Troubleshooting an humming WOPL : need help!

[Coldsmoke]

Just a general statement, I am still amazed about how fast and helpfull you are on these matters guys. Thanks a lot.

 

[laatsch55]

The green one is going to chassis ground. It really isn't doing anything with the ground prong cut off at the plug end. I'd say you are good to go.

 

[laatsch55]

Just a general statement, I am still amazed about how fast and helpfull you are on these matters guys. Thanks a lot.

That's why we get the big bucks.......and you are very welcome..

 

[Coldsmoke]

The green one is going to chassis ground. It really isn't doing anything with the ground prong cut off at the plug end. I'd say you are good to go.

Ok, thanks for your answer. Would it be better to get rid of it? As you may know I'm still facing light humming issues and my last chance are the snubber caps here

 

[Coldsmoke]

That's why we get the big bucks.......and you are very welcome..

Ah ah! You desserve the $$$ for sure

 

[laatsch55]

Yep, I would cut it off where it enters the chassis. If you still have hum after the snubber caps there might be something you can do with the wiring. Is this a 240 volt model?

 

[Coldsmoke]

Yes, it's a 240V

 

[laatsch55]

Ah ah! You desserve the $$$ for sure

You know I was being facetious?

 

[Coldsmoke]

BTW, when I say humming, I'd rather talk about a white noise (or HF...) rather than a 50Hz buzz... (hard to describe)

 

[laatsch55]

Yes, it's a 240V

Thought so. Like I said if the hum persists the wiring could certainly be cleaned up to help. Have you perused Joe's posts in the WOPL archives for the "Improved Grounding Scheme"?

 

[Coldsmoke]

You know I was being facetious?

We get sarcasm by this thise of the Atlantic see as well

 

[laatsch55]

BTW, when I say humming, I'd rather talk about a white noise (or HF...) rather than a 50Hz buzz... (hard to describe)

What do you have for test equipment?

 

[Coldsmoke]

Thought so. Like I said if the hum persists the wiring could certainly be cleaned up to help. Have you perused Joe's posts in the WOPL archives for the "Improved Grounding Scheme"?

It rings a bell, I probably read it a few months ago when I was looking for solution, I'll definitly look again for it

 

[laatsch55]

We get sarcasm by this thise of the Atlantic see as well

LMOAO!!!!

I didn't know if you were going through a translator or not, so I had to check!!

 

[Coldsmoke]

What do you have for test equipment?

A scope

 

[Gepetto]

Here you go, I hope the quality is good enough.
View attachment 19129 View attachment 19130 View attachment 19131

Based on what I see here, you may not have a ground to the control board.

It appears that the original jumper between the speaker terminal negative and the copper input plate has been correctly removed. There seems to be a white wire connection between that same copper plate and pin 5R of the control board. If this visual is correct, then my recommendation is to remove this white wire between the copper plate and pin 5R and replace it with a white 20AWG wire connection between 5L and the copper bus bar between the 2 caps.

I cannot tell for sure but this is what it looks like.

A couple of close up shots around the input plate to right side of control board would help, as well as a closeup of all the wire connections to the bottom edge of the control board.

 

[laatsch55]

Can you get a trace of the noise frequency?

 

[Coldsmoke]

LMOAO!!!!

I didn't know if you were going through a translator or not, so I had to check!!

AH AH , I suppose it says A LOT about my skills in english

 

[Coldsmoke]

Can you get a trace of the noise frequency?

I'll try to, once I'll have put everything back together.

 

[laatsch55]

Good catch Joe.....


We need a photo of the trace side of the control board now...we are trying to determine whether the control board is grounded to Star ground...