INTELLIGENT WORK FORUMS
FOR COMPUTER PROFESSIONALS

Log In

Come Join Us!

Are you a
Computer / IT professional?
Join Tek-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Tek-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

Humming noise with Mitel 7187a analogue phone

Humming noise with Mitel 7187a analogue phone

(OP)
Dear Sirs
If you use your analogue phone Mitel/Aastra 7187A and a headset is connected in the headset port, - and the headset is charging - the user will hear humming noise in the analogue phones handset.

We have tried to install ferrite cores on all cables - between the PBX and the analogue phone Mitel 7187A, the cable between the phone and headset and the power cable.
All this w/o success.

Our customer has also many Aastra/Mitel 4187A analgue phones and these phones do NOT have this problem.
The Wireless headsets used are Jabra 9120 and 9450 and Sennheiser.

We have tried to swap the cords towards the PBX (-48V and 0V). But no change here.
The idea, we have currently is to insert a 10 nF capacitor in the analogue phones handset in parallel with the speaker??

Maybe you have some hints.
Let me know your opinion.

BR doktor

///doktor
____________________________________
http://www.kandu.dk/spg153996.aspx

RE: Humming noise with Mitel 7187a analogue phone

Your post is unclear. Is this hum prevalent on ALL phones with headset plugged in? Are the handsets plugged into the phone or the headset amp?

Marv ccna

RE: Humming noise with Mitel 7187a analogue phone

Asstra 7187A:
Jabra 9120 not supported
Jabra 9450 4 flavors supported

Aastra 4187A:
Jabra 9120 not supported
Jabra 9450 3 flavors supported

Sennheiser:
No model given by you

You may have some interference from other devices or power bars at the station/cubical/office.
Find a working combo then move them both to a station/cubical/office that has an issue to help troubleshoot.

You may need to try an RFI Filter for the handsets on the 7187a's

________________________________________

Add me to LinkedIN


=----(((((((((()----=
www.curlycord.com
Toronto, CAN

RE: Humming noise with Mitel 7187a analogue phone

(OP)
Hi Again

Thank you for your fast replies.

We see the issue only when the Wireless headset is charging in the charger/bay.
If the user chooses to use the Mitel 7187 phones handset, then he/she will hear the humming noise.
The user will not hear any noise when using the headset.
We do not have this issue with the elder analogue phone type Mitel/Aastra 4187.

Ferrite cores have been tried on all cables, w/o luck.

BR Henrik

///doktor
____________________________________
http://www.kandu.dk/spg153996.aspx

RE: Humming noise with Mitel 7187a analogue phone

(OP)
Update:

Is this hum prevalent on ALL phones with headset plugged in?
Yes, hum is heard in the handset, if the Wireless headset is charging.
On all 7187 phnones, NOT on the 4187 model.

Are the handsets plugged into the phone or the headset amp?
The headsets are Wireless and the bay/charging station is connected to the 7187 phones special headset connector.

///doktor
____________________________________
http://www.kandu.dk/spg153996.aspx

RE: Humming noise with Mitel 7187a analogue phone

You did not really answer the question but will assume "the handset is plugged into the phone as normal"

Do not confuse Ferrite coils with RFI Filters.


A crackle or buzzing sound – try moving your headset base about 30cm away from your telephone (radio transmission may be too close) This includes things like radios, stereos, ipods or any other electrical transmitting items. They should not be in the room if you are using a telephone headset and get interference.

As I said above test a non working combo in place of a working combo to test this theory.

Have you called the manufactures support line yet?

________________________________________

Add me to LinkedIN


=----(((((((((()----=
www.curlycord.com
Toronto, CAN

RE: Humming noise with Mitel 7187a analogue phone

(OP)
Hi Curlycord

Yes, "the handset is plugged into the phone as normal".
So both handset - connected to the handset interface of the analogue phone and the Wireless headset are simultaneously connected.
I will test with a longer cable, but I guess that that work-around will not be acceptable.

Can you recommend a RFI filter or should we try with a capacitor over the handset-speaker?

I have contacted the different Companies involved in this matter.

BR Henrik

///doktor
____________________________________
http://www.kandu.dk/spg153996.aspx

RE: Humming noise with Mitel 7187a analogue phone

I only know Plantronics makes one, I have no experience due to never having your issue.

Using a longer cable and also trying to swap the combo's will narrow down the issue but if both headsets have issue with the same model phone then you would think the model phone is the culprit.

________________________________________

Add me to LinkedIN


=----(((((((((()----=
www.curlycord.com
Toronto, CAN

RE: Humming noise with Mitel 7187a analogue phone

(OP)
Hi there

The idea, we have currently is to insert a 10 nF capacitor in the analogue phones handset in parallel with the speaker.
Maybe that could help?

///doktor
____________________________________
http://www.kandu.dk/spg153996.aspx

RE: Humming noise with Mitel 7187a analogue phone

I do not know but I am sure others will charm in soon....long weekend over here.

