Hum and no audio

[Paul Birkeland]

Can you remove the inner lead of the 0.1uF coupling cap and the 0.47uF coupling cap and pull them straight up, then post some more pics with those mostly out of the way?

[ryburdman]

https://photos.app.goo.gl/TX6NB1XGS8EAw8DU6
 EDIT
Now with the new link

[Paul Birkeland]

I would scrape this off.  I'd also get those solder balls away from terminals 17/18, you don't want those to make a connection between the red wire and the chassis plate!

[Paul Birkeland]

This could also cause problems.   This and solder joints is the kind of stuff you want to look for when your DC voltages look good but sound isn't making it through.

If cleaning out these jacks doesn't work, let me know what kind of multimeter you have (brand and model) and we can send some signal voltage into your Reduction and take some measurements.

[ryburdman]

I have a fluke 115
How do I go about cleaning the RCA's out?
Do you mean the mark around 29? its not a solder ball it was an arc I had when I most recently voltage tested it was a trimmed wired that wasnt cleared out and made a spark

[Paul Birkeland]

You can use a toothpick to clean out the jacks.  I would do that before doing any signal testing.

[ryburdman]

Cleaned out the RCA's and resoldered the caps. Tested it still nothing out of one channel. I have to go pick my boys up from school. I will be able to make a run at this again tomorrow.

[Paul Birkeland]

OK, post the make and model of  your meter and I can give you some follow up instructions.

-PB

[ryburdman]

I have a fluke 115

[Paul Birkeland]

OK, find a device (phone/tablet) with a headphone jack and download either a signal generator app or a 60Hz tone.  With an 1/8" TRS to RCA cable, you should be able to measure the AC voltage coming out of the RCA jacks and turn the device all the way down, then up one step on the volume control.  Let us know what AC voltage this is.

Plug the RCA cables into your Reduction with the Reduction off an measure the AC voltage across each RCA jack and let us know what it is. 

The Fluke 115 has a mV range and it looks like it will default to AC mV, which is what you want. I would expect your phone to put out maybe 300mV at max volume and somewhere between 5 and 10mV one step above mute.

[ryburdman]

Sorry for the delay I had life get in the way and had to get a TRS to RCA sourced. I am a big unclear as to where to and how to measure on the RCA I want to make sure I get you a good reading.

[Paul Birkeland]

Plug the TRS to RCA into your device, download a signal generator app and play a 60Hz tone.  Put your black meter probe on the shell of one RCA plug and the red probe on the center of one RCA plug, set your meter to AC millivolts, then adjust the volume all the way down on your device, then up one click.  Let us know what that AC voltage is that you see.

[ryburdman]

Black input 49mv
Red input 52mv
Black output 55mv
Red output 81mv

It fluctuates a lot and is tough get get a good reading on it.

[Paul Birkeland]

You're not quite following what I'm asking you to do. 

1.  Put the Reduction in another room, close the door, leave it alone for now.
2.  Plug the 1/8" TRS to RCA cable into your phone/tablet/whatever.
3.  Download a signal generator app.
4.  Play a 60Hz tone though it.
5.  Turn the volume all the way down, then up one click.
6.  Now measure the AC voltage across each RCA plug at the end of your TRS cable. 

The minimum AC voltage that can come from most devices will be a lot lower than 50mV.  Be aware that your meter has a different setting for AC millivolts that will give you more stable readings.

[ryburdman]

Gotcha,
2.5mv Red and White outputs