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MrCRTing
Joined: 03 Feb 2008
Posts: 35
Location: Brighton UK
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| Posted: Sat Dec 07, 2013 10:53 pm Post subject: HT crack noise from Sony VPH-1271 from start up. |
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Hi
My 1271 is starting to play up, when powered up from cold for about the first 5 mins or so occasionally I get for this duration around 15 - 20 loud crack / spark / arc noises, these obviously affect the picture causing it to flash on all 3 tubes.
After 5 mins it settles down and never does it at all for the entire time PJ remains on.
PJ never seems to shut down either.
As of yet I have been unable to locate the issue as when I open the unit and hinge the DC & E board up and leave it never does it.
Have even breathed out all over the HV areas hoping the moist air might help bring the fault out.
I have previously re-soldered pretty much every solder joint on the DC & E boards and upon close inspection they are still good so I think I can rule these boards out.
In a black room when I turn the PJ off with board hinged up I get a lot of static discharge from the aquadag on the tubes to the metal tube bracket, and for the first couple of seconds at power on from cold the same thing, there does not seem to be an corona discharge from the EHT caps or leads, distribution blocks or line output transformers.
Also waved an earthed to chassis screwdriver around all of these when on in the dark to see if any corona is being thrown out, no ozone smell either.
If definitely seems to be coming from the HV area and not the PSU as I pulled the PSU out and left it dangling with top boards down and the sound was not from the PSU it sounded like the heart of the PJ.
PSU voltages checked all are stable (even from power up)
Anyone have any idea what this could be ? or know of a known breakdown of EHT leads, distro blocks or rubber caps etc ?
Cheers
J
_________________
How does 3D TV / movies work when you only have one working eye? IT DON'T !
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draganm
Joined: 08 Mar 2006
Posts: 8990
Location: Colorado
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| Posted: Sun Dec 08, 2013 12:05 am Post subject: Re: HT crack noise from Sony VPH-1271 from start up. |
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| MrCRTing wrote: | Hi
Anyone have any idea what this could be ? or know of a known breakdown of EHT leads, distro blocks or rubber caps etc ?
Cheers
J |
sure all those things break down over time, also any black sooty carbon build-up will cause it happen on an otherwise healthy high voltage section.
You should be able to see where on the lid it's arcing to, then the closest HV section to that is your leak. My money's on the splitter area, right next to the Blue tube. I would go over it and inspect carefully after a through cleaning with Isopropyl Alcohol.
if the splitter and transformers are good then any of the HV boots
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Sun Dec 08, 2013 2:34 am Post subject: |
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I agree with Dragan, if you can hear it, you should be able to see it, you're probably not looking in the right place yet. Be careful with the heavy breathing, leaky HV can arc!
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MrCRTing
Joined: 03 Feb 2008
Posts: 35
Location: Brighton UK
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| Posted: Sun Dec 22, 2013 7:45 pm Post subject: |
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Fixied it
It was the focus wire on the red tube base board, the internal core insulation had broken down and it was jumping to GND pins when breathed on.
Cut it shorter and re terminated in white tube socket then went mad with silicone !
Tube had to come out to do it as focus cable not long enough to work on while tube was still fitted.
Job done
_________________
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