Sound Skulptor forums

Build help and troubleshooting => MP573 Microphone preamplifier => Topic started by: hugh on March 14, 2021, 08:43:50 PM

Title: 1200 Ohms and line don' work
Post by: hugh on March 14, 2021, 08:43:50 PM

Hi everyone
I just have a signal on the 300ohms nothing on the 1200 and nothing on the line
I checked my diodes and capacitors polarity and soldering.
I have noticed that the measurements are not good on
G=0V
H=1,07
I=0V
J=OV
K=OV
L=OV
The DC resistance is good
could someone please help me
Thank you.

Title: Re: 1200 Ohms and line don' work
Post by: hugh on March 15, 2021, 03:56:41 PM

Hi
I had not connected the output transformer for the test.
So all measurements are good from A to L
Sorry I'm a beginner in diy.........:-[:-[:-[
I still have the problem.
I have reviewed my soldering, polarized, no short cut
from what I see.....

when I am 300 ohms all is perfect

at 1200 and  LINE I only have Hum when I touch the gainswitch.
I don't know what to do.

Thanks for your help.

Title: Re: 1200 Ohms and line don' work
Post by: JPK on March 16, 2021, 07:56:51 AM

The issue seems to be around RLY3.
You will need to remove the input transformer to check the solder joints.
Follow the instructions here (https://www.soundskulptor.com/forum/index.php?topic=5.msg5#msg5) to do so.

Title: Re: 1200 Ohms and line don' work
Post by: hugh on March 16, 2021, 09:37:38 AM

I was thinking about this yesterday while doing connectivity tests, I will take the time to do it right. 
I'll keep you informed of the result
thanks

Title: Re: 1200 Ohms and line don' work
Post by: hugh on March 17, 2021, 10:06:15 PM

Hi
I redid the soldering of the relay, everything works
perfectly.
Thanks for your help

Title: Re: 1200 Ohms and line don' work
Post by: JPK on March 18, 2021, 11:29:30 AM

Congratulations!