are these pins shorted????

[shaiqbashir]

HI guys!

well! im using the IC CM8870 in a telephonic project. I made some circuit, in which this IC was not working properly, i checked my connections and i found that pin 8 and pin 9 of this IC are shorted internally.

I checked its block diagram (given below) and dint find any reason for that.

 

[hotwaterwizard2]

I see a resistor of unknown value between those 2 pins. It could be low ohms.
Or your meter is reading this.

Datasheet https://www.bgmicro.com/pdf/ics8870.pdf

View attachment 39339

View attachment 39340

 

[audioguru2]

The resistance between pins 7 and 8 is about 1M and is used to self-bias the inverter to be a linear amplifier.
Shaiq's IC is shorted between pins 8 and 9.

 

[shaiqbashir]

thanks for ur help!

i found that as an abnormality.

I purchased a new piece and its working fine.

Pin 8 and 9 are not shorted normally!

 

[hotwaterwizard2]

Excellent Job finding the problem.

View attachment 39378