BRUEL & KJAER 2502 Operating instructions

BROEL & KJ..€R
N ce rum -Denmark
Consisting of:
Removal of the Case.
Serv i ce Instructi ons
Vibration Meter
Meter Circuit
Output Amplifier
Function Sele~tor
Position of Components
Parts List
Circuit Diagram
2502.1
2502.2
2502.3
2502.4
2502.5
2502.6
2502
After removing the four HEX/HD screws on the front panel, it is possible to slide the chassis and the front panel out of the rack or
the wooden case.
The metal case con be pulled out after the two screws on the bock panel hove been removed.
Block Diagram
Accelerot1on
Density~
Input Acc . Oens..
Alt
Function Meter
Selector Indication
l.F. Cut-Off Vibration
(Remote lewl {Remote Centro!.
Controt Potentiom.rters from generator)
Function
(R~Mnote Control Selector from
fromLL.ll) {RernoteControl
geMrator
from 441 1)
Trouble Shooting.
(-Control
from generator)
l DC
f Output
Control
S1gnol
Output
If the reason for a fault is not on obvious one such as a dead tube or transistor, broken down resistor, blown or disconnected fuse
etc., then first test the voltages of all the tubes and compare them with the voltages shown in the circuit diagram in order to loca-
lize the defect. Should this method of finding the fault prove unsuccessful, then check the instrument by adopting the method de-
scri bed in the adjustment procedure. When the troub le has been found and remedied, the voltages and adjustments which ore influ-
enced by the remedy must be rechecked.
The tolerances stated in the instructions can only be used as a guide for adjustment and control,. but any deviations must not be cor-
rected without being sure that the tolerances of the instruments used for making the adjustment ore so small as to have no influence
on the measurements.
The instructions in this Manual ore given purely as a guide to the service of equipment with minor faults. Some faults, as f. inst.
small deviations in tolerances require for their correction special control equipment and extensive ex p erience, and in these cases it
is necessary to send the instrument to the factory.
Spore P orts.
P lease state type and seria l number of apparatus when spa re ports are ordered.
Instruments Necessary for Service and Repair:
F re q uency Analyzer type 21 07
( El ectronic Voltmeter type 2409)
Oscil l oscope
Bea t F requency Osci ll oscope type 1013
B eat F requency Osc il loscope type 101 7
F requency Counter
Mu l timeter (50 IJA)
2502 - 3.67

BROEL & KJJ£R
Ncerum - Denmark
1 .1 . Mechanical Zero-paint
METER TIME CONSTANT : "Off"
1. 2. Electrical Zero-paint
METER TIME CONSTANT: "1 sec."
1.3. Sensitivity
METER TIME CONSTANT: "1 sec."
1. 4. Ba l ance
METER TIME CONSTANT: "1 sec . "
2502 .1 - 3 .67
M . eter Circuit
2502.1
v alid from serial no. 172571
Adjust meter
scale for 0 .
Connect pin 7 of "Vibration Level Potentiometer" socket to ground .
Check that the painter is still at 0 .
Tolerance: Y2 painter "width" .
Vibration Level
Potentiometers
V 1 removed.
(00000)
2512
Frequency: 1000Hz. Adjust input signal for full scale deflection on type2502 .
Input voltage: Appro x. 9 V.
V 1
removed.
Frequency: 1000Hz. Adjust input vo ltage for full scale deflect ion on type
2502,
Measure the voltage across R 135 and R 1 36. Approx. : 9 V, max. di fference: 0. 3 dB.
(located on printed circuit XC 0258)
continued

1 .5 . Frequency Response
METER TIME CONSTANT: "1 sec."
1 .6. Overload
MEtER TIME CONSTANT: "!Osee . "
1.7. DCAmplifier
METER TIME CONSTANT: "1 sec."
1 .8. Meter Time Con.stdh.t
METER TIME CONSTANT: "30 sec. '1
l .9. Ripple
V 1 removed .
Frequency :
1000Hz. Adjust input vol tage foro 9,8 V deflection on type 2502.
Chec k the frequency response from 5 Hz to 100 kHz .
Tolerance: ± 0,2 V. (+ tolerance of type 1013, 1017:0 ,5 dB)
If necessary adjust P6 ot 100kHz . (locat ed on printed ci r cuit XC 0258)
V 1 removed.
Frequency: 1000Hz. Input voltoge:l2 dB abo ve full deflection on type 2502.
Chec k with an osci lloscope across R135 and R136 that the signal is not distort-
ed .
V 1
removed.
Frequency: 1000Hz. Adjust input voltage fdr full scale deflection on type
2502,
Measure the DC v oltage on "DC - Output" socket, pin 3:-6 .5 V.
Tolerance: ±2 % .
If necessary short-circuit C 47 to ground and adjust P7 for 0 Von "DC Out-
put" sockei, pin 3.
(C 47 is located on printed circuit XC 0258 arid P7 on XC 0226)
V 1 removed.
Frequency: 1000Hz . Adjust input voltage far a 10 V deflection on type 2502.
The meter time constant means the time it takes the meter pointer to fall from
10 V to 3,5 V when the input signal is disconnected.
in pcjslti~n "30 sec" the meier time constant should be 30 sec.
Cfieck METER tiME CONSTANT in position 0;3 -1-3-10 sec.
METER TIME CONSTANT: "Ali positions Vi re moved.
except0,3sec," Frequency: 1000Hz. Adjust input voltage far full scale deflection on type
2502,
MedSure the ripple on pin 3 of "DC Output" socket by me.:ms of voltmeter type
2409 .
tolerance : Max. 1 mV.
b .
METER TIME CONSTANT: "0,3 sec."
As item a .
Tolerance : Ma x. 5 mV.
2502 .1 - 3.67

