u/kbhkiss

My friend is releasing a comic which I think it's being a great piece of work.
It's a story about a revolutionary fighting game that becomes the most popular in the world, featuring unique characters for every player and life-sized battles set in holographic arenas, where a 12yo girl finally earns a character of her own and starts to compete in virtual combats.

A rich work made with care and in color!

It's available on mangaplus-creators through this link:
https://mangaplus-creators.jp/titles/5r2607311809480027431117

I really recommend checking it 😉

(There's also an animated trailer with a dedicated song, but in Portuguese, its original language: https://youtu.be/wtbeylwBSjY )

My friend is releasing a manga which I think it's being a great piece of work.
It's a story about a revolutionary fighting game that becomes the most popular in the world, featuring unique characters for every player and life-sized battles set in holographic arenas, where a 12yo girl finally earns a character of her own and starts to compete in virtual combats.

A rich work made with care and in color!

It's available on mangaplus-creators through this link:
https://mangaplus-creators.jp/titles/5r2607311809480027431117

I really recommend checking it 😉

(There's also an animated trailer with a dedicated song, but in Portuguese, its original language: https://youtu.be/wtbeylwBSjY )

Before explaining anything, here is the full schematic: http://yates.ca/dx7/Schematics%20&%20PCBs/DX7IIFD%20Schematic.pdf

I recently acquired a synthesizer (Yamaha DX7ii-FD) made in 1986 where the right channel of the Phones output wasn't working. I decided to try fixing it but I'm having a really hard time with the analog audio board. After I removed it from the main board, it seems to have a common conductivity across the whole board.

This board (called "YA3") has 46 pins soldered to the main board. The audio circuit is on the bottom part of the board, so I had to remove it all from the main board to access the circuit that I was planning to probe. I put machined pin headers in the main board so I could plug and test it again.

After removing it and seeing that it wasn't working properly anymore, I found out that there's a short-circuit/conductivity running across the board. You can see in images 2 and 3 that when probing two pins, where the left one is only structural and fully isolated from the circuit, I get a resistance that keeps oscillating between 50~200MΩ. I found this after finding voltage on another pin that was supposed to be fully isolated from the circuit as well.

I used cleaners like MG Chemicals' Safety Wash II, and IPA when working on soldering. I've never seen this behavior; I've tried a lot of things that didn't make any change like:

• Soaked in 99.9% Isopropyl Alcohol for some time, cleaned it all with toothbrushes and used compressed air to dry;
• Tried scraping around pads to see if it was a superficial contamination;
• Removed all the original soldered pins, so I could have the pad clean and free;
• Left in an 45°C oven overnight to see if it was the substrate absorbing moisture (maybe form the cleaners?);
• Checked the main board and it doesn't have this problem. The keyboard it self is working normally, besides this audio output stage;
• The list of basic troubleshoot goes on and on...

At the moment, I'm convinced that my only option is to build a clone board to substitute (which will be a little pain), but I'd like to share it here and ask if anyone has any idea of what exactly is going on(?).

I'm sorry about the long post. I can share any other details on the comment section if needed. Thanks in advance.

TLDR: After disassembling a vintage circuit board, I keep finding conductivity between every pin. (Even on unconnected pins)