Tektronix 434, Инструкция по эксплуатации

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Maintenance—434
1. Check Control Settings.
In c o rre c t c o n tro l settings
can indicate a tro u b le th a t does n o t e x is t. If there is any
q u e stio n a b o u t th e c o rre c t fu n c tio n o r o p e ra tio n o f any
c o n tro l, see the O p erating In s tru c tio n s section.
2 . Check Associated Equipment. B efore proceeding
w ith tro u b le s h o o tin g o f th e 4 3 4 , check th a t the e q u ip m e n t
used w ith th is in s tru m e n t is o p e ra tin g c o rre c tly . Check th a t
th e signal
is p ro p e rly connected and th a t th e in te r­
co n n e ctin g cables are n o t d e fe ctive . A lso , check the pow er
source.
3. Visual Check. V is u a lly check the p o rtio n o f the
in s tru m e n t in w h ic h th e tro u b le is located. M any tro u b le s
can be located b y visual in d ic a tio n s such as unsoldered
c o n n e c t io n s , b ro ke n w ire s, damaged c irc u it boards,
damaged co m p o n e n ts, etc.
4. Check Instrument Calibration.
C heck th e c a lib ra tio n
o f th is in s tru m e n t, o r th e a ffe cte d c ir c u it if the tro u b le
appears in one c irc u it. The a p p a re n t tro u b le m ay o n ly be a
re su lt o f m is a d ju s tm e n t o r m ay be co rre cte d b y c a lib ra tio n .
C o m p le te c a lib ra tio n in s tru c tio n s are given in th e C a lib ra ­
tio n section.
5. Isolate Trouble to a Circuit.
T o isolate tro u b le to a
c irc u it, n o te th e tro u b le s y m p to m . The s y m p to m o fte n
id e n tifie s th e c irc u it in w h ic h th e tro u b le is lo ca te d . F or
e xa m p le , p o o r focus indicates th a t th e C R T c ir c u it
(includes high voltage) is p ro b a b ly at fa u lt. When tro u b le
s y m p to m s appear in m ore th a n one c irc u it, check affected
c irc u its b y ta k in g voltage and w a ve fo rm readings.
In c o rre c t o p e ra tio n o f all c irc u its o fte n indicates tro u b le
in th e p o w e r s u p p ly . Check fir s t fo r c o rre c t voltage o f the
in d iv id u a l supplies. H ow