I completed the project of restoring the broken, vandalized and rusty Yamaha YIS-805/128, the Russian version. The list of the initially found problems was quite long:
- Front panel was broken into 4 pieces, those pieces din't fit together as vandals used excessive force
- All front panel's clamps except one were broken/missing
- A few electrolytic caps on the motherboard leaked
- Tons of rust found under VDP
- The VDP's heatsink rusted off
- Both floppy drives were broken, rusted and missing microswitches
- Both floppy eject buttons were broken/missing
- RTC batteries rusted out, decomposed and leaked onto everything around them
- On the case 3 out of 4 feet were broken/missing
- Network module got damaged by battery leakage
- Power cord was cut off and missing
- One slot cable connector's clamp was missing
- Power LED's cable was torn off
- Power button was stuck (misaligned spring)
- Video board was not working, dirty, a few electronic components had rust on them
- Left slot housing's holder was broken
- Some ICs had rust and dirt on/under them (Z80, MSX Engine, VDP)
- A couple of ceramic capacitors were broken in half (HOW?)
- Almost all metal case's elements were bent and rusty
- Keyboard connector's lock was broken/missing
- Power switch had a bent and chipped pusher
- PSU's back bezel was broken
- A half of the screws was missing
- Floppy bay's bottom cover was missing
- Both joystick port covers were missing
- Slot cable's grounding wire was broken
- Keyboard was missing 2 keys, its cable was loose
Below are some pictures before the restoration:
The keyboard was cleaned and restored first. To fix the keyboard I used the 2 keys, that I had made long ago with the DLP printer for this project:
https://www.thingiverse.com/thing:3446006
Then I cleaned and restored motherboard and made a new VDP heatsink:
The floppy drives were both broken. Didn't read the diskettes at all. Both eject buttons were broken/missing. I had to completely disassemble both drives to remove rust and dirt:
In both drives the disk presence and write protection switches were broken or missing. I had to find an alternative solution as buying those switches nowadays would be impossible. My solution used the modern switch and the special 3D printed holder, but the write protection had to be sacrificed in favor of the disk presence:
https://www.thingiverse.com/thing:4638857
The floppy drives were cleaned, re-assembled and manually tuned to correctly read all diskettes. Both eject buttons were 3D printed and installed:
The PSU's back bezel was replaced as the original one was broken:
The slot cable socket's clamps were 3D printed and installed. There was only one original clamp left on the connector:
https://www.thingiverse.com/thing:4640010
The computer's case elements were cleaned from rust, oxidation and dirt with 100g of citric acid dissolved in 5l of tap water:
After the case's parts were cleaned, their original shape was restored with a hammer and some other tools. The top and the back of the case were sanded, degreased and painted:
The video board and the side slot casing were cleaned, the dead decomposed batteries were removed (not without an effort!), the battery holder bracket was replaced with a newly-made one. The video board was also repaired (one transistor rusted off):
Fixing the broken (vandalized) front panel was the biggest challenge. Not only I had to assemble the panel from 4 pieces that didn't match each other properly, but I also had to add the missing clamps. Out of 7 ones, 6 were broken/missing. Then the scars/gaps were filled as well as I could and the panel was painted:
I also made the 3D model of the front panel in case I would not be able to fix the original one:
https://www.thingiverse.com/thing:4651279
Some minor missing parts were 3D modeled and printed for this project:
https://www.thingiverse.com/thing:4645678
https://www.thingiverse.com/thing:4644908
https://www.thingiverse.com/thing:4634065
During the post-restoration testing at least 3 RAM and VRAM chips died. So, I replaced all RAM and VRAM chips and put all RAM, VRAM, Z80 and ROM chips into sockets. I also installed jumpers to change RAM size and configure the missing ROM (will be used in upgrade):
And here's the final result after restoration:
That was not a perfect restoration, but the machine looks way better now and it works well. :)
Now the machine is waiting for upgrading to MSX2+ with on-board RAM extension to 2mB:
