Hi, I had the RCA cable from my CDJ disconnected and just hanging about but got a shock when my arm touched the RCA and my newly built diy amp simultaneously.
I measured it with my multimeter and found that there is roughly 200V AC between the RCA and the chassis. I don’t really understand this consider that both are at very low voltages when I measure them to ground.
The amplifier has been properly earthed with the paint stripped away and locking washers to dig into chassis.
Is this unusual behaviour or should I just move the rca cable?
Edit:
I should clarify the RCA was not connected to the amp only to the CDJ.
I measured it with my multimeter and found that there is roughly 200V AC between the RCA and the chassis. I don’t really understand this consider that both are at very low voltages when I measure them to ground.
The amplifier has been properly earthed with the paint stripped away and locking washers to dig into chassis.
Is this unusual behaviour or should I just move the rca cable?
Edit:
I should clarify the RCA was not connected to the amp only to the CDJ.
Last edited:
The input and chassis connections should be at the same potential.
Sounds like you have a dangerous fault!
Is the CDJ earthed properly?
Sounds like you have a dangerous fault!
Is the CDJ earthed properly?
Do not further use this equipment until the problem is resolved. This is extremely dangerous.
Post the schematics and photos. What test equipment do you have?
Post the schematics and photos. What test equipment do you have?
I’ll be honest I’m not an expert when it comes to this. They were bought second hand but I’ve been using them for many months now without noticing any issue. It’s been connected to my DJ mixer and the output of the DJ mixer is at the same potential as the chassis of the amp. Does this suggest it’s not an issue with the amp but more likely the CDJ?
I have dim bulb tester and everything seems fine when I use that on the amp… haven’t tried it on the CDJ. I only have a simple wiring scheme of the amp I’ve attached it here. What would you like photos of?
I’ve also made sure that there’s no continuity between transistors and the chassis as that is a mistake I’ve made in the past. Also for your information there is a 1.6 A fuse in the IEC of the amp
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I just checked the AC voltage between touching the chassis of my dj mixer and the RCA and got the same 200V which means it must be an issue with the CDJ. I find this a bit strange considering that I’ve been using it with my mixer for so long I wouldn’t think that my mixer would be too happy to receive 200 V in its line input. Another strange thing is that the power switch on the CDJ is not even on
Do you have a "death cap" inside?
Disconnect all cables and test each piece of equipment individually for chassis potential relative to utility ground.
Disconnect all cables and test each piece of equipment individually for chassis potential relative to utility ground.
Sounds like leakage current, you're in Europe so it will be higher voltages than we see here.
Connect a 1K0 resistor between the RCA ground and the other chassis with both unplugged from the wall. Plug it all back in and measure the AC voltage across it to figure out how much leakage current there is. Compare that to the specifications in your country. If the resistor gets warm or begins to smoke, you have a very serious problem. Unplug immediately. I don't think you will see this from your earlier description.
If you had much current available you probably would have had a loud hum or smoking wires already. That and a much bigger shock.
If your leakage current is too high, try reversing the polarity of one AC plug if possible. You'll have to trace the source of the leakage current and fix it.
Connect a 1K0 resistor between the RCA ground and the other chassis with both unplugged from the wall. Plug it all back in and measure the AC voltage across it to figure out how much leakage current there is. Compare that to the specifications in your country. If the resistor gets warm or begins to smoke, you have a very serious problem. Unplug immediately. I don't think you will see this from your earlier description.
If you had much current available you probably would have had a loud hum or smoking wires already. That and a much bigger shock.
If your leakage current is too high, try reversing the polarity of one AC plug if possible. You'll have to trace the source of the leakage current and fix it.
Your CDJ has a two pole mains lead. There is no earth on the CDJ so ensure the phono leads are connected to an earthed amplifier at all times or connect a mains earth to one of the deck input ground terminals.
What is happening here is probably the interference suppresor class Y capacitor which connects the case and chassis of the CDJ to one side of the mains, usually the neutral wire. If the mains input is the wrong way around, (Neutral and Live swapped), the chassis will float up to mains voltage but a low current and that would explain the voltage presence when switched off.
The cure is to earth the CDJ chassis and amplifier.
