Problem with CM8870

[joshua17ss2]

I bought a CM8870 DTMF decoder, with all needed components on ebay. and assembled it all on a bread board. i followed diagrams for the exact chip. it should take a dtmf tone and output it on 4 pins (binary) along with a signal led.

When i power up the board all 4 signal leds are lit. when i play the audio file (clean file made with audacity dtmf generator) 2 of the 4 leds turn off, and the good signal led flashes with each tone from the computer.
The problem is that the signal leds are not changing to the new state with each tone. i have checked the circuit and cant find any reason for this

I attached pictures and the schematic i followed, and a picture of it on the bread board any suggestions on how to get the signal state to change with the tones. i cant seem to get it to work.

thanks for any help.

 

[mneary]

One vital part that many manufacturers leave off of their app notes, is a bypass capacitor. I'm sure they don't intend to trip novices, but they often do.

Try 100nF (0.1uF) as close to the chip as possible, from pin 18 (+5V) to pin 9 (ground).

 

[joshua17ss2]

I only had a .22uf electrolyte cap and installed that and it did the exact same thing it was doing. i decided to build it on a slightly larger board, just to have a little more room and allow me to double check connections and still same results.