T-View 100 » History » Revision 47
- Table of contents
- T-View 100
- External photos
- Internal photos / circuit boards
- Phone disassembly
- Display/camera disassembly
- Common faults
- Bootlog (RS232 Debug)
- External Camera
T-View 100 was a video telephone, made by Deutsche Telekom / Siemens.
Power supply is called STN20, output DC 22.5V; 0.9A. Center positive, 5.5/2.5mm barrel jack.
The RCA connectors are (from left to right): Audio out, Video out, Video in, Audio in
Mini-DIN / RS232¶
The Mini-DIN (8pin) connector carries a RS232 serial. It was used to connect to auxiliary devices like relay control boxes (to alert deaf people of calls), VCRs (remote control) and PCs (for firmware updates).
We have a copy of the 1.2 firmware update and the RS232 communication protocol.
Serial settings (for debug output) seems to be 19200, 8n2.
The framing and at least some commands are described in V24-Control.pdf
There is a hidden service menu. Scroll to "Service", press OK, type the number 7.
Enter passcode "3570" and press OK.
"Service" -> 8 is another hidden option for a "Factory SETUP". The passcode is 3745.
Internal photos / circuit boards¶
- Philips SAA 7111 VIP (Video Input Processor) SAA7111.pdf
- 8x83104AKAB VCP (Video Codec Processor)
- Motorola XC68307FG16 XC68307.pdf
- 2x Epson SRM2B256SLMX70 32Kx8 SRAM
- AM29F400BB-120C Flash AM29F400B.pdf (label: VCod14)
- NEC V30145-J4681-V29
- Siemens PSB7230 JADE (Joint Audio Decoder-Encoder for Videophone) V2.2 PSB7230.pdf
- NatSemi P78SF MM74HC244
- Analog Devices ADV7176KS Digital CCIR-601 YCrCb to PAL/NTSC Video Encoder ADV7176KS.pdf
The telephone PCB has a debug header with a UART interface on it:
This debug header can be used to supply +5V (~100mA) to the phone board externally.
The phone board will work stand alone and this can be very useful for trouble shooting display issues!
The bottom cover plate has 6 Phillips screws and is clipped together at the bottom. Use multiple guitar picks to get them free.
The plastic does not seem to be brittle (yet), some force is OK.
Backside of the main video / interfacing PCB is visible under the cover plate:
Lift the video / interfacing PCB out by pulling it straight up, it's connected via a rigid interface PCB (but not screwed down):
Unscrew the 7 Phillips screws attaching the plastic shield. Be careful with the speaker wires on the right, they are not detachable!
Lift the plastic shield out of the way to the right. When re-assembling, make sure the hook-mechanism and speaker are correctly in-place.
Disassembling the display/camera unit is a bit tricky. You'll need a 10mm socket (and possibly socket extension)!
Start by removing the 4 screws on the connector:
then remove the 3 screws in the top of the unit.
The sides of the display/camera unit are covered with round covers. They can be pulled out with a bit of force.
Use a 10mm socket to unscrew the nuts on both sides.
Lift the connector cover. This is tricky! Please fill in a good way to do this. The author broke 2 plastic clips by doing it:
Remove both bolts (and the washers). The swivel piece can now be bent inwards slightly with a bit of force to get it out.
Unscrew the 2 remaining screws holding the display unit together.
There are clips all around the display/camera unit. Use guitar picks again and open the display.
Faulty LCD hotbar¶
Symptoms: Missing (pixel) rows / columns on the (24x2) character LCD.
Fix: Try and reheat the hotbar (~180°C) with a clean soldering iron tip and a lot of pressure
Faulty HD44780 hotbar¶
Note: The LCD is part of the phone's 68000 CPU bus!
A problem with the HD44780 will keep the whole telephone from working. The phone board won't start and will wait for LCD init. The TFT will stay off, all LEDs will stay off.
Symptoms: Phone not booting at all, no display, no LEDs, completely dead. Current draw ~250mA.