________________________________________

Add me to LinkedIN


=----(((((((((()----=
www.curlycord.com
Toronto, CAN

RE: Humming noise with Mitel 7187a analogue phone

In the sound business, when we have a hum, it's usually due to a ground fault.

Might try a different circuit for charging the headset. Just a thought.

Just my $.02

"What the captain doesn't realize is that we've secretly replaced his Dilithium Crystals with new Folger's Crystals."

--Greg

RE: Humming noise with Mitel 7187a analogue phone

Have you tried connecting the headset amp to the handset port of the phone and connecting the handset to the handset port on the headset amp?

Marv ccna

RE: Humming noise with Mitel 7187a analogue phone

Marv please record and say that 10 times really fast and then post the link to the wav file here when done.
Thanks

I also had ground in mind but so many users having same issue but doktor really needs to do the stated tests above and report back the findings.

________________________________________

Add me to LinkedIN


=----(((((((((()----=
www.curlycord.com
Toronto, CAN

RE: Humming noise with Mitel 7187a analogue phone

Paul LOL

Marv ccna

RE: Humming noise with Mitel 7187a analogue phone

(OP)
Dear Sirs

We have tried this:
"Have you tried connecting the headset amp to the handset port of the phone and connecting the handset to the handset port on the headset amp? "

But sorry to say -> w/o luck.

Any ideas about the capacitors value? 10 nF or 100nF or?

We tried different grounding an even let the analogue phone run through an ATA box (analogue-to-LAN) box , also w/o luck.

Sorry to say...

///doktor
____________________________________
http://www.kandu.dk/spg153996.aspx

RE: Humming noise with Mitel 7187a analogue phone

"Find a working combo then move them both to a station/cubical/office that has an issue to help troubleshoot."
You have not answered this.

What I mean is swap the phone, the headset and the charger with another person/location (that has a working setup) as a test and see if the issue follows.


"I have contacted the different Companies involved in this matter."
And what was the suggested solutions?
Did they both agree they are compatible with each other?

________________________________________

Add me to LinkedIN


=----(((((((((()----=
www.curlycord.com
Toronto, CAN

RE: Humming noise with Mitel 7187a analogue phone

(OP)
Hallo.

What I mean is swap the phone, the headset and the charger with another person/location (that has a working setup) as a test and see if the issue follows.
-> this has been tried w/o luck


"I have contacted the different Companies involved in this matter."
And what was the suggested solutions? -> Proposals does not solve my problems with the noise.

Did they both agree they are compatible with each other?
-> The headset and phone are on the white lists.

BR Henrik

///doktor
____________________________________
http://www.kandu.dk/spg153996.aspx

RE: Humming noise with Mitel 7187a analogue phone

How many Mitel 7187A's are there?
What runs them? a PBX or dedicated line to each set?

________________________________________

Add me to LinkedIN


=----(((((((((()----=
www.curlycord.com
Toronto, CAN

RE: Humming noise with Mitel 7187a analogue phone

(OP)
Approx 300 pcs. Running on Mitel MX-ONE 5.0 PBX with ELU29 boards

///doktor
____________________________________
http://www.kandu.dk/spg153996.aspx

RE: Humming noise with Mitel 7187a analogue phone

Is the problem local to one of the ELU29 boards? In other words, if the extension is moved to a different ELU29, does the problem go away?

Just my $.02

"What the captain doesn't realize is that we've secretly replaced his Dilithium Crystals with new Folger's Crystals."

--Greg

RE: Humming noise with Mitel 7187a analogue phone

...or are both model phones on the same cards?

Since they are analog why not take the package home or office and test offsite?
If onsite then issue would then be the MX-ONE 5.0 PBX or something on site such as the Florescent lights.

Maybe get a ground tester and test a station as well the PBX receptacle.

________________________________________

Add me to LinkedIN


=----(((((((((()----=
www.curlycord.com
Toronto, CAN

RE: Humming noise with Mitel 7187a analogue phone

(OP)
Hi there.

We did some test and her is some:

Additional information:
If we swap the handset and headset interfaces - i.e. put the handset in the headset interface and the headset in the handset interface, the noise disappears.
But then the users still need to use the hedset button when using handset and vice versa.
So we need your help again concerning how to solve this issue.

The PBX is grounded after "the book", so I don't think we have to use more time on that direction.
We also tried with 3 ferrite cores on the power cord for the headset and some ferrite cores for the cable between the phone and the headset base/charger - w/o luck.

So I guess we need to look into the headset interface - to install a capacitor some where to eliminate the noise, Or??

BR Henrik

///doktor
____________________________________
http://www.kandu.dk/spg153996.aspx

RE: Humming noise with Mitel 7187a analogue phone

"s the problem local to one of the ELU29 boards? In other words, if the extension is moved to a different ELU29"
You have not answered this, this determines if the phones are not liking these cards when a headset set is connected or cards not grounding.

