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HP 456A, Инструкция по эксплуатации и обслуживанию

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Model 4S6A 

equivalent,  and  two  Mallory  Type  TR 233R  batteries 

in  series.  BE SURE  TO  INSTALL  THE BA TTERIES 

WITH  THE  SAME  POLARITIES  AS  MARKED  ON 

THE  BATTERY  HOLDER.  Note  that  the  small termi­
nal  on  the  battery  is 

not  positive  as with 

dry cells . 

BE  SURE  THE  BATTERIES  ARE  MAKING  GOOD 
CONT AC T  WITH  THE  BATTERY  HOLDERS. 

If 

necessary,  bend  the  battery  holders  so  that  they  do 
make  good  contac t.  In  the  holder  where  two  batteries 
are  used  in  s eries  cut off  part  of the  ca rdboa rd  tubing 
a round  the  batteries  at the  ends  which  meet  in  order 
to get  good  contact  between  them. 

4 -6. 

C O N VE R TING  TO  AC-O PERATED  M O DE L .  

T h e  battery-operated model c a n  b e  quickly  a n d  easily 

converted  to  an  ac-powered  model . 

Remove  the 

instrument  from  the  cabinet  as  ins tructed  in  pa ra­
graph  4- 2.  Unsolder  the  wires  going  to the battery 
holder  at  the  battery  holder  end .   Remove  the  twO 
sc rews 

the  battery 

chas s is.  Remove 

the  battery  holder  chassis  and  batteries,  if  any. 

Substitute  the  ac  power  supply  (�  stock 

#456A-95B) 

in  the  space formerly  occupied  by  the  ba ttery  holder 
chassis . 

Fasten  the  supply  with  the  same screws used to  mount 

the  battery  holder  chassis.  Solder  the  loose  wires 

to  the  terminals  (marked  with  the  corresponding 

colors )  on  the boa rd.  Replace the  cabinet. 

4 -7. 

TEST  EQUIPMENT  REQUIRED. 

The  following  tes t  equipment  is  required  to test the 
Mode14S6A : 

1)  Vacuum  Tube  voltmeter  accurate  to  within 

± 

1%. 

such  as  �  Model  403A  or 400H/L. 

2)  Signal  Generator  with  output  to  4  me,  such  as 

� 

Model  6S0A . 

3)  Shunt  Resis tor  of  1 0  ohms  accurate  to at least 

± 

5% 

such  as  �  Model  470C . 

4) 

DC 

Vacuum  Tube  Voltmeter,  such  as 

� 

Models 

4l0B  or  4l2A . 

5) 

Variable  Transformer  continuously  adjustable 

from  1 00  to  130  volts ,  equipped  with  a  monitor  volt­
meter accurate within ± 

1 

volt. 

6)  Clip-On  Milliammeter,  such  as 

� 

Model  428A. 

4-8. 

FRONT  PANEL  P E RFO R MAN C E   C H E CK. 

Perform  this  check  upon  receiving  this  instrument 
or whenever trouble  is  suspected. 

A.  NOISE. 

1 )   To  check  ac-powered  456A  turn  instrument  off 

and  read  the output  nois e  on  an oscilloscope or  meter. 
If there is appreciable hum see paragraph 2-50, Ground 

00395- 1 

Section  IV 

Pa ragraphs  4-6  to 4-9 

Loops .  Follow  the  procedure  in  that  paragraph  until 
any  appreciable  hum is  eliminated. 

2) 

Turn  on  the  456A  with  no  input  to  the  probe.  The 

noise  as  read on  the  meter  or  oscilloscope should  be 

less  than  7

5 

Jl 

volts  (100 

Jl 

volts  with  ac -powered 

model). 

If  not  check  C94,  power  supply  capacitor 

(if  ac  powered),  or  try  replacing  CRI ,  Q1 ,  or 

Q2. 

Check  with  456A  POWER  s witch  off  to  see if ground 
loops  exist .  If they  do,  see pa ragraph  2-50. 

B. 

CALIBRATION  A ND  FREQUENCY  RESPONSE. 
Perform  the  procedure  illus trated  in  figure  4-2. 

Note  that  this  test  is  used only for  rough  testing with 

readily  available  equipmen t .   In  almost a l l  cases  the 

test  accuracy  will  be  much  poorer  than  the  probe 

deviation  from  specification. 

