Old amplifier problem

Thread Starter

frusciante89

Joined Nov 13, 2012
10
Hi everybody, I have a problem with my my 1030...
I bought it used in the US and I immediately changed all the capacitors...
I then got back to my country (Italy) and I decided to change the transistors as well, since the amplifier was making a very strange noise...
I then bought a transformer (200 Watts) In order to adapt the power cord to the Italian plug. I was finally able to switch it on and everything works fine, it sounds very crisp and clear... however there is an annoying charge on the front plate: it's not electrocuting, but you can definitely feel it... I noticed that when the iPod is connected to the auxiliary wire, and I touch at the same time the metal case of the iPod and the front plate, then this effect disappears...
Does anybody have an explanation for this? Could it be because the power cord is only a two way? I was thinking of replacing the power cord with a 3 way and hook the ground prong to the chassis: would it make any difference?
Another thing I can think of is that I made some kind of mistake in the transistors substitution...
What do you suggest?
 

Dodgydave

Joined Jun 22, 2012
11,277
If the Chassis is Live then its because there is no Earth or it has a live chassis design. Better to replace the mains lead for a 3 wire type and Earth it.
 

tubeguy

Joined Nov 3, 2012
1,157
If it's a Marantz 1030 then it has a 2.2meg resistor from 1 leg of the AC supply to ground. That explains the tingle.
 

tubeguy

Joined Nov 3, 2012
1,157
Old equipment with 2 wire AC power cords frequently had a high-value resistor or a high impedance AC-rated capacitor (like .047uf) connected this way to provide a low current high-z ground reference.
Reversing the AC cord in the wall can eliminate the tingle.

I don't know about other countries but in the early days the US only had 2-wire, (and I recall) non-polarized mains outlets.
 
Last edited:

BobTPH

Joined Jun 5, 2013
8,765
Supposedly keeping the at the potential of the neutral wire, but in your case it is do keeping at the potential of the live wire. Take it out, use a 3 prong plug and connect the case to the ground lead.

Bob
 
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