Maker Pro
Maker Pro

Buzzing Makita DC1414 F charger

Cirkit

Oct 28, 2015
145
Joined
Oct 28, 2015
Messages
145
I have the above Makita charger which is buzzing with a variable frequency when the green LED flashes.

I have tried prodding the transformer and various components but the buzzing doesn't stop.

I don't want to start replacing capacitors on the chance that may cure the buzzing.

Attached are photos and a video showing the buzzing can be downloaded from this link:

https://ufile.io/v78dr3o2

Any suggestions on where I should start looking?

Thanks.
 

Attachments

  • Makita DC1414 F PCB top.jpg
    Makita DC1414 F PCB top.jpg
    288.3 KB · Views: 9
  • Makita DC1414 F PCB rear.jpg
    Makita DC1414 F PCB rear.jpg
    298.7 KB · Views: 8
  • Makita DC1414 F case.jpg
    Makita DC1414 F case.jpg
    270.1 KB · Views: 10

Martaine2005

May 12, 2015
4,218
Joined
May 12, 2015
Messages
4,218
Hi CirKit,
The free (slow) D/L doesn’t work.
Can you describe the buzz?.
Is it only when the LED flashes?.

Is it definitely a buzz rather than a high pitch tone?

Martin
 

Harald Kapp

Moderator
Moderator
Nov 17, 2011
12,518
Joined
Nov 17, 2011
Messages
12,518
Download worked for me.
It is a medium to high pitched sound (similar to an electric razor, but not so loud). The frequency changes with the blinking of the LED: LED on -> frequency high, LED off, frequency low. Notable peaks are around 4 kHz and 6 kHz:
upload_2021-1-5_11-56-6.png
 

Martaine2005

May 12, 2015
4,218
Joined
May 12, 2015
Messages
4,218
It sounds like the caps aren’t doing their job. Given the stresses these caps go through in SMPS, they are also the first components to fail.
I would replace them as a matter of course.

Martin
 

Cirkit

Oct 28, 2015
145
Joined
Oct 28, 2015
Messages
145
Thanks for uploading the spectrum @Harald Kapp.

@Martaine2005 do you have any suggestions which capacitors I should replace? Is it likely to be the main filter capacitor?
 

bertus

Moderator
Nov 8, 2019
2,574
Joined
Nov 8, 2019
Messages
2,574
Hello,

The mains capacitor could cause hum.
The output capacitor could cause screeming (high frequency noise), when the ESR is going up.

Bertus
 

bertus

Moderator
Nov 8, 2019
2,574
Joined
Nov 8, 2019
Messages
2,574
Hello,

When you change the fourrier size and look at the spectrum, the 100 Hz is good visible:
Makita_spectrum.png
You will also see signals at 4000, 8000 and 12000 Hz.

Bertus
 
Top