AML EZ1073- 500 kit - Low bias and relay not clicking on.
« on: January 21, 2019, 10:27:46 PM »
Just put together the EZ1073-500 kit however the max bias I can get with the trim pot is 24mV (should be 90mV) and the relay is not clicking in.

With the vertical boards it's hard to trouble shoot but from the few spots a could check it appears the proper 16 volts is reading at points I can measure.
Before I start removing boards It would be nice to narrow the problem down and pretty sure the relay not clicking in is a clue.

Also it does power a condenser mic with 48 phantom and passes signal, albeit a little crunchy. It is also quiet so no noise or hum, so I don't think completely screwed it up. Pretty sure something in the output stage is botched.

Link to schematics. http://www.audiomaintenance.com/downloads/ez1073pre_colourbook.pdf


Any ideas or advice greatly appreciated.

Thanks,
Scott


Re: AML EZ1073- 500 kit - Low bias and relay not clicking on.
« Reply #1 on: February 11, 2019, 01:08:00 AM »
 Got it working! Good news is I got to practice trouble shooting and was fairly certain it was the surge control board. It was, and it was something stupid.  Because the resistor leads were pre-bent I couldn't flip the board over and because the roll of tape was nowhere to be found, I soldered from the top.  Nothing wrong with that except I missed one and it's harder to catch looking from the top.  Why did I not inspect the board before putting everything together?  Because I inspected from the back of the board and when I saw a missed solder joint I figured it was  a resistor.  :o Did I double check the top? No. Lesson learned? Don't be a dumb ass, Inspect Every Thing!



 

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