ULN2803 Output Driver
If an MTP-7/8 circuit fails due to overload of one or more of its note switching outputs, the most common damage is to whichever on-board ULN2803 device drives the overloaded output. In many cases, the MTP circuit can be returned to full working order simply by replacing the damaged device. Since the ULN2803 devices are fitted into sockets, replacement only takes a few seconds requires no soldering. It is advisable to have one or two spare to try in case of damage before sending the entire MTP circuit back to j-Omega Electronics for repair. ULN2803 devices are priced at £1.70 (UK Pounds) each.