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Post by jaredjaric on Sept 14, 2020 13:15:53 GMT -5
My 909s has lost its focus on all RGB, and the whole image is modulating.
What i mean by modulating is like the magneting focus yolk on all three crts , are being pushed back and fort by an invisible hand.
Seems like there is a discoloration or slightly burnt resistor on the focus board (SR1 ).
I have swapped out all boards from smps to all the boards in the convergence tray and still no changes.
The only ones unswaooed are the Crts and the magnetic coils and also neck boards.
also prior to this , i had busted my vertical sync board and had two failed splitter,
I was using a ZIdoo 4k player and had some issues with the sync at first, but was able to have about 8 hours of good use,
Until it shut down, it was the splitter at first, then the vertical board , then another splitter , then lost focus and image modulation.
What should i look into, had four good smps board changes already, still the same, even the power factor board was swapped.
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Post by robin36mac on Sept 14, 2020 13:53:04 GMT -5
Hello,
That still looks like it is splitter-related...
Do you have a multimeter? There is a coaxial wire on the splitter we can probe, giving the value of the EHT voltage. That can confirm/infirm it is EHT-related or not.
But do so only if you are aware of the high voltage risks.
Robin
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Post by jaredjaric on Sept 14, 2020 13:56:21 GMT -5
Dear Robin,
Thanks for the reply, yes I can test it.
What is the voltage i need to have ?
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Post by jaredjaric on Sept 14, 2020 14:26:07 GMT -5
Hello, That still looks like it is splitter-related... Do you have a multimeter? There is a coaxial wire on the splitter we can probe, giving the value of the EHT voltage. That can confirm/infirm it is EHT-related or not. But do so only if you are aware of the high voltage risks. Robin Hi Robin,
What should be the value on the coaxial cable ?
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Post by robin36mac on Sept 14, 2020 14:29:41 GMT -5
It should be around 33-34V, but stable, if the value is swinging, something in the EHT line is wrong.
This is a feedback of 1:1000 of the EHT voltage.
Robin
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Post by jaredjaric on Sept 14, 2020 14:39:31 GMT -5
It should be around 33-34V, but stable, if the value is swinging, something in the EHT line is wrong. This is a feedback of 1:1000 of the EHT voltage. Robin I just measured it, it is very stable at 34v DC.
still can not focus well and the image is still modulating.
Lawrence
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Post by robin36mac on Sept 14, 2020 14:46:46 GMT -5
Ok, so apparently, quad/splitter/EHT board are doing their job properly.
Issue is likely in the focus board, you tried swapping it?
SR1 is supposingly 0.1 Ohms, and as you have a multimeter...
Robin
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Post by jaredjaric on Sept 14, 2020 14:55:27 GMT -5
yes swapped in four focus boards, it is becoming very strange. swapped three quads also.
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Post by jaredjaric on Sept 14, 2020 14:56:34 GMT -5
it seems like a diode or something shorting
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Post by robin36mac on Sept 15, 2020 10:06:54 GMT -5
It's better to unsolder one side of the resistor to test it properly. Unless, the rest of the circuit will mess the measure.
Another test you can do : keep on focus coil connected at a time, and check if the issue is still present on the connected coil, each time.
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Post by jaredjaric on Sept 15, 2020 10:46:41 GMT -5
 here is the out of focus image |
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Post by jaredjaric on Sept 15, 2020 10:47:59 GMT -5
 and another one ,whole image is blooming, also very shaky. |
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Post by robin36mac on Sept 15, 2020 12:57:21 GMT -5
Can you post a video (youtube may be an easy way to publish it), so we can see how it shakes/modulates?
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Post by jaredjaric on Sept 16, 2020 7:39:24 GMT -5
Can you post a video (youtube may be an easy way to publish it), so we can see how it shakes/modulates? Hi Robin,
The video can not show the glowing or modulation, but it shows it fully out of focus. i will send it via youtube and send the link.
And the good news is, the culprit is found, it's another failing splitter.
It now measures 33.7 vdc, and is quite sharp and very stable.
I will send pictures of the images later.
You were on it and i just never thought it could be a splitter again and again.
You could see on my old 2018 post, that i had this exact issue, missed out on the actual suspect again.
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Post by jaredjaric on Sept 16, 2020 10:25:58 GMT -5
  Thanks for the advice and heads up, i am happy that this unit is razor sharp again |
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