delabs Circuits

Showing posts with label Production-Notes-2. Show all posts
Showing posts with label Production-Notes-2. Show all posts

Sunday, October 05, 2014

Testing Points and Pilot Production

Some Pilot Production And testing points when building electronic Projects.  These are also important while prototyping and Bread-boarding. These are things that i used to keep telling youngsters when they are new in manufacturing. This was when i was running my own firm making industrial equipment and instruments.

I used to even give this and some other pages around in printed format, it was composed with word on windows 3.11. Then i realized it has to instructed at every incident by example. Reading does not help unless someone is passionate and enthusiastic about learning.

Tutorials on Basics and Instrumentation

Testing Points and Pilot Production

Components
  • Use 1% MFR 100 ppm resistors for all analog instrumentation.
  • Use plastic or-and multilayer capacitors as ceramics are leaky.
  • Product should have minimum number of fasteners.
Assembly
  1. Nuts, Bolts and screws locked with adhesive so that they do not slip and the product falls apart.
  2. Potentiometers should move smoothly and not get twisted, strained or locked due to cabinets.
  3. Use Strain relief for wires and strip the wire and solder properly where required.
  4. Strip with a stripper do not use your teeth., Twist all the strands Tin the tip of the wire.
  5. After Tweaking and setting presets or trimpot lock it with paint or varnish.
  6. Big Components should have large pads and separate mechanical fixing to PCB.
  7. Acrylic and plastic can get blurred or deformed with some solvents.
Testing
Do assembly of the card with a tested assembled 3D reference. Even after all the care if the card does not work, then after full assembly do visual inspection in this order First keep both the cards one reference and the other manufactured under a bright light.
  • Compare resistor color patterns one by one.
  • Compare Electrolytic capacitors physical appearance and POLARITY.
  • Verify values of plastic and ceramic capacitors.
  • Cross-check Diode sizes and POLARITY. Verify Zener values.
  • Check IC and Regulator POLARITY and Exact type number / brand
  • Check Transistor, MOSFET, LED, POLARITY. and verify display type No. and Polarity .
  • Check for connector patterns and polarity and switches etc.
  • Reverse the card and Check for solder bridges between close pins .
  • Reverse card and Check for hairline shorts and solder streaks due to bad PCB processing or Soldering.
  • Reverse card and check for hairline cuts or pads lifted off card.
  • Closely observe for dry solders on big electrical parts (L and TX) a dry solder will cover the pin and will be dull in shine.
  • before calibration allow for product to warm up for 15 mts.
If all the components were subject to incoming inspection and testing. If still unit does not work remove power and do cold check comparison with reference unit in DMM 200K R range, if still problem persists continue with power on testing and solve by DMM or scope tests.

Danger ! when DMM is in Ohms Mode, Even if one probe touches 230 V, DMM is Gone, so take extra care while doing this. test probe.

delabs Technologies

First written and printed offline in the Nineties. Word on Windows 3,11 with Epson 24 Pin Dot Matrix Printer., updated 2014.

Electronic Tables and Charts

How to Test Verify the Testing Methods Itself

Testing and Evaluation tools must have dynamic decoys added into the device under test DUT or the batch under test. In a Conveyor system, identifiable (RFID) decoys must be artificially introduced every 100 pieces. This will constantly counter check the Testing system and in not a One time operation. The decoys should be defective or have a fault, a little above threshold. This is caught by the testing system. Even when the testing system ages or goes out of calibration, this method can raise a alarm.

Even in software and text/data processing; this method ensures database quality and software program integrity.

Tuesday, June 10, 2014

Electronic Product Production.

a. PCB Assembly.

First Inspect PCB for hairline shorts and cuts and also traces of unwanted copper in the edges and repair them. Also Check if all Drill holes & Slots are proper size and PCB is Fitting in its Place properly, This is because Drilling and Filing should not be done after assembly as it causes serious reliability problems.

Second populate all the resistors, Jumpers, Diodes and Ceramic Capacitors these are tough components. Then Insert all Transistors, LEDs, Displays, Electrolytic Capacitors and IC s (Bases), Here care should be taken not to overheat any component as it may damage them. Lastly Solder Connectors, Relays, Coils and Transformers which may require a high wattage Iron, and Mechanical Reinforcements.

Electronic Product Production - delabs Technologies

b. Precautions during Production.
  • Observe Polarity for Diodes, El-caps, Connectors, etc.
  • Make sure of Pin 1 for IC s, Regulators, Transistors and Mosfets before insertion.
  • Avoid bases for ICs in production as these fail on use.
  • Make use of Electrostatic protection for CMOS devices.
  • When Cutting Leads use protective Goggles and do it in a separate place as the cut leads fly all over the place.
  • Use Iso Propyl Alcohol (IPA) as de-greasing agent on PCB.
  • Water & Detergent wash is very good but only if coils, Transformers, Relays are hermetically sealed- Impregnated.
Use a Lacquer-Varnish or RTV rubber coat on both sides of PCB including on the components to prevent corrosion and also it helps maintain accuracy-precision.

Lead is a kind of poison, use gloves or wash hands with soap after work is over. Flux, IPA, Thinner Fumes can cause respiratory health problems. Work in a ventilated area use Exhaust Fans and Open Windows. Dispose of Metal, Plastic and Chemical waste separately and well packed as these can contaminate the environment and also cause Injury.

Published online around - Nov 1999

Contents

Basic Electronics
Basics of Electronics
Product Production
Work Discipline
Testing Points
Learning Electronics
Electronics Theory

Production Notes
Prototype Fabrication
Electrical Circuits
Electromechanical


Library
Scots Guide Electronics
Engineering - Wikibooks
Design Lab - Jim Svoboda
DC Circuits UOG
Socratic Electronics
Blobz Guide Electric Circuits


Product Design
Product Development
Constant Current Source
Good Voltage Regulators
Insulation Resistance
Digital Insulation Tester
DN Schematic PCB 04
DN Product Design 07


Hobby Circuits
VU Meter Circuits
LED brightness control
555 Incredible Chip
Process Control
liquid level measurement
Thermocouples and RTD
Design ADC Interface uC
Thermocouple Amplifier
IA Instrumentation 02
Temperature on DMM
Optical Proximity Switch
Analog Mux - Data Acquisition


Test Measurement
Instrumentation Automation
NI Test and Measurement
DMM Digital Multi Meter
Oscilloscope in T&M
IA Automation 01
Build Instruments
Tektronix T&M Equipment
Educators Corner – Agilent


Power Electronics
UPS Background
Transformer Connections
DN Power Electronics 03
DN Power Electronics 02
Half Bridge Convertor SG3525


Embedded
Interfacing Microcontrollers
Embedded Process Control
80C31 8052 Microcontroller
Microprocessors and uC
Embedded Systems Design

Components
Good Voltage Regulators
Relays and Contactors
Potentiometers Trimpots
Prototype Boards Types
Types of Capacitors
Types of Switches
Resistors How they Work
Coils Transformers SMPS
Mains Transformers Types
DN Components Selection 05

Tutor Gadgets
Count-Up Timer
Digital Logic Gates
Electronics Tutors

History
Teaching Instruments
Charles Proteus Steinmetz
Muntzing a Circuit Design
Teralab Electronics projects
Historical Instruments


Tables, Charts, Videos
Binary and Hex
Resistor Color Code
Ohms Law
Giga, Tera, Pico, Nano
High Resistance Materials

Analog
School - Analog Design
DN Analog Basics 06
DN Op-Amps 01
TI Semiconductors