"Since they are analog why not take the package home or office and test offsite?"
Have you done this yet?
This determines if a Site(ground or objects/lights with interference) and/or PBX issue.
This test must be done.

"he PBX is grounded after "the book"
Did you actually test the ground with tester to make sure it's done right?
Do not just look at it or assume.5

Capacitor
You should not have to install a capacitor, that is the manufactures job otherwise best to ask that question in an electronics forum.

From Jabra:
have set up my GN9120/GN9125 correctly, but I am getting a buzzing sound on my headset.
Your telephone may not be fully immune to the radio transmission between your headset and base. To
overcome this problem, move the base at least 30 cm/12” away from the phone. If you have a European
version
, you can instead choose to set the headset to Low Power mode.

Make sure you answer all question and do all tests provided to you above.

________________________________________

Add me to LinkedIN


=----(((((((((()----=
www.curlycord.com
Toronto, CAN

RE: Humming noise with Mitel 7187a analogue phone

(OP)
Yes, we will test and report back ,-)

///doktor
____________________________________
http://www.kandu.dk/spg153996.aspx

RE: Humming noise with Mitel 7187a analogue phone

(OP)
Hi There

Here is our report:

"s the problem local to one of the ELU29 boards? In other words, if the extension is moved to a different ELU29"
You have not answered this, this determines if the phones are not liking these cards when a headset set is connected or cards not grounding.

Answer from doktor: We tried with diffrent ports on different ELU29 and even a direct PSTN line - still the problem with the noise exists.

"Since they are analog why not take the package home or office and test offsite?"
Have you done this yet?

Answer from doktor: We tested this w/o luck.

This determines if a Site(ground or objects/lights with interference) and/or PBX issue.
This test must be done.

Answer from doktor: We can now say that this problem with noise from the Wireless headset - does not come from bad grounding of a PBX.

"he PBX is grounded after "the book"
Did you actually test the ground with tester to make sure it's done right?
Do not just look at it or assume.5

Answer from doktor: Taken notice of this.


Further tests done:

We have tested with other power supplies, but still we have the noise.

We have tried to use different Wireless heasets and used diffrent power supplies, but still we hear the noise.

Recommendations from Jabra (and other headset suppliers) is to use a longer cable between the phone and the headset base/amplifier.
This has been tried without luck - the noise is still there.


We have also tried to add ferrite cores on the PBX line (or PSTN, if used), but this does not remove the noise either.

Workaround:

The only workaround with a bit of succes was to insert the handset cable in the headset connector and vice versa.
But with this workaround the user should use the handset button for the headset and vice versa.


Let me know if you have other ideas.
/Henrik

///doktor
____________________________________
http://www.kandu.dk/spg153996.aspx

RE: Humming noise with Mitel 7187a analogue phone

From Jabra:
"If you have a European
version, you can instead choose to set the headset to Low Power mode."

Aside from that I am Outta Ammo!

And based on the hordes of people chiming in they have never had this issue so guessing their call centers all use digital sets or do not use wireless headsets with this model of phone.

300 sensitive phones, if they were new I would seek a return for another model.


________________________________________

Add me to LinkedIN


=----(((((((((()----=
www.curlycord.com
Toronto, CAN

RE: Humming noise with Mitel 7187a analogue phone

(OP)
Sorry to say that they have been used for a longer period than the guarantee period...

///doktor
____________________________________
http://www.kandu.dk/spg153996.aspx

RE: Humming noise with Mitel 7187a analogue phone

(OP)
The trick with lowering the DECT radio signal (low power mode) did not Work either.

///doktor
____________________________________
http://www.kandu.dk/spg153996.aspx

RE: Humming noise with Mitel 7187a analogue phone

I suspect you have over loaded the 2.4Ghz spectrum with that many units in one place. I know Plantronics puts in their spec max number of units in any one location and it's not very many ( aprox. 10 if I recall).

Check out this PDF from SenheiserDECT Density

Marv ccna

RE: Humming noise with Mitel 7187a analogue phone

Wonder if this might help:

http://headsetplus.com/product1353/product_info.ht...

Have a look at the install instructions. there are different requirements for different phones. It doesn't list the 8178 specifically, but then again, most sites that deal with headsets and Aastra phones don't either.

You've tried everything else. might as well give this a shot!

RE: Humming noise with Mitel 7187a analogue phone

(OP)
I will test.
The phone and headset will also be sent to the R&D at the manufacurer - for further investigation winky smile

///doktor
____________________________________
http://www.kandu.dk/spg153996.aspx

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Tek-Tips Forums free from inappropriate posts.
The Tek-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Tek-Tips forums is a member-only feature.

Click Here to join Tek-Tips and talk with other members!

Resources

Close Box

Join Tek-Tips® Today!

Join your peers on the Internet's largest technical computer professional community.
It's easy to join and it's free.

Here's Why Members Love Tek-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close