 12026 Location: Fort Collins, CO
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Link Posted: Fri Nov 30, 2018 12:22 am Post subject: |
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pcheadaches wrote: | Open up the back of the tv. On the P/S board you will see a 4 dip switch. Switches 3 and 4 are probably off. Plug in the tv but do not try to turn it on. Slide switch 3 and 4 to on. Then see if tv turns on. If it turns on and stays on put the back, back on and enjoy. |
Well, here's the power supply board. I see a diagram of 4 switches (highlighted), but I don't see the switches themselves!! Am I missing something obvious?
It looks like there are thru-holes in that diagram. Am I supposed to stick jumpers in there??
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pcheadaches
Joined: 09 Dec 2013 Posts: 62
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Link Posted: Fri Nov 30, 2018 1:30 am Post subject: |
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Looks like the right board just no switch. Interesting. Why do those pads look funny on the burn section? Was there something there and cut off?
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HaydnG90
Joined: 22 May 2006 Posts: 1335
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Link Posted: Fri Nov 30, 2018 2:29 am Post subject: |
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Seems some boards do and some don't have the dip switches. Maybe depends on the model its going into. The component top middle looks discolored compared to its partner. Maybe worth further investigation. The capacitors under the ventilated cover appear abnormal too, especially the right one.
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kal Forum Administrator
Joined: 06 Mar 2006 Posts: 17860 Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
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pcheadaches
Joined: 09 Dec 2013 Posts: 62
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Link Posted: Fri Nov 30, 2018 3:49 am Post subject: |
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That was my assumption also. I am looking for confirmation.
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garyfritz
Joined: 08 Apr 2006 Posts: 12026 Location: Fort Collins, CO
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Link Posted: Fri Nov 30, 2018 4:27 am Post subject: |
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That's my guess too. There are little cut-off bits of wire in those holes.
HaydnG90 wrote: | The component top middle looks discolored compared to its partner. Maybe worth further investigation. The capacitors under the ventilated cover appear abnormal too, especially the right one. |
The two brownish things top-center are large capacitors. They're slightly different in color but neither one looks cooked.
I think the cap under the cover just had odd lighting. It looks fine. All of the electrolytics look good, no leaks or bulging.
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pcheadaches
Joined: 09 Dec 2013 Posts: 62
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Link Posted: Fri Nov 30, 2018 2:30 pm Post subject: |
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Well then since there is no switch there I would try soldering a wire across the 2 burn pads and see if the tv works or not.
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garyfritz
Joined: 08 Apr 2006 Posts: 12026 Location: Fort Collins, CO
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Link Posted: Fri Nov 30, 2018 7:16 pm Post subject: |
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So, just across the BURN connections? Which is presumably "switch #4" ? What about the EPWM pads?
Any idea what shorting the BURN or EPWM connections actually does?
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kal Forum Administrator
Joined: 06 Mar 2006 Posts: 17860 Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
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Link Posted: Fri Nov 30, 2018 7:20 pm Post subject: |
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pcheadaches wrote: | Well then since there is no switch there I would try soldering a wire across the 2 burn pads and see if the tv works or not. |
I wouldn't do that. The missing jumper wires is not why the TV doesn't work. It's not like the previous owner desoldered them. The missing jumpers is most definitely normal.
In electronics often boards are etched for use in multiple (different) models. This model TV may not offer certain features so not all the parts were soldered on to the board, but the actual board with the copper traces will be the same across models. It's simpler/more cost effective to have one circuit board etched for 5 models instead of making 5 different board runs. In some models the circuit boards will appear empty or missing parts. Completely normal. It could also be that over the years they simplified the circuit by dropping certain parts but didn't bother to redo the board as that costs money. Again, completely normal.
Kal
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pcheadaches
Joined: 09 Dec 2013 Posts: 62
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Link Posted: Fri Nov 30, 2018 7:44 pm Post subject: |
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garyfritz wrote: | So, just across the BURN connections? Which is presumably "switch #4" ? What about the EPWM pads?
Any idea what shorting the BURN or EPWM connections actually does? |
Just do the burn one for now. Yes it would of been switch 4 if it were there.
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kal Forum Administrator
Joined: 06 Mar 2006 Posts: 17860 Location: Ottawa, Canada
TV/Projector: JVC DLA-NZ7
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garyfritz
Joined: 08 Apr 2006 Posts: 12026 Location: Fort Collins, CO
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Link Posted: Sat Dec 01, 2018 5:08 pm Post subject: |
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Kal, I understand your caution. But consider that in its current state, the TV is a boat anchor. If I do nothing, it stays a boat anchor, and I'll have to pitch it. So I'm not worried about damaging it. As long as it doesn't set my house on fire, I'm willing to try possibly-crazy stuff to see if it helps resurrect it.
That said, I'd like some assurance that this is a reasonable thing to try. pch, can you explain what the BURN and EPWM jumpers are supposed to do, and why you think it might help the situation?
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