HEATHKIT SERVICE BULLETINS - HP POWER SUPPLY SERIES
Joseph W Lutz
joelutz at JUNO.COM
Wed Jul 9 22:10:00 EDT 1997
AUGUST 15, 1979
HP-13 SERIES BULLETIN NO:
DC POWER SUPPLIES HP-13-1
USING HP-1144A AS BENCH SUPPLY
WHEN USING THE HP-1144A AS A BENCH SUPPLY TO CHECK THE HP-13 SERIES OF DC
POWER SUPPLIES, THE CROWBAR CIRCUIT IN THE HP-1144A MAY CAUSE THE 20A
FUSE TO BLOW AT TURN-ON. THIS IS DUE TO HIGH TURN-ON CURRENT OF THE
HP-13 CAUSING THE HP-1144A REGULATOR CIRCUIT TO COMPENSATE FOR SUDDEN
OUTPUT VOLTAGE DROP. THIS, IN TURN, CAUSES AN INSTANTANEOUS VOLTAGE
INCREASE TO THE CROWBAR CIRCUIT AND CAUSES THE 20A FUSE TO BLOW.
SO, WHEN USING THE HP-1144A TO TEST THE HP-13'S, DISCONNECT THE CATHODE
OF THE SCR Q4 TO DISABLE THE CROWBAR CIRCUIT.
BE SURE TO RECONNECT THE CATHODE LEAD TO Q4 AFTER SERVICING THE HP-13.
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MAY 3, 1966
HP-14 BULLETIN NO:
DC POWER SUPPLY HP-14-1D
CAPACITOR OVERHEATING
REPLACE R1 AND R3 [195 OHM 7W] WITH PN 3-24-1D [125 OHM 10W] RESISTORS.
REPLACE THE FOUR TRANSISTORS [PN 417-60] WITH FOUR [PN 417-120]
TRANSISTORS.
WHEN INSTALLING MODIFICATION BOTH TRANSISTORS AND RESISTORS MUST BE
CHANGED.
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JUNE 12, 1967
HP-23 BULLETIN NO:
AC POWER SUPPLY HP-23-1D
INCREASE FUSE CAPACITY
INCREASE THE FUSE CAPACITY FROM 3 AMPS [PN 421-2], TO 4 AMPS SLO-BLO [PN
421-5]. THIS WILL AVOID NEEDLESS FAILURE IN USE AND WILL NOT OVERTAX THE
FUSED CIRCUITS.
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MAY 23, 1974
HP-23 & HP-23A BULLETIN NO:
AC POWER SUPPLY HP-23-1
HP-23 & HP-23A SERVICE GUIDE
CHECK THE RESISTANCE TO GROUND AT THE POWER PLUG PINS:
PIN 1 48K OHM
PIN 3 50K OHM
PIN 4 100K OHM
PIN 7 ZERO RESISTANCE
PIN 11 11K OHM
THE FILER CHOKE L1 HAS A RESISTANCE OF 100 OHMS.
THE SILICON DIODES USED IN THE HP-23 ARE STANDARD POWER DIODES RATED AT
500V PIV & 705MA.
MAKE FORWARD & REVERSE RESISTANCE MEASUREMENTS ON THE DIODES D1 THROUGH
THE DIODE, A RESISTANCE READING OF ABOUT 10 OHM IN ONE DIRECTION IS
CORRECT. REVERSING THE LEADS SHOULD SHOW A READING OF INFINITY FOR A
NORMAL DIODE. SHOULD THE READINGS BE MORE OR LESS, IT WOULD INDICATE AN
OPEN OR SHORTED DIODE.
FOLLOWING ARE THE RESISTANCE OF THE TRANSFORMER WINDINGS AS MEASURED WITH
A 11 MEGOHM VTVM:
BLACK TO BLACK 1 OHM
RED TO RED YELLOW 12 OHM
BROWN TO BROWN YELLOW 1.4 OHM
BROWN YELLOW TO BLUE 4.5 OHM
GREEN YELLOW TO YELLOW .2 OHM
GREEN YELLOW TO GREEN .1 OHM
GREEN TO YELLOW .1K OHM
SHOULD YOU EXPERIENCE FUSE BLOWING, THIS COULD BE CAUSED BY THE SURGE
CHARGING OF THE FILTER CAPACITORS. IN THE EARLY HP-23 SUPPLIES, A 30 AMP
FUSE WAS USED. NOW THE SUPPLY IS FURNISHED WITH A 4 AMP SLO-BLO FUSE.
NOTE: HP-23A USES CIRCUIT BREAKER.
