Chapter 6 Replacement of the TM-T88V Maintenance Counter The TM-T88VI has a maintenance counter just as the TM-T88V has. Buzzer TM-T88VI is available with a built-in buzzer or without the buzzer. Even if you purchase the one without the buzzer, you can attach an optional external buzzer. You can beep the buzzer with the pulse signal using a command. 6 111 Power Supply Box The optional power supply box (OT-BX88VI) is available to be attached under the TM-T88VI to hold the power unit.