Ground loop issues in D-lator

[jlatrace]

I've been troubleshooting my D-lator for the last few weeks and cured most of it sills. However, I have a nagging earth ground loop issue between the D-lator and the amp. My amp (#102) is wisper quiet. When the D-lator is hooked up, I get earth ground hum. The hum stops if I lift the earth ground on the D-lator.
I have cleaned, resoldered (with 63/37 solder), re-built with cliff jacks, re-did the lead dress, & snipped the shield ground on the wiper of the recovery pot.

Does anyone have other suggestions on how to cure a ground loop between the ODS #102 and D-lator? As long as the cables are plugged in, lifting the D-lator earth ground, but I'd rather find the signal ground that is the problem and lift it.

Question, when using cliff jacks, should I try lifting some or all of the grounds at the jacks? Or is there something I need to try inside the ODS such as installing cliff jacks on the send & return?

[markr14850]

Check if this has an effect: Use some twist-ties to run the power cable for the d-lator directly next to the power cable for the amp, all the way back to the outlet. (They should be on the same outlet or power strip.)

[jlatrace]

Thanks, I will try this. I just noticed that the hum is induced when I plug the D-lator into the the power supply (or into another plug, it makes no difference). Also the hum is induced when I plug the return cable into the amp and it doesn't matter whether the D-lator is turn on or not, the D-lator just must be plugged in.

I have also tried some cables with the shield broken on one end, it made no difference, hum was still there.

[markr14850]

There's lot's of good info here: http://sound.westhost.com/earthing.htm

I eventually installed the yin-yang diode breaker into my d-lator.

Edit:
The ground breaker described in that link uses diodes, a resistor, and a cap. The diodes are essential. I seem to remember that it worked better for me in this case without either the resistor or the cap (I forget which). You should check this for yourself.

If you install a breaker like this, you'll need to ensure that signal ground never contacts the chassis.

It's possible that a ground breaker like this violates electrical codes.

--Mark

[jlatrace]

Tried tying the cables together, it made no difference. So far the only thing that helps is lifting the earth ground on the D-lator.

[jlatrace]

There's lot's of good info here: http://sound.westhost.com/earthing.htm

I eventually installed the yin-yang diode breaker into my d-lator.

--Mark

Do you have a diagram of a "Yin-yang diode breaker"?

[markr14850]

Do you have a diagram of a "Yin-yang diode breaker"?

Here's the relevant picture from that site, though he may not call it "yin-yang". (The name comes from the anti-parallel wiring of the diodes.)

[Structo]

When I built my D'lator there was a ground loop.

I clipped the ground wire on the middle pot, wiper.

On the picture I circled the pot, find the middle lug and disconnect the ground shield from that cable to the buss.

It completely cleared up any hum I was having.

[markr14850]

I clipped the ground wire on the middle pot, wiper.

I believe that it was mentioned in the first post that he had tried this.

[jlatrace]

Thanks, I'v done that and it made no difference.

How about going to balanced jacks on the ODS and the D-lator? My effects unit use balanced inputs/outputs. If this would solve the issue, it would be worth the trouble.

[Structo]

Now that you mention it, I think I also installed isolation washers on the jacks as well.

[markr14850]

How about going to balanced jacks on the ODS and the D-lator? My effects unit use balanced inputs/outputs. If this would solve the issue, it would be worth the trouble.

You could investigate using transformers to go balanced on the send/receive. Good ones (Jenson JT) are expensive.

You might be able to get away with lower cost/quality than that, for guitar, with the right kind of supporting circuitry. Have a look at RG's "Hum free A/B/Y box", as a possible route for driving the transformers: http://www.geofex.com/FX_images/humfree2.gif I remember reading RG's description of this circuit with explanation of why these cheap transformers are acceptable, but can't find it with a quick search.

[jlatrace]

Now that you mention it, I think I also installed isolation washers on the jacks as well.

When you isolated the jacks in the ODS, where did you run the ground? To the pre amp ground buss or elsewhere.

[martin manning]

This is puzzling. There must be some ground in the D'lator that is not what it should be. In my ODS and stand-alone D'lator I am not using isolated jacks, they are all grounded together, all the shields are grounded, and I have no hum problems.

[jlatrace]

I am very puzzled. It's odd to me that I get the hum when the D-lator is plugged in, but not turned on.

Here is a pic (before I cleaned up and re-did the solder joints using 63/37 solder.). Do you see any ground issues? One question is:
Should I separate the cliff jack grounds, running the in/out to a different point than the send/return jacks?

https://tubeamparchive.com/viewtopic.php?t=17245