Retronetworking

h1. T-View 100

T-View 100 was a video telephone, made by Deutsche Telekom / Siemens.

@manawyrm has two of these phones, @LaForge owns one as well. 

h2. External photos

!{width:40%}DSC00422.jpg! !{width:40%}DSC00423.jpg!

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

The purpose for the Mini-DIN port (marked with a computer icon) is currently unknown. It's connected to a MAX202 internally, so probably carries a RS232 serial.

h2. Internal photos

Video/Interfacing PCB:

!{width:40%}IMG_3633.JPG!

Telephone PCB:

!{width:40%}IMG_3644.JPG!

Display/Camera PCB:

!{width:40%}IMG_3656.JPG!

h2. Phone disassembly

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.

!{width:40%}IMG_3647.JPG!

Backside of the main video / interfacing PCB is visible under the cover plate:

!{width:40%}IMG_3631.JPG!

Lift the video / interfacing PCB out by pulling it straight up, it's connected via a rigid interface PCB (but not screwed down):

!{width:40%}IMG_3634.JPG!

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.

!{width:40%}IMG_3642.JPG!

h2. Display/camera disassembly

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: 

!{width:40%}IMG_3650.JPG!

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.

!{width:40%}IMG_3652.JPG!

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:

!{width:40%}IMG_3653.JPG!

Remove both bolts (and the washers). The swivel piece can now be bent inwards slightly with a bit of force to get it out.

!{width:40%}IMG_3654.JPG!

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. 

h2. Common faults

- Faulty display 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

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

!{width:40%}IMG_3779.JPG!

- Faulty capacitors

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":https://www.youtube.com/watch?v=-1S3F6_g3Sw

|_.Capacity|_.Voltage|_.Count|_.Width x Height (mm)|_.Replacement part|

|220µF|35V|8|10.31x10.31|Nichicon UCL1V221MCL6GS|

|470µF|16V|2|10.31x10.31|Nichicon UCX1C471MCL1GS|

|47µF|35V|6|8.28x8.28|Nichicon UUE1V470MNS1GS|

|220µF|10V|1|8.28x8.28|Nichicon UWG1A221MNL1GS|

|47µF|16V|3|6.60x6.60|Nichicon UCB1C470MCL1GS|

|100µF|10V|1|6.60x6.60|Nichicon UUT1A101MCL1GS|

|2.2µF|35V|2|3.33x3.33|Nichicon UWJ1H2R2MCL1GB|

|10µF|16V|1|3.33x3.33|Nichicon UUT1C100MCL1GS|

- Bad connections

Symptoms: Phone working, no picture, no backlight

Fix: Replug the display assembly a couple of times

- ???

Symptoms: Nothing, black screen, no LEDs, ~500mA current draw

Fix: ???