In  this  case  assume 

that  the probe  is  within  specifications. 

4-9. 

TR O UB L E   LO CALIZAT IO N . 

Adopting  a  sys tematic approach to troubleshooting will 
enable  you  to  find  the  trouble in  the  shortest  possible 
time  and  eliminate  the  possibility  of  damaging  the 
transis tors  or  other parts of the instrument.  Whenever 
trouble  is  suspec ted,  perform  the  following  s teps  in 
the  order  gi ven  until  the  trouble  is  located.  A fter  the 
trouble  has  been  loca ted proceed to the next paragraph . 

1)  Perform  the  front-panel  performance  check  as 

given  in  paragraph 

4-8. 

If  ins trument does  not meet 

specifica tions  proceed  to next  step. 

2)  Clean  probe  jaws as described  in  paragraph 2-5A3 
and  figure  2-3. 

3)  If  instrument  does  not  operate  at  all  check con­
tinuity  of both cables  with  an  ohmmeter .  Check probe 
by  substitution  if another probe assembly is availabl e .  

4)  Check  the  voltage  o f   the  ba tteries  as  described 
in  paragraph  4-4,  Checking  the  Batteries .  At  the 
BA TIER Y  TEST  jacks  on  the  front  panel  of  an  ac­
operated  instrument,  the  VOlta ge  should  be approxi ­
mately  8  volts 

± 

10% 

with a n  input  of  1 15  volts  ac .  If 

the  voltage  is  much  below  8  VOlts,  either the s upply 
is  faulty or the inst rument is drawing too much  current. 

5)  Meas ure  the  current  in  the  red  ( B+)  lead  running 

around  the  front  of  the  etched-circuit  boa rd  with  a 

milliammeter,  such  as  the 

� 

Model  428A  Clip- On 

Milliammeter.  The  cu rrent  should be S . 5ma±0.5  rna. 

It  too  high ,  check  voltages  across  CRl , 

Ql, 

and Q2. 

6)  Measure  current  in  violet-white  lead  (ground) 
going  to  switch .  There  should  be less  than  0.02 rna 
in  this  lead.  If  there  is  more  cu rrent,  s omething i s  
wrong  in  the  amplifier  (provided  the  supply  voltages 
a re  correct). 

7) 

Meas ure  the  rippl e  on  the  ac  s upply  by  connecting 

an ac  voltmeter,  such  as  the 

� 

Model  403A (or  Model 

400D/H/L).  from  any  pink (B-) lead  to any  red 

(B+) 

lead.  This  is  a  very  difficult measu rement to  make 
because  eliminating  all  ground  loops  is  necess a ry .  

Refer  t o   paragraph  2-50 for  instructions  concerning 

4-3 

Содержание 456A

Страница 1: ...56A AC CURRENT PROBE SERIALS PREFIXED 103 PRINT O 3 61 I 00395 1 ...

Страница 2: ...00395 1 OPERATING AND SERVICING MANUAL MODEL 456A SER IALS PREFIXED 103 AC CURRENT PROBE Copy ht HEWLETf ACK UD COM ANY 1961 ISOI AGE Mill ROAD AlO AlIO CALIFORNIA U S A Printed MAR 1961 ...

Страница 3: ... 13 Replacing the Probe Cable REPLACEABLE PARTS 5 1 5 2 5 3 Introduction Table of Replaceable Parts Ordering Information 4 L 4 1 4 L 4 1 4 1 4 3 4 3 4 3 4 3 4 4 4 4 4 4 4 4 5 1 5 L 5 1 5 1 LIST O F IllUSTRATIONS Number Title L l General A rrangement of Model 456A 1 2 Model 456A AC Current Probe 1 3 Typical Change in F requency Response 2 1 2 2 2 3 2 4 2 5 with Load Capacitance Probe used with Mcxi...

Страница 4: ... probe Less than 50 milliohms in series with 0 05 h This is approximately the induc tance of 1 1 2 inches of hookup wire Approximately 4 pf added from wire to ground For 1 2 amp input at least 50 db down For 10 rna input at least 70 db down Less than 50 a rms 100 a when ac powered 220 ohms at 1 kc Approximately 1 volt dc component Should work into load of not less than 100 000 ohms shunted by appr...

