Heathkit Service Bulletins: HP-XXXX Series (1966-89 Complete)
Joseph W Lutz
joelutz at JUNO.COM
Thu Apr 9 17:52:39 EDT 1998
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.
-------------------------------------------------------------------------------------------------------------------
May 3, 1966
HP-14 Bulletin No:
DC Power Supply HP-14-1D
Capacitor Overheating
Replace R1 and R3 195 OHM 7W wth [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.
--------------------------------------------------------------------------------------------------------------------
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 filter choke L1 has a resistance of 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 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 conections & check ground
connection between the capacitor mounting tab and metal mounting wafer.
--------------------------------------------------------------------------------------------------------------------
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 power supply, it is
necessary to splice wire onto the leads.
The next producton run of these kits will have the AC switch S1 rewired,
so 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 changed so that the LV 250 DC and LV 300 DC are
interchanged.
(This change will be in 04 level kits)
--------------------------------------------------------------------------------------------------------------------
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.
------------------------------------------------------------------------------------------------------------------
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, HW-7 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.
-------------------------------------------------------------------------------------------------------------------
July 24, 1978
HP-1144A Bulletin No:
Power Supply HP-1144-2
New Product Information for the HP-1144A
An updated and improved version of the HP-1144 Power Supply is about to
be shipped.
The "A" version is identical in size and specifications, but has one
outstanding feature: a "crowbar" protection circuit.
Unlike its predecessor, the Hp-1144A will "shut down" when the DC output
voltage at the connector execeeds 15.5 volts. By opening the DC line
fuse, F2, the current flow to the unit under load is interrupted.
The over-voltage protection will be of great advantage. Many units will
be saved from the 28-volt surge which happened when various components
malfunctioned in the original supply.
A modification kit [PN 830-33] will be available at the end of August for
customers wishing to update their present HP-1144 Power Supplies. The
"mod" kit consists of a new circuitboard with all components, plus
new-type pass transistors. The board is to be installed and wired in
place of the existing circuit board. Selling price will be approximately
$9.00.
-----------------------------------------------------------------------------------------------------------------
November 20, 1978
HP-1144A Bulletin No:
Power Supply HP-1144-3
Fuse Blows When Switchng From Tune to Receive Mode Or
On Voice Peaks At High Power Output
High RF power or high voice peaks can cause the SCR to trigger in the
HP-1144A and blow the fuse.
To prevent this, install a .1 uf capacitor [PN 21-195] from the anode
lead to the gate of the SCR. Remove the brown wire from the gate lead to
hole G on the circuit board. After you pass the one capacitor lead
through the gate lead, slip a piece of sleeving [PN 346-1] over the lead
and insert the free end of the lead into hold G and solder. Then
resolder the anode connection [large lug] with the new capacitor lead and
heavy brown wire attached.
This change will appear in new production.
--------------------------------------------------------------------------------------------------------------------
March 7, 1980
HP-1144 Bulletin
No:
Power Supply HP-1144-4
Crowbar Circuit Blows Fuse
+ + + + Information not yet available + + + +
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April 20, 1978
HP-1175 Bulletin
No:
AC Power Supply HP-1175-1
Use of the HP-1175 and the HW-202/HW-2036 and HA-202
Combination
A number of HP-1175 Power Supplies have been shipped with connectors that
are not compatible with the above combination.
To power the combination from the HP-1175, do the following:
Remove the present connector [if any] from the gray cable on the
HP-1175. Strip the wires and connect a female connector [PN
432-73]
to each of the two wires. The wires will be a tight fit into
these
connectors. Then pust these connectors into connector housing
[PN 432-723]; This connector will mate to the existing female
connector
on the HA-202.
Connect spade lugs [PN 259-22] to one end of the DC (mobile)
cable
furnished with the HW-202 or HW-2036. The other end should
already
have the male connector housing which connects to the
transceiver.
Now connect the transceiver power cable (spade lug end) to the
connector block on the HA-202 along with the power cable for the
HA-202. Be sure to observe polarity markings.
The transceiver and amplifier can now be powered together from
the
HP-1175 power supply.
This combination will not exceed the current capability of the
HP-1175.
Future production will incorporate this connector scheme.
-----------------------------------------------------------------------------------------------------------------
That's all that is listed for the HP-XXXX series (1966-89). Enjoy.
73 de Joe W7LPF/4 [NNN0KUU]
QWCA - SOWP - NCVA - FISTS - RCC
Gordonsville, Va 22942 [Orange Co]
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