Heathkit IO 4550 Schematic

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Copyright © 1975
Heth Coinpany
AT/ Rrgms Essen/ad
PrInIed In The Ohm sums OI AmeTIca

SCHEMATIC OF THE
HEATHKIT®
DUAL TRACE OSCILLOSCOPE
MODEL lO-4550/SO-4550

NOTES:

1. ALL CAPACITOR VALUES ARE IN [IF UNLESS OTHERWISE
SPECIFIED.

Z. ON THE VERTICAL CIRCUIT BOARDJHE WATTACE VALUES OF 1/8»

WATT AND II4-WATT RESISTORS ARE NOT MARKEDJLL OTHER
RESISTORS ARE 1/? WATT.5I- UNLESS MARKED OTHERWISE.
RESISTOR VALUES ARE IN OHMS (K1000;M=1DDO,DOO],

3, O INDICATES A LETTERED WIRE CONNECTION ON
A CIRCUIT BOARD.

INDICATES CHASSIS GROUND.
INDICATES CIRCUIT BOARD GROUND.

6, c INDICATESA PART MOUNTED ON THE CHASSIS.
ALTHOUGH ITS LOCATION IN THE SCHEMATIC
SUGGESTS ANOTHER LOCATION.

7, CIRCUIT COMPONENT NUMBERS ARE IN THE FOLLOWING

GROUPS:
» 9? PARTS ON CHASSIS,

100 - m PARTS ON THE VERTICAL CIRCUIT
BOARD.

zuu - 299 PARTS ON THE HORIZONTAL CIRCUIT
BOARD.

sou - 3W PARTS ON THE Low VOLTAGE CIRCUIT
BOARD,

ADD , m PARTS ON THE HIGH VOLTAGE CIRCUIT
BOARD.

5. O INDICATES A DC VOLTAGE MEASURED FROM THI.
POINT INDICATEDTO GROUND WITH THE VERTICAL
AMPLIFIERS BALANCED, THE TIME/CM SWITCH IN
THE EXT POSITION, AND THE HORIZONTAL POSITION
CONTROL CENTERED. VOLTAGE NIAV VARY t 20%.

9. TRANSISTOR TRANSISTOR LOGIC ITTLI LEVELS AREAS
FOLLOWS: A lOCIC 0, OR LOW, IS A: 0.8 VOLTS, A
LOGIC 1. OR HIGH,IS > 2.0 VOLTS BUT < 5.5 VOLTS.

ID. . THIS SVMBOL INDICATES A LINE THAT CONTINUES.
TO FIND THE CONTINUED PORTION,LAY A STRAIGHT
EDGE ON THE LINE THAT THE SYMBOL IS ON.

II. CRT UNRLANKED - DEPENDS ON POSITION OF INTENSITY
CONTROL.

12 CRT BLANKEO.

13. ONLV IN DUAL TRACE CHOPPED MODE DURING SWEEP OR
EXT'X DUAL TRACE OPERATION,

14. UNIT NOT SWEEPING. SPOT CENTERED HORIZONTALLV.

7% DEPENDS ON LINE VOLTAGE,
HD . HOLD OFF IINCLUDES RETRACE).

HIGH VOLTAGE I

.
.
Part of 595-1850-04 I CIRCUIT BOARD

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