[slothproductions]

Jean Pierre, Im hoping for that especially you will hear my call and find time to read this thread

While measuring across pin 8 and 10 on the XT500, as I was adjusting a unit (not Sound Skulptor), I accidentally glided a DMM probe from pin 10 onto one (or some?) of the solder joints for the ribbon cable back to the rack. This move resulted in a shorted rack, and now it is not delivering +48V. I am still able to measure +/- 16V.

While not sitting in the rack when this accident happened, my MP573 is also not working. Some minutes after the short happened, I put the unit into the rack to make sure, that something bad hasn't happened, but the unit was not sending out any audible signal.

I've tested the MP573 with a SK501. If I turn up the trim and gain knob to max on the preamp, Im able to hear the same inaudible signal with noise all over the place (sound example: https://shorturl.at/x7Pkb). When speaking into the microphone, the LED turns green and red (clipping), just as it should, but no audible output.

I've made the initial setup procedure again and completed the troubleshooting guide and got following measurements:

Initial setup

Short circuit check
V- and 0V: DMM says O.L
0V and V+: 8.33M?

General power check
Transformer output CN2 disconnected: 24.66 VDC
Transformer output CN2 connected: 24.55 VDC

Bias adjust
3.05 VDC

Sound check
As said earlier, only a nearly inaudible output when gained to max. Tested with both a dynamic and condenser - result is the same.

DI check
Same low output as with XLR.

Troubleshooting guide

Values in the left columns are actual measurements and values in the right columns are the ones stated in the troubleshooting guide.

DC voltages check

A:  2.6      2.5
B:  4.1      4.0
C:  22.6    22.0
D:  13.6    13.3
E:  2.0      2.0
F:  12.9    12.7
G:  0.9      0.9
H:  4.0      4.2
I:    0.35      0.35
J:  3.5      3.6
K:  22.9    22.3
L:  3.0      3.0

Following the signal
0.5 VAC sine input

Input transformer pin 7:                3.7      0.9
TP 1:                                                0.0      4.8
Output transformer yellow wire:  0.0      8.4

Transformers DC resistances

VTB1847

Yellow-orange: 8      7.6
Red-brown:      6.8      6.4
Blue-green:      21      21
Violet-black:      21      21

VTB9045

2-4:    13      24
3-5:    13      24
7-9:    136      144
8-10:  135      142

As the results show, I don't get any reading on TP1 and transformer output yellow wire and the reading across V- and 0V says O.L.

Are you able to help me with this problem?

[JPK]

Have you placed the jumper on CN1 (step 34 of the build guide)?

[slothproductions]

Ohh man, it is freaking working again!....!!! I had previously connected it to the EQ573 and forgot all about that...

Thank you so much for your help 8)