Scrounging a Desk Phone

This is the first article I wrote over at www.UcHobby.com, cross listed over here so anyone finding me first here can see what I have done in the past.

Scrounging is a good way to get parts your your electronics workshop. Rather then throwing away that old piece of electronics, take it apart to salvage reusable parts. In this article an old Small Business 4 line Phone is salvaged for parts. This article was submitted by Charles Stutzman as part of the uCHobby giveaway program.

How often do we see an office throw away good electronic components in the guise of slightly malfunctioning items, or doing a blanket upgrade to a new system. I work in a small business with 3 people in the office, and we have a 4 line phone system. Every time our boss decides we need to get a new phone, he buys one for every phone location, so that they interact with each other, allowing use of the intercom, and hold functions. This leaves anywhere from 4-8 good used phones being put to the curb. The need for a good alphanumeric LCD got me looking at that pile a little closer, and I decided to start scrounging. On opening the case I found more parts than I would ever have thought. Most of these are generic resistors, diodes, capacitors and the like, but there are a few items like headers, RJ11 and RJ14 connectors, a 12 volt power supply(wall wart), and that 16X2 LCD that happens to be a common interface type, with plenty of data to be able to use it, even one article showing how you can use dip switches, a breadboard, and a few other common items to manually drive it as if you were the software (I am thinking my daughter would love to play with that).

Tools needed: small Phillips head screwdriver, Flathead screwdriver (for prying open the handset), de-soldering gun (or heat gun), and optionally a cordless drill (makes it all go quicker).

First flip the phone over so you can see its back, some of these have a plastic pop off piece that makes the phone sit at an angle. These usually are popped off with a release tab. There should be four to eight small Phillips head screws usually at the corners. Take those out. You don’t have to remove the battery cover screw unless you need a good nine volt battery contact set, but you might still want to check the charge on the nine volt, why throw a good project battery.

After the four to eight screws are removed, you can split the case and you will have two to three cables connecting the top to the bottom half. One to the LCD, and the other two go to the keypad. Unplug these from their headers on the bottom board carefully so you can reuse the headers and cables.

Now you have two separate halves of the phone, and you can see the goodies inside. As mentioned before the main things of interest will be RJ14 and RJ11 jacks, headers with matching cables (14, 10, and 9 pin), 16X2 alphanumeric LCD, Piezoelectric speaker, and microphones.

After looking at the boards and seeing if there are any obvious items you are interested, then you can make note, and start taking it apart. I first went to the LCD which is attached by four Phillips head screws.

Most of these have a clear plastic guard that unless scratched can be reused in your projects as long as you don’t scratch it. Next attached by entirely too many screws is the keypad, which is useless unless you can figure out its logic processes for each button.

I look at it as too much to play with for now, but will keep the item in case I get a wild hair to tackle a challenge. I may take one of these and cut around the board to use each button as a single switch, by soldering wires to each trace and breaking the line beyond the wire splice in. Removing the board with all the goodies on it is simple, it has four screws holding it on. After it is removed you can put it in a vise, or clamp, and start removing components that you are interested in.

The handset is really simple to pull apart, and get a mic, piezo-speaker, and RJ14 connector.

I started with the through hole components since I can reuse them easily. There are capacitors, transformers, RJ14 and RJ11, headers, and more. The heat gun method makes this process quick if you are careful. I did a full pull apart of this board with the heat gun freeing only the surface mount parts, in 15 – 25 minutes. The total tear apart from fully intact phone to as far as I pulled it apart, in 30 – 45 minutes. Below are pictures of the items I have scrounged. Mainly it boils down to capacitors, capacitors, capacitors, with a sprinkling of other surface mount parts. Listed out the components are as follows: 1 16X2 alphanumeric LCD screen, 2 transformers, 4 reed relays, 4 fuses, 3 RJ14 jacks, 2 RJ11 jacks, 1 stereo headphone jack, 1 power port with matching 12 volt 500ma wall wart. 2 microphones, 1 piezoelectric speaker, 1 normal speaker, about 10 resistors of varying value, and about 40 varying size capacitors.

