Behringer S16 Digital Stagebox power supply repair

Problem description
Issues with adjusting microphone preamp gain remotely through AES50 or locally on the stagebox itself.

This guide assumes knowledge of soldering and desoldering through-hole components and the competency to open the stagebox and identify and remove the power supply safely.

Symptoms



 * Audio gain control on microphone inputs failing to work partially or fully when adjusted remotely through AES50 or locally in the stagebox.
 * Audio gain rising by itself to about middle of the range of the preamp or higher, leading to the input often clipping uncontrollably with louder sound sources.
 * No adjustments to a particular preamp gain are effective when made through the AES50 connection beside the -10/+10dB digital trim on the console itself.
 * Problems may appear when the stagebox is warming up to operating temperature and may not manifest if the device is cold.
 * Other issues with setting menus and other intermittent issues may be solved as well with this repair.

Solution
Take apart the stagebox when it's unpowered and either replace the whole PSU module or carry on with repairing the capacitors as listed below.

Replace most or preferably all electrolytic capacitors in the power supply board with higher quality capacitors with better thermal ratings since the box has no active cooling and migh sit in racks with other hot running equipment 24/7.

Use a powerful enough soldering iron (60W+) or desoldering iron with suction (I used the Hakko FR-301 but this can also be done without one). Have solder wick and solder sucker at hand also.

'''Make sure that you know what you are doing with mains power electronics to not hurt yourself or others or create damage to property. Always operate on unpowered boards and check for remaining voltages with a multimeter! If you are not confident in repairing devices with potentially lethal voltages, please don't attempt this repair.'''

Capacitor list for S16/DL16
Select the highest temperature rating and best (lowest) ESR available when possible when picking components from a distributor site. You can find components depending on your geographical location from distributors such as DigiKey, Mouser, TME etc.

Capacitors inside the Midas DL16 are probably from a different supplier and might have different temperature ratings. The ones I've fixed had the same capacitance and voltage values to the S16 box so the same parts should fit both.