Sencore PR 57 User Manual

PR57

AC “ POWERITE” *

Variable Isolation Transform er & Safety Analyzer

Operation, Application, and

M aintenance Manual

S E N O O B E

AC “ POWERITE”

VAMABUE ISOLATION TRANSFORMER A SAFETY ANALYZER

	0 - 3 AMPS CONTINUOUS			3 - 4 AMPS INTERMITTENT USE
LINE	OUTPUT	17SW		470W HI SIDE	LO SlOE	0 D
□	□	□	□	□	□	□
TZT						t T

SENCORE

3200Sencore Drive, Sioux Falls, South Dakota 57107

----------------------- WARNING------------------------

Please Observe These Safety Precautions

There is always a danger present when testing electronic equip­ ment. Unexpected high voltages can be present at unusual locations in defective equipment. Become familiar with the equip­ ment you’re working with and observe the following safety pre­ cautions.

Every precaution has been taken in the design of your instrum ent to insure that it is as safe as possible. However, safe operation depends on you, the operator.

1.Never exceed the limits of this instrum ent as given in the specifica­ tion section and the additional special warnings in this manual.

2.Never use the PR57 to isolate your test equipment, only use it to isolate the equipment that you are servicing.

3.Never plug more than one unit at a time into the PR57. To do so could defeat the isolation transformer and present a possible shock hazard to the technician.

4.Remove the circuit power before making connections to high voltage points.

5.Discharge filter capacitors before connecting test leads to them.

6.Be sure your equipment is in good order. Broken or frayed test leads can be extremely dangerous and can expose you to dangerous voltages.

7.Remove the test leads immediately after the test has been com­ pleted to reduce the possibility of shock.

8.Do not work alone when working on hazardous circuits. Always have another person close by in case of an accident. Remember, even

aminor shock can be the cause of a more serious accident, such as falling against the equipment, or coming in contact with high voltages.

9.Improper Fuse(s) Void W arranty. Fuses are for your protection, so always replace fuse with proper type and current rating. The proper fuse type description is marked near the fuse holder and in the instruction manual. Always:

a.Have the proper size replacement fuse in stock. With each new instrument, be sure to update your fuse inventory with any special value fuses your instrum ent may require.

b.Avoid situations th at will blow the fuse. When a protection fuse blows, note what caused the fuse failure. Prevent future fuse failures by following proper measuring procedures.

PR57

AC “ POWERITE”

Variable Isolation Transformer

& Safety Analyzer

Operation, Application, and

Maintenance Manual

SENCORE

. . . t h e electronic instrument “analyzer people"

3200 SENCORE DRIVE, SIOUX FALLS. SOUTH DAKOTA 57107 -[phone]

VCQ». «*

1

MMMMi

TABLE OF CONTENTS

SIMPLIFIED OPERATION
To Read Voltage of AC Line or Isotated O u tp u t ...................................	4
To Read Wattage or C u r r e n t .......................................................................	4
To Read Leakage...........................................................................................	...5
DESCRIPTION
In tro d uctio n ....................................................................................................	6
F e a tu r e s ..........................................................................................................	6
Specifications ...............................................................................................	7
Supplied A ccessories ................................................................................	8
Controls............................................................................................................	10
OPERATION
Introduction ....................................................................................................	12
Power C o n n e c tio n .......................................................................................	12
Magnetic Circuit Breaker/Power Switch O p e ratio n .......................	12
Fuse R eplacem ent.......................................................................................	13
Leakage Test Probe Mounting C lip .......................................................	13
Using the Variable Voltage Output F u n c tio n ......................... ..........	14
Using the AC Line Monitor P o s itio n .....................................................	14
Using the PR57 Current F u n c tio n .........................................................	15
Using the PR57 Watts F u n c tio n ..............................................................	15
Determining the W attage Rating of a U n it...........................................	16
Performing the Leakage T e s t ..................................................................	16
Determining the Allowable Leakage L e v e l.........................................	18
Testing Leakage on Three-Wire Units...................................................	18
Checking the Calibration of the Leakage T e s t ..................................	19
APPLICATIONS
Troubleshooting Power Supplies ............................................................	20
Troubleshooting Constant Voltage Transformer Power Supplies..	20
Checking Circuit Repairs at reduced Input AC V o lta g e s .............	21
Reforming Power Supply Electrolytic F ilte rs ....................................	21
Checking the Wiring of the AC Line Cord and Power S w itch ___22
Testing Transformer Operated Devices for AC Leakage ...............	23
Reading AC Leakage Levels Below 100 M icroam ps .......................	23
MAINTENANCE
Disassembly In s tru c tio n s ........................................................................	24
PR57 Calibration P ro c e d u re ....................................................................	24

SERVICE AND WARRANTY

Inside Back Cover

NOTES

SIMPLIFIED OPERATION

TO READ VOLTAGE OF AC LINE

OR ISOLATED OUTPUT

m onitor AC	m onitor AC	to "O N "	to be tested
line voltage	voltage from
	isolated
	output