I decided not to remove surface mount parts, as I can’t use them currently, but they are still there to be used by anyone else who wants to go further with a tear down.
Here is the board empty of all the through hole components.

There is an article from Everyday Practical Electronics, February 1997, by Julyan Ilett, titled "How to Use an Intelligent LCD". It can be found here. With a breadboard, some resistors, a dip switch array (8 switches), two momentary on switches, a variable Potentiometer, and the scrounged LCD from the phone system, you can make up a small manual operated LCD screen. The article walks through manually operating an LCD based on the HD44780 controller. Searches for the HD44780 controller interface will yield info for you to integrate with many different microprocessors.
The parts can be identified fairly easily for the standard items using Google. A search for transistor part number KSP 44 214 pictured below right

This search will get you many sites, and this is where I found information, fairchildsemi.com with information as to how the item is marked. We find out that the transistor is a three lead, with collector/emitter voltages of 400V and dissipation of 625 mW. The capacitors are easy to identify as they are marked for their size in most applications, usually. The blue and the white components shown are a little more difficult to determine. The harder to identify parts on the left of the picture are as follows: the blue items is a varistor, and the white is a capacitor.

These items I believe are 4 pin relays, but I am guessing on that, as the searches are coming up empty when I look by Cosmo and 4010 and c16 which are the markings on them.

The transformers are tricky, but some simple experimentation could give you some data on it.

The fuse is useful, the push button is potentially useful, and the reed relay (the 8 pin IC type chip).
There are a few really difficult items such as an item marked TECOM 561-100006 HJ66 0224 to find info about, and in reality looks like a component made up of many surface mount parts, in a heat shrink wrap with pins coming off in an inline fashion, with 17 pins.

I hope that this scrounge article helps others have ideas as to new places to scrounge. I plan to use the LCD soon, and the rest of the parts as needed. I may tear a few apart so I can have a few LCDs at least. You may notice that the phones changed in the pictures, because I already had one mostly scrounged when I realized that I didn’t have photos of the process that were usable, so I started scrounging a second one.
A list of the scrounged items is as follows:

1. 42 capacitors from 1 microfarad to 220 microfarad
2. 4 black 4 pin photo coupler anode cathode emitter collector
3. 3 black 2 pin 682j inductors
4. 2 102j 2 pin white inductors
5. 4 8 pin reed switches D2A050002
6. 4 ksp44 transistors epitaxial silicon transistors collector base 500v collector emitter 500v emitter base 6v
7. 7 varied resistors
8. 1 5.5v .47F Super capacitor useful as backup power for CMOS
9. 1 121j – 120 uH inductor
10. 5 varistors light blue flat discs brand _ _ _ varistor voltage – _ tolerance (k-10% l-15%,m -20%) – _ Type (disc or square) – _ _ element diameter
11. 4 EPCOS tantalum chip capacitors
12. 3 152j – 1.5 uH inductor
13. many screws
14. 2 transformers

The easiest way I have found with modern technology to identify parts is to type all of the markings on the part into a Google search, and refine your search from there. If you then find numerous instances of the same repeated part of the markings such as, the 4 reed switches made by KUAN HIS. A search for KUAN HSI D2A050002 C35 results in no matches, but drop the C35 and you get 2 results. If you go the first link you find that the part number is D2A050002 and the manufacturer is KUAN HSI. Drop the Manufacturer and you can obtain more manufactures of the common part, and then if you weed through the results you should be able to find a data sheet for the item in question. You may have to omit some numbers to get rid of date codes, or manufacturer’s plant codes, the last digit or three. I never found a data sheet for a D2A050002, but I did find one for a D2A050000, at alldatasheet.com.

More info on uses for the LCD can be found on uCHobby.com.

Charles Stutzman