Sony KV-T25SZ8 TV problem

Hi All,

I'm about to start working on the above model - apparently it stopped
working after a lightning storm. The tv has no standby lights, but you can
hear it momentarily "thump" when the power point is first turned on. I'm
guessing that the main capacitor is still charging - the fuse is still
intact.

Does anyone have any ideas on where to start first. I'm guessing I'll have
to get a manual to start tracing.

Any thoughts would be greatly appreciated.

David

 

Yes trouble shoot the SMPS section first.

kip

 

Agreed. I have found that in a SMPS that a power surge can take out
ceramic disc caps in the power supply. Sometimes they are hard to see as
they don't fail like electrolytics.

Bruce

 

Many thanks for your reply.

How do I check ceramic disc caps without an ESR meter?

 

David:
Use a DMM to check for shorts or leakage and if your DMM has a capacitance
function you can measure the accuracy of the disc cap for the proper
value....
Not to be condescending here but are you certain you have the necessary
electronics experience and knowledge to be working on one of the most
dangerous electronic devices in your home????
For lots of helpful information regarding repairs and troubleshooting you
should go to the website for this newsgroup at
http://www.repairfaq.org/
plan to spend some quality search time there.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - - - - - - - --

 

Why do you want to? Ceramics don't change ESR as they age.

 

I finally got around to having a look at the set today. I found a ceramic
capacitor on the AC (next to a 470 ohm resistor) side that was open circuit.

The capacitor is marked 103P. Am I right in assuming that it is a 130 pF ??

 

"David" bravely wrote to "All" (08 Jan 06 09:25:07)
--- on the heady topic of "Re: Sony KV-T25SZ8 TV problem"

Da> From: "David" <>
Da> Xref: core-easynews sci.electronics.repair:354497

Da> I finally got around to having a look at the set today. I found a
Da> ceramic capacitor on the AC (next to a 470 ohm resistor) side that was
Da> open circuit.
Da> The capacitor is marked 103P. Am I right in assuming that it is a 130
Da> pF ??


That cap is probably not 130pF.
Capacitors are normally open circuit for DC, what do you mean by this?

The marking 103 would mean 10 with 3 zeros, so this would mean it was
a 10,000pF or a 0,01uF capacitor. However the letter P is a tolerance
of +100/-0% so the cap may measure as much as 0,02uF. Finally, its
thickness and diameter would give a rough approximation of its voltage
rating, unless it is written.

Typically, P tolerance 0,01uF or 0,1uF ceramic caps are used for
bypassing and this means these would be unlikely to cause a major
problem if they did fail with a reduced capacitance.

A*s*i*m*o*v

.... High Voltage Electronics: Life's a glitch, then you fry.

 

I tested the capacitor and it measured -.598 on the 2uF range on my
meter. I'm wondering if my meter is stuffed.

 

"David" bravely wrote to "All" (09 Jan 06 09:26:11)
--- on the heady topic of "Re: Sony KV-T25SZ8 TV problem"

Da> From: "David" <>
Da> Xref: core-easynews sci.electronics.repair:354617

Da> I tested the capacitor and it measured -.598 on the 2uF range on
Da> my meter. I'm wondering if my meter is stuffed.


If the cap was across a diode it might be rectifying the test signal
and resulting in a negative reading. First try unsoldering just one
leg and then take the measurement.

A*s*i*m*o*v

 

I tested the cap out of the circuit initally. I'm wondering if my meter is
on the way out.

 

"David" bravely wrote to "All" (10 Jan 06 06:56:16)
--- on the heady topic of "Re: Sony KV-T25SZ8 TV problem"

Da> From: "David" <>
Da> Xref: core-easynews sci.electronics.repair:354740

Da> I tested the cap out of the circuit initally. I'm wondering if my
Da> meter is on the way out.


If the cap tested open circuit on the DC ohms range then I certainly
would wonder about the capacitance range since caps don't typically
exhibit a negative value.

A*s*i*m*o*v

 

What DC ohms range could I expect from this capacitor?