CHECK FOR LOOSE HARDWARE, INTERMITTENT SOLDER CONNECTIONS & CHECK GROUND
CONNECTION BETWEEN THE CAPACITOR MOUNTING TAB AND METAL MOUNTING WAFER.
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JUNE 21, 197
HP-23A, B BULLETIN NO:
AC POWER SUPPLY HP-23-2
FAILURE OF POWER CONNECTOR WHEN USED IN
SERVICE
FAILURE OF THE HP-23B POWER CONNECTOR WIRING WILL OCCUR WHEN THE HP-23B
IS USED ON THE SERVICE BENCH, CAUSED BY PULLING ON THE POWER CABLE TO
DISCONNECT THE PLUG, OR AS A RESULT OF REPEATED ROTATION OR MOVEMENT OF
THE CABLE WHILE UNITS ARE BEING SERVICED.
THESE FAILURES CAN BE REDUCED BY CHANGING THE 11-PIN PLUG CAP TO A CAP
WITH CABLE CLAMP [PN 440-8]. THE CLAMP PREVENTS LEAD SEPERATION CAUSED
BY THE CABLE ROTATING IN THE CAP AS THE UNIT IS BEING SERVICED, AND WILL
RELIEVE SOME OF THE STRAIN PLACED ON THE CONNECTOR WHEN THE CONNECTOR IS
REMOVED BY PULLING ON THE POWER CABLE.
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SEPT 20, 1976
HP-23B BULLETIN NO:
AC POWER SUPPLY HP-23-3
PN 57-27 REPLACEMENT DIODE LEADS TOO SHORT
QA NOW CUTS THE LEADS OF DIODES TO REMOVE THEM FROM A STRIP ON WHICH THEY
ARE RECEIVED. THIS RESULTS IN A DIODE LEAD LENGTH ABOUT ONE INCH SHORTER
THAN THE OLDER DIODES.
TO USE THIS SHORTER LEAD DIODE AT D7 OF THIS POWR SUPPLY, IT IS NECESSARY
TO SPLICE WIRE ONTO THE LEADS.
THE NEXT PRODUCTION RUN OF THESE KITS WILL HAVE THE AC SWITCH S1 REWIRED,
DO D7 CONNECTS TO A SWITCH LUG NEXT TO THE TERMINAL STRIP; PERMITTING USE
OF THE SHORTER LEAD DIODES. THE SCREENING OF SWITCH S1 POSITION ON THE
CHASSIS WILL BE CHANGES SO THE LV250DC & LV300DC ARE INTERCHNAGED.
(THIS CHANGE WILL BE IN 04 LEVEL KITS)
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OCTOBER 13, 1978
HP-23 SERIES BULLETIN NO:
AC POWER SUPPLY HP-23-4
INTERMITTENT OPERATION
RIPPLE AND VOLTAGE VARIATIONS ON THE DC OUTPUT LINES WHEN THE SUPPLY IS
BUMPED OR VIBRATED MAY CAUSE INTERMITTENT OPERATION.
CHECK THE TWIST TAB CONNECTIONS ON C2 AND C4 WHICH MAY BE MAKING POOR
CONNECTION TO THE GROUNDED MOUNTING WAFER.
BE SURE THE METAL TWIST TABS ARE SOLDERED TO THE WAFER. ALSO, YOU MAY
WANT TO ADD A WIRE FROM LUG 4 OF TERMINAL STRIP H [GROUND] TO THE
GROUNDING TABS ON CAPACITORS C2 AND C4 TO INSURE PROPER GROUNDING.
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DECEMBER 2, 1976
HP-1144 BULLETIN NO:
POWER SUPPLY HP-1144-1
PRECAUTIONS NECESSARY WHEN USING AS A 12VDC
BENCH SUPPLY
IF HP-1144 IS USED FOR TEST POWER SUPPLY, THE 20A OUTPUT FUSE SHOULD BE
REPLACED WITH A LOW AMP FUSE WHEN REPAIRING HW-8, HW7 OR OTHER LOW
CURRENT UNITS. FAILURE TO DO THIS MAY RESULT IN FOIL BURNS IN THE EVENT
OF SOLDER OR FOIL BRIDGES, THE FOIL WILL NOT WITHSTAND 20A AT 12VDC.
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73 de JOE
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QWCA - NCVA - SOWP - FISTS
Gordonsville, Va 22942 (Orange County)
Looking for: Heathkit HR/HX-20, MR/MT-1,
Collins 516F-2, 312B-4, EFJ TR Switch
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