August 15, AC Power Suplly. Using HP-1144A as Bench Supply

Transcription

1 HP-13 Series DC Power Supplies August 15, 1979 Using HP-1144A as Bench Supply HP-13-1 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 DC HP-14-1D Capacitor Overheating Replace R1 and R3 [195 Ohm 7W] with PN D [125 Ohm 10W] resistors. Replace the four transistors [PN ] with four [PN ] transistors. When installing modification both transistors and resistors must be changed. June 12, 1967 HP-23 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 AC Power Suplly HP-23-1 HP-23 & HP-23A Service Guide Check the resistance to ground at the power plug pins: PIN 1 PIN 3 PIN 4 PIN 7 PIN 11 48K OHM 50K OHM 100K OHM ZERO RESISTANCE 11K OHM The filter 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.

2 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 2 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. JUNE 21, 1976 HP-23A, B 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. Sept 20, 1976 HP-23B HP-23-3 PN Replacement Diode Leads Too Short QA now cuts the leads of diodes to remove them from a strip on which the 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 production 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 changes so the LV250DC & LV300DC are interchanged.

3 (This change will be in 04 Level kits) OCTOBER 13, 1978 HP-23 SERIES 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 HP 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. July 24, 1978 HP-1144A HP New Product Information for the HP-1144A An updated and improved version of the HP-1144 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 ] 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 HP

4 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 ] 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 HP Crowbar Circuit Blows Fuse This can happen during a rapid high-to-low current transition. Due todelays in the regulator circuits, Q1 and Q2 (which were conducting heavily to maintain VDC) may not go towards cutoff fast enough. The output voltage can then exceed the VDC trip point of the crowbar circuit, causing F2 to open. If this happens too often, the operating lifetime of BR1 can be seriously shortened. To prevent this, make the following modification. Parts Required: Procedure: 2 ea. 39 ohm, 1/2 watt resistor [PN 1-156] 1 ea. 68 ohm, 1/2 watt resistor [PN 1-2] 2 ea. 0.1 uf ceramic capacitor [PN ] 1 ea V zener diode [PN 56-36] Refer to the schematic as you performthe following steps. - Remove C4. - Replace diode D4 with a 16.1 V zener diode [PN 56-36] - Install a 39 ohm resistor [PN 1-156] from the base to emitter of Q1 and Q2. - Install a 0.1 uf capacitor [PN ] from gate to cthode of Q4. This capacitor may already be installed on some units. - Install a 68 ohm resistor [PN 1-2] and a 0.1 uf ceramic capacitor [PN ] from base to emitter of 03 (on foil side). Perform this change on all units serviced. April 20, 1978 HP-1175 HP

5 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 Strip the wires and connect a female connector [PN ] to each of the two wires. The wires will be a tight fit into these connectors. Then push these connectors into connector housing [PN ]; This connector will mate to the existing female connector on the HA-202. Connect spade lugs [PN ] to one end of the DC (mobile) cable furnished with the HW-202 or HW 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 Future production will incorporate this connector scheme. That's all that is listed for the HP-XXXX series ( ). Enjoy. 73 de Joe W7LPF/4 [NNN0KUU] QWCA - SOWP - NCVA - FISTS - RCC Gordonsville, Va [Orange Co]