Initial Power Up; Test Equipment Required; Power Up Pre-Set Conditions; Initial Power Up Tests - Hallicrafters SR-2000 Repair Manual

REPAIR AND RESTORATION OF THE SR-2000

1-4. INITIAL POWER UP

Note: Initial assumption is, the power supply has been fully restored and meets original specifications.

1-4-1. TEST EQUIPMENT REQUIRED

DVM or VTVM

1-4-2. POWER UP PRE-SET CONDITIONS

First and of critical importance, you must have a power supply that has been tested and meets all the original
specifications. You will not be transmitting power until late in this process so there is no need to activate the
high voltage. The power supply front panel switch should be in the SSB LOW POWER position. Do not turn
on the High Voltage until you get to the Transmitter PA tests. It is not necessary to start with a low AC voltage
and increase the voltage over time to cook the rig. There are no domino circuits in the SR-2000. If you have a
short somewhere, you may cook a resistor and it will smell bad but it will lead you straight to the problem. So,
set all the gain and drive controls to minimum. Every time you turn on your SR-2000 all these controls
should be at minimum. The STANDARD PRE-POWER UP CONFIGURATION will always be: all gain
controls set to minimum, RIT off, RIT CONTROL at mid-range, CAL ADJ at mid-range, CAL OFF, NOISE
BLANKER OFF, Preset the PRESELECTOR to the approximate position in the band you will be operating. Set
the FUNCTION switch to either USB or LSB depending upon which band you will be testing the default is 80
meters LSB @3.900MHz. Insure that a jumper plug in installed in J2 on the rear of the radio. The jumper plug
should have a jumper between pins 2 and 10.
CAUTION: FATAL VOLTAGES ARE OPEN AND EXPOSED ONCE THE COVERS OR CASE IS
REMOVED.

1-4-3. INITIAL POWER UP TESTS

Ok it is time apply power. It is assumed that you have a fully recapped power supply that meets all
specifications. Attach the power supply and plug it in. Set the operation switch to REC. Now let it sit there for
10 to 15 minutes. Locate R50, 3300 ohm, 10 watt resistor connected to V10. The voltage at one end should
150vdc and 280vdc at the other. If you do not have the 280vdc assuming your power supply has been proven
functional then there is a wiring error between J6 and R50. If you do not have the 150vdc you have a fault in the
wiring or the 150v regulator. This fault must be cleared before you proceed. Now the only thing we need to do
at this time is rough set the bias voltage.
Measure the voltage on the wiper tab of R114 (BIAS ADJ control). The control should be set for -68 to -70vdc.
This is a setup setting done in the receive mode, a rough adjustment and will be precisely set later. If you cannot
set this voltage then you have a fault in the power supply or the bias divider network, R114, C182 and R113.
Insure that you have -90vdc on pin 4 of J6 and -20vdc on pin 3 of J6. This fault must be cleared before you
continue.

1-5. CHECK AND ADJUSTMENT OF OSCILLATORS:

Before starting any receiver or transmitter troubleshooting or the RF or I.F. alignment it is imperative that the
xtal oscillators and the VFO are precisely on frequency. If you will devote the time to these considerations you
will be rewarded with a rig that performs as well as any modern rig. A frequency counter and scope are
required. The procedure in the book will work ok, but will compound errors. If you get all the oscillators "on
freq" with proper output levels individually, then all else will fall into place. Do not make any adjustments until
the rig has been on for at least 30 minutes. Optimize the VFO last to insure it is stable. Do not hurry. Take your
time, these processes are critical.
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WDØGOF 3/7/20014