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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

06-09-2013, 09:53 AM
Re: plasma tv out of service

hello clydeuk hello Tom66

I noticed no changes since replacing the IPM . I mean the picture with osd is still dark. the sound is ok. When you switch on the tv, some black stains appears on the screen. After several minutes these stains disappears.

Thanks to the tom66's guide, I'm going to check the pass top and bottom FETs if they are failed or not.

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

06-08-2013, 04:45 PM
Re: plasma tv out of service

hi clydeuk

thank you for your reply

the DC converters for the -Vy and Vscan (Vsc) on this version are on the main Y Sus PCB. I heard the problem is due to the IPM failure so I changed it but no result.

I've found only two diagrams related to the Ysustain board but there are not a full diagram....

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

06-08-2013, 04:07 PM
Re: plasma tv out of service

hi clydeuk

normally the Vy voltage is -95 according to the specifications. you suggest that the DC DC converters isn't working or it's driving into a short-circuit but I think the second option is more interesting

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

06-08-2013, 03:58 PM
Re: plasma tv out of service

hello clydeuk

the model of my tv plasma is PDP42V7 from LG

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

06-05-2013, 03:35 PM
Re: plasma tv out of service

yes I have made the following measurements and I get :

Vscw = 114 volt
-Vy = - 1 volt
vset = 0 volt

Vs = 183 volt
Va = 65 volt

there are 2 inverters. one for the Vscw and the there one is for Vy. I have change almost all components around the Vy inverter but no result

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

06-05-2013, 02:52 PM
Re: plasma tv out of service

there are two fuses in the y sustain board. one for the vs voltage and the other one for the +5 voltage. there are ok after my measurement.

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

06-05-2013, 02:22 PM
Re: plasma tv out of service

hello tom66

I have already check the fuse from the vs voltage and it is ok. If this fuse did not work, i will not have vscan voltage on the ysustain board

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

06-04-2013, 03:43 PM
Re: plasma tv out of service

you right tom66

Vs = Vset on R14 but I noticed there is no Vs voltage on R24 and R26. It seems that the Vs voltage (183 volt) coming from the power board is defective in some parts of the y sustain board.

The vscan voltage is ok = 115 volt

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

06-03-2013, 04:46 PM
Re: plasma tv out of service

hello tom66,

I have replaced the ipm but the problem is still there : no Vy voltage. In addition, there is no Vs voltage on the resistor R14 (please see the diagram attached).

do you have any idea ?
thanks ...

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

05-19-2013, 09:49 AM
Re: plasma tv out of service

hello

yes I can highlight the 2 mosfets on the attached picture. There are located on the left hand side.

Yesterday I made a mistake. I wanted to test the resistor R4 but I did a short circuit. The lead of my multimeter has touch one of the leg of this standard resistor R4 and the other leg of a cms resistor. A short circuit appeared and the 2 resistors became black. The tv switch off (stand by mode) automatically as a security position .

The value on these resistor is still OK but now they...

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

05-18-2013, 01:14 PM
Re: plasma tv out of service

you right !

I also wondering if the 2 mosfets STP9NK70ZFP which are attached with screw can bring down the Vy and Vsetup voltage. I cannot test them directly on the ysus board. I have to desolder them before.

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

05-18-2013, 06:17 AM
Re: plasma tv out of service

thanks Tom66

Could I disconnect the control board connector from the Ysus board to test if I note some changes ?

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

05-18-2013, 03:13 AM
Re: plasma tv out of service

I noted that I heard a noise (Bzzzz) every 2 or 3 seconds near or under the IPM heatsink.
The IPM could be in short circuit even if the fuse is not blown ?

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

05-17-2013, 05:30 PM
Re: plasma tv out of service

Hello tom66,

I have disconnected the buffers from the Ysys board but the Vy voltage is still the same (between 0 and 8 volt). it is not stable. Normally the specification for that is -95 volt.

In addition, I've forgot to tell you there is 0 volt at the Vsetup voltage. Normally the specification for that is 183 volt.

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

05-05-2013, 04:09 PM
Re: plasma tv out of service

I read the specifications indicated behind the screen : the -Vy voltage must be at -95 volt.
I've made also some measurements with the vsc, va and vs which are OK.

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

05-05-2013, 12:34 PM
Re: plasma tv out of service

please find below the picture showing the boards of the tv....

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

05-05-2013, 12:09 PM
Re: plasma tv out of service

hello Tom66,

thank you for your reply. you suggest to check the buffer board but I do not kown where is it located on the tv.As I said previously, I read a book which shows an inverter producing this famous -Vy voltage. This inverter is surrounded by a optocopler, transistor an IC model NCP1200D6 and 4 condensators.

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takara replied to plasma tv out of service

in Troubleshooting TVs and Video Sources

05-04-2013, 05:10 PM
Re: plasma tv out of service

hello,

I can send a picture of the probleme. I forgot to announce the model of my TV plasma : PDP42V7

regards,...

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takara started a topic plasma tv out of service

in Troubleshooting TVs and Video Sources

05-04-2013, 01:45 PM
plasma tv out of service

hello,

I own a plasma tv which does not work now . the sound is ok but display is dark like a photographic film. I found the -Vy voltage in the Y-sustain board has between 0 and -6 volt. I heard this problem could be provoked by the inverter into the board.

I will appréciate some help to fix this failure.

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