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Post by luukneele on Jun 2, 2015 11:10:44 GMT -5
hi guys, i got a crt tv which is a pretty neat one, but i made a mistake in the SAM (service alignment menu) i accidentally upped the vertical amplitude too much because the button on the remote stuck. the set jumped into vertical guard mode. the problem is, i need to set the Vamp back to normal and it should be fine. but i need to do that from the SAM menu, which i can no longer access. i can bypass the software protection that triggers the vertical guard by shorting the SDM pad on the video board which will force me access to SDM and the set stays on. however, when i switch to SAM menu, the vertical guard kicks in within 3 to 5 seconds shutting the system down. i know that the vertical guard comes from the video board and goes into the plate where the flyback and the PSU are, the vertical guard triggers the standby processor to shut the system down. so if i can circumvent that i can get the set back to normal. anyone that can give me a hint? i got full schematics. schematics and service manual: link |
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Post by mastertech on Jun 2, 2015 16:12:02 GMT -5
Try pressing and holding at the same time the volume+ and volume- keys "on the TV" and see if it does anything.
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Post by luukneele on Jun 2, 2015 16:35:07 GMT -5
Try pressing and holding at the same time the volume+ and volume- keys "on the TV" and see if it does anything. That's virgin mode, when do I do that? On power up? Power off? When it's on? |
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Post by mastertech on Jun 2, 2015 17:36:43 GMT -5
When it is off. Don't press power. Just those 2 buttons.
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Post by luukneele on Jun 2, 2015 17:53:15 GMT -5
When it is off. Don't press power. Just those 2 buttons. Doesn't work. set just switches on, blue screen, shows install then 3 secs and it shuts down again. I have to bypass the vertical guard protection to get it to stay on, in sdm entered by shorting pads, the set bypasses the software protection and stays on. Unfortunately I can't change the Vamp there. If I can't bypass the software protection or the vertical guard, this TV is toast as it won't stay on |
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Post by mastertech on Jun 2, 2015 20:01:57 GMT -5
When you force the set to stay on, can you get into the alignment menu and reduce the V amp there?
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Post by luukneele on Jun 3, 2015 0:26:33 GMT -5
When you force the set to stay on, can you get into the alignment menu and reduce the V amp there? Yes, but as soon as i switch to alignment menu, the timer starts. 3 secs and it's off |
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Post by Casethecorvetteman on Jun 3, 2015 2:34:57 GMT -5
Is there a factory reset procedure?
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Post by luukneele on Jun 3, 2015 4:14:12 GMT -5
Is there a factory reset procedure? theres only virgin mode, which i cannot access because you need the set to stay on, the set shuts off after a few seconds, cant navigate the menu that fast. if you look at the schematics i provided, you can see the way the vguard travels along the signal path. apparently the vguard samples a voltage, which if it exceeds or goes below a certain level it tells the standby processor to cut power. theres a way to trick the set apparently and bypass the protections, which is what i did with the SMD solder pad-hack. but there seems to be no way to bypass the protections when you go anywhere else. bypassing the vguard (or tricking it) seems to be the only solution. but, how do i do that? i'm afraid this is now a piece of junk. |
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Post by mastertech on Jun 3, 2015 8:28:13 GMT -5
See if you can test the voltage on the Vguard line.
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Post by luukneele on Jun 3, 2015 12:57:37 GMT -5
See if you can test the voltage on the Vguard line. Standby is: .23 on meter On power: .85 on meter Then it drops to 0 and it shuts down Meter is set to DC voltage, max 2 volt |
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Post by mastertech on Jun 3, 2015 14:12:10 GMT -5
Well it should be 12.2vdc
My guess is transistor 7407 is pulling it down so I would try removing it and see if it stays on.
If it goes off again then recheck the Vguard voltage and see what it is at.
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Post by luukneele on Jun 3, 2015 16:33:49 GMT -5
Well it should be 12.2vdc My guess is transistor 7407 is pulling it down so I would try removing it and see if it stays on. If it goes off again then recheck the Vguard voltage and see what it is at. Can't find the damn thing. Dya know where it's supposed to be? It should be on the large signal panel, right? But I don't see it |
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Post by luukneele on Jun 3, 2015 17:07:44 GMT -5
Nvm I got it, didn't help one bit.
It's a software protection apparently.
Also I'm throwing the thing out.
I removed the lsp panel and every solder joint is either a cold one, or a dry one.
Talk about a crappy solder job, at least 5 components broke completely off without any force. This is not worth my time. I'm hauling the thing out on Saturday.
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Post by Casethecorvetteman on Jun 4, 2015 3:40:33 GMT -5
Probably fixing those solder joints would have an impact on this issue, but id expect you could add a resistor to the vgaurd line to hold it off the upper limit. Sounds more like its hitting the lower limit though, which bad solder joints could cause id expect?
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