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messerfloh
Joined: 04 Dec 2007
Posts: 18
Location: Bavaria, Germany
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| Posted: Mon Feb 18, 2008 3:51 pm Post subject: LVPS failure Sony 1252 |
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Hi guys!
recently I pulled out the optics of my 1252 for cleaning the lenses and the tube faces. As you know you have to pull out the LVPS and the HV block to reach the nuts for the blue lens.
After reassembling I fired up the PJ and there was a tiny "zap" and power went off. the error code was "20" which, according to the manual, is "power shutdown". Well yes, the power went off as a matter of fact, but now??? I tried to restart (green button) and all what happened was a faint short hiss out of the insides of the LVPS. This hiss comes every time I hit the start button. Think its better to wait for some advice instead of retrying the start button
Any ideas what could have happened? Does the LVPS have any fuses inside that I could check? Or is this a major Problem?
I have only a multimeter (could get an oscilloscope though), what can I measure for troubleshooting?
Eventually could a good TV technician repair this or is it better to send the LVPS to Curt?
Any hints and advice appreciated!
So long
Floh 
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messerfloh
Joined: 04 Dec 2007
Posts: 18
Location: Bavaria, Germany
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| Posted: Thu Feb 21, 2008 10:39 am Post subject: |
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Ha! Yesterday we found the bug: the transistor on the PC board was over (2SC3998). I ordered it and hopefully tomorrow i can solder the new one in.
Greetz Floh
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tony359
Joined: 04 Aug 2006
Posts: 378
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| Posted: Sun Feb 24, 2008 1:20 am Post subject: |
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Pay attention, the lens screws can pull wires and touch or move something, it's easy to touch something.
Ciao
A
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messerfloh
Joined: 04 Dec 2007
Posts: 18
Location: Bavaria, Germany
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| Posted: Mon Feb 25, 2008 9:05 am Post subject: |
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Yes, thereŽs not much space under the lenses. I noticed it because I added a heat sink to the transistor. Without, the tranny  just is toast after a minute or so. I wonder why it was just clamped to the lvps housing originally...
On Saturday the parts arrived (I ordered three of them) and the first which I soldered in for testing WAS toast after a short while... 
But, for a price of ~3USD each I thought its good to have some spare...
today IŽll give the PJ a test run for some hours and watch the temperature of the heat sink. But I think it should be done now.
And next week IŽll have a look at a 1272 from the guy that sold me my 1252, perhaps iŽll upgrade to this (21 point convergence and higher scan rate...) !
Greetz Floh
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