Eros is humming

Why1504

New member
I have a new build.  probably has 100 hours of burn in.  I noticed a yesterday that I had a hum.  It is coming from the Eros.  There is a minor hum when it is powered off and is more pronounced when powered up.

I have no idea how to proceed here.  Please help.
 
got to the bench this morning.  on the A side the of the chassis,  A side of the C4S card, when powered up, the A side LEDs light, B side  LEDs do not light.  After about 4 seconds the A side LEDs go out.
 
I would add, that all of this was operating normally when I did the testing at the conclusion of the build.  Eros has about 100 hours on it.
 
Why don't you post your voltages, noting the ones that are not to spec. That is always the place to start. It could be that you have a bad connection that has shown itself after a few heat cycles, and voltages might help us isolate where the problem lies.
 
Finally got a chance to catch my breath this morning ( I run a company and the last two weeks have been insane.  Today I leave on travel for a week, back Friday and Sat of next week then gone for two more weeks)  Here are my voltages:

                  A                      B
KREG        .6                      1.77
BREG        7.42                  96.8
OB            221.4                95.1
OA            220.8                169.7
bA                  0                    0
IA            223.0                223.9


Thanks for any assistance!!
 
Why1504 said:
KREG        .6                      1.77
BREG        7.42                  96.8
OB            221.4                95.1
OA            220.8                169.7
bA                  0                    0
IA            223.0                223.9
I would suspect you have a broken wire or very loose solder joint in your build somewhere.  It could be the ground connection for the board with all the out of whack voltages. 
 
I added the MourQuiet to my Stereomour and wasn't totally happy with the sound.  When I turned it back over to investigate, I had totally forgotten to solder a terminal tab with a bunch of resistor leads.  I could have sworn I double- and triple-checked everything.  Sounded much better after I applied a bit of solder to the oversight.  Good luck finding your problem.
 
After 4 weeks of travel followed by 3 weeks of sickness I finally got in this morning and began doing some serious investigation.  Almost immediately I found a wire that wasn't connected.  Fixed that.

All of the voltages are now in spec.

But, the preamp has now developed a white noise with some thumps that sound much like a dirty album.  the noise is coming out of both channels.  I get it with the turntable disconnected.

HELP!!
 
I cleaned up a couple of solder bridges. I know I have a bad joint somewhere.  When I tap on the chassis the noise will come and go.

All of the LEDs are glowing.  I have requested one of my engineers to help me with this next week.
 
Why1504 said:
I cleaned up a couple of solder bridges. I know I have a bad joint somewhere.  When I tap on the chassis the noise will come and go.
You can get in there and poke around with a wooden chopstick to find the joint that is aggravated by tapping on the chassis.

-PB
 
I found the bad Joint!! Fixed it!!

The rattle is gone.  However, I still have a hum but it only becomes audible at about 1/2 volume which is a significant improvement.

Any suggestions on the hum??
 
The hum is still there but with music the sound is fantastic.

I ma guessing the signal is way overpowering the hum.
 
Is the music too loud to listen to at 1/2 volume? If the cartridge has a relatively low nominal output level, the hum can just start to be audible with no signal playing at very high volume settings. That hum would be a soft, sine wave type of hum. If the hum is buzzy that would be a grounding issue, most likely between the turntable and the Eros.
 
Doc B. said:
Is the music too loud to listen to at 1/2 volume?

YES!!


Doc B. said:
If the cartridge has a relatively low nominal output level, the hum can just start to be audible with no signal playing at very high volume settings. That hum would be a soft, sine wave type of hum. If the hum is buzzy that would be a grounding issue, most likely between the turntable and the Eros.

It is a soft sine wave hum.


I am guessing I finally have my issues solved.
 
Well, I was premature in my assessment that I had it fixed.  After about 3 hours of playing, I began to have some very nasty pops and static.  I shut it off, let it cool for a couple of hours fired it back up and within about 5 min the same noise returns. 

This noise is coming thru regardless of whether music is playing or not. 
 
I touched up several solder joints.  none were particularly bad.  Retook all of the voltage measurements,  the only one that was out of spec was Kreg.  Specification is 1VDC it came in at 1.5VDC and 1.8VDC.

Is this an issue??
 
Problem only exists on the "B" side.

Using the chopstick tap the to LED's on the A end of the B board flash on on off. I touched up several joints that made the flashing significantly less frequent.  However the pops, snaps and rumble continues on the B channel. 

My next step is to remove the board, and touch up every other joint, then re-install and move forward.
 
It may be fixed.  I touched up every solder joint.  1/2 of a album in, no noise.  I guess I will know in a few days.

On the upside, I have learned a ton about troubleshooting this kind of equipment.  Should the noises return, I now have a good idea on how to proceed.
 
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