I have gotten into the service mode on this TV Zeb, very useful in adjusting the over scan and a few other things. There is no feature in the service mode to change the default AV mode on power-up however. If I have to I'll automate a button press via Arduino to change to component in on power on.
Let's accept for now that the default behaviour cannot be changed. If all you need is a button press, you may be able to simulate that with a single capacitor.
You'll want an electrolytic, say 10uF or 100uF. Positive lead to active signal line, negative to ground. Now, when power is applied to the TV, the micom circuit wakes up. Signal line become live, starts charging the capacitor. Until the cap is fully charged it conducts, that line is grounded, circuit closed, like the button has been pressed.
This usually happens in microseconds. Then the cap becomes charged up, no longer conducts, circuit open, like the button has been released.
You can vary the closed period (charge time) by using a larger or smaller capacitor. Adding a resistor in series will also extend it.
Won't work for every occasion but give it a go. Cheaper and easier than an Arduino
I have a question for you though. Supposing I wanted to reset the TV to factory reset settings in the service mode. Is this advisable? I ask because I'd like a second go at making adjustments for over-scan but from factory standard settings if there is such a thing.
Before fraggling around with such stuff, I recommend you make a backup of the jungle memory EEPROM. This is an 8-pin chip somewhere near the jungle, perhaps a DIP-8 (through-hole) but maybe a SOIC-8 (SMD). You may need to remove the EEPROM.
Go on ALiexpress and grab a CH341a set (they are really cheap). The set will include some extras like a "grabber" for the SOIC ICs (saves you from removing the IC to read it). You may as well order a few matching blank EEPROM chips in case you want to keep a physical backup separately, or just want to burn some EEPROMs later. And grab a USB 2.0 extension cable (male/female ends) while you are there if you don't already have one. This last bit, the cable, is to save you constantly bending down and also from having the CH341a sticking out like a sore thumb from your USB port (you can place it somewhere more approriate, like on your desk).
Some TVs have a 4-pin I2C header for the EEPROM on the motherboard, which you can use to plug in a logic analyser. In some cases the header is missing, but there remains a footprint to which you could simply add a header. It is possible to hack into this with the CH341a, which would save you the trouble of removing the EEPROM from the board.
I wrote up a thread on this EEPROM hacking a while back on the Monitor/Video branch, so check it out for more info.If you really want to master TV hacking the you can learn how to snoop the jungle data traffic (I2C, UART etc) using a logic analyzer. This is because some data/options are coded into the jungle itself. For some TVs I think this may be the only way to unlock hidden but unused/disable features like RGB mode and remembering prior AV mode selection. It may be essential for RGB modding certain TVs. This is new territory for me, something to dive into when I have the time and right equipment.
With AttractModePlus the problem is with OpenGL failures in CRT Emudriver involving atig6pxx.dll. OpenGL applications crash. I'm looking at various options here. Happy to test older/other versions of Attract Mode if you think it will work. I am also looking at the revamped Mala but I'm more interested in testing that for the longer term and maybe other projects.
Yeah look it was years ago I looked at this stuff. AM+ seemed perfect, but some things didn't work how I expected them too. So I went back to AM vanilla and that does what I need for a pretty straightforward FE. AM has some nice default layouts that you can use like the Pacman maze one which would look cool on this Pacman Legion cab.
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