PA Chime Generator

Upon replacement of the audio system in 2020, some individuals remarked that they missed the four-tone chime of the prior system.

Background

The prior PA unit was an Inkel PA-9100RC Public Address Cassette Receiver, produced by the Korean Inter-M corporation. Unfortunately, as the unit was in disrepair, it was discarded after an extended effort to sell it on eBay. In hindsight, the chime circuit could have probably been recovered...

Research

The schematic in the PA-9100RC/9200RC Service Manual shows that the chime tone is generated by IC101, a BXA4240. No datasheet could be found for this part. Fortunately, a datasheet for a pin-compatible equivalent (the IK Semiconductor BT8040N) has been found here.

Project Status

As of February 2021, a small quantity of the BXA8240 has been sourced from a surplus dealer in China. When (or if) these parts ever arrive is "TBD". Once they do, experiments will be carried out to see if the tones can be replicated on the bench.

A schematic is being developed. The chime circuit will nearly duplicate that of the PA-9100RC. A mixer circuit, along with a mic pre-amp, will also be included. Details to follow.