Fix: Check resistance between pins on the HD44780 itself and the phone board. Usually pins like VCC, GND or some of the datapins won't have continuity or more than ~1kOhms.
Run extra wire(s) from the test points (see "Display test point pinout" below) to the 2x8 footprint on the HD44780 LCD itself. Enamelled copper wire works well for this.
You can run the phone board seperately, without the video board. Apply +5V to the debug header as shown above.
Symptoms: Garbled characters/stuck bit
Fix: HD44780 interface is connected via Hotbar as well.
Find out which bits (D0-D7) are affected and solder wires for those bits directly to the LCD
Symptoms: No LCD output at all
Fix: Buy a new LCD. You'll need one with HD44780 ROM code A00 charset (the Japanese/Kana charset). The 0xE1 character should be "ä" (a with Umlauts).
- remove the transparent plastic carrier for the old LCD module
- remove the old LCD module (just tear the flex cable from the top side of the board)
- use solder wires to connect the new LCD to vias on the PCB (see picture)
- either fix the contrast voltage to GND, or re-work the existing contrast voltage biasing circuit. The original Siemens circuit consists of a 5V PWM feeding into a resistive divider of two 24kOhms resistors. Replace the GND-facing resistor with a 2.2kOms (or even lower). Play with the contrast settings (+/- buttons while receiver is on-hook) to see if you hit the right voltage range. Adjust resistive divider as needed.
- re-work the plastic cover that is located between the two boards as needed. You can either make more space for the LCD module by creatng a cut-out, or you can use it as-is and adjust the spacers on the "video" side.
Display test point pinout¶
Pinout hotbar/flex-cable vs. 2.54mm header¶
Notes regarding adjusted resistive divider for backlight¶
Symptoms: Crashing, low display contrast, flickering LEDs, poor video quality, mains hum on the speakers
Fix: Replace all electrolytic capacitors
Remove the old caps using the Twist method
|Capacity||Voltage||Count||Width x Height (mm)||Replacement part|
Symptoms: Phone working, no picture, no backlight
Fix: Replug the display assembly a couple of times
Bootlog (RS232 Debug)¶
A logfile of the external RS232 connector while booting and making a call can be found here:
There was an official external camera accessory , a Deutsche Telekom 663701-001 (re-branded Minolta EDUKCM-100)
manawyrm stumbled across a suspected T-View prototype:
Noticeable differences include:
- Green LEDs (instead of Red LEDs)
- White printing on the connectors (instead of embossed text in the plastic)
- Handset has a magenta T-symbol, instead of the white T-symbol
- HD44780 display is connected via jumper wires (instead of hot bar flat-flex cables)
- ProfiTel70 / Phone board is powered only by S0 bus voltage, not through DC in
- 0.1" pin header populated on the phone board
- handwritten label for firmware flash IC on the phone board
- PLCC socket for firmware flash IC on the video board
- VCP is still manufactured by IIT, later split off into 8x8
- bad mechanical fit (RJ45 latch cannot be accessed without tools, recessed too deep)
- CNC toolmarks are visible in plastic housing (CNC aluminium soft mold was probably used for injection molding)
- generic FRIWO FW 7324/3 24V power supply, instead of the 22.5V STN20 PSU
The broken display was replaced with the new Newhaven type (see above):
VCP (version 4014) dump: https://osmocom.org/attachments/5688
Firmware¶There are four known firmware versions:
Telefon/Codec/VCP/Jade firmware versions can be checked in the service menu (see above).
The firmware consists actually of different images for different processors on the unit.
|vcvcp.bin||binary||presumably for the video codec/processor|
|vsetrel.abs||srec||for the VSet (telephone) board, derived from ProfiTel70|
|vcodrel.abs||srec||contains strings related to H.261, H.221 and VCP|
- "Talkset" (abs format, programmed via SPI or "RS232 direct")
- "VCODEC" (abs format, programmed via via "RS232 direct")
- "VCP" (bin format, separate programming mode "VCP")