Everywhere I found that UM66, BT66 and FT66 melody generator ICs work in the similar fashion (circuit design). But I recently observed that FT66T-2P starts generating music after approximately 2 minutes of powering the circuit. The same circuit works absolutely fine with UM66T.
I tried the circuit with 4-5 different pieces of FT66T to make sure the IC is not faulty, but all the pieces behaves alike.

The circuit I'm trying with is very generic and simple; using the IC with BC547 transistor, and powering with 3V DC supply.

Let me know if someone has any idea. Thanks

 

FT66T-2P, are you sure that's the correct part number?
I couldn't find any info on that part number.
Normally the last letter should be a "S" for one shot or "L" for level hold operation.
Maybe the "P" means PAUSE for 2 minutes.

 

FT66T-2P is clearly visible on the IC.
Though, as per datasheet also, it should be in the form of FTxxS or FTxxL where xx is the song/melody number. Number 2 represents "Jingle Bells". My IC is playing Jingle Bells; so 2 looks correct mention on the IC.
But not sure what does "P" indicates, and why does it starts after 2 minutes.

 

Please read FTxxS as FT66TxxS and FTxxL as FT66TxxL.