My teck and I tried to fix this "hum" sound particularily present on phono. It still present thru music on auxiliary.
All the caps has good resistance, all the tubes are ok. We just cannot find from where it's comming!

Is somebody around know what i'm talking about?
Any tricks to find out?

Thanks an have a nice day!

Now disconnect the input to the HF85. Is the hum still there? If so, then it may be power supply hum or something else internal to the HF85. If not, it's the source. Check your ground, cables and source equipment.

Grounding problems are very common, so make sure your ground is good.

The problem belong to the Eico preamp. My tech try to ground everywhere he should but never obtain results.
Power supply then!... (gosh!)

I hardly dont understand these ground problem on old appliances. With no electric ground (two prong plug) and no attach to the ground anywhere, how ground can be good? There is black wires attach to the body, yes, but is that sufficient?
How could I be sure ground is good?!

Thanks again

Just to make no mistake, from what point to point do I have to measure the chassis? (from the chassis to the eventual 3th wire prong?)
I just want to be sure of what i'm doing because I remember an old radio I had... I was unable to touch it... electrifying!

My source is a recent CD player. Should I wire the chassis to the amp too?

Thanks again