Beepre2 hum

Alby0521 · 2689

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Offline Doc B.

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Reply #15 on: February 05, 2021, 05:53:14 AM
That is not smooth 60Hz hum from a transformers magnetic field. That is classic buzzy 120Hz hum from either a bad ground connection somewhere or a ground loop. Probably time to inspect ground connections and reflow some stuff.

Dan "Doc B." Schmalle
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Bottlehead Corp.


Offline Alby0521

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Reply #16 on: February 05, 2021, 06:12:30 AM
Hello.

I reflowed the 2 ground tabs (see pictures circled in red) and all the IEC connection. Is there anything I'm missing. What other solder point would be involved?




Offline Paul Birkeland

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Reply #17 on: February 05, 2021, 06:28:06 AM
Everywhere there's a black wire or the banded end of any capacitor other than the ones on the PC board.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Alby0521

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Reply #18 on: February 05, 2021, 06:34:31 AM
Ok I'll re solder all the points with those characteristics this afternoon and report back.

Thanks for the help so far.

Best

AB



Offline Doc B.

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Reply #19 on: February 05, 2021, 09:03:10 AM
You probably want to check the connections around the little double diode, cap and resistor filter thingamajig between terminals 32 and 36.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline Alby0521

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Reply #20 on: February 05, 2021, 04:14:47 PM
Hi

I solder again all the black wires, all the banded caps, removed the strip on 31 32 33 and re built that with new solder. Also I re solder all the 3 strips in that corner including 36, 35 and 34.

Nothing changed. Still the same hum.

Also I connected the beepre to another amp in another room. Still same hum.

I’m out of ideas.

Any ideas?

Thanks

AB



Offline Paul Birkeland

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Reply #21 on: February 05, 2021, 04:51:17 PM
Are the outlets in your house earthed?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Alby0521

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Reply #22 on: February 05, 2021, 04:57:52 PM
Yes l, I plug all the equipment into a power bank. And that it’s plugged into a earthed outlet.



Offline debk

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Reply #23 on: February 06, 2021, 01:25:31 AM
I would unplug (not just turn off) all the sources from AC and see if hum is still there.  I once had an issue with hum and it turned out it was the cable box causing the ground loop.  I ended up getting a power-strip with coax in and out and connected all the equipment to it,  and this broke the ground loop
« Last Edit: February 06, 2021, 01:34:36 AM by debk »

Debra K

Eros 2Phono amp
BeePre2, Psvane ACME 300b
Kaiju, Linlai Elite  300b
Monamour 2a3 amps various tubes
Sota Sapphire, Pete Riggle Woody Tonearm, Kiseki Purpleheart Cartridge
Rega P6 Ania Pro cartridge
Roon Nucleus
MHDT Labs Orchid DAC
Jager speakers


Offline Alby0521

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Reply #24 on: February 06, 2021, 05:07:04 AM
Ok I unplugged everything but the Kaiju and beepre. Still hum. So I plugged the Kaiju alone in the power bank and run an extension cord to the garage to plug the beepre on another breaker. Still hum.

Any other idea?
« Last Edit: February 06, 2021, 05:08:55 AM by Alby0521 »



Offline johnsonad

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Reply #25 on: February 06, 2021, 05:38:51 AM
While it's on, if you touch to metal of the chassis plate, does that change the sound?

Aaron Johnson


Offline Paul Birkeland

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Reply #26 on: February 06, 2021, 05:39:05 AM
This could also be something as simple as a loose filter capacitor that isn't sucking down the power supply noise like it should. 

I had a SEX amp in for repair last year that made a similar noise to this.  I went through and repaired a bunch of other operational issues with the amp and was ultimately left with an amp that functioned fine but had that kind of dirty 120Hz buzzy noise at the output.  It took me forever to track down that what had happened was the builder put a lock washer from one of the binding posts on the ground screw between the chassis plate and the #8 ground lug.  This is very unlikely to be what's going on with your BeePre, but it may help to illustrate the kinds of things that can cause that noise that you're having.
« Last Edit: February 06, 2021, 06:26:11 AM by Paul Birkeland »

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Alby0521

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Reply #27 on: February 06, 2021, 06:34:49 AM
Should I re solder the black banded caps on the board? I already re soldered all the 3 brown. Anything else to look at while I’m on the board?



Offline Paul Birkeland

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Reply #28 on: February 06, 2021, 06:36:40 AM
You could pop the screws off the board and show a photo of the bottom of it. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Alby0521

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Reply #29 on: February 06, 2021, 06:37:23 AM
While it's on, if you touch to metal of the chassis plate, does that change the sound?

No it doesn’t change. I also run a wire from the bell to the chassis and no change.