How to test voltage regulator IC?

The 3 pin IC’s are generally used for LINEAR, FIXED and ADJUSTABLE output voltage regulator applications (FIXED POSITIVE, FIXED NEGATIVE AND VARIABLE TYPES). 78XX series IC regulator have intern overload protection and short circuit current limiting.
Check your 78xx and 79xx series, 3 Pin Voltage Regulator ICs.
Fixed Positive voltage type: 78XX series.
Fixed Negative voltage type: 79XX series.
Adjustable Positive voltage type:   LM 338 SERIES.
Adjustable Negative voltage type: LM 337 series.
3 pin Positive voltage regulator (78XX series), Here seven voltage options

Device Typeo/p voltage Max., I/p voltage Dc
78055.0v35v
78066.035v
78088.035v
781212.035v
781515.035v
781818.035v
782424.0 

 

Pin Identification 78xx Data sheet Pdf Details:  7805 to 24V Regulator-datasheet 

7805

CIRCUIT DIAGRAM OF 78XX SERIES REGULATOR
VR5
HOW TO CHECK YOUR 78XX SERIES REGULATOR?
(DMM) Means Digital MultiMeter
Step-1.    
Select Digital MultiMeter Selector Knowb to DIODE MODE,
Connect   DMM  positive test lead to  PIN-1
DMM Negative test lead to PIN-2 = Display reading shows OL  DMM READING ( OL MEANS OVER LOAD)

VR3

                    DMM Negative test lead to PIN-3     = Display reading shows OL Step-2.
Connect   DMM  Negative test lead to PIN-1
DMM  positive test lead to  PIN-2   = 0.527V OR It means 527 mV

VR4

DMM  positive test lead to  PIN-3   = 0.544VStep-3.
DMM  positive test lead to   PIN-2
DMM  Negative test lead to  PIN-1   DISPLAY READING  0.521.v
DMM  Negative test lead to  PIN-3   DISPLAY READING  0.578.v
Step-4.
DMM  Negative test lead to PIN-1
DMM  positive test lead to  PIN-2  =DISPLAY READING shows OL.
DMM  positive test lead to  PIN-3  = DISPLAY READING shows OL
Step-5.
DMM  Positive test lead to   PIN-3
DMM  Negative test lead to PIN-1    Display Reading shows 0.538v
DMM   Negative test lead to PIN-2    READING  shows OL
Step-6.
DMM  Negative test lead to PIN-3
DMM  positive test lead to  PIN-1  =DISPLAY READING shows OL.
DMM  positive test lead to  PIN-2  = DISPLAY READING shows 0.578V.
Verification: If the DMM above reading shows the condition is GOOD.


3 pin Negative  voltage regulator (79XX series)
The 79XX type are 3 terminal negative voltage regulators (complements to the 78xx series device)

7905

9-OPTIONS BELOW

Device Type o/p voltage Max., I/p voltage Dc
7902-2.0v-35v
7905-5.0-35v
7905.2-5.2v-35v
7906-6.0-35v
7908-8.0-35v
7912-12.0-35v
7915-15.0-35v
7918-18.0-35v
7924-24.0-40

Pin Identification 79xx Data Sheet Pdf Details:  7905 Negative Regulator-datasheet

VR6

         
How to test a Negative voltage regulator with DMM?
Step-1.   Select Digital MultiMeter Selector Knowb to DIODE MODE,
Connect  DMM  positive test lead to  PIN-1
DMM Negative test lead to PIN-2 = Display reading shows OL  DMM READING ( OL MEANS OVER LOAD)
DMM Negative test lead to PIN-3 = Display reading shows OL
Step-2.
Connect  DMM  Negative test lead to PIN-1
DMM  positive test lead to  PIN-2   = 0.507  V OR It means 507mV
DMM  positive test lead to  PIN-3   = 0.634V
Step-3.
DMM  positive test lead to   PIN-2
DMM  Negative test lead to  PIN-1 DISPLAY READING  0.508.v
DMM  Negative test lead to  PIN-3 dISPLAY READING  0.505.v
Step-4.
 DMM  Negative test lead to PIN-1
DMM  positive test lead to  PIN-2  =DISPLAY READING shows OL.
DMM  positive test lead to  PIN-3  = DISPLAY READING shows OL
Step-5.
DMM  Positive test lead to   PIN-3
DMM  Negative test lead to PIN-1    Display Reading shows 0.638v
DMM   Negative test lead to PIN-2    READING  shows OL
Step-6.
DMM  Negative test lead to PIN-3
DMM  positive test lead to  PIN-1  =DISPLAY READING shows OL.
DMM  positive test lead to  PIN-2  = DISPLAY READING shows 0.508V.
Verification: If the DMM above reading shows the condition is GOOD.

Positive Adjustable voltage Regulator – LM 338.
An adjustable voltage regulator a single IC satisfies many voltage requirements from 1.2v to 57v and Current is 0.4A  To 1.5A Input DC voltage 65V.

VE1

It consist of 3 terminals like;  Data Sheet For ADJ +ve  Type
LM317 Pin Details Pdf: LM317 Positive Regulator-datasheet
1. ADJUSTMENT (ADJ)
2. OUTPUT.
3. INPUT.
Package Types are;
Metal can Package TO-3 STEEL      TO-39 METAL


Negative Adjustable voltage Regulator – LM 337.
An adjustable voltage regulator a single IC satisfies many voltage requirements from -1.2v to -57v and Current is 0.4A To 1.5A, Input DC voltage 65V.
It consist of 3 terminals like;  Data Sheet For ADJ -ve  Type
LM 378 Pin Details Pdf:  LM337 Negative Regulator-datasheet
1. ADJUSTMENT (ADJ)

2. OUTPUT.
3. INPUT.
Plastic package LM338 Data sheet pdf : LM338-Regulator-datasheet
HOW TO CHECK YOUR ADJUSTABLE NEGATIVE  REGULATOR? LM 338.

Comments(3)
  1. bbwora June 11, 2015
  2. abdul June 23, 2015
  3. Keith Mann March 29, 2016

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