BROEL & KJJER
Nc:srum - Denmark
Ou~put Amplifier
2502.2
2.1 . Sensiti vi ty
. ~ ,,
;0i
:•!· : ·: ~ ! - .: .~;~• ·
1013
(1017)
METER TlME CONSTANT: "1 sec."
FUNCTION SELECTOR: "Ext. Eilter"
v alid from ser ial no . 1 7257 1
1
o Ext
3 o J.O o 5 Fitter
6 0 0 7
2502
Frequenc y: 500 Hz . Adjust inp ut vo ltage foro 10 V deflection on ty pe 2502.
The input v oltage should be appro x . 10 mV.
1013 p 10
(1 01 7)
2.2. Acceleration Density
METER TIME CONSTANT: "1 sec . "
FUNCTION SELECTOR: "Ace. D en ."
ACCEL. DENS IT Y RANG E: "0,0 1"
2502.2 - 3. 67
Le 1e ~
Pote r1t1om eters
Input signa l: 100 mV, 500 Hz .
D eflection on type 2502: Full scale (<'0 dB)
If necessary adjust P 10
continued

2. 3. Frequenc y Res ponse
METER TIME CONSTANT:"! sec."
FUNCTION SELECTOR: "Ace. Den ."
ACCEL. DENSITY RANGE: "100"
ACCEL. DENSITY RANGE to "0,01"
2.4 . Overloading
FUNCTION SELECTOR: "Ace. Den."
2 .5 . ACOutput
FUNCTION SELECTOR: "Acc.Den . "
LEVEL BELOW CROSS-OVER: "0 "
ACCEL. DENSITY RANGE: "1 00 "
b. LE V EL BELOW CROSS-O V ER to "10"
LE V EL ABOVE CROSS-O V ER to "0"
d. LE V EL ABOVE CROSS-O V ER to "1 0"
2 .6. Noise and H um
FUNCTION SELECTOR: "Ace. D en."
ACCEL. DENSITY RANGE: "100"
2502.2 - 3 . 6/
Input signal: 10 V, 1 000 Hz.
Deflection on type 2502:100 g2 / cps
Check t he frequency response from 10 - 100.000 Hz.
Toler ance:± 2%
If ne cessa ry change v alue of C 79 (located on printed circuit XC 0258)
Input signal: 100 mV, 1000Hz.
Deflection on type 2502: l g2 / cps
Che ck the frequency re s ponse again::!:" 2 %.
If necessa ry adjust P 5 at 100kHz. (located on printed circuit XC 0258)
Input frequency: 1000Hz.
Connect on oscilloscope to "Vibration Level Potentiometer" socket pin 3, and
check that the signal is not distorted until12dB obove full scale deflection on
type 2502 .
Monitor
Frequency: 1000Hz. Adjust the input voltage for 10 Von "Vibration Level
Potentiometer" socket pin 3 .
The v
oltage on "Monitor" socket should be 10 V,
The output on "Control Signal Output" socket pin 1 should be max. 1 dB be-
low 10 V.
Output voltage on "Control Signal Output": 22-26 dB below 10 V
Connect a shorting link on "Cross-over" socket between pin 3 and 6 in order
to energize relay 0 16.
Output on "Cont rol Signal Output" socket pin 1 should be ma x. 1 dB below
10 v.
O ut put vol loge on "Control Signal Output": 22-26 dB belo w 10 V
The instrument must be in its case or in another w ay effectively screened.
Disconnect sign al in put and check noise and hum on "Vibration Le vel
P otentiometer" s ocke t pi n 3.
Max . 10 mV.

