croissantking's conquests
- Thread starter croissantking
- Start date
Progress with my spare 840AV board. I discovered why it wasn’t outputting video. It turns out the DAC (or what I think must be the DAC) wasn’t receiving a required -5V input. I traced this back to the voltage regulator that was instead outputting 0.65V. Yeah, that’s not going to work. So I checked its input and found 0V, but it should be -12V. Aha! There’s a break in continuity of an internal trace running back to the -12V pin of the PSU.
One bodge wire later, and I’m
now getting video output:
Another issue I was having is resolved too, namely that some Nubus cards weren’t working. This was due to the missing -12V feed.
There’s one outstanding issue with this board - sound output doesn’t work. Well, it does chime, but it dies once the OS has loaded.
One bodge wire later, and I’m
now getting video output:
Another issue I was having is resolved too, namely that some Nubus cards weren’t working. This was due to the missing -12V feed.
There’s one outstanding issue with this board - sound output doesn’t work. Well, it does chime, but it dies once the OS has loaded.
Swapped out the audio amp and the sound is fixed! This board is REPAIRED.
I bumped a couple of PowerBook RAM cards to max capacity, the first being a partially populated ‘death chime’ card suitable for a 165c/180c.
Well, I did my thing and found the bad chip, then put all the spare chips back on one bank at a time after testing them first.
Here’s the finished result, a lovely fully working 10MB card:
It has three buffer chips onboard which my other three 10MB cards not have. And interestingly, it’s the only one that fully works in a ‘fussy’ PB180 daughtercard that usually has stability problems when maxed out with RAM.
I also maxed out this (formerly 8MB) PowerBook 500 series RAM card to 32MB. It replaces another which was collateral during my quest to build a 48MB card.
Thanks to @imactheknife for the bits
Well, I did my thing and found the bad chip, then put all the spare chips back on one bank at a time after testing them first.
Here’s the finished result, a lovely fully working 10MB card:
It has three buffer chips onboard which my other three 10MB cards not have. And interestingly, it’s the only one that fully works in a ‘fussy’ PB180 daughtercard that usually has stability problems when maxed out with RAM.
I also maxed out this (formerly 8MB) PowerBook 500 series RAM card to 32MB. It replaces another which was collateral during my quest to build a 48MB card.
Thanks to @imactheknife for the bits
Last edited:
Similar threads
