Solving a Yamaha RX-V430 Ground Buzz / Hum

[Johnny_Law]

My brother's old AV receiver sounded great ... but had a buzzing hum coming from the speakers which became noticeable at really low volumes.

The buzz remained the same volume and pitch regardless of input, volume, input mode, etc. It was present via headphones as well.

https://youtube.com/shorts/oPqB4l6L3po

I have a sound spectrum app on my phone, here's what it showed when held up to a speaker:



And for a control, what it showed with the sound off:



So, pretty clear spikes at ~200Hz and then every 200Hz above (400Hz, 600Hz, 800Hz, 1kHz, 1.2kHz).

My first thought had been a smoothing cap going bad or something else in the power supply, but I thought that the buzzing should have been 60Hz if that were the case.

Here's how it looks under the hood:



So I started with simple stuff, wiggling components that might have bad solder joints, making sure grounds were all in place.

Lo and behold, tightening this screw ground connection on the PS board immediately eliminated the buzz!



There we go. Fixed! Somehow the loose ground was causing that weird 200Hz-resonant buzzing through the outputs. Learned something new.

Not that complicated, but maybe this'll help someone out in the future with the same issue.

 

[mbz]

Somehow the loose ground was causing that weird 200Hz-resonant buzzing through the outputs. Learned something new.

+1

200Hz would be a WTF moment. Looks like main GND connection between filter caps.
Nice "get".

 

[Sparkplug]

My brother's old AV receiver sounded great ... but had a buzzing hum coming from the speakers which became noticeable at really low volumes.

The buzz remained the same volume and pitch regardless of input, volume, input mode, etc. It was present via headphones as well.

https://youtube.com/shorts/oPqB4l6L3po

I have a sound spectrum app on my phone, here's what it showed when held up to a speaker:

View attachment 2752515

And for a control, what it showed with the sound off:

View attachment 2752516

So, pretty clear spikes at ~200Hz and then every 200Hz above (400Hz, 600Hz, 800Hz, 1kHz, 1.2kHz).

My first thought had been a smoothing cap going bad or something else in the power supply, but I thought that the buzzing should have been 60Hz if that were the case.

Here's how it looks under the hood:

View attachment 2752518

So I started with simple stuff, wiggling components that might have bad solder joints, making sure grounds were all in place.

Lo and behold, tightening this screw ground connection on the PS board immediately eliminated the buzz!

View attachment 2752519

There we go. Fixed! Somehow the loose ground was causing that weird 200Hz-resonant buzzing through the outputs. Learned something new.

Not that complicated, but maybe this'll help someone out in the future with the same issue.

This being a receiver, seeing a spurious signal (possibly an intermod of sorts from the Rx circuit) roaring its ugly head shouldn’t be surprising. Fastening the mounting screws was a very wise move … well done.

 

[Nashou66]

Love simple fixes!!

Nashou

 

[Wael_oqaily]

My brother's old AV receiver sounded great ... but had a buzzing hum coming from the speakers which became noticeable at really low volumes.

The buzz remained the same volume and pitch regardless of input, volume, input mode, etc. It was present via headphones as well.

https://youtube.com/shorts/oPqB4l6L3po

I have a sound spectrum app on my phone, here's what it showed when held up to a speaker:

View attachment 2752515

And for a control, what it showed with the sound off:

View attachment 2752516

So, pretty clear spikes at ~200Hz and then every 200Hz above (400Hz, 600Hz, 800Hz, 1kHz, 1.2kHz).

My first thought had been a smoothing cap going bad or something else in the power supply, but I thought that the buzzing should have been 60Hz if that were the case.

Here's how it looks under the hood:

View attachment 2752518

So I started with simple stuff, wiggling components that might have bad solder joints, making sure grounds were all in place.

Lo and behold, tightening this screw ground connection on the PS board immediately eliminated the buzz!

View attachment 2752519

There we go. Fixed! Somehow the loose ground was causing that weird 200Hz-resonant buzzing through the outputs. Learned something new.

Not that complicated, but maybe this'll help someone out in the future with the same issue.

Thanks man! Definitely helped me after spending two days googling and fiddling with my HTR-3066 without a solution.
It was the same ground screw!

 

[tnsilver]

Old thread, but this is for posterity, so bear with me. Got a customer's RX-V430 with a terrible hum. Scope showed a distorted 60Hz ramp waveform coming out the main speaker terminals, quite loud and annoying enough, but nearly inaudible with valid input - like tuner or CD. Volume knob levels didn't affect it, and it remained at a constant gain - it was definitely power supply related.

Long story short - rectifier bridges and all LM78XX regulators checked out, but a number of electrolytic capacitors in strategic locations had turned so sour, they were more of a resistor than anything else. Resistance went in the hundreds of K ohms range. Oddly enough, none were bulged or leaking. I had to fish them out with an LCR meter. Nichicons and Elna's. Ususally very good capacitors. Appearanty they can go bad too.

These were:

• One of the two 4700uF/25V C602/C603 (the other actually checked out fine) on the 'Function 5' PCB, the one with the 4 bigger black 10000uF/16V horizontally mounted capacitors.
• The pair C926/C923 (10uF/63V) on the mains power relay 'Function 7' PCB - both decraped and gonski - but none bulged
• The pair C387/C386 (100uF/50V) on the 'main 2' PCB (the one with the big filter capacitors). Those two caps are adjacent to the four rectifier bridge diodes D382...D385.

In addition the vacuum florescent display had gone very dim. I've swapped out a couple 330uF elco's on the display PCB, and it got better, but still dim. It's impossible to fix a VFD once the phosphor inside burns out, or oxidizes, or whatever the chemical process that wears it off is. Yamahama places an orange filter over the VFD, proly for the orange glow display theme, rather than leaving it natural blue. I've peeled off the filter, and that brought most of the display back to life. Lame - but living and visible enough to skim through the self diagnostics menu. Good enough for me.

I wish it was as easy as turning a grounding lead fastener screw - but life isn't always easy. It will be for the next dude that reads this.