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qbancoffee / imac_g3_ivad_board_init

iMac G3 IVAD board initialization with an arduino
GNU Lesser General Public License v3.0
146 stars 14 forks source link

Everything is assembled, but the monitor doesn't show anything. #14

Closed Clochard123 closed 10 months ago

Clochard123 commented 2 years ago

Hello, I followed the wiki step by step but something isn't working. I'm trying to understand if it's because some shoddy soldering, some faulty component or rather my Italian iMac G3 that may want a different edid. When i connect a laptop to the vga port on the J20 board, it recognizes a new monitor. As soon as the power chord is connected, the green led on the button turns on and I can hear the cathodic tube warming up. But no image is shown and after a few seconds of inactivity everything turns off. Then if i push the power button, all that happens again, it turns on with no picture just to turn off a few moments later. Do you happen to have seen this behaviour before? Can it tell us where is the issue in my boards? Thank you in advance.

qbancoffee commented 2 years ago

There could be a number of reason why there is no picture so let me ask you a couple of questions. -Does the iMac work with the original logic board? -Are you using the latest version of the firmware? If you are, you can comment line 180 so that the iMac that it doesn't turn off after 30 seconds of inactivity. The reason it turns off is because it isn't detecting a vertical sync pulse coming from the video source.

//do stuff whn vsyncDetect is 0
if (vsyncDetect <= 0) {
  startTime = 0;
  currentTime = 0;

// externalCircuitOff(); <----Comment this line to disable sgutting off when there is no vertical sync pulse

Upload it to the J20 board after commenting.

-Do you have another computer you can use as a video source? Sometimes in two monitor configurations the second display is turned off by default and the signals are not sent in time to the second display.

-Are you using some sort of video converter like an HDMI to VGA converter? I've had a handful of converters that don't work well.

From the sounds of it, you are very close to getting this to work so don't give up. A handful of people have gotten this mod to work in Europe and Japan so I think that your Italian iMac should work.

Clochard123 commented 2 years ago

Thank you for answering so quickly! The iMac worked before I tore it down, and I'm not using video converters. I tried using different computers to no avail.

But commenting the line 170 // externalCircuitOff() DID prevent the monitor from turning off! So I suspected the v-sync pulse was cut somewhere. But the tester says there is continuity between the vga port and the corresponding j20 pin.

GerardPolloRebozado commented 1 year ago

Thank you for answering so quickly! The iMac worked before I tore it down, and I'm not using video converters. I tried using different computers to no avail.

But commenting the line 170 // externalCircuitOff() DID prevent the monitor from turning off! So I suspected the v-sync pulse was cut somewhere. But the tester says there is continuity between the vga port and the corresponding j20 pin.

Did you solve it? Im having same issue the monitor is detected but doesnt show anything

Clochard123 commented 1 year ago

Did you solve it? Im having same issue the monitor is detected but doesnt show anything

I'm sorry but I had to interrupt the project because I got really busy with college and job stuff. When I'll have time again I'll try making new boards from the beginning. If that doesn't work then I'll have to look for another iMac: I lost the motherboard in the meanwhile so I can't test the CRT properly. Good luck and keep us updated.

qbancoffee commented 1 year ago

No worries, good luck with school, this will be around for a while!

qbancoffee commented 1 year ago

Have you made any progress with this?

Clochard123 commented 1 year ago

Here I am! I must confess that I completely gave up when I found a working Apple Studio Display from 1999 for just 15 euros. It's bigger, has higher resolution and already has a vga socket. Maybe it's better to close the issue here. Probably my G3 went simply bad and I can't test it anymore because I lost the motherboard. I did see however your last video so maybe I could test this new method just to see if the problem was inside the imac or the custom boards.

Clochard123 commented 10 months ago

The raspberry pi method works! Whatever was the problem with my boards now I completely circumvented it. This is perfect, because my plan was already to use it connected to a rpi and this just cuts down the middle man. Thank you so much!

qbancoffee commented 10 months ago

I'm just now reading all of these messages.

Glad to hear it's working! Are you still using the custom boards or are you directly connecting the raspberry pi?

If you are directly connecting the raspberry pi without the custom boards, consider using this python script to adjust your settings. https://github.com/qbancoffee/imac_g3_osd_cli

Clochard123 commented 10 months ago

I'm directly connected with the raspberry pi and yes, I really need an easy way to adjust the settings because the left side of the desktop is missing and I can't even see the applications menu. Problem is, I don't know a thing about Python! I guess I'll have to clone the repo first, and then run the scripts from the terminal top to bottom, but if you were planning to make some guide I'll gladly wait... I don't want to take chances now that I'm so close!

qbancoffee commented 10 months ago

I added install and start instrcutions. https://github.com/qbancoffee/imac_g3_osd_cli/tree/main

This should be enough to get you going. The menu is pretty self explanatory but I will write instructions when I get some time.

Clochard123 commented 10 months ago

Thank you! the installation was a breeze and I had fun with the menu. But no matter how far I pushed Width and Horizontal position I didn't manage to see the whole desktop. On the left I can't go further than the browser icon, and even on the right side a piece is missing. It's like there is some sort of overscanning even when I shrink it down.