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Posted

Hi, my Pioneer LX608 plasma no longer seems to be able to get to standby mode, let alone turn on the screen.  Could this be a capacitor problem?  Any good recommendations for repair in Melbourne east?  The tv is out of warranty, and since Pioneer closed shop I've no idea where to look.

 

Cheers.

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Posted

Pull the back off the TV mate, grab a good little LED torch and check the capacitors for yourself.

It's normally quite easy to see if they have 'popped'. the seams on the ends will be split slightly and a brown residue apparent.

I'm not sure this was ever and issue with the Kuro's however. Could more likely be the power board.

Posted

This TV was released in 2008 and Pioneer stopped making TVs in 2010. 2013 Panasonic stopped making plasma screens.

Jutta do not suggest examining inside plasma TVs which contain high voltage supplies. These capacitors store a considerable charge which can last a long time even with the power disconnected.

You have no idea of the poster's knowledge of electronics and their awareness fo potentially lethal situations.

High voltage electrolytic capacitors are not easily obtained.

Since the TV is around 6 to 7 years old, and plasma techology has also been discontinued, you should really think about replacing this TV.

UHD TVs designed for the new HDR signals have a greater contrast range than the plasma, particularly one which has been used for > 6 years where the brightness of white must have reduced.

Alanh

 

 

 

Posted

thanks for your input guys, glad to see the old regulars are still around.

yeah i won't pull the back off the tv, i'll give impulse electronics a call, peter.

i'd like to avoid getting a new tv if i can, i don't mind paying a few hundred to get this fixed.  still love my kuro, and it'll be cheaper too.

 

cheers.

Posted

Well capacitors do discharge. Unplug from the wall and let sit for a few days. I did say examine with a torch. Cost me $1 to fix mine.


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Posted
  On 20/10/2016 at 1:04 AM, kermuffle said:

I'd like to avoid getting a new tv if i can, i don't mind paying a few hundred to get this fixed.  still love my kuro, and it'll be cheaper too.

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Yeah, there's something kinda cool in fixing up a great piece of tech instead of just scrapping it. 

Hopefully it is the capacitors as Jutta says, in which case the store should be able to repair it quick and cheaply.

Let us know how it goes.

Regards

Peter Gillespie

Posted

Jutta,

Yes capacitors do discharge, but those in the switchmode power supplies are directly across the rectiifier output can kill you if touched after switchoff, just how long do you wait. There has been no mention of a volt meter here! Dangerous advice.

 

Alanh

Posted

Well perhaps you need to do a search on the word capacitors and post the same advice on every other mention of them over the years. Apologies for endangering lives

Not much use offering advice around here anymore. Always someone to point out everyone's shortcomings



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Posted

While it's true that AlanH often posts a lot of utter garbage, I happen to agree with him on this (in general, at least).

Encouraging someone who may have no experience with soldering or electronics to replace capacitors in a non-mains-isolated switchmode PSU or high-voltage plasma display drive supply is irresponsible, verging on dangerous.

Posted
  On 20/10/2016 at 11:43 AM, jutta said:

Not much use offering advice around here anymore. Always someone to point out everyone's shortcomings

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Keep your chin up mate !!

Posted
  On 20/10/2016 at 11:43 AM, jutta said:

Well perhaps you need to do a search on the word capacitors and post the same advice on every other mention of them over the years. Apologies for endangering lives

Not much use offering advice around here anymore. Always someone to point out everyone's shortcomings



Sent from my iPhone using Tapatalk

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AlanH has seldom been known for empathetic posting :) FWIW I've always viewed forums like this as a conglomeration of viewpoints. I like the discussion but usually don't try 'win' a thread. Your comments are here and so are Alan's. The OP (and others) will read through and place weight on them as they see fit.

Regards

Peter Gillespie

Posted
  On 19/10/2016 at 2:24 AM, kermuffle said:

Hi, my Pioneer LX608 plasma no longer seems to be able to get to standby mode, let alone turn on the screen.

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Sorry, just to clarify... did you mean that it just stays in standby and won't switch on? Does the standby light flash at all?

