Sound Skulptor forums

Build help and troubleshooting => MP573 Microphone preamplifier => Topic started by: batchas on February 06, 2025, 11:47:33 AM

Title: No DI input: what did I forgot in the calib prodedure? [SOLVED]
Post by: batchas on February 06, 2025, 11:47:33 AM

I did all checks mentionned here: https://www.soundskulptor.com/forum/index.php?topic=5.0
Check the usual suspects: ok.
Check the DC voltages: ok.
Check you didn't forget to remove the JMP3 jumper: ok.
Check you didn't swap the 2 transistors on the DI board: ok.
I also did read the threads but cannot find a concrete answer.
I hear the relay when I plug a cable in the DI input as soon as the tip touches the metallic part of the 1/4" jack (the ground).


I'm sorry I have to ask, also the answer might be obvious, but I can't find what stage I missed in the procedure which concerns the DI input.
I'm thankful for any hint.

Here my tests: https://youtu.be/yqsP-PPcG1Q

EDIT: adding [SOLVED] in title

Title: Re: No DI input: what did I forgot in the calib prodedure?
Post by: JPK on February 06, 2025, 06:01:06 PM

The XLR input works, right?
Make sure you inserted Q8 in the correct A holes.
Check that you have the V+ voltage on CN3 pin4 (counting down), against pin1.
Check if you can measure the DI AC voltage on CN3 pin3, against 0V.

Title: Re: No DI input: what did I forgot in the calib prodedure?
Post by: batchas on February 07, 2025, 10:50:49 AM

Quote from: JPK on February 06, 2025, 06:01:06 PM

The XLR input works, right?
Make sure you inserted Q8 in the correct A holes.
Check that you have the V+ voltage on CN3 pin4 (counting down), against pin1.
Check if you can measure the DI AC voltage on CN3 pin3, against 0V.

Q8 is correct in A.

I measure by having black probe of DVM on 0V and red probe on pin 4, setting DVM to DC:
V+ voltage at 4 is +15V

I measure by having black probe of DVM on 0V and red probe on pin 3, setting DVM to AC:
AC voltage at 3 without anything plugged into DI = 0V
AC voltage at 3 when cable and signal plugged into DI = 0V

EDIT: I checked continuity with module powered off on all CN3 pins between main board and DI board and all is fine.

(https://batchas.com/DIY/Sound-Skulptor-MP573/MP573-DI-pins.JPG)

Title: Re: No DI input: what did I forgot in the calib prodedure?
Post by: batchas on February 07, 2025, 11:23:21 AM

(https://batchas.com/DIY/Sound-Skulptor-MP573/MP573-DI-board-01.JPG)

(https://batchas.com/DIY/Sound-Skulptor-MP573/MP573-DI-board-02.JPG)

(https://batchas.com/DIY/Sound-Skulptor-MP573/MP573-DI-board-03.JPG)

Title: Re: No DI input: what did I forgot in the calib prodedure?
Post by: batchas on February 13, 2025, 02:10:34 PM

I wanted to inform you that the DI input is now working.
I traced this morning a short between 2 points on the DI board. A tiny blob of solder between 2 pins on 2SK170 that I did oversee when cleaning the board.

Title: Re: No DI input: what did I forgot in the calib prodedure? [SOLVED]
Post by: JPK on February 13, 2025, 04:27:16 PM

(https://fonts.gstatic.com/s/e/notoemoji/16.0/1f44d/32.png)