Now We Start The Troubleshooting Phase

faskenite · 1975

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Offline faskenite

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on: January 25, 2018, 09:15:47 AM
Just finished the Quickie, hooked it up to the system, spun a disc and got (1) loud hum in both channels, (2) apparent very low signal volume in both channels.  I am completely new to this and am not surprised that things have not gone flawlessly.  I'm sure this is not an unusual experience.  I did manage to build it without serious damages to me or it (I think).  Any suggestions or comments?  Could this be a grounding thing fixed with a cheater ac plug for other components? 



Offline fullheadofnothing

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Reply #1 on: January 25, 2018, 09:34:20 AM
Does it hum if you connect the Quickie to your amp but NOT the source to your Quickie?

What are the components in the system? Be specific.

Joshua Harris

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4krow

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Reply #2 on: January 25, 2018, 09:51:43 AM
  As has been stated before about the Quickie, it cannot Produce hum by itself. Since it is DC powered, there is no hum to start with. The idea that a grounding issue is the cause, is a good start to find the problem.



Offline faskenite

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Reply #3 on: January 25, 2018, 10:40:54 AM
As to the system, the Quickie is punching way above its weight - 47 Labs CD transport/combo and Manley 300B monoblocks, REL Strata III subwoofer with Lowther EX3 Medallions (there are a whole bunch of vinyl components too but I'm just using the CD front end and the amps for testing the Quickie).  The idea with building the Quickie was to get an intro to DIY, with a view to bigger things in the future.
I'm not at home right now but I will see what happens with the CD front end disconnected and report. 
By the way, it was a lot of fun building this thing!



Offline fullheadofnothing

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Reply #4 on: January 25, 2018, 11:33:51 AM
Are these components all plugged into the same power outlet? Source, amps, subs...?

Joshua Harris

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Offline Paul Birkeland

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Reply #5 on: January 25, 2018, 11:41:56 AM
How were your voltage and resistance checks?

Paul "PB" Birkeland

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Offline faskenite

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Reply #6 on: January 25, 2018, 11:45:47 AM
Voltage checks were fine, I may have done the resistance checks too quickly.  Can redo. 

All the components for testing the Quickie were plugged into the same power outlet.  47 Labs transport and DAC powered by a Power Dumpty power supply plugged into the wall;  amps and sub plugged into an Audio Sensibility passive power distributor plugged into the other of the two wall outlets.  Haven't previously plugged the digital front end into this wall outlet (it used to be across the room).  I did so for setting things up for testing.  Didn't turn the sub on given the loud hum and low audio signal. 

A question.  With the selector switch, there are several 'clicks' possible.  Am I right that the first click is power on, and the second and third clicks are the first pair of inputs and the second pair, respectively? 

I am also wondering whether I have not cabled the CD front end correctly, with its various components.  I'll mix things up for trouble shooting purposes.



Offline Paul Birkeland

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Reply #7 on: January 26, 2018, 03:46:13 AM
The Selector switch should be set so that it has 3 positions.  All the way counterclockwise is off, the next position powers up the Quickie and selects input 1, then the next position keeps the power on and selects input 2.

Does the hum remain if just the Quickie is plugged into the power amp, but no sources are connected?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline faskenite

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Reply #8 on: January 27, 2018, 09:48:46 AM

Does the hum remain if just the Quickie is plugged into the power amp, but no sources are connected?
[/quote]

Apologies for not responding earlier to the help provided.  Work!  Anyway, I just unplugged the CD components, powered on the Quickie and powered on the amps. The loud hum is gone.
Now to step 2 - amps off, Quickie off.  Unplug digital cable from output 2 on the 47 Labs transport.  Reinsert in output 1.  Plug DAC into Quickie. Put Quickie on different level from CD rig. Turn on Q and amps.
Sonic mayhem, loud ringing!  Put finger on DL92 tube.  Ringing gone, I presume I have gotten my first lesson in the legendary microphonics of the DL92 (Mullards I bought for the project).  Press play on CD.
SUCCESS!
Time to listen to this thing!