A question about the 2N7002NXBKR Trench MOSFET about td-crt HOT 9 OPEN

Hi,

Yes, you can use a plain old 2N7002. The exact one I used is just a particular manufacturer's model that I chose at the time based on availability.

There are two RGB circuits in this repo - one is on td-deflect, and one is in td-rgbinput. The td-deflect one is older and works well, but uses an old stock IC. The td-rgbinput one is functionally similar but built with discrete components.

The td-rgbinput circuit has 4 separate functionalities - a DC restore circuit for AC coupled inputs, a blanking circiut, a gain control circuit, and a bias circuit. You might not need all these parts depending on where you're inserting the signal.

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I'm gonna take a look and try to implement them to test, I'm connecting directly to the neckboard of the TV, more specifically, to the video output amplifier that drives the cathodes (TDA6107AJFN1), i'm connecting just the RGB signals to it and letting the TV's circuitry take charge of the Sync. Between the neckboard and the device I've added some simple circuitry to control the signals, but not nearly as elegant as your aproach. It works quite well, this TV actually became my main way to play old video games, but I think that its possible to make it even better adapting your designs to it.

Do you recommend any resources to learn more about TVs and analog electronics? While i've been playing around with this TV, i lack a lot of the knowledge to really understand deeply how all of these parts work

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from td-crt.

Thanks for the resources, it is quite hard indeed to find these things on internet

Was taking a look at the TV service manual, unfortunately the neck board doesn't seem to have a blanking input, it does have a AKB output from the video amplifier that drives the cathodes, but I suspect to me that the blanking is done on the MCU/Jungle chip before this step (TDA11115NDS, a chip which not datasheet could be found).

I took a look at the td-deflect board and saw that you used a M51387P as video amplifier which i found pretty interesting, not that I didn't like your discrete aproach, but the M51387P seems to be quite cheap where I live. This amplifier is suposed to be used to drive tube directly? In the case of my TV that uses a TDA6107AJFN1 to drive the tube, should the M51387P outputs drive this amplifier or the tube directly?

from td-crt.

The outputs should drive the amplifier.

I think that the AKB signal is actually an input to the amplifier, not an output.

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Are you sure? I found the amplifier datasheet, from what I understood, AKB is connected to the amplifier pin 5 which is a "black-current measurement output" in the datasheet words. It would be very helpful if it was the blank signal input.

from td-crt.

No, not sure. Didn't realize a monitor like this would bother measuring that, but I suppose it could.

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Hey, the M51387P finally arrived, i'm taking a look at the TV schematics and signals, having a hard time to find how to extract the blanking signal from sync. I see that it is very similar to H-sync, can i use it or do i need another solution?

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Yes, you can use H-sync to blank. However, clamping needs to not intersect with blanking - it needs to happen after blanking.

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