Next up is an interesting Picasso IV Zorro 3 board that I’ve worked on earlier this year. A friend gave it to me for repair with the comment: it doesn’t do anything.
Symptoms:
- no autoconfig (not visible in earlyboot)
- no video
Diagnostics
So, after visually looking around the board, I noticed some bad solderings on the Cirrus logic chip. Touching them, at least 10 pins were loose.
Can you spot the bad solderings?
After reflowing loose pins of the Cirrus chip, the board was detected and I could load Picasso96 and select a screen mode. It looked like this:
Nice, progress! But garbage.
Further investigation
Carefully checking it’s pins again, more loose pins were found. And reflowed properly. Now the image looked like so:
Big square noise thingy is actually the mouse pointer 😀
But no, this is not right, but the picture is stable except for flickering pixels.
The final blow
This looks like something may not be right with the VRAM. Checking voltages .. whut what? Vcc on the RAMs is a little over 1 volt. That can’t be right, right? It’s a 5v only board.
Following the source of the Vcc line I found this little bad boy:
It decided to be a 1k ohm resistor in stead of a 0 ohm one! Hence no power to the RAM chips. Decided to replace it with a ferrite bead since no 0 ohms in stock. The RAMs shall get a nice clean power now 😛
Measuring again.. yup, now the RAMs do have a nice 5v power.
Let’s see what it does now:
Yes!! Other screenmodes also work nicely now, including the native video passthrough 🙂
Dang! I have one that’s doing something like this. I don’t have the expertise to work on it myself. You wouldn’t want to take a look at it would you? I can send you pictures of what it’s doing. The video comes up but it has blotchy colors and artifacts all over the screen. I thought to might be because I’m now using a LCD monitor but now I’m thinking that was just wishful thinking. Anyway any ideas would be appreciated.
Sure I would want to have a look at it for you.
Are the display issues in RTG modes or in native modes?
Thank you for the reply! I am really excited to get this old friend back up and running. I bought my first Amiga (1000) in 1983. Still have it 🙂 This A4000 has been sitting in disuse in my computer room for close to 10 years but the card was working beautifully when I shut it down for the last time. I’m in the middle of modifying an ATX mid tower to fit it into and I really, REALLY was hoping I could get this Picasso IV going but I was beginning to run out of hope.
As to your question. When I first boot I get a ton of ghosting and artifacts. When it gets to the WB I have a marked pattern running across the screen and discolored artifacts through out. That’s in Picasso mode. When I switch to a native mode there is little or no change. Still loaded with artifacts and a vague pattern.
Thanks again for your help.
Sounds like it needs some love, if re-seating it into the slot doesn’t help.
Could you take some screenshots and email me at triszon atat gmail dot com and we’ll see from there where it goes.
Cheers
I don’t think my last post got through. The display in both native and RTG suffer from the ghosting pattern and colorful artifacts. Thanks for taking the time to look at this. I sent an email to your contact page with my info. Please let me know what I need to do from here. I really want to get this guy back up and running fully.
Did the pictures give you any clue as to what’s going on?
I was just thinking about my Amiga 1000. Actually bought it in Germany in 1986 when I was stationed in the Army there. I bought my first Commodore C64 in 1983. While waiting for your thoughts I went digging through my trove of stuff and found a Highway board, 2 Xsurf boards, 2 GVP TBC’s, a Toaster, a IV24, 2 CV643D boards, and an EGS Spectrum board. Plus a few others I haven’t identified. Dang, I think I may have been an Amigaholic! 🙂