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Roland® TR-808 Repairing a Cracked Ribbon Cable

After taking the Main PCB Assembly out of the Roland TR-808, you'll notice a flat, flexible ribbon cable running from the step switch board to the Main board (right).

This Flat Flexible Cable, or FFC, unplugs from the Switch board, letting you move the Switch board freely while working on it.

These flexible circuits sometimes crack, as seen here, and need to be repaired or circumvented.

Roland TR-808 cracled ribbon cable

Here you see a TR-808 whose broken FFC had been discarded and replaced with a ribbon of twelve wires.

At one end of the ribbon, the wires were soldered to the circuit traces underneath the FFC connector on the Switch board (right).

Wires replacing the FFC

At the other end, the wires were soldered to the pins on the Main board (right) that previously soldered to the flexible cable.

The disadvantage of this fix is that the Switch board and the Main board are always wired together.

During repair and maintenance, whenever you turn over the Switch board, the wires bend, quickly breaking them at the solder points.

Repairing interconnect wires

Here you see another TR-808.  Its ribbon cable was in good shape except for one fatal crack that kept many of the step switches from working.

As shown here, we used a small X-ACTO knife to scrape away the resist from several of the copper circuit traces.

Both sides of the crack looked sturdy so we decided to repair the FFC with some solder and some small wire jumpers.

Fixing a Roland TR-808 flexible connector

We taped it down to a flat surface and scraped some resist from both sides of the crack on all 12 of the circuit traces.

Taping down the FFC

We then melted a drop of solder onto each copper pad.

Then we cut short pieces of flexible, stranded wire and pre-tinned their ends with solder.

Finally, we re-melted each solder drop and quickly merged a pre-tinned wire end into the drop.

We didn't want to give the molten solder enough time to seep into the center of the jumper, making it inflexible.

Use stranded wire to bypass the FFC's crack.

Here you see the finished repair of the Roland TR-808 ribbon cable.

The advantage of this fix is that the switch board still disconnects from the main board, making the switch board much easier to work on.

In addition, everything except the mended cable remains original.

Repaired flexible connector in the Roland TR-808

We insulated the exposed wire jumpers with plastic electrical tape so they wouldn't short out to the front lip of the TR-808 chassis.

Repaired FFC in position

Roland® TR-808

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