TO READ WATTAGE OR CURRENT

4 .	Adjust tor
6. Read w attage or	117V on

tested

TO READ LEAKAGE

12. Depress if any	7. and 10. Make
leakage shows	contact with
on meter	exposed metal
	parts

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DESCRIPTION

INTRODUCTION

Many electronic devices th at operate from the AC line do not have an isolation transformer. Some of these chassis have one side of the AC line connected directly to the chassis. Other devices use a full-wave bridge rectifier connected to the chassis which places the chassis at one-half the line voltage no m atter how the line cord is connected to the AC line. These chassis m ust be isolated from the common side of the AC line with an isolation transformer to prevent shock hazards and to prevent the possibility of damaging the device under test or test equipment connected directly to the chassis.

Many new circuit troubleshooting procedures require th at the AC line voltage be adjustable to test regulators, shut-down circuits, and other voltage sensitive circuits. Increasing or reducing the line voltage can also help locate interm ittent problems th at do not show up with 117 volts applied to the input.

The ability to monitor the current or power drawn from the AC line often simplifies troubleshooting of power supply or power output stage problems. Abnormally high power consumption indicates a problem that may not be immediately recognized but which may cause problems in the future.

Finally, every unit serviced should be checked to make sure that exposed metal parts do not pose a shock hazard to the user. A safety test is recommended by all manufacturers. This test is often not done because the procedures given in service literature are difficult to per­ form and interpret.

The PR57 AC POW ERITE iM is an AC safety supply designed to make sure th at every factor related to power is correct. The operation is simplified and all of the features needed to meet these needs are includ­ ed in a single, compact instrument.

FEATURES

The Sencore PR57 POW ERITE™ features four functions in one compact package. First, the PR57 has an isolation transformer to isolate chassis that have one side connected directly to the AC power line to elim inate shock hazards during service. The isolation transformer also provides safety for the test equipment and prevents possible damage to the set itself.

Second, the PR57 has a variable AC transformer th at allows you to vary the isolated AC output voltage from 0 to 140 volts AC. You can apply a high and low line to check regulator and shut down circuit operation or apply a high line to cook out th at interm ittent trouble.

Third, the PR57 meter lets you monitor the AC line voltage or the AC voltage from the isolated output. The meter also allows you to monitor the wattage and current being drawn by the unit under test. The PR57 meter lets you know when the voltage and power are right.

Fourth, the PR57 provides a safety leakage test so you can check each custom er’s set for AC line leakage as recommended by m ost manufac­ turers. There is no external resistors or meters to hook up with the PR57. Simply depress a button, touch the exposed metal parts with the Safety Leakage Test Probe and read the leakage current on the meter.

The PR57 POW ERITE™ also features a magnetic circuit breaker backed up by a 4 Amp slo-blo fuse. The PR57 is protected, even from a direct short on the isolated output. The PR57 also has only one isolated output to prevent plugging in more than one unit and defeating the isolation of the isolation transformer and creating a potential shock hazard.

SPECIFICATIONS

ISOLATED OUTPUT:

VOLTAGE: 0-140 VAC (typical) continuously variable.

CURRENT: 0-3 Amps continuous; 3-4 Amps interm ittent usage (five minutes on, five minutes off).

AC LINE LEAKAGE: 50 uA max., either isolated output to ground.

AC LINE MONITOR:

LINE VOLTAGE: 0-150 VAC ± 3% F.S. (calibrated at 117 VAC). OUTPUT VOLTAGE: 0-150 VAC, ± 3% F.S. (calibrated at 117 VAC). OUTPUT CURRENT: Ranges: 0-1.5, 0-4 Amps AC; Accuracy at any

output voltage: 3% F.S.

OUTPUT WATTAGE: Ranges: 0-175, 0-470 watts; Method: volts times amps product; Accuracy: 3% F.S. with output voltage set to 117 VAC.

SAFETY LEAKAGE TEST (Patent Pending):

RANGE: 0-800 uA, ± 3% F.S. (calibrated at 500 uA).

METHOD: Referenced to either side of isolated output jack (switch selected).

PROTECTION:

AC INPUT: 4 Amp magnetic circuit breaker built into power switch. ISOLATED OUTPUT: 4 Amp type 3AG slo-blo fuse on back panel.

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GENERAL:

METER: 4 V2”, moving coil, 1900 ohm, 100 uA F.S., diode protected against overload; Accuracy: ± 2%.

INPUT POWER: 105-125 VAC, .4 Amps idle current with no output load with 117V AC input.

SIZE: 6” x 11 Vi” x 1 2 W ’ (15.2 x 29.2 x 32.4 cm.) HWD. W EIGHT: 18 lbs. (8.2 Kg.)

ACCESSORIES (Supplied):

39G148 Safety Leakage Probe with built-in calibration check. 64G35 Leakage Probe Mounting Clip

44G23 Spare 4 Amp type 3AG slo-blo fuse.

NOTES

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