ASAT Classic Custom - tracing down ground hum

[JonnyMuck]

Hi everyone,

I've grown to like the sound of my ASAT classic custom but it is becoming a bit unbearable with a ground hum when the volume is at 100% and switch selected to the neck pickup.
The sound goes away once I place my hands on the strings or place my hand on the bridge.
I like the sound of the jumbo MFD, but is this a common occurrence for these guitars? or these style pickups?

Im playing directly through a Line 6 HD500 and can usually place a noise suppressor to prevent the hum.

In an effort to diagnose the ground issue, I took a look at the following wiring schematics and verified connections and solder joints.





When comparing the ASAT classic custom wiring to other diagram, it has a ground wire between the tone pot and volume pot which doesn't exist in the other diagram. I assume this replaces the wire from the tone pot to the bridge?

I went ahead and ran a ground wire from the tone pot to the bridge itself. However, that did not solve the issue.

Am I stuck with just using a noise suppressor or turning down the volume put and turning up the output source?

Any help is appreciated.

-Jon

[Craig]

Any luck in tracking down your ground hum?

If not, you might try searching our forums using the Search feature.
Try "ground hum" for the search string.

If so, let us know what you found and how you fixed it.

[JonnyMuck]

Any luck in tracking down your ground hum?

If not, you might try searching our forums using the Search feature.
Try "ground hum" for the search string.

If so, let us know what you found and how you fixed it.

Hi! Nope I’m just guessing it’s the MFD itself. I’ll try to search around but it seems like it may be a common issue with these guitars. It’s a shame because I really like the guitar.

-Jon

[Craig]

Any luck in tracking down your ground hum?

If not, you might try searching our forums using the Search feature.
Try "ground hum" for the search string.

If so, let us know what you found and how you fixed it.

Hi! Nope I’m just guessing it’s the MFD itself. I’ll try to search around but it seems like it may be a common issue with these guitars. It’s a shame because I really like the guitar.

-Jon

It's not a specific issue with the MFD pickups, rather an issue with the ground wiring of your guitar. I suggest focusing on all the ground connections including the ground wiring to the bridge, which has the ground wire exposed end placed under the bridge between the body and bottom of the bridge and is not soldered to the bridge on the ASAT Classic models.

If you could post apicture of your control plate wiring we might be able to visually check your ground connections.

Hope this helps.

[JonnyMuck]

I took a snapshot of my wiring and it seems okay. It’s odd the bridge pickup has red and yellow wiring though.

How do I attach a picture to a new reply?

[Craig]

I took a snapshot of my wiring and it seems okay. It’s odd the bridge pickup has red and yellow wiring though.

How do I attach a picture to a new reply?

Why do you think the color of the bridge pickup wiring is odd. It is listed as such in the ASAT Classic Custom wiring diagram from your first post.

To post photos, see: Tutorial: Posting photos.

Hope this helps.

[JonnyMuck]

[quote="JonnyMuck"]I took a snapshot of my wiring and it seems okay. It’s odd the bridge pickup has red and yellow wiring though.

http://www.guitarsbyleo.com/GALLERY2/ma ... alNumber=3

http://www.guitarsbyleo.com/GALLERY2/ma ... alNumber=3

I used a multimeter to track down connectivity between the white and black wire coming from the input jack. When I plug in a cable and measure the tip and ring, there is connectivity.

The cable was tested before being plugged in and tip and ring area does not have connectivity.

I just replaced this input switch as well. Thoughts?

[Craig]

I took a snapshot of my wiring and it seems okay. It’s odd the bridge pickup has red and yellow wiring though.

http://www.guitarsbyleo.com/GALLERY2/ma ... alNumber=3

http://www.guitarsbyleo.com/GALLERY2/ma ... alNumber=3

I used a multimeter to track down connectivity between the white and black wire coming from the input jack. When I plug in a cable and measure the tip and ring, there is connectivity.

The cable was tested before being plugged in and tip and ring area does not have connectivity.

I just replaced this input switch as well. Thoughts?

Did replacing the output jack fix the problem?

I notice that the green ground wire looks like it is broken (though it might be the angle of the picture):

[bigjim711]

Did replacing the output jack fix the problem?

I notice that the green ground wire looks like it is broken (though it might be the angle of the picture)

Yeah and that is the neck pickup ground wire too, according to the diagram, which is where he's getting the hum. I think I'd get some heat shrink and solder splice that wire back together after trimming some of the damaged bit off. While it's cut I'd pull out the neck pickup and inspect that wire where it runs through the body too.