I bought a cheap telephone PBX for my small business and much to my dismay it has horrible music that plays while the caller is put on hold. It's like midi Fur Elise or something. There seems to be no way to change it in the normal settings.
I popped off the top of it just to have a look inside and I noticed all the IC's are socket mount big old things and it's a pretty simple looking device. I'm just wondering if there might be something I can do to disconnect the music. Any ideas about what IC might be the culprit and what I might be able to do about it?
The IC's:
AT89S51 - 8-bit Microcontroller with 4K Bytes In-System Programmable Flash AT24CO4PC - 4Kbit, 2-Wire Bus Serial EEPROM DLT 8816 - This chip has a scratched top and looks like it is a re- badged processor, same form as the AT89S51 CS9370DGP - DTMF demodulator (there are 3 of these) HEF40106BP - Hex inverting Schmitt trigger PS2501-2 - High isolation voltage single transistor type multi photo coupler NEC 2501 - probably older version of the PS2501 HD74HC244P - Octal Buffers/Line Drivers/Line Receivers with Non- inverted 3-state outputs M402100BP - Crosspoint Switch Circuit - Dual 4x4 Crosspoint Switch
The first 3 are my prime suspects. Here's a pic of the board:
Dave