LM1875 PCB + Schematic overview

Thread Starter

askDIY

Joined Oct 18, 2023
17
I made this PCB from the LM1875 datasheet for single supply operation, but when testing across an 8ohm load, the oscilloscope outputs nothing. Here my Altium schematic which is identical to the single supply operation on the LM1875 datasheet. Here is a picture of my PCB as well. Is there anything visually that could be wrong with it? It is modeled exactly from the datasheet yet the o-scope shows nothing at the output.

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Preview attachment IMG_3382.jpg




IMG_3382.jpg
2.4 MB


 

Jolly13

Joined Mar 25, 2018
27
Tons of thing to eliminate.
IS the supply at least 8v spec show no data below that .. 1875 likes 12+
IS Voltage making to chip. What voltage are you feeding it . ( do you have VCC as expected from VEE on chip )
What does nothing on output mean ? Assuming a steady ground is what scope is show between ground and j3-1 = 0v.
What do you see on pin 4 before cap6 on output ( is it mid supply or hammer to a rail ) .. should be about 1/2 rail or close to what you see in+
What does scope show on in+ is their an AC signal their to amplify
All it takes is one bad solder or trace misrouted .. prove the simple things first .. GO from their.
 
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