Recent content by jmacz

Note the ribbon cables sometimes visually look ok when they aren’t. Won’t know until you beep out each pin on both ends with a multimeter. I have found two that looked perfect but had an issue. I am referring to all three ribbon cables. If the cables an issue, you can find a replacement or do...

Yes, mental typo. Had in my mind cleared the BSRs and the DAC so mentally kept referring to them as a unit and wrote it down that way. Oops. 😅 Cool, thanks for the tips! Hopefully will get this resolved soon. Trick has been more finding contiguous time to work on this as work has been so busy.

That additional column I stumbled upon (driven by VRAM Chip U12 pin 2) was a different problem. I found a shorted set of pins on SMT02 and fixing that resolved that one. So I hope I'm really down to the last column of pixels to fix which is the original VRAM Chip U19 pin 26. Picture is much...

More progress while in Black and White mode. The vertical line artifact I have been chasing is from VRAM Chip U19 pin 26 which goes to RAMDAC U44 pin 5. This one continues to be a problem. The VRAM gets the value for this particular output via input on U19 pin 23 which is connected to the SMT02...

I'm a bit concerned about drilling especially because it may be difficult to figure out the path of an internal trace? I was thinking that if I determine which chips are impacted by internal trace damage, that I lift the legs of those chips and use a bodge wire instead? Yeah, it's actually...

Congrats! Really cool watching you run into a problem and then building a product to solve it! :)

Ok, finally made a bit more progress on this particular card this evening. The RAMDACs seem fine. I was able to individually tie the inputs to the RAMDACs to HIGH or LOW and get the expected output on the screen. But the decision to make that nubus interposer is helping... with the video card...

You might be right... both of my working batteries had Sanyo cells in them.

Ok cool, thanks for confirming! Nice!!

Yup, there was enough clearance luckily! LOL!

Hmm, I'm actually not sure what I was writing there... I think I was trying to say more easily probed the voltage since the card was flat on my workbench, but I mentioned traces so maybe I meant to say "while the card was not running". Guess I was tired.. but no, did not test continuity nor the...

I was able to get the card working again. Hopefully this time it sticks. Recap of Problem: various artifacts appearing all over the screen at accelerated 24 bit only. Any other bit depth or turning acceleration off eliminates the issue. The artifacts had gotten progressively worse (in amount...

@demik for the four LEDs, the accent and caps lock ones are working fine for me (accent is always on and caps lock is on when caps lock is activated). For the other two, there's one under the home button and one under the power/function button. These two blink when I turn the machine on, but...

Installed a 30.24MHz crystal which didn't help. I used a nubus interposer that I made to observe the card. The ACK, TM0, and TM1 lines are stuck active (ie. low). These signals are coming from a SN74F534N flip flop (for the TM0/TM1) and a S74F367N buffer (for the ACK) and the traces to/from...

I used these circuit boards from Amazon. https://www.amazon.com/gp/product/B082PV1V6S