Is this noise power cycle, or shorting? - Badcaps

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Spode

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Join Date: Dec 2010

Posts: 41
#1

Is this noise power cycle, or shorting?

02-10-2011, 01:00 PM

Hi Guys,

Trying to fix another TV (now have a small pile of them that I'm struggling with).

The unit was turning on, and after a short amount of time, the backlights would stay on but the signal to the unit would just stop and then slowly fade away off screen (logic board issue?).

I found a swollen cap in the PSU which I replaced - on the 24V side of things. Made no difference.

The PSU was making a bit of noise in the top right, which using a straw I found to be one of the large red ceramic capacitors. I decided that perhaps the power was failing to the logic board, so thought I'd investigate further.

I decided to resolder the joints for the two transformers and the toroid coils on that side of the PCB.

After that, the unit no longer turns on and instead I'm getting a fast clicking. I can't work out what I could have done wrong! I've checked everything I've soldered and all appears to be in order

What does the sound in the MP3 file I've attached indicate? Is it arcing, or the safety mechanism of it trying to turn on/off?
Attached Files
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retiredcaps

Badcaps Legend

Join Date: Apr 2010

Posts: 9271
#2

02-10-2011, 01:24 PM

Re: Is this noise power cycle, or shorting?

1) It would help if you listed the make and model number of the TV.

2) A clicking suggests the SMPS is trying to start. It might be the small capacitor next to the SMPS.

3) We could use a better focused picture of the picture as close to 2000x2000 resolution.

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Spode

Member

Join Date: Dec 2010

Posts: 41
#3

02-10-2011, 02:57 PM

Re: Is this noise power cycle, or shorting?

1) Medion 20099-S 32"

2) Did you listen to the MP3 I attached? I was wondering about the start-up cap, but it was working fine before I decided to re-solder the joints - so that didn't make sense?

3) Attached something a little better. I really should dust off my SLR for these things...
Attached Files
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retiredcaps

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#4

02-10-2011, 03:04 PM

Re: Is this noise power cycle, or shorting?

Originally posted by Spode

2) Did you listen to the MP3 I attached?

No. I'm not blaming you, but having been burned in the past with zip attachments, I avoid opening them.

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retiredcaps

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#5

02-10-2011, 03:11 PM

Re: Is this noise power cycle, or shorting?

Still too blurry to read the legend next to all the connectors, but do you still standby voltage on any of the connector pins?

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Spode

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Join Date: Dec 2010

Posts: 41
#6

02-10-2011, 03:41 PM

Re: Is this noise power cycle, or shorting?

Originally posted by retiredcaps

No. I'm not blaming you, but having been burned in the past with zip attachments, I avoid opening them.

That's understandable - there wasn't a way for me to attach an MP3 though!

Here it is on SoundCloud:

http://soundcloud.com/spode-1/recording-20110210-184854

Here are a few more pictures, from the SLR too to see if these help. Will check the standby voltages later. I found 1.2, 3.3, 5 and 24 when it was up and running.
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retiredcaps

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Posts: 9271
#7

02-10-2011, 04:00 PM

Re: Is this noise power cycle, or shorting?

Originally posted by Spode

Here it is on SoundCloud:

Comes up with an error message.

Here are a few more pictures, from the SLR too to see if these help.

SLR makes huge improvement.

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Scenic

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Join Date: Sep 2007

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Country: Germany
#8

02-10-2011, 04:14 PM

Re: Is this noise power cycle, or shorting?

Originally posted by retiredcaps

No. I'm not blaming you, but having been burned in the past with zip attachments, I avoid opening them.

lol for being that paranoid..

the mp3
http://bambooz.pytalhost.net/badcaps...210-184854.mp3
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ben7

Capaholic

Join Date: Jan 2011

Posts: 4059

Country: USA
#9

02-11-2011, 05:11 PM

Re: Is this noise power cycle, or shorting?

Ok it looks like the unit was repaired before, because of the odd panasonic capacitor on the output, compared to the other crap-looking ones.

I think there is either too little load on the PS, or there is a short somewhere that you made. When you tested the PS did you put it in the TV?

-Ben

Muh-soggy-knee
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Scenic

o.O

Join Date: Sep 2007

Posts: 2642

Country: Germany
#10

02-11-2011, 05:23 PM

Re: Is this noise power cycle, or shorting?

^
blue -> G-Luxon
green -> seems to be CrapXon
black-gold -> Lelon

so pretty much the crappiest caps possible for a LCD TV PSU..

ticking sounds usually indicate that the PSU is trying to start up, but can't. either due to crapcaps or a short somewhere on the secondary side..
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mbates14

Senior Member

Join Date: May 2005

Posts: 169
#11

02-11-2011, 10:48 PM

Re: Is this noise power cycle, or shorting?

its funny though, it was working before you re-soldered. and not after, better check you didnt bridge a connection. ive done this by accident in the past.
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Spode

Member

Join Date: Dec 2010

Posts: 41
#12

02-13-2011, 11:39 AM

Re: Is this noise power cycle, or shorting?

The black-gold cap was put in by me, to replace a swollen green one. Didn't make a difference though.

I think you're right mbates14 - it could well be a mistake I've made, but I've looked and looked and can't see anything

Before I started soldering, using a straw one of the red caps was making a noise. Now, the clicking is coming almost entirely from that same red cap. Could the cap have gone - or is it just an indication of something further down the line?
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Spode

Member

Join Date: Dec 2010

Posts: 41
#13

02-13-2011, 12:01 PM

Re: Is this noise power cycle, or shorting?

I just plugged it all back in, and it made odd clicking noises, which sped up and eventually just became a hum - and it powered on as it was before I started working on it.

Worked for 5-10 minutes and then eventually the same issue occurred.

So now I'm pretty sure that I haven't made the issue worse - so the startup issue is probably related to a bad cap somewhere. So which area should I start replacing first? What is the most likely culprit?
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