Sound Skulptor forums
Build help and troubleshooting => AB528 Microphone preamplifier => Topic started by: BramP on June 17, 2023, 10:56:52 AM
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Hi, so I received my AB528 kit last week, very nice and professional kit with excellent build documents, I manager to finish it up in just a couple of hours and it sounds wonderful!
However, there seems to be an issue with the phantom power; when I use a condenser mic now and again the phantom power seems to randomly cut out for a minute or so. After turning the mic pre off and on again the phantom power's back. What could be the issue here?
Gear used: Midas L6 lunchbox, Brauner Phanthera mic, only other module installed is a Zahl EQ1
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The phantom voltage goes directly from the lunchbox to the mic via SW1, R3, R1, R2. Check the solder joints on these components.
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I've resoldered the resistors there and been recording with it for a couple of hours after, problem seems solved! Awesome :)
Great preamp, won't be the last thing I'll be ordering from Sound Skulptor ;)
Greetings, Bram
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Hi unfortunately the issue is not yet resolved, the preamp intermittently shuts off at random times (maybe once every 15-20 hours that it's on or so), the signal indicator keeps working but there's no output. After a couple of minutes and turning it on and off again it then works again.
I'll check the board and resolder any suspicious connections, or could this indicate a failing part somewhere?
Still enjoying the sound, but in this state it's too risky to use in a tracking session.
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This looks like a bad solder joint.
You could leave the pre on, waiting for a failure and when it happens, check if you can measure the signal on TP2, TP3 and TP4. this would narrow the search field.
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Resoldered and cleaned up some of my sloppy work, fingers crossed :)