Introduction: SMD TEST PROBES

Make these probes to enable you to test small 3 terminal

SMD transistors out of circuit using your component tester from china

add the test /reset switch to make using the probes simple

Step 1: SMD TRANSISTOR TESTING PROBES 1

Have you ever wanted to test small SMD transistors out of circuit but find you do not have not enough hands and they skip around as you try to get the probes on

WELL here is a handy simple tool you can make and use with your component tester from china

first cut one piece of single sided pcb about 10mm by 40mm

then another one 5 mm by 40mm

then the larger one cut a groove along the length of the middle using a hacksaw see photo

then get 3 pieces of copper or brass strip approx 4mm x 10mm long these will be your probe tips

Step 2: SMD TRANSISTOR TESTING PROBES 2

The next step is to solder the flat tips to the pcbs allow about half to overhang the ends and solder them

be carefull to leave a small gap between the larger pcb with 2 tips so as to not short them out see picture

by having the tips this width you can test both the smallest and the slightly larger SMD transistors/mosfets

(You could make the probe tips smaller if you want to use the probes on a smd that is actually on a circuit board

You can make all types to suit your requirements)

This one is for testing out of circuit and doing both sizes of transistor

Step 3: SMD TRANSISTOR TESTING PROBES 3

Your now ready to solder your wires on to the top of the pcb probe units

get three different colour wires and solder them slightly down from the top this

will help the heat shrink to secure them better

Cut some heat shrink and place it over your new probes see next photo and secure

by appyling heat

you can now file your flat probe tips carefully and square the ends and sharpen the contact tips edge this will help grip the device being tested and make good contact

Step 4: SMD TRANSISTOR TESTING PROBES 4

Heres are 3 of my finished probes

one has the added component tester test/ reset switch added

i would advise adding it as it makes testing things so much easier to do

you can add a 3 pin connecter at the other end to suit your tester and a socket for the added switch connections at the tester ....see next step

my china tester denotes pin connections as 1,2,3,

I labelled my leads to match those... i used number 3 as the single probe 1 and 2 on the double probe

TO USE

Place the smd device on a firm surface

with one hand gentley place the double probe down onto the top of the 2 legs of the smd transistor making sure the probe gap is in the middle of the device then using the other probe place this down onto the 3rd contact to the other leg or tab then press the button to get your tester to read

you will find that it will hold down even the smaller SMD one quite well

Step 5: SMD TRANSISTOR TESTING PROBES 5 Final

I did have the idea of adding a footswitch to the component tester but after using it this way i decided the best way was to add a press switch to the double probe and useing this made it much better as you could concentrate on looking at the probes and component tester

I added the switch and held it in place with some more heatshrink and a blob of hot melt glue the 2 wires go to a socket i added on the component tester bottom rhs in pic.. and the internal wires go to the reset/on switch in the tester

this makes using the probes so much easier

I can now test loads of these small SMD transistors in no time at all
This as far as i know is an original design and you may copy it for personal use only 13/02/2017

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Bio: I have been in electronics since 1973 I have worked as a TV engineer, Automotive test equipment repairs, Warehouse control systems,Computer and color printer ... More »
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