Страница 5: ...or The probe operates with an accompanying small ampli fier to convert the ac current being measured to a pro portional voltage The current to voltage conversion factor is 1 millivolt output for 1 milliampere flowing th rough the probe Current readings can thus be taken directly from the voltage calibrations on the voltmeter or oscilloscope Table 1 2 is a list of instruments w hich can be used wit...

Страница 6: ... The Model 456A is available either as a battery powered or ac powered instrument The AC Power Supply srock 456A 95B fits into the space nor mally occupied by the battery supply and takes the place of it electrically The ac power supply must be ordered separately When the 456A is powered with its own internal bat teries it is independent of power lines It may be used in the field with battery oper...

Страница 7: ...ribed in text 00395 1 In this manner currents even below 10 microamperes can be measured 2 3 OPERAT IN G T HE PRO BE The probe jaws may be operated with one hand While holding the probe handle in the palm squeeze the flanges together with the fingers This action will open the jaws Move the probe to the vicinity of the insulated wire being measu red and slowly release the flanges until the jaws fit...

Страница 8: ...by squeezing flanges on probe together 3 Connect ground clip to instrument under test if necessary see paragraph 2 5E Figure 2 2 2 2 Model 456A 4 t 1I t f RO 4 Read current being measured on meter or oscil loscope read millivolts as milliamperes S Note direction of arrow on probe Conventional current flow in direction of arrow gives positive going output voltage Opera tion 00395 1 ...

Страница 9: ...n the signal being measured should preferably be kept below 1 2ampere Direct current below that value will have no effect on the measurement C ALTERNATING CURRENT FIELDS The probe is shielded against external ac magnetic and electric fields Extremely strong fields may cause an erroneous reading If a strong ac magnetic field 00395 1 is suspected rotate the empty probe head with the jaws closed If t...

Страница 10: ...u may choose which side of the circuit to measure the current See figure 2 5 Note in figure 2 5 the probe measures the current flowing in the circuit on the same side as the wide side of the arrow on the probe Occasionally at high frequencies above 15 me a greatly magnified voltage effect exists at a particular frequency This effect is caused by a resonance be tween excessive external ground lead ...

Страница 11: ... to the tube output capacity hp 456A PROBE HEAD Section II Paragraph 2 6 Cont d The probe is valuable in a number of other current equalizing applications EspeciaUy common among these are equalizing the input and output currents in push pull and balanced circuits in both transistor and tube applications Figure 2 6 Bucking OUt Capacitive Component of Plate Current 00395 1 2 5 2 6 ...

Страница 12: ...results in a better frequency response lower input impedance dc bias stability lower distortion etc le 4 RD Figure 3 1 Equivalent Circuit 00395 1 The equivalent circuit can be thought of as shown in figure 3 1 where CL is the current gain of the tran sistor The transistors have internal resistances as shown Emitter resistance re is small but relevant to this discussion while the collector resistan...

Страница 13: ...lowed extensive damage to the etched circuit board will result 1 Apply heat sparingly to lead of component to be replaced If lead of component passes through an eyelet in the circuit board apply heat on com ponent side of board If lead of component does not pass through an eyelet apply heat to con dUctor side of board 3 Bend clean tinned leads on new part and care fully insert through eyelets or h...

Страница 14: ...tion unless otherwise specified It can be quickly and easily converted to operate from a nominal line 00395 1 voltage of either 115 or 230 volts and a frequency of 50 to 1000 cps To convert for 230 volt operation remove the short across R90 Turn the instrument off before doing any soldering 4 4 C HECKIN G THE BATTERIES Whenever trouble is encountered check the voltage at the BATTERY TEST terminals...

Страница 15: ...il400D H L reads exactly 0 1 volt Model 456A 456A 5 Connect the OUTPUT cable of the 456A to the input of the 400D H L in place of the 470C Leave the wires still connected to the 470C 6 Read 400D H L Reading should be within sum of specifications of the 470C and 456A 7 Repeat above steps with 650A set at other fre quencies up to 100 kc If the 456A calibration or frequency response is poorer than te...