JSmith :ninja:

Posted

Begs the question: Have the obvious things been checked? Power cord OK, power cord plugged in correctly at the back of the TV,main power switch on the bottom of the TV turned on?

I've come across these scenarios over the years.

I'm inclined to think if there is no activity, a fuse could be blown, which then requires analysis as to the failure mode causing this event. It seems to me faulty capacitors have entered the general online lexicon as to the reason for equipment failing, something I also posit on occasions. (I do, however, fix a lot of stuff where this is the case.)

 

Be interesting to know what it was if the OP comes back with a result.

 

BTW I have no trouble finding high voltage capacitors, there are a number of suppliers on the east coast of Australia.

Posted (edited)

I have never seen a capacitor that could hold a lethal voltage for hours let alone a day and have never had any issue working on equipment. If you are only looking and not touching its a non issue anyway. Just leave the TV disconnected for 24 hours and you are good to go.

There are many more issues that affect operation than just capacitors, especially with switch mode power supplies, and a blown fuse suggests a mores serious problem like an output stage gone short circuit.

If it is a power supply problem, which is likley, it should be repairable as the parts are normally generic and obtainable.

Just because Plasma is no longer in production doesn't make it any less desirable as a display device, thats a crazy concept.

The Kuro has higher native contrast than any of the HDR LCD TV's on the market today by a WIDE margin.

Edited by Owen

Posted
  On 23/10/2016 at 12:29 AM, Owen said:

I have never seen a capacitor that could hold a lethal voltage for hours let alone a day

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Whereas I have*, so I treat all capacitors in high voltage circuits with due respect.

As an apprentice i was taught the:

Ten Commandments of Electrical Safety

(1) Beware of the lightning that lurks in an undischarged capacitor lest it cause thee to be bounced upon thy backside in a most ungainly manner.

(2) Cause thou the switch that supplies large quantities of juice to be opened and thusly tagged, so thy days may be long on this earthly vale of tears.

(3) Prove to thyself that all circuits that radiateth and upon which thou worketh are grounded lest they lift thee to high-frequency potential and cause thee to radiate also.

(4) Take care thou useth the proper method when thou taketh the measure of high-voltage circuits so that thou doth not incinerate both thee and the meter, for verily though thou hast no account number and can be easily replaced, the meter doth have one and as a consequence bringeth much woe upon the supply department.

(5)Tarry thee not amongst those who engage in intentional shocks for they are surely non-believers and are not long for this world.

(6) Take care thou tampereth not with interlocks and safety devices, for this incureth the wrath of thy seniors and bringeth the fury of the safety officer down upon thy head and shoulders.

(7) Work thee not on energized equipment, for if thou doeth, thy mates will surely be buying lunch without thee and thy space at the table will be filled by another.

(8) Verily, verily I say unto thee, never service high-voltage equipment alone, for electric cooking is a slothful process, and thou might sizzle in thy own fat for hours on end before thy Maker sees fit to end thy misery and drag thee into His fold.

(9) Trifle thee not with radioactive tubes and substances lest thou commence to glow in the dark like a lightning bug.

(10) Commit thee to memory the works of the prophets, which are written in the instruction books, which giveth the straight info and which consoleth thee, and thou cannot make mistakes.

 

I've been zapped a couple of times a long time ago, sufficient to reinforce the message in the first commandment.

 

*I repair VAST boxes that have the SOPS start-up resistors go o/c, the mains capacitor in them can hold a charge for more than 24hours.

Posted (edited)

What where you zapped by?

Had it been off for 24 hours?

 

Edit.

Missed your bit about the VAST boxes, whatever they are. So it wasn't from a switch mode supply in a TV where the chances of having absolutely no load on a capacitor is effective ZERO, and that capacitor would need to have perfect internal insulation. That's a far fetched set of circumstances and the residual voltage plus energy stored would still need to be pretty high to be seriously dangerous. There is a big difference between an uncomfortable zap and dangerous zap.

I would be far more concerned about working on CRT TV's, they where nasty.

Switch mode supply repair is not the sort of thing the OP should contemplate anyway, let a professional do it.

