hum on page port?? 3

[rollfig]

Hello everyone,
I have "hum" problem when i convert an analog extention to a page port with a 70V amp. Paging is working but there is always "hum" coming out of the speaker..
It look like if there was somekind of voltage on that port or something like that..any hint why?? When i connect same paging equipment on a different phone system (norstar in my lab) everything work fine.
IPO release 8.1.67

Thanks

 

[smokinjoe2938]

are you using an analogue port or a trunk port?

acss sme acis sme acss cm 5.2.1 acss cm and cmm acss aura messaging.

 

[rollfig]

analog station port

 

[snowman50]

You will get 38v dc on this port
Put a 100 ohm resistor across the pair and the voltage will drop to 2v dc

 

[Nortel4Ever]

We stopped using the analog station port in this manner because of the hum issue and now sell a Bogen TAM-B while leaving the port configured as a phone port. Works great.

 

[Westi]

@Nortel4Ever I do the IPO since 2003 which is a decade and I have had 1 or 2 incidents with a hum and they are all caused by either a ground mismatch or sh!tty paging amplifier that should be in the garbage rather than on the wall.
paging interfaces are high or low impedance and with a Wheelock WMT1A you can go between them.
IPO is low impedance and if you have a high impedance input then use the WMT1A to match between the IPO and the amp done.
Never had too many issues with it except when you needed the 600Ohm resistor on a reboot to activate the paging interface but that is long gone.
So don't harp about the IPO being bad if the peripherals are causing the issue or you just can't get it working
TAM-B is an inferior solution that will not let you do simultaneous paging which is what a lot of customer want and telling them the IPO can't do it is wrong as it works a charm.

sometimes you just have to vent when you see things like that.

@rollfig
take your butt set and put it instead of the paging amp and see if the hum is still there, I bet it is not, make sure all other inputs on the amp are down to 0 and also see that the plug is properly grounded, you can also try and run a groundwire from the amp to the IPO if all the other ones seem OK but measure if there is actually a difference in voltage and if there are some mA crossing from one to the other as that should not be measurable (actually not there at all).
If you have a master volume and a telephone input leave the master volume not more than 2/3 up and regulate with the Tel input as the lower the input the less hum will get amplified should it come from there. also the amp should be close to the system and not fed with a long cable to it (just in case that this would be the case)



Joe W.

FHandw, ACSS (SME), ACIS (SME)

http://convergednetworks.ca

Interrupt the silence only if you improve it by saying something, otherwise be quiet and everybody will be grateful.

 

[rollfig]

Westi , ive done a lot of paging with IPO and it`s only the second time that i have this problem..
And like you said, i connect my butt set and there is no "hum" the only thing i didn`t try is to get the IPO ground directly to the amp.
But thanks anyway for the response

 

[sbcsu]

Do you have an isolation transformer 600 ohm should do it

 

[rollfig]

A star to Westi, after installing a Valcom VMT-1 problem was gone!!