Loud buzz on OBi110 line PSTN
Rick:
Re-read what Steve said. He's basically telling you that YOU are frying your OBi's and telling you how to properly test for that. If you do what he says and leave it like that over night and the OBi doesn't fry you have your answer.
Shale:
I suspect that his AC protective ground could be hot, although I don't know if that would account for the symptoms.
Jon9999:
Shale,
OK, I borrowed a voltmeter. I'll try to test the phone line voltage as you and Steve described earlier. So I should put one probe on the red wire of the wall jack and the other into the ground plug of a wall socket, right? And then do it again with the green wire and the ground plug? And then do both again while calling my number from another phone to make it ring?
Can you please tell me how to test the protective ground? (And just wondering... why would it matter about the ground? The OBi's AC adapter is only 2-prong, so it doesn't even connect to ground, right?) Oh, and I'm using a surge protector that has a "Grounded" and "Protected" lights, and they're both normal. Does that answer the question about the ground being okay, or is it something else?
Thanks.
Jon9999:
Quote from: SteveInWA on July 24, 2013, 12:23:34 am
you might be inadvertently feeding your external (POTS) line 1 or 2 into into the line 1 wiring somewhere, and it's getting into the OBi on the PHONE side, thus frying the circuitry
Good thought, but I doubt it for a few reasons:
- With the 2nd OBi, I had connected the OBi PHONE jack only to an individual phone, not into the bus or into the house wiring, before it died. So nothing could have been getting back into the OBi PHONE jack from anywhere.
- I don't hear Line 2 when I use a Line 1 phone or vice versa, and when there's an incoming call on one of the lines, the other one doesn't ring. So I don't think there's any feed from one of the lines into the other.
- The PHONE side of the dead OBi units continued to work just fine. I could still make GV and SIP calls, with no buzzing. It was only the LINE side that was buzzing, so it seems that if there was some sort of damage, it was on the LINE side only.
I've received the new unit, but I'll hold off on hooking it up until I get a better handle on this. I'll try to do the volt testing that you and Shale suggested, but I'm a little leery of sticking things into electric sockets.
Shale:
Quote from: Jon9999 on July 24, 2013, 08:22:22 am
Shale,
OK, I borrowed a voltmeter. I'll try to test the phone line voltage as you described earlier. So I should put one probe on the red wire of the wall jack and the other into the ground plug of a wall socket, right? And then do it again with the green wire and the ground plug? And then do both again while calling my number from another phone to make it ring?
Can you please tell me how to test the protective ground? (And just wondering... why would it matter about the ground? The OBi's AC adapter is only 2-prong, so it doesn't even connect to ground, right?) Oh, and I'm using a surge protector that has a "Grounded" and "Protected" lights, and they're both normal. Does that answer the question about the ground being okay, or is it something else?
Thanks.
I must apologize. I was thinking that the OBi power adapter was 3-prong and the protective ground pin was connected to the chassis of the OBi. I was wrong-- it is a 2-prong plug on my OBi202. . Thus a problem with the protective ground would not have affected the OBi110-- presuming your AC adapter is a 2-pin 120 VAC (volts AC) power adapter also. Sorry I brought this up, but since you have the meter in hand, probing around won't hurt, and it might help. Since I don't have a specific theory now, I will ramble on a bit.
Let me say that it if the meter is in the AC volt setting with a high enough range, there is no place around your phones or computer that you can stick the probes that will damage the meter. With most digital meters, sticking the probes on a 120 vac voltage will not damage the meter, even if the range is much lower. The thing to be careful of is to not have the meter in the current (ma, A, or amps) mode or the resistance mode when probing voltage.
For your personal safety, hold the meter probes by the insulated handles. If you use sewing needles to probe the phone line, and you need to hold the metal part of the probes to a sewing needle, wear gloves. Thin cotton is fine. Rubber gloves are fine.
I suggest putting the meter into the 20 volt AC range and see what you get across a battery. If the voltmeter rejects DC, you will probably get near zero in the AC (direct current) mode of the meter and about 9 or 1.5 volts on DC -- depending on the battery. My OBi power adapter shows 12.26 DC between the inner and outer conductors of the plug that plugs into the OBi.
Then, with the exceptions of the protective grounds, look for AC voltages where they should not be, such as the pins of the telephone wires. It is OK to measure voltages between the protective ground pin on an outlet (5 in picture) and the phone wires.
Here is a cable connector that might plug into your OBi110 in the Line position. In this image, pair 1, which the OBi110, is labeled as pins 2 and 3. The other pair, which I would have thought would be not connected internally to the OBi are pins 1 and 4. There may be some suspicion that the OBi110 might connect to those pins internally. I don't know.
So anyway, probe around. Report what you find, and something anomalous may pop up.
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