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.
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.
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 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.
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……