What is happening here is probably the interference suppresor class Y capacitor which connects the case and chassis of the CDJ to one side of the mains, usually the neutral wire. If the mains input is the wrong way around, (Neutral and Live swapped), the chassis will float up to mains voltage but a low current and that would explain the voltage presence when switched off.
The cure is to earth the CDJ chassis and amplifier.
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Hi, I just tried flipping the cable around and that seemed to work now the phono sits at 4v when turned off and 20v when turned on. Isn’t this a terrible design though? Why do they let you put the cable in the wrong way and have the phono floating like that.
AFAIK it would be a good practice, when building up/connecting your audio gear -before you connect all interconnects- to test for the right orientation of the live and neutral pins of the power prong. This for the reasons already mentioned.
You can do this with a voltage meter and see what gives the least voltage between the chassis and mains ground pin. After checking all devices, you can then connect the signal interconnects. Afterwards it is a hassle as you need to disconnect the interconnects, measure, and connect again. It also may make a small improvement in sound quality.
You can do this with a voltage meter and see what gives the least voltage between the chassis and mains ground pin. After checking all devices, you can then connect the signal interconnects. Afterwards it is a hassle as you need to disconnect the interconnects, measure, and connect again. It also may make a small improvement in sound quality.
Curious, in the US this two prong plug would be a polarized plug to ensure it gets plugged in correctly. And I thought and have seen when a home is purchased an inspector goes thru and verifies every wall socket in the house is correctly wired. They even make a little gizmo, my neighbor gave me one, with 3 lights to identify if the socket is wired correctly. Is this not true in other countries?
In Europe, it is a mixed situation. There are outlets that allow only one orientation, but the majority of outlets allow for two orientations. Normally with household gear it is not really a problem, but it is worth it to check this in case of audio gear, as it can make a perceivable difference.
Well, trust.
In Canada we have polarized plugs, which are a joke. Many residential outlets aren't wired correctly. Most are these days, but you can't count on it. I have one of those gizmos simply because you cannot trust the outlet is wired properly. On top of this, the wiring standards make this pointless. Both sides should be isolated. Older stuff may have issues, which need to be addressed. (Just like always)
All they did was to prevent older stereo components from being plugged into preamps and receivers as they were designed to do. Many people file the widened plug down to the same size as the other side. Another example of bright bulbs forcing change without solving the root of the issue.
In Canada we have polarized plugs, which are a joke. Many residential outlets aren't wired correctly. Most are these days, but you can't count on it. I have one of those gizmos simply because you cannot trust the outlet is wired properly. On top of this, the wiring standards make this pointless. Both sides should be isolated. Older stuff may have issues, which need to be addressed. (Just like always)
All they did was to prevent older stereo components from being plugged into preamps and receivers as they were designed to do. Many people file the widened plug down to the same size as the other side. Another example of bright bulbs forcing change without solving the root of the issue.
True. In many older homes in the NL, you have non-PE sockets except in "wet areas" like kitchen or bath rooms, sheds. I had to connect an "earth" connection from a chassis to the piping of the central heating... 🙄 if you didn't you could get moderately shocked when touching things that needed an earthed socket and when live-neutral was not properly oriented.
That is pretty funny. I know it can be a problem in older homes in the US. And houses can last a very long time. I think my parents house built around 1950 only had 2 wire, no ground pin. I think it did have polarized outlets. Then you go to the other side of the coin where now they want ARC and other specialized very expensive circuit breakers as standard.
I've seen the hot wired to the outlet ground (not the common!).
In the past, if something hummed or you got a shock, you simply turned the plug around. No biggie. If the widow maker capacitor shorted, you got a bang or healthy shock. That would inspire people to take the thing in for service or throw it out. People often need a dramatic reason to do the right thing. They will use something until they simply can't use it.
You cannot legislate intelligence, and stupid people will always find a way to hurt themselves or others. I'd like a way to prevent it, but there just isn't. These same characters drive and kill people.
In the past, if something hummed or you got a shock, you simply turned the plug around. No biggie. If the widow maker capacitor shorted, you got a bang or healthy shock. That would inspire people to take the thing in for service or throw it out. People often need a dramatic reason to do the right thing. They will use something until they simply can't use it.
You cannot legislate intelligence, and stupid people will always find a way to hurt themselves or others. I'd like a way to prevent it, but there just isn't. These same characters drive and kill people.