BRO EL & KJ.ER
Ncsrum -Denmark
. ~·:
:~:i:
.~~
=·!·:i:~!- ·'•~;~• :·
1022
3.1. Sensitivity Control
Function Selector
valid from serial no. 172571
1022
Ace. Gen.
Input
Relay Control Cross-over
1022- 2502
Relay Control
2502.3
2502--.1025 Relay Control B
· METER TIME CONSTANT: "1 sec . " The 2502's meter should read the v
alues given in the table (within 4% ) under
the stated conditions .
METER INDICATOR: "RMS"
Input to
ACC.GEN.
Relay Control
energized 1)
on pins
11
Accel.
11
g
11
Grad
11
gF
11
Vel.
11
in/sec.
11
Displ.
11
inches
11
Auto
11
D-A
11
Auto
11
V-A
11
Auto"
A-G
2502.3 - 3.67
It will be necessary to select suitable settings of the four RANGE selectors
according to the meter readings.
Readings in the 3 programmed "AUTO" positions of FUNCTION SELECTOR de-
pends on whether or not the cross-over rela ys are energized via pin 1 of "Relay
Control".
If a type 1008, 1019, 1025 or 1040-1042 is used, the "Relay Control" will be
energized automatically.
If a type 1022 {1 013 and 1017) is used, the - 6 V can be taken from pin 3
the "Crass-over" socket an type 2502.
10Hz
40Hz
125Hz 500Hz 2000Hz 8000 Hz
100 mV 100 mV
1V 1V 1V
1 v
52)
52) 52)
3 3 3
2 2 2
10 10 100 100
100
100
1,26 0,63 3,57 1,78 0,893 0,447
-
61,6 15,4
49,2
12,3 3,1
0,98 0 ,0613 0,0627 0,00392
-
-·~-
0,0627 100
in g - -
49,2 100
in/sec. g
100
3,57
g
gfs&.
Notes: 1) 6 V negative with respect to pin 4.
2) Energizing these pins should suppress low-frequency noise from the
generator but should not affect the sensitivity at the signal frequen-
cy.
If the sensitivities are w rong, make the following adjustments .
After
each adjustment check the values given in the table.
continued

3.2. Acceleration Sensitivity Adj.
ACCEL. RANGE: "100"
METER TIME CONSTANT: "1 sec."
METER INDICATION: "RMS"
FUNCTION SELECTOR: "Acceleration"
b. METER INDICATION to "A.V. peak"
3.3. Displacement Sensitivity Adj.
DISPLACEMENT RANGE: "fJ.Ol"
METER TIME CONSTANT: "1 sec."
METER INDICATION: "RMS"
FUNCTION SELECTOR: "Displacement"
b. METER INDICA Tl NG to "D peak-peak"
DISPLACEMENT RANGE to "1"
METER INDICATION to "RMS"
3.4. Rangex10
ACCEL. RANGE: "100"
METER TIME CONSTANT: "1 sec."
METER INDICATION: "RMS"
FUNCTION SELECTOR: "Acceleration"
b. FUNCTION SELECTOR to "Auto"
ACCEL. RANGE to "10"
3.5. Noise and Hum
2502.3 - 3.67
Frequency: 500Hz. Adjust the input voltage to exactly 1 V.
It is recommended to use an electronic counter to monitor the test frequency.
Adjust P 3 for a 100 g deflection. (located on printed circuit XC 0258)
Adjust the input voltage for a 11 dB deflection on type 2502.
Adjust P 2 for a 20 dB deflection. (loco ted on printed circuit XC 0258)
Input frequency: 500Hz. Input voltage exactly 2.55 V.
Connect "Relay Control" pin 4 to ground and pin 5 to -6 Von "Cross-over"
pin 3 in order to energize 0 14 for a better low frequency stability.
Adjust P 4 (on ;>ri;1ted circuit XC 0258) for full scale deflection.
Adjust the input voltage for a 11 dB deflection on type 2502.
The deflection should now be 20 dB.
Remove connection to
11
Cross-over" socket pin 3.
Input frequency: 5Hz. Input voltage exactly 25.5 mV.
Adjust P 1 to 4% below full scale deflection.
Input signal: 1 V, 500 Hz
Deflection on type 2502: 20 dB.
Connect "Remote Function Selector" pin 4 to ground and pins 2 and 7 to -6 V
on "Cross-over" pin 3 in order to energize -Range x 10 Relay 0 1
Deflection on type 2502:20 dB.
Type 2502 must
be in its case or in other way effectively screened.
Measured on "Vibration Level Potentiometer" socket pin 3 in the frequency
range 20-40000 Hz .
Switches in all positions .
Max. noise and hum: 75 mV.

BROEL & KJJER
Ncerum -Denmark
+250V
6,3V "v
-6V
+ 250 v
C11
c 26
02
I
I
:.
Position of Components
val id from serial no. 172571
Control Signal
Output
pin 1 +250V
Vibration Level
Potentiometers
pin 2 pin 3 6,3VtV
C11
2502.4
I
I
I
.:
'-- --------- ~
-----~
Ground -6V Ext. Filter 0 27 0 26
XC 0258
2502.4 -3,67

025 025 025 025 025 025 -30V 6V pin3 C47 V17e
Ace. Density
Input
021
Ground
-6V
Ace. Gen.
Input
0 27
Ground
2502.4 - 3. 67
Ground
+ 250 v
6 V"V
c 11
C10
DC· XC 0258
Output
XC 0226
XC 0380
V11c Ground C5 Ground V11 b
~ - --1 - Ground
30 vrv
~~ ~(tQ ~ - 30V
R181. XC 0258
aa ;...._ --+-- - c10
'-- --- -+ -c 10
L..+- - - -- --- c10