I have a JBL PSW1000 powered subwoofer. I just finished wiring a whole house audio system and when I hooked up the subwoofer using coaxial cables with rca hook ups on the end into my Denon AVR-887, amp, my home theater speaker connectors became line voltage. I've pulled the back off the sub woofer and nothing seems amiss, like a paper clip or something bridging a connection. No evidence of any problem. Any ideas?
I had this in Subwoofer but I've isolated it to the subwoofer amp. There is 110 voltage from the RCA inputs for connection to the regular amp. I noticed this morning that the fuse that in it is rated high amp than it should be I can't imagine that causing this problem.
Also I see that the wider spade of the plug (to the wall outlet), which I thought was the ground spade is the wire that unioned to the transformer wire at the circuit board. Is that right? (though it doesn't look like anyone re-soldiered it.
I had this in Subwoofer but I've isolated it to the subwoofer amp. There is 110 voltage from the RCA inputs for connection to the regular amp. I noticed this morning that the fuse that in it is rated high amp than it should be I can't imagine that causing this problem.
Also I see that the wider spade of the plug (to the wall outlet), which I thought was the ground spade is the wire that unioned to the transformer wire at the circuit board. Is that right? (though it doesn't look like anyone re-soldiered it.
Does the subwoofer have a safety ground (3 pin plug) ? If not.. check for continuity between the transformer primary and secondary. There is no way in hell you should have line voltage on the RCA's 
I guess this is a no brainer, but I'll say it anyway - do NOT use the sub until you figure out wtf is wrong!
I guess this is a no brainer, but I'll say it anyway - do NOT use the sub until you figure out wtf is wrong!
I see. I wonder why the transformer does burn or melt or spark or something if the winding's insulation are compromised. So in other words, you think the insulation (the plastic covering of the little wires that wrap around to form the transformer) has failed somewhere and voltage is leaking from the windings?
No Andrew. At least I don't think so. I was just pointing out that when I took the back panel off to see if there was any noticable short of some kind, I traced the power wire and the squared spade plug (which I thought was supposed to be the neutral) was connected to the transformer in the amp of the subwoofer. That seemed strange.
The hot and neutral both connect to the transformer. Typically the hot wire should go via a switch and a fuse.
I can't think of another reason for line voltage appearing on your RCA jacks. This definitely needs looking at properly.
I assume the rest of the system operates normally without the sub being connected? Does the Denon amp have a 2 or 3 pinned plug?
I can't think of another reason for line voltage appearing on your RCA jacks. This definitely needs looking at properly.
I assume the rest of the system operates normally without the sub being connected? Does the Denon amp have a 2 or 3 pinned plug?
Are you sure you are describing the symptons properly? I have no problem believing that the sub out RCA's have AC on them, or that the receiver speaker outs have AC on them, but that putting AC into the receiver and getting AC out on the speaker connections without something frying seems far fetched to me.
I just finished opening up a manual that is for a PSW-D110 JBL subwoofer and it is similar to your model. The hot goes thru a fuse to the transformer and as we might expect the neutral also goes to the transformer.
I am wondering if you were making a ground connection with your body and touched the speaker connections and thought you got shocked or experienced a small sensation. If your sweating you will feel voltage that is a lot lower. If there were actually 120 volts present at the speaker terminals you could kiss your speakers goodbye.
If there was 120 volts present at either the speaker terminals or the RCA jacks you would either blow the speakers sky high or the amplifier.
I suggest you use a meter and recheck and post your findings.
I am wondering if you were making a ground connection with your body and touched the speaker connections and thought you got shocked or experienced a small sensation. If your sweating you will feel voltage that is a lot lower. If there were actually 120 volts present at the speaker terminals you could kiss your speakers goodbye.
If there was 120 volts present at either the speaker terminals or the RCA jacks you would either blow the speakers sky high or the amplifier.
I suggest you use a meter and recheck and post your findings.
