Kenwood Ka-35 grounding issue.. I think

[Clinno]

Hi, I just brought an old kenwood stereo system from a garage sale for $10 dollars without the turntable or speakers,
The trouble I am having is that the amp (KA-35) is causing a humming noise to come through the speakers at all times when the power is on.
(the speakers work fine wired to there original sharp stereo)
The diagram for installation on the back has the ground wire running from the amp to the turntable, however I do not have a turntable and I know absolutely nothing about electronics to know where to run the earth wire to! (if this is even the problem!?)
Hoping someone can help me simply here, cheers

 

[Harvey]

If it has a two prong AC power connector, try turning the plug over. If it has a three prong connector, make sure the AC in your home is wired correctly and that the ground lug (third prong) is actually connected.

Try running a wire from the ground lug on the amp to any grounded pipe. If the hum goes away, you've found your problem.

Given the age and presumed lack of care given to the amp, the filter capacitors in the power supply may be dried out and failing. They're probably old through hole parts so, if you have any soldering skills, you may be able to replace them, yourself or have it done by someone who knows what they're doing.

Good luck.

 

[Modelworks]

With nothing but the speakers connected, no other connections, tape, cd, etc , select one of the inputs, not phono, and turn the volume up and down. If you still hear the humming noise then the amp will need repair.

If the noise occurs only when connected to a cd, tape or other device then you have a ground loop and will need to determine if it is the outlet or cabling.

Ground loops are rare in older amps because of the use of transformers for the power supply.

 

[NutBucket]

My vote is bad caps as well.

 

[Harvey]

Modelworks reminds me -- If you have nothing plugged into a selected input, it isn't terminated, and it could easily be subject to hum. This is especially true for a phono input, which provides more gain than line level inputs such as Aux, Tape, Tuner, etc.

You can test this by plugging a standard hifi cable with RCA connectors. Start with the volume down, and turn it up until you hear hum. Then, use a clip lead, wire or metal object such as a screwdriver to short between the center pin (hot) lead and the sleeve (ground). If the hum goes away, you've found your problem. If not, go back to my previous suggestions.

 

[Clinno]

The first thing I did was unplug everything except the amp and speakers but the hum remained, constant and consistent, turning the volume knob did not change the consistency of the hum at all? I am not home to try the earth but it sounds like the amp needs repairing? I have/had an old Sharp stereo a Tele and a bunch of gaming consoles hooked up to the same power supply with no troubles..
Appreciate the posts, cheers.