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Build help and troubleshooting => MP573 Microphone preamplifier => Topic started by: MATTHEW_KING on August 05, 2024, 03:57:15 PM

Title: MP573, Ripped up pad at R39, location of GND(V) ?
Post by: MATTHEW_KING on August 05, 2024, 03:57:15 PM

Hi so this is my first build ever, and I accidentally ripped up the pad / bronze sylinder at R39 looking at the schematics it seems R39 and R38 should have a clean 0 resistance path between them. As with R38 and R37. As this was not the case I soldered a wire between R39 and R38 and they now have a path between them. But in the schematics R39 is connected to GND(V) "ground V" And I've figured out where some ground points are located but not this one. I just wanted to confirm if connecting a wire between these two is indeed correct, and the location of GND(V) so I can check the connection between these and perhaps solder a wire to the GND(V), Thanks. :D

Link to schematics: https://www.soundskulptor.com/skdocs/mp573-schematic-04.pdf

Title: Re: MP573, Ripped up pad at R39, location of GND(V) ?
Post by: JPK on August 05, 2024, 05:54:17 PM

I just wanted to confirm if connecting a wire between these two is indeed correct
Yes correct.
Be carefull this circuit uses 2 different grounds, separated by 9VDC.
The ground you want on R39 is the one connected to TP2, different from the 0V ground of the lunchbox.
The closest ground point from R39 top is R37 right.

Title: Re: MP573, Ripped up pad at R39, location of GND(V) ?
Post by: MATTHEW_KING on August 05, 2024, 07:54:36 PM

Thank you. When testing R39, it shows a 0 resistance connection to TP2, indicating it is grounded. However, I have not yet connected the top of R39 to the right side of R37.

Additionally, the connection of R39 and R38 goes from the top of R39 to the top of R38. The bottom of R39 is properly connected to C22.

Should I still proceed with connecting the top of R39 to the right side of R37?

One last question: Since R39 in the schematic is the last resistor connected to the ground GND(V), if its connection to GND(V) is broken, will that affect the entire ground connection for other components connected to GND(V), or am I misunderstanding how these ground connections work?

Title: Re: MP573, Ripped up pad at R39, location of GND(V) ?
Post by: JPK on August 06, 2024, 03:46:19 PM

Should I still proceed with connecting the top of R39 to the right side of R37?
Not necessary as you've already restored the ground connection via R38.

will that affect the entire ground connection for other components connected to GND(V)
No. You are OK now. The ground connections are made via the ground plane on the top side of the PCB.