Up top, we have the battery holder (will cut and re-attach the wires later).

On the left and right are the speakers.

Between the speakers are a pair of circuit boards, one brownish and one green, one mounted above the other with standoffs and screws.

At the bottom is the backside of the keys, conveniently colored brown as well.

In fact, both brown boards are just key/button mounts (one for the keyboard, one for the control panel) with pullup resistors and ribbon cables.

This leaves the main green board, which is the one most interesting to us.

Gaining access to the main board

First, we have some shielding/padding to get through.

This is here to prevent interference from below the device from affecting the main circuit board.

For now, I’m removing it, but will add it back when I’m done.

Identifying chips and key areas of the board

Removing some more screws, I obtained access to the top of the board. This was cumbersome, as the ribbon cables to the keyboard/button panels were not detachable.

Fortunately, we only need to have a quick look to see where the chips (Integrated Circuits) are (on the left) and where the power-related areas are (on the right). There’s even a chip with a heat sync, which I removed temporarily to discover it was a powered pre-amp. For the most part, any power-related area is off-limits for bending. While some bends can be made here with careful use of resistors and luck, the chances of frying a chip are too great.

The chips of interest, however, are all easy to see on this side of the board.

The CPU.

This is responsible for taking input from the keys and buttons, keeping track of the state of the keyboard, and talking to the other components.

Bends here are highly varied.

In fact, the model of CPU may vary from the owner’s manual, as is the case here.

The sound chip, a YM3812 by Yamaha, was so popular that it appeared in dozens of keyboards and sound cards including the AdLib, the SoundBlaster, and even merits a Wikipedia page.

A significant number of bends will be made here.

Some other chips (a D-Latch and possibly a demux).

These are mostly related to temporarily holding data from button pushes and translating hundreds of buttons and LEDs into addresses so the CPU can perform input/output to each without needing a pin for each.

There are rarely bends here, and most short circuits here will behave as though you pressed one or more buttons/keys.