Let me think this through again. I first noticed the problem when I tried to hook up the center speaker. I flat out got shocked - a hard shock. I have a multi-meter and check the speaker connection by putting the red probe to the connection and the black to the ground hole on a line voltage outlet (I pulled the tv plug out slightly. The meter was set to 250vac, and it showed a strong reading.
After thinking it thru I realized the powered subwoofer had just been hooked up, so I unplugged it from power, re-tested at the speaker outlets and and got no voltage reading. Then I unplugged the sub at the rca connections (the input), plugged it back into power and tested the RCA inputs and got a voltage reading of 110v (not quite halfway up the meter).
Then using an extension, I hooked the sub into a GFI outlet in the kitchen and re-checked it with the multi-meter and got the same reading.
I can't think of what I could have done wrong.
After thinking it thru I realized the powered subwoofer had just been hooked up, so I unplugged it from power, re-tested at the speaker outlets and and got no voltage reading. Then I unplugged the sub at the rca connections (the input), plugged it back into power and tested the RCA inputs and got a voltage reading of 110v (not quite halfway up the meter).
Then using an extension, I hooked the sub into a GFI outlet in the kitchen and re-checked it with the multi-meter and got the same reading.
I can't think of what I could have done wrong.
one question...... was this voltage reading across the speaker terminals with signal applied? a sub amp could give you a nasty shock if signal is present, even if nothing is wrong.
GFI outlets sense current flowing through the ground (3rd) wire and kick off if any ground current is flowing. a 2 wire plug has no leakage protection from a GFI outlet.
you could connect a megohm meter from the primary side of the transformer to the RCA ground and see if there's any leakage current there. a handheld DMM goes up to 2 or 20 meg usually, and a "Megger" goes up to about 200 or more meg, and it uses a high voltage (100V i think) to measure leakage current. another useful item would be a "Hipot" tester that tests the insulation breakdown voltage up to about 3kv.
GFI outlets sense current flowing through the ground (3rd) wire and kick off if any ground current is flowing. a 2 wire plug has no leakage protection from a GFI outlet.
you could connect a megohm meter from the primary side of the transformer to the RCA ground and see if there's any leakage current there. a handheld DMM goes up to 2 or 20 meg usually, and a "Megger" goes up to about 200 or more meg, and it uses a high voltage (100V i think) to measure leakage current. another useful item would be a "Hipot" tester that tests the insulation breakdown voltage up to about 3kv.
I'm afraid you're out of my league on the megohms and hipot. All I have is a multi-tester (with an ohm meter, but what you describe sounds like some sort of induction tester.
And there isn't an signal coming from the subwoofer since I'm actually measuring the voltage at the rca inputs (for a signal from the main amplifier). I'm touching the red probe of the tester to the rca input and the black to the ground on an electrical outlet on the wall.
And there isn't an signal coming from the subwoofer since I'm actually measuring the voltage at the rca inputs (for a signal from the main amplifier). I'm touching the red probe of the tester to the rca input and the black to the ground on an electrical outlet on the wall.
lews said:
WOW! You have 120 VAC at the input to your sub amp? You measure between the centre of the RCA jack (not the ouside barrel) and the wall recepticle ground terminal?
That's 100 times more voltage then that input can handle!
There should be lightning bolts and black clouds of smoke and flames of every colour shooing out of that thing!
And did you mention that it was connected to a HTR and it was working fine??
There's something not right here...
In another thread I've mentioned to "lews" to verify the correct house wiring with this.
http://toolprice.net/product/7290A?META=nextag-7290A
http://toolprice.net/product/7290A?META=nextag-7290A
That's right, both the inside and the outside of the input connection (I checked separately) are showing 110V. I don't see how I can be reading the multi-meter wrong. It's set at 250vac and I get a reading close to halfway up the scale. I will check it against an outlet tonight and see if I get the same reading.
And yes it was temporarily hooked to a whole house system. No smoke. When I check the inputs, I get a speaker pop sound that makes it still seem that the sub is working fine.
And yes it was temporarily hooked to a whole house system. No smoke. When I check the inputs, I get a speaker pop sound that makes it still seem that the sub is working fine.
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