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TU 717 Buzzing.

hughman61

hughman61

Active Member
Just took possession of the above mentioned tuner and hooked it up to my AU 717 and I'll be darned there's a hum.

I thought maybe the interconnects? Nope swapped em out still a buzz.
I thought it was the AU 717 tuner inputs, don't think so, when I disconnected the interconnects from the TU output plugs buzz went away. When it was still connected and I turned the TU off the buzzing was still there.

Could this be a grounding issue? Or maybe something more sinister like a bad FM board?
 
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The grounding is a longshot. You can try grounding the tuner to the amp. Any metal screw on the back should work. If that fails, do you have a buddy whose system you can try the tuner on.
 
What are you using for an antenna? Ground loops are often caused by the antenna. I've also had cable box connected to my computer feed through the USB DAC to my system and sometimes only interfered with the tuner. Have you tried other stations? I have experienced hum that was actually broadcast by the station. Then there could be a power supply issue with your tuner or other problem.
 
Antennas seldom cause grounding issues. I would disconnect the cable box, but then no other inputs have the hum. If it's the box, you will get lucky & get off cheap with a video ground isolator. They start @ c. $15. The cheap ones work as well as the pricey ones.
 
@Punker X , @Lesterbest It's the antenna connection. The house had an antenna when we purchased it. I hooked up the antenna with a UHF/VHF/FM xfmr to coaxial cable and another UHF/VHF/FM xfmr at the tuner. Even when the tuner is off but connected to the amp I get the low buzzing. I'm thinking it's a ground loop issue.

@Lesterbest you think grounding the tuner to the amp frame could resolve this?
 
hughman61 said:
@Punker X , @Lesterbest It's the antenna connection. The house had an antenna when we purchased it. I hooked up the antenna with a UHF/VHF/FM xfmr to coaxial cable and another UHF/VHF/FM xfmr at the tuner. Even when the tuner is off but connected to the amp I get the low buzzing. I'm thinking it's a ground loop issue.

@Lesterbest you think grounding the tuner to the amp frame could resolve this?
Click to expand...
It couldn't hurt & its easy to try. Any hookup wire will suffice. If it was on all inputs, then I expect a video isolator is the answer. Try the easy way 1st. Good luck.
 
I would pop the TU cover and look at the solder joints at the RCA jacks. Give the unit a Deox-it cleaning and see If that works for now.
 
Twas a grounding issue. Found some wire and connected the two units together and voila! I just need to remember to keep it simple and proceed to the more difficult.

Thanks to all for the input.
 
You need to un-ground your antenna and or run a ground from your antenna ground to your main power ground. The second being the proper way and should have been done at install. The problem is they are different grounds at different potentials. Using a simple dipole should also eliminate the problem. Grounding your amp and tuner together probably won't do it. They should already be grounded together via the RCA connection. May try reversing your power cords also sometimes that can work wonders. Do one at a time. Ground hums are the worse.
 
As for FM antenna grounding, the sole purpose is lightening protection. If you don't live in a lightening prone area, there's virtually no reason to ground. Obviously if you live in a lightening prone area, it would behoove you to ground the sucker.
 
Got another question. Can a ground loop case dame to a amplifier? I've read that if you have two different ground potentials then current can flow through the interconnects. If that's the case I can't see how that would be good.
Now my left outputs to the loudspeakers are messed up, little to no output. Could, A.) the ground loop damage the amp? B.) By making a ground jumper from the tuner to amp could I have done damage?
 
Very glad this was a simple fix, as I'm the one who sold him the tuner and I had never heard a hum through it. Love the accumulated wisdom in this community.

And enjoy that tuner, hughman61. I sure hope there's nothing actually damaged in the rest of your system.

Nolan
 
As long as 1 correct AC ground is made, the others are grounded thru the ICs. When I was in the service biz, I was advised on day #1 to not hook up unnecessary grounds, lest a star ground was required. Some suffer ground phobia & buy $2K to > $10K ground boxes. A ground loop with the vol control @ max could conceivably damage an amp. File this under extreme longshots.
 
hughman61 said:
Got another question. Can a ground loop case dame to a amplifier? I've read that if you have two different ground potentials then current can flow through the interconnects. If that's the case I can't see how that would be good.
Now my left outputs to the loudspeakers are messed up, little to no output. Could, A.) the ground loop damage the amp? B.) By making a ground jumper from the tuner to amp could I have done damage?
Click to expand...
Put the system in Mono; Swing the balance control from L to R. & report back. Is 1 channel down on all inputs? If so the problem lies elsewhere.
 
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