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Post by mastertech on Dec 6, 2018 16:08:49 GMT -5
Wait. If the leakage is occuring in Q1058 then I should have no problem reading the gate value after its removal. That should tell me right there if the problem is elsewhere ? Not necessarily. It could be the functioning of the gate that is causing another component to break down. So, without the gate in action the other bad component may seem to be working normal. A component may only fail when under load. Over the years I have found that when a part does not completely fail and is only breaking down it can cause all sorts of strange things. This is why I usually don't say something is definitely the problem. You just narrow down to your best guess and change it out and see what happens. And based on what you have been saying and testing there is still no definitive part. There are still a whole pile of possibilities. You haven't really ruled anything out yet. |
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Post by mmartell on Dec 6, 2018 16:42:14 GMT -5
Ok very good.
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Post by mmartell on Dec 7, 2018 3:22:36 GMT -5
Alright I have made a mistake. I don't think it has affected this thread but it has affected my understanding of the schematic I posted above.
To know which pins were which on the board I mentally rotated the device from the image in the datasheet. However I used the same logic for the schematic and just realized I had the gate and source mixed up the whole time.
So... a couple of questions... since it now makes more sense to me than it did before...
When Q1057 turns on, the gate of Q1058 gets pulled low through R1777. Why isn't the source voltage also grounded (or shorted?) through R1776 ?
Also, what is the purpose of Q1032 as it seems both the gate and source of Q1058 would charge without it ?
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Post by mastertech on Dec 7, 2018 12:17:55 GMT -5
When Q1057 turns on, the gate of Q1058 gets pulled low through R1777. Why isn't the source voltage also grounded (or shorted?) through R1776 ? Also, what is the purpose of Q1032 as it seems both the gate and source of Q1058 would charge without it ? 1) Because that is the purpose of R1776. It is a choke per sea. It prevents the line from also being pulled low. 2) As to Q1032 purpose, I have been asking myself that same question, what is it's purpose. It is not required. Look at Q1074. It is switching the same voltage with no added circuit. You would have to ask the engineer of this board. |
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Post by mastertech on Dec 7, 2018 12:24:47 GMT -5
Just to elaborate on that Q1032 circuit, as you can see that if for some reason the voltage at pin 4 of Q1058 was to go low (for whatever reason) then Q1032 would be turned on which would then send voltage through it to pin 3 of Q1058, turning it off. Under this scenario, R1777 would be the choke, canceling out Q1057 wanting to pull that voltage low also.
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Post by mmartell on Dec 7, 2018 16:48:46 GMT -5
Interesting insights. Perhaps Q1032 is protection against the output of Q1058 being pulled low by a short in a connected display ?
As for R1776 I don't see how the circuit wouldn't be served the same or better by it not being there.
Going to look for a 10k resistor to bypass Q1057 will let you know how that goes.
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Post by mastertech on Dec 7, 2018 20:38:52 GMT -5
The circuit would not function without R1776. Without R1776, pin 3 of Q1058 would always be low, no matter if Q1057 was on or off.
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Post by mmartell on Dec 7, 2018 23:17:21 GMT -5
Soldered a 10k resistor from gate to DGround and the video is staying on. The implication then is Q1057 is bad or is it still possible a leak in Q1058 is mitigated by this resistor ?
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Post by mastertech on Dec 8, 2018 10:50:11 GMT -5
I would say it is most likely Q1057 or a problem with the CEC line after the CPU.
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Post by mmartell on Dec 9, 2018 22:50:05 GMT -5
Will follow up when I get the parts to repair the SB channel. Will remove the hdmi board at that time.
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Post by mmartell on Dec 11, 2018 17:34:56 GMT -5
Does the KRC404E look like a good sub for the RT1N441C ? I have plenty of these on a failed Onkyo HDMI board here. (I don't see where to attach a pdf ?)   |
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Post by mastertech on Dec 11, 2018 20:09:11 GMT -5
Looks good.
It is easier to just post the link to the PDF.
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