(Like most houses, we have 3 corded AC power line.
The power transformer has two lines input(120V)
with two lines output (240V)
I've finished to build up a 6v6 SE amp.
It sounds pretty good except hum.
When I connected all ground of the amp
to the ground (green) of ac cord, the power
transformer began to vibrate!!!
I measured voltage level between chasis (ground)
and three AC lines. Two of them were more than
300V, and the other was 0.
I don't know what's wrong with?
The power transformer has two lines input(120V)
with two lines output (240V)
I've finished to build up a 6v6 SE amp.
It sounds pretty good except hum.
When I connected all ground of the amp
to the ground (green) of ac cord, the power
transformer began to vibrate!!!
I measured voltage level between chasis (ground)
and three AC lines. Two of them were more than
300V, and the other was 0.
I don't know what's wrong with?
Sounds like either:
1. Your amp was wired badly
2. Your house was wired very badly
Standard practice in the USA is to run a 120-0-120 line to the house, grounding the middle (neutral) at the panel. From here on out, ground is ONLY a safety ground; no current is supposed to flow in it. (In fact, GFCI breakers detect a ground current and break the circuit if it rises above say 20mA.) From there, 120V circuits are wired to either side, and 240V circuits are wired between them (requiring a four wire connection of hot, hot, neutral and ground).
Now, for what you are seeing, I'm guessing the 0V you saw was ground, since you said you grounded the chassis. If it were possible your house was wired wrong, you might see 120V or 240V (AC only, no DC) on hot or neutral (neutral should have minimal voltage to ground, as they are joined back at the panel). It might be that hot and neutral are both 120V and between them is 240V, although you would only see 120V from each individual to ground.
But nothing can produce 300V, and you didn't state if that was AC or DC. I'm going to guess you were somehow reading the supply voltage (240VAC * 1.4 ~= 330VDC rectified and filtered), which means that your wiring is really. badly. done.
Tim
1. Your amp was wired badly
2. Your house was wired very badly
Standard practice in the USA is to run a 120-0-120 line to the house, grounding the middle (neutral) at the panel. From here on out, ground is ONLY a safety ground; no current is supposed to flow in it. (In fact, GFCI breakers detect a ground current and break the circuit if it rises above say 20mA.) From there, 120V circuits are wired to either side, and 240V circuits are wired between them (requiring a four wire connection of hot, hot, neutral and ground).
Now, for what you are seeing, I'm guessing the 0V you saw was ground, since you said you grounded the chassis. If it were possible your house was wired wrong, you might see 120V or 240V (AC only, no DC) on hot or neutral (neutral should have minimal voltage to ground, as they are joined back at the panel). It might be that hot and neutral are both 120V and between them is 240V, although you would only see 120V from each individual to ground.
But nothing can produce 300V, and you didn't state if that was AC or DC. I'm going to guess you were somehow reading the supply voltage (240VAC * 1.4 ~= 330VDC rectified and filtered), which means that your wiring is really. badly. done.
Tim
All measured are AC...................
And I tested AC wirings of my house.
See the picture.
The AC powerline have three wires;
Black, White, and Green.
Yes, Green wire is definitely ground.
However, I can't remember exactly
which one is neutral or hot between black
and white.
Anyway, I made both B and W wired to
input of the power transformer.
ps@How about switch Hot with Neutral to
power transformer?
And I tested AC wirings of my house.
See the picture.
The AC powerline have three wires;
Black, White, and Green.
Yes, Green wire is definitely ground.
However, I can't remember exactly
which one is neutral or hot between black
and white.
Anyway, I made both B and W wired to
input of the power transformer.
ps@How about switch Hot with Neutral to
power transformer?
Attachments
OK,
Black is suppose to be hot
White is neutral/ground
Green/bare is ground (safety)
Use your meter between black/green and white/green.
One combo should give you 120 and one should give you 0.
This should let you figure out whether Black or White is Hot.
If you get anything above 120 your house wiring is really bad.
If they're both 120 then your ground is hot.
Black is suppose to be hot
White is neutral/ground
Green/bare is ground (safety)
Use your meter between black/green and white/green.
One combo should give you 120 and one should give you 0.
This should let you figure out whether Black or White is Hot.
If you get anything above 120 your house wiring is really bad.
If they're both 120 then your ground is hot.
The standard for AC house wiring in the US is; Green Is ground, White Is neutral, and Black is hot. Now the Black could be Red or some other color to indicate a hot wire for a different circuit, but neutral is always White and ground is always Green. Each circuit should have it's own neutral and ground and not share them with other circuits.
On the plug Ground is the round pin, neutral is the wider of the two flat blades and hot is the narrow blade. Carefully measure the voltage from ground to neutral. The voltage should be 0 VAC or at least not more than 2 or 3 volts.
If this is not the case get the AC outlet/house wiring fixed before someone gets fried.
Good luck and be safe
BZ
On the plug Ground is the round pin, neutral is the wider of the two flat blades and hot is the narrow blade. Carefully measure the voltage from ground to neutral. The voltage should be 0 VAC or at least not more than 2 or 3 volts.
If this is not the case get the AC outlet/house wiring fixed before someone gets fried.
Good luck and be safe
BZ
thanks, but
I measured and found that all AC wirings of my house
are normal.
Ok, so be it, is a matter of my half-wave
power transformer ?
I said once, the transformer has two lines (input)+ two lines (output). Each side is colored with white and blue.
See the picture again for more detail pleaz!
I measured and found that all AC wirings of my house
are normal.
Ok, so be it, is a matter of my half-wave
power transformer ?
I said once, the transformer has two lines (input)+ two lines (output). Each side is colored with white and blue.
See the picture again for more detail pleaz!
Attachments
Are you sure that you have the transformer wired correctly? I would think that the 2 blue wires go to 1 winding and the 2 white wires go to the other winding.
I suggest that you check and make sure. Transformers don't always follow the same color code as house wiring. The most reliable way to check is with an ohm meter. Disconnect the transformer and test for resistance in the area of less that 100 ohms for the primary and a higher reading for the secondary if the transformer is for steping up the voltage. The resistance from winding to winding should be infinate.
good luck
BZ
I suggest that you check and make sure. Transformers don't always follow the same color code as house wiring. The most reliable way to check is with an ohm meter. Disconnect the transformer and test for resistance in the area of less that 100 ohms for the primary and a higher reading for the secondary if the transformer is for steping up the voltage. The resistance from winding to winding should be infinate.
good luck
BZ
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