Northern Telecom Meridian Phone (1994)

The Nortel Meridian office phone was a very common phone with many versions made (This is model #M9216).  It’s not uncommon to still find them in use today in offices in this part of the world.  

(Reminder to myself must get better lighting for product shots!?)

According to the (comprehensive) label this handset was manufactured in Canada in January 1994.

 

Just a few screws and the phone comes easily apart.  One noticeable thing is the speaker wires are soldered to the board (and speaker).

Detaching the speaker and lifting the board reveals an interesting arrangement for the keypad

The is a large plastic support sandwiched between the keypad membrane and the PCB.

The membrane buttons short tracks on what is two screen printed carbon/metal tracks on what looks like an overhead foil. There is a feedthrough slot in the plastic that contains a (13 pin) flexible gel connector that links the foil tracks to the PCB (With just contact pressure) which seems pretty unusual to me.

Now lets look at the board.  The reason I was interested in an old Nortel phone, is that Nortel until the mid 90’s had a wafer fabrication plant here in Canada (Ottawa).  I am interested in looking at a rare ‘made in Canada’ chip.There it is in the bottom right a 44 pin QFP package part # QMV493CT5 with a wk 39 1993 date code – the Korea label is reference to where it was packaged, the silicon inside I am sure is Canadian – we shall take a look at it.

Also on the board:-

As it is a QMV part number I suspect also a Nortel part (But this package has no NT makrkings – QMV491BT5

Motorola MC145447DW – A “Calling Line Identification Receiver and Ring Detector” one of the few die on the board with a datasheet I was able to find.

Motorola SC409222FN

STM L7805ACV   – 5V regulator

Microchip 24LH08X   –  Unable to find this, but almost certainly an EEPROM perhaps 8kbit

Allegro V155B  (Maybe QMV155B part made for Northern Telecom?)

34119 – Chip near the speaker wires, after depot found it is a Motorola MC34119 A ‘Low Power Audio Amplifier’  that drives the speaker.

 

So lets start with the Nortel QMV493

 

 

 

Here is the high resolution die photo. The die is 4.68 mm x 4.30 mm (20.1 mm2)

Here is the Northern Telecom logo with copyright and mask registration symbols and a internal name the B44 (A1A version which would indicate it didn’t need a design re-spin)

I don’t know the chip function (No datasheet exists, likely was only available internal to Nortel and has long since been lost with Nortel’s demise) but I guess it is an audio codec. There are blocks that could be the DAC’s and ADC’s.

The chip is made on a 3μm analog CMOS process,  with 2 aluminum metal layers.  This image shows several MOS transistors.

I call it analog because there are very large numbers of capacitors on the chip made with polysilicon top and bottom plates  and oxide dielectric (poly-poly caps) like this array of 20 capacitors

There is also a number of Bipolar transistors, I am pretty sure this is a CMOS process and not BiCMOS, so these transistors are almost certainly lateral PNP transistors that are formed using the diffusions available on a CMOS process

I have other devices imaged from this phone, but to ensure the post loads ok I am going to break it up into two parts……

 

 

 

 

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3 Responses to Northern Telecom Meridian Phone (1994)

  1. rasz_pl says:

    Isnt this phone 100% analog, no digital audio processing?
    Those 6 rows in middle left make it look very similar to 4 bit microprocessors(something between 4004 and 6502). Are QMV493 and QMV491BT5 connected to each other with a lot of tracks? would make sense for one to be microprocessor while the other integrates rom/ram and IO,

    • Gary says:

      My (limited) understanding is that these Meridian phones are digital, they require a central office PBX, and do not work on a regular POTS analog line. I think they maybe using ISDN standards. You are right the QMV491 does look a lot like a custom micro-controller. I did check and could not see a lot of tracks between QMV491 and QMV493. The only tracks I could clearly see are from the line-in socket going to the QMV493.

  2. Jean Simard says:

    I just purchased a Vintageteardown tel. How can I remove all the names and phone number that are still registered in the mémory spaces.? This will leave me place to insert my personnal numbers.
    Thank you.
    ************
    j’ai acheté un tél. Vintageteardown usagé et, il y reste plusieurs anciens num. de tél en mémoire. Comment les effacer? Je voudrais bien y inscrire les miens.
    Merci.

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