MFM no dial tone

[leahyj]

One of our MLX-10DP phones had a MFM in it and was used with a POLYCOM Speakerphone. One day it stopped working. Not sure why. I diagnosed it as the MFM card going bad. I got a new card and it still doesn't work. It doesn't work with a regular single line analog phone either. Are there a special setting on the card itself? Does the phone/phone system have to be programmed in anyway?

 

[aussie88]

Read the installation manual, and make sure that the MFM is set for T/R operation, and not SAA.

 

[leahyj]

I didn't get an installation manual, can you point me to one? Thanks for the help.

 

[leahyj]

Actually, the card is set the way the old card was set, Jumper One set is W & Y on, and Jumper 2 is A & B on.

 

[aussie88]

That sounds right. Make sure that you are using ALL 4 pairs to wire the phone, not just 2 pairs. The MFM requires the extra power. Also, try installing the MFM in a different phone, and see if that works. And once again, check all of your wiring.

 

[merlinman]

Different Phone, -OR- Take the phone back to the Control Unit....

 

[leahyj]

I took the MLX-10DP and plugged it into an available port on the control unit, as suggested, and it works. So, does this mean that the phone jack that I plugged it into is not sending enough power? Also, why doesn't it work on any of the phone jacks that I've tried it on. My only theory is that the control unit module that it is plugged into is overloaded and therefore isn't sending enough power, but the test port I plugged into was not overloaded.

 

[merlinman]

An MLX Set will work on only 2 pair.

We used to always recommend 4 pair wiring to insure that all circuits are available.

To run an MFM or a DSS, you must have AT LEAST the Brown Pair for power.

Most likely, the jacks are only wired with 2 pair cut through.

It works at the control unit because ALL 4 Pair are there.

I'd be willing to bet that your Location is wired with 4 pair, but not all 4 are cut down.

So, connect up all 4 pair and it should work.

 

[leahyj]

All wires are there. Is it possible that the problem is at the other end. How it is punched down at the block?

 

[jgideon]

My MFM's came with an adapter that looks like a two-way splitter (plugs into the jack on the wall, has two jacks for two other devices) but it is actually an 'injector' where you'd plug in the 'wall wart' power supply. Have you found that? It can be on either end (phone end or switch end) depending on how it was wired. If you post your email address, I can send you the two page document I got with mine.

 

[aussie88]

You must have a problem with the Brown Pair somewnere in the wiring. Check your punchdowns, your cross connects, and your jack. Even follow the wire to make sure that a rat did not feast on it.

 

[jgideon]

I wasn't able to make mine work without the external power supply, even with all four pair wired back to the MLX card. Are there really people out there with an MFM that doesn't use a wall wart?

 

[aussie88]

Well, perhaps you had one of the older power supplies, or you had a bunch of DSS's. Or maybe you had ALOT of MFM. Or even a bunch of 20L's. Because I have never needed to use external power for an MFM.

 

[leahyj]

Everybody,

Thanks for all of your help. I believe in the long run, that it was a wiring issue as ausiie88 said. But I wasn't able to verify that exactly. I needed to get it working by today, so on Friday, I used a ethernet port on the LAN instead of the telephone jack and it works fine.

Thanks again.