Please help.... Grounding issue, and 60 Hz hum

[Jimmy154]

12 Ohm will be fine. Yes, circuit ground is the ground on your PCB. Yes, you seem to have this correct.

You may have a hum loop. If you have two wires connecting at your star ground that connect somewhere else as well, that will form a loop, and could cause hum.

Thank you for the confirmation, it worked great. You're pretty smart for a cat

I would have tried it anyway eventually, but I would not have know if 12 ohms is exceptable, since I'm not to good with electrical concepts.

Now all I have to do is get rid of the occational popping I here that comes from the RCA's not being shielded. It's the same problem PaulHilgeman has or had, I was hoping I could use some kind of RFI filter (instead of shielding 7 meters of cable), but it the thread http://diyaudio.com/forums/showthre...rpage=10&highlight=gainclone+pop&pagenumber=6 no one could come to a consus on a filter, I read the entire thread. Post a filter you have a pretty good idea will do the job, if you can please

The popping is caused by fans being turned on or anything, but fans are the worst, there's one in the attic that goes on and off all the time. And it only happens when RCA's are plugged in so I think it's the RCA's. Also I wanted to ask, should I buy/make shielded RCA's or go with filter if possible?

 

[Jimmy154]

Re: Re: Safety

I'm not too good with the techical terms. Circuit ground refers to the PCB grounds? And they both go to a 10 resistor (is 12 ohm okay?) and then to the star ground, where my earth ground goes to the AC line cord. Do I have this correct?

I'm asking because I had a slight buzzing noise from the tweeter and woofer on both channels and I tried to get it to go away. And relised my power strip (that my gainclone is plugged into) had no ground wire where it plugs into the wall (although all the plugs on the power strip have ground wires for some reason). So I plugged my gainclone into the wall and the slight buzz turned into a pretty loud and very noticeable buzz.

I still have a hum after putting this 12 ohm resistor in. It always gets audiable at night. Should I put in the 10 ohm resistor, will it get better? Or should i put in a larger resistor? Or should I do something else? Or should I stop asking questions?

 

[fdegrove]

Hi,

10 or 12 Ohm won't make any diff. Try something close to 100R and stop humming.

Cheers,

 

[EC8010]

If you know which fan is the culprit, the best solution for stopping the clicks is to fit a contact suppressor (100n in series with 100R) across the switch concerned. Not only will this stop the clicks, but it will also make the switch last longer. Contact suppressors can be bought ready-made, they look like a standard capacitor, but have the 100R resistor built in and are rated for 250VAC.

 

[Jimmy154]

If you know which fan is the culprit, the best solution for stopping the clicks is to fit a contact suppressor (100n in series with 100R) across the switch concerned. Not only will this stop the clicks, but it will also make the switch last longer. Contact suppressors can be bought ready-made, they look like a standard capacitor, but have the 100R resistor built in and are rated for 250VAC.

The fan is not the only thing that causes the pops. I'm interested in stopping the pops, but i think with some shielded RCA's they will stop. Although knowing myself i will probably never make them. I have to make 8 x 2 meters worth. I wanted to make this cable http://www.tnt-audio.com/clinica/piano6_1_e.html or some other one on the website, which I can no longer find. I need to find a source for this "Type 6/1 IBM cable." And figure out if this cable helps.

But I am more interested in stopping the hum. And the 12 ohm resistor helped, but I did not no if I should go higher or how much on the resistance. If I can use the 100 ohm, I will and hopefully it will solve my problem.

 

[EC8010]

If the 12 Ohm resistor helped, that rather suggests that you do have a hum loop. Bearing in mind my earlier comments about leaving the mains earth bond to chassis in place, try removing the 12 Ohm resistor entirely.