Introduction: Fix Electronics With IC-Tester!
With this Instructable I will show you how to assemble and use the IC-Tester in order to fix electronic devices that are built with integrated circuits 7400 and 4000 series.
The Instructable is composed by a motivation of the project, a brief introduction to integrated circuits, the structure of the IC Tester and the Assembly Guide.
After assembly a video is available to understand the four operating modes.
Every Arduino Code and Solid Works documents are linked at the bottom.
Step 1: Why Is Useful?
Repairing electronics is a complex and extensive activity, very often can be an infinite or impossible task to find out the problem and apply the correct solution.
Fixing electronic devices becomes even harder when there is a lack of information which may arise for two reasons:
- The schematic of the entire device has not been shared.
- The compounds are not tagged.
While trying to fix a device if the compounds cannot be identified then we are not able to know if the compound is working correctly, how the compound should work and the worst: we don't know how to replace it!!!
Fortunately, most of the basic compounds such as resistors, capacitors or diodes are factory tagged showing nominal values, limits, tolerances... But integrated circuits that are most responsible for the correct functioning of the device are frequently unknown.
That is the motivation to elaborate the IC Tester which main functions will be to identify and analyze integrated circuits.
Step 2: Brief Introduction to Integrated Circuits
Integrated Circuits also referred as an IC or chip is a set of electronic circuits made out of semiconductor material. These structures are packed into small plastic containers which through metallic pins allow the interaction between the inner circuits of the chip with the outside.
Each pin of the IC has a specific function and properties that can be observed on the datasheets of the chips. Another valuable information found on the datasheets is the truthtable, a table which displays the possible behavior of the integrated circuit, depending on all the entries that are applied to the IC as inputs, the truthtable will give us the state of each outputs.
As an example the picture above shows the pin names of the 4002 IC as well as the truthtable which explains the state of nY Output for each possible nA, nB, nC and nD Inputs. If all the inputs are L the output will be H...
When testing, in order to identify and verify a chip we will compare the chip's behavior to it's respectively truthtable, then we will be able to identify which ever pin we have stored in our memory. However, on this project, we are starting by testing only 7400 and 4000 IC series.
Step 3: Ic-Tester Structure
The IC-Tester is composed by six functional structures.
Most important one is the Arduino board Mega 2560 which will be the brain of our device. The Mega 2560 will control and connect all other structures receiving and sending information as the Arduino code will dictate.
The Laptop will be used to write down the Arduino code and record it into the board.
An EEPROM, electrically erasable programmable read-only memory, a non volatile memory will keep all the data from truth tables of the integrated circuits that we want to test. We will use the 24LC256 EEPROM.
The interaction with the user will be done through the display, a 1602 LCD and the control buttons.
Finally the communication between the IC-Tester and the circuit to test will take place through the IConnect which will be attached to the pins of the integrated circuit to test.
All the connections will be shown properly with the Schematic on next Step.
Step 4: Schematic
During the assembly many connections will take place, having a Schematic is a huge aid to reduce errors and time clarifying all cabling.
Most of the connections, with the exception of the Eeprom may be modified depending on the final case design, there is no problem in changing connections into the Arduino, but the Arduino code must be modified consequently.
Note that there are two IConnect structures, one analogical and the other digital, each for a different operating mode.
Each switch used for user control and interaction with the LCD will dispose its own LED which will light up when the control button can be pressed.
Step 5: Assembly Guide
Introduction, Schematic and 16 Steps to assemble the IC-Tester.
Step 6: Code Flowchart
Four operating modes can be accessed from the main buttons by pressing the select button, or the down button to move on to the next mode.
1. Identify IC will interact with the integrated circuit to test and the EEPROM, at the end, we will obtain the name of the tested IC if found.
2. Analyze IC using the IConnect will test circuits obtaining the entire pin state.
3. View Data will show on the LCD all the saved data on the EEPROM.
4. Replace IC will provide through the IConnect all desired inputs to send into the circuit reaching a partial substitution of any integrated circuit.
Step 7: Case Designs
All designs have been made with Solid Works can be download for modification and 3D printing.
Step 8: Files
1. Solid Works
2. 3D Printing
3. Arduino Code (IC Truthtables inside)
Participated in the
Fix It Contest