 

Edited by Owen
Posted

Yeah, it's real simple. Doesn't matter whether it's been charged up and allowed to discharge or whether it's been deliberately discharged, if it's disconnected or in a high-impedance circuit then due to dielectric absorbtion an electrolytic will eventually settle at ~15% of the peak voltage it was previously subjected to. And depending on dielectric impedance (not the same as ESR or 'active' impedance), it can maintain that state for years.

If you consider that, say, an input or reservoir cap in a mains-powered switchmode supply could easily be 1000uF or more and subject to peaks of 400V+, then that means it's storing ~ 2J or more energy. Depending on the type of contact & your own bulk resistance, that's enough to be fatal.

And, FWIW, I too have gotten the odd nasty zap from smaller caps in equipment that has been disconnected and sitting on my bench for several weeks or more.

Posted

If you take that school of thought its virtually impossible to service equipment safely. Each and every capacitor that could have a dangerous voltage on it must be manually discharged every time anyone needs to work on the gear, who ever does that with a TV or other similar gear.

After 24 hours the OP has more chance of being injured or killed by a plain crashing on his house.

Posted

I had a picture tube which uses the glass envelope as a capacitor charged to 25 kV produce an arc after a week. Waiting for 24 hours is no guarantee, because you can easily forget and switch it on to test it and then wait another 24 hours if you remember! Capacitors don't contain a display to say what their voltage is so you will not be warned!

I had a student who despite my warinings , discharged a the main capacitor in a large switchmode power supply with a screw driver. He went home to change his pants. It was a very loud bang. Fortunately the screwdriver had an insulated handle. A calculation of the energy stored in the capacitor when charged to the peak of mains voltage is sufficient to kill.

I supplied a physically large high wattage well insulated resistor connected to insulated probes for discharging high voltage large capacity capacitors. .

Since iron cored transformers are expensive heavy and bulky switchmode power supplies are used in nearly all modern equipment so this danger is ever present for the untrained.

Electric cars, inverters used for air conditioners, generators etc all contain high capacity high voltage capacitors all of which are lethal when charged.

NOTE: The safety switch (RCD) in the meter box if installed is not designed protect you from discharging capacitors.

 

Alanh

Posted
  On 23/10/2016 at 1:38 AM, Owen said:

If you take that school of thought its virtually impossible to service equipment safely.

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No, it simply reinforces to the school of thought that it's difficult to service equipment safely if you don't understand what you're doing.

And I'm happy to help people (with one or two obvious exceptions) learn enough to understand what they're doing. It's a common attitude on genuinely technical or specialist forums where people turn to help for understanding / repairing something, and I enjoy sharing that. Unfortunately, on forums like this where the general technical level is lower and a lot of 'received wisdom' really isn't that wise, it's not.

Q: How do you feel when someone insists that current LCD TVs are equal in picture quality to plasmas? Yeah, it's like that ... but with the added potential for someone to physicaly hurt themselves...

If someone wants to take the chance themselves, that's fine. But my personal opinion is that it's pretty irresponsible to insist that it's OK for someone with no known/stated knowledge or experience to take the chance.

Posted
  On 23/10/2016 at 12:51 AM, Owen said:

What where you zapped by?

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Colour CRTs. More than once, more fool me. One hand in the pocket doesn't always work in this case :(

The criticality could be the reaction from the shock. For me it was my elbow hitting a small projection on the concrete wall in my workshop. My ulnar nerve took ages to recover from that.

  On 23/10/2016 at 12:51 AM, Owen said:

Had it been off for 24 hours?

Expand  

In the case of the CRT no. I just have a healthy respect for components that store a charge, it doesn't stop me from repairing things.

 

 

Posted

Note;

If you read US websites the main supply capacitor in a switchmode power supply only charges to 165V Where as ours charge to 339V and the energy store increases as a square of the voltage applied. So in the USA you will not kill yourself on this capacitor but the burns and the shock still exist.

Alanh

 

Alanh

Posted
  On 23/10/2016 at 3:00 AM, alanh said:

Malich,

I have never made any comments on the quality of Plasma vs LCD images!

Stop making things up.

 

Alanh

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Alan,

I never said you did. Stop making things up.

My reply was clearly to Owen, since he's who I quoted. An apology for your error would be nice too, but I won't hold my breath...

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