Страница 16: ...illoscope should be less than 75 Jl volts 100 Jl volts with ac powered model If not check C94 power supply capacitor if ac powered or try replacing CRI Q1 or Q2 Check with 456A POWER switch off to see if ground loops exist If they do see paragraph 2 50 B CALIBRATION A ND FREQUENCY RESPONSE Perform the procedure illustrated in figure 4 2 Note that this test is used only for rough testing with readi...

Страница 17: ...o the semi conductor Table 4 1 lists the tests which should be made after replacing the components 4 11 CALIBRATION Perform the procedure in figure 4 2 at 1 kc Adjust R9 Gain Set Potentiometer so that the voltage out is exactly 0 1 volt millivolts output equals milli amperes input If you can t reach calibration check R7 9 10 and 12 and the probe 4 4 Model 456A 4 12 FREQUEN CY R ESPO N S E Perform ...

Страница 18: ...TEXT LOCKWASH ER l 2190 0012 PROBE CABLE ASSEMBLY COMPLETELY ASSE MBLED 4 5 6A 2 IA B PROBE G R OU N D LEAD ASSEMBLY CONTAI NS 2 2 OHM RESI STOR 456 A 2I A 10 PROBE F L CENTER SECTION COIL SP R I NG TO C3 i FRONT PANEL I I O F I NSTRUMENT LI INTERNAL LOCKWASH E R Figure 4 3 Exploded View of P robe Assembly Section IV Figure 4 3 00395 1 4 5 ...

Страница 19: ...T 1101 OPEN leOV K T9 II o 11 0 Y 111 0 f nUIA t1191 r Y IV WK 011 1110 wlff v NOMINAL 11 0 2 J TO ull o RII 2 7 BL f WHT A 860 C90 4OI1F O OI f e5 O OI F e6 10UF R7 3300 AC POWER SUPPLY Rn 90 10K 40 IIf R93 6100 c 1 Q Q90 2N650 REGUL ATOR 131 BATTERY SUPPLY IIC IJLATC D r o 811 lIT 1 T lIT 2 f oOV BTl C O S 4V n 14 R IZ 100 U1 Figure 4 4 Model 456A AC Current Probe R9 ICO e93 lOll RIO 100 RI lao ...

Страница 20: ......

Страница 21: ... 3 O R DERI N G IN FORMAT I O N To order a replacement pa rt address order or in quiry either to your authorized sales office or to CUSTOMER SERVICE Hewlett Packard Company 395 Page Mill Road Palo Alto California or in Western Europe to Hewlett Packard S A Rue d u Vieux Billa rd No 1 Geneva Switzerland Specify the following information on a part 1 Model and serial number of the instrument Be s u r...

Страница 22: ...Diode germanium IN38A Diode silicon Connector female red Connector female black Connector male output Not assigned Cable power Transistor 2N1 516 0C1 70 ot assigned rransistor 2N6 50 esistor fixed composition 24 ohms 5 1 W esistor fixed composition 22 ohms Part of Probe Ground Lead Assembly Component not separately replaceable Mfr 1 Stock No 9 609 5 01 50 0008 5 6289 0 180 0050 5 62 89 0180 0061 5...

Страница 23: ...igned Resistor fixed composition 1 5 000 ohms 10 2 W Resistor fixed composition 680 oluns 10 1 2 W Resistor fixed composition 10 000 ohms 1 0 1 2 W Resistor fixed composition 6800 oluns 10 1 2 W Resistor fixed deposited carbon 4000 ohms 1 1 2 W Resistor fixed depOSited carbon 2 2 50 0luns 1 1 2 W Switch slide DPDT Not assigned Transformer powe r Section V Replaceable Parts Sheet 3 of 4 Mfr J Stock...

Страница 24: ...onnec tor male Can shield Boot cable Spacer standoff Lead probe ground includ e s R 5 Replaceable Parts Sheet 4 o f 4 Mfr 2 8480 2 8480 2 8480 i 99109 24655 24655 28480 28480 00866 28480 I F Stock No G 64B G 64C 8520 0017 456A 16A 8 120 0048 1 2 50 009 1 1 250 0092 4 56A 55A 4 12A 8 3A 0380 0048 4 56A 2 IA J rQ R S 1 0 1 0 1 0 1 1 1 0 1 0 1 0 1 0 1 0 1 0 1 1 See introduction to this section Model ...

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