Loud buzz on OBi110 line PSTN
Shale:
Quote from: Jon9999 on July 23, 2013, 11:56:46 am
Again, this isn't just a background hum. It's a very loud buzz, with no other sound (no dial tone, no voice), as soon as the call switches into the PSTN line.
OBi Support thought it might be "a coincidence" that I got two defective OBi110's in a row, but I'm skeptical. I'm thinking that something, somehow caused the OBi line port to fry itself when I connected it to my phone line. But I've never had any phone, fax machine, or computer modem get fried from the same phone line, so it really doesn't make any sense.
I agree that this is not just coincidence.
I would probe things with a voltmeter. See what kind of voltages you get from protective AC ground to the phone line wires. Normal would be about -50 DC volts on one phone wire and about zero on the other phone line. Check with AC also. It should be near zero on both wires if your meter is one of those which ignores DC when it is in the AC mode.
I would also check for voltage from AC protective ground to an independent ground such as a water faucet or other available ground. Use the AC mode on the meter for that.
It may be that the OBi110 was not fried, but some kind of ground fault was interfering. I have not figured out what that could be.
RFord:
Try plugging the unit on a separate circuit in another room of your residence. If you have another surge protector, I would try that unit as well. Do a test with and without the "new" surge protector.
Better yet, could you take the unit to another location (one of your neighbors?) that have a PSTN line and test. There might be a problem with either your PSTN Line or your electrical system as Shale suggested.
Jon9999:
To Shale:
Probe with a voltmeter??? Really? I wouldn't know a voltmeter from an ice cream cone. And my A/C is nowhere near the phone system, so I know it's not coming from that.
To RFord:
I tried plugging it into another electric outlet on a different circuit, and it still buzzes. At this point, the unit seems fried so it will buzz no matter where I plug it in. I also tried plugging it into a different PSTN line -- same. I didn't have the phone connected through a surge protector, so I'll make sure to do that when #3 comes -- but I can't imagine that two power surges came through the phone line at the precise moment when I hooked up the OBi, given that I've never had any phone/fax/modem equipment damaged ever on the same line from a power surge.
I will try to protect
Shale:
Quote from: Jon9999 on July 23, 2013, 02:05:08 pm
To Shale:
Probe with a voltmeter??? Really? I wouldn't know a voltmeter from an ice cream cone. And my A/C is nowhere near the phone system, so I know it's not coming from that.
Ask your friends, your children, or your parents. One will have a voltmeter. That person will know how to use it. After watching, and presuming you are not a dedicated technophobe, you too could buy and use a $10 or $20 multimeter (voltmeter and ohmmeter combined). They are helpful with cars and more.
The phone system is plugged into the Line port of the OBi110. It may take more than 2 hands, but you can probe the two middle conductors of the cable that you unplugged from the OBi using a sewing needle as a small probe. One person can do that-- maybe your friend. The other person probes the protective ground on your outlet strip. Both of you can see the meter, which is sitting on something. The protective ground of an outlet is the roundish or D-shaped hole, rather than the flat holes.
Jon9999:
Thanks, Shale, but nobody I know is going to be sticking sewing needles into electric outlets. I just don't run in that kind of crowd, I guess. I can hire an electrician, but it's just not worth it in the end.
Is there any type of plug-and-play device (not expensive) that I can use to test this out?
And what I really don't understand is that if there is indeed something wrong with my voltage or my ground or whatever, then how come I've never had any problem with any other phone or answering machine or fax machine or modem or TiVo that I've plugged into the very same phone line?
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