DSL hiss on WE 554

[dhortvet]

All,

Just joined the group and have the following problem: 

My parents have a model 554 in their kitchen, been there since 1962 and works just fine.

A while ago they signed up with DSL service - I installed the filters that came with the modem and all was well, except the 554.  There is a continual hiss on the line - not a 60 Hz. hum, more of a hissing sound - which is only present when the DSL modem is connected.

The 554 is hardwired in, which required installation of modular connectors to accommodate the in-line DSL filter.

In researching this condition on Internet, I read there were filters to pass voice and others to pass DSL - was not aware of that.

They have an AT&T DSL modem - would it be common for the model to be supplied with two types of filters - one to pass DSL and others to pass voice?

Have also read comments regarding having the correct polarity at the NIB - while I understand the basics of what polarity is - is not clear what that means regarding telephone wiring.

My mom is very much attached to the 554 - she is in poor health and is restricted in what she can do, and is not at all receptive to having a 'modern' phone installed to replace the 554.

She claims she cannot hear very well on modern phones, although that is not the case with the 554.

Any comments / guidance regarding how to eliminate the hiss are very much appreciated.

Thanks in advance and Best Regards,

Doug

[Phonesrfun]

Doug:

Polarity is not an issue on the 554 rotary dial phone.  If you are getting the DSL hiss, it has to be that somehow the DSL filter is being bypassed, and not in-line before the phone.  Can you take a picture of how you have wired the DSL filter to the phone?  It may prove helpful.

[dhortvet]

Thanks for the reply Bill.

Will send a photo later this week.

Understand what is relevant is the location of the filter wrt to the wires coming out of the wall and where they terminate on the phone.

Regards,

Doug

[dsk]

A typical filter is described here: http://www.sentex.net/~mec1995/circ/dslfilt.html
It is usually nothing, or only capacitors in series with the modem.

It is also 2 different ways of thinking when designing the system.
1: One central filter, and all telephone outlets are connected through  that one. The modem is connected before the filter.

2: The modem is connected to a random telephone jack, with no filter. Each telephone has a filter.

No problem to combine these systems, but very rare.

If a phone is connected with no filter, it may slow down the data speed.

The 500 series telephones should make less problems than many modern phones.

so to the extreme odd way to do it. not written in any book, and may only work on the best lines.
At the network in the telephone you should have 3 leads connected to the terminal marked L1: 1 from the line, Black from the ringer and a 2 colored one to the hook-switch.   Move this last one to the terminal marked K, and test. If its working OK....Problem solved   if not, move the wire back and follow the book by installing a regular filter.

dsk

[dhortvet]

DSK,

Thank you for the informative reply.  I will check for the connections you mentioned and move per your suggestion when next at my parents later this week - will also get photos of what the installation looks like.

From the DSL filter diagram you provided the link to, appears it would be possible to connect the filter backwards, is that correct?  Has been long enough since I did this I do not recall if the filters could be installed in either direction.

Thanks again for the great information - very much look forward to seeing if moving the one wire removes the hiss.

One other quick question - I recall reading somewhere before I first installed the filter that it is strongly recommended to leave another phone off the hook when working with the wires coming out of the wall - so the line is busy, which removes the possibility of getting shocked should there be an incoming call. 

Is this correct?

Regards,

Doug

[AE_Collector]

To the best of my knowledge the individual filters can be put in the circuit in either direction but there are many different makes and models so maybe some types may not work if backwards?

You might be able to quickly confirm this by putting one in reverse on your other phones to see if it makes a difference or not.

The "whole house" filters are generally regarded as being "better" than the individual type but you have to be prepared to deal with some wiring changes to accomodate this type of filter. You need to have a "home run" cable from the telephone protector (NID) to the location of the ADSL modem OR a second pair of wires in the cable that can be converted to the unfiltered output leaving the original pair of wires filtered for a telephone at the modem location.

Terry

[dsk]

DSK,

From the DSL filter diagram you provided the link to, appears it would be possible to connect the filter backwards, is that correct?  Has been long enough since I did this I do not recall if the filters could be installed in either direction.
The capacitor across the line should be at the telephone side of the filter. The capacitor may reduce the modem signal.

Thanks again for the great information - very much look forward to seeing if moving the one wire removes the hiss. This way to do it is not officially recommended. The telepohe will use a part of the ringer coil to filter high note signal, and may wery well filter far to much, and making the telephone failing to operate normally. It may not harm the telephone!

One other quick question - I recall reading somewhere before I first installed the filter that it is strongly recommended to leave another phone off the hook when working with the wires coming out of the wall - so the line is busy, which removes the possibility of getting shocked should there be an incoming call.  
Is this correct? Not a bad idea.     If your demarkation poin is easy to locate it may have a unit like this and may just unplug the line.  

dsk

[dhortvet]

Thanks Terry.

I will try reversing another filter that is working to see if there is any difference.

Is a whole house filter a different device than those used for an individual phone or is it the same, just connected ahead of all other phones?

The whole house approach is preferred - however in this case, with just one phone to be addressed - will see if I can resolve the interference problem.

If that proves to not be possible - have the alternative to replace the phone with an a wall mount push button of the same size and color.  As long as my mom can hear OK with it, that will work.

Thanks again!

Regards,

Doug

[AE_Collector]

Hi Doug:

Yes the whole house type filter is different though the differences might just be in the packaging of the unit. It has a phone line IN, phone line out and DSL out. Presumably the Phone Line In & Out are the same as the in-line filters and the ADSL out just bypasses the filter.

Terry

[dhortvet]

Thanks to all who replied to my request for assistance.

Have been delayed getting back to the phone in question as my mom had round 2 hip surgery week before last - suffice to say things have been a bit unsettled and removing the hiss from the 554 took a back seat to other priorities.

A replacement 2554 was purchased - went to install today and discovered the mounting plate for the 554 will not work.  Wish the folks that sold me the phone had mentioned that.

With the benefit of everyone's experienced input, a thorough examination of the existing DSL filter installation revealed the wiring was incorrect - i.e., I made a wiring mistake when installing the filter.

Once the wiring was done correctly - no more hiss!

Once a new mounting plate is in hand the 2554 will be installed - in addition to the benefit of push button capability, the cord is longer, which is a good thing for my mother as she is going to be in a wheelchair for some time.  Although they have a cordless phone - she much prefers using the 554 and hopefully the 2554 will be similarly well received.

Again - thanks to all for the great comments and support!

Regards,

Doug

[Kenny C]

Don't throw that 554 out!!!!!!

[dhortvet]

Kenny,

No way that will happen - in the event the 2554 is not well received, it is back on the wall for the 554.

Otherwise, it will be carefully stored.

Regards,

Doug

[dhortvet]

All,

Did the model 2554 phone ever use a wall mounting plate similar to the 554?

The 2554 has mounting slots in the metal frame similar to those for the 554, although do they do not properly align.

Understand there is a wall plate with studs for mounting the 2554 - although would prefer a mounting plate similar to that used for the 554 if one exists.

Thanks again in advance for any and all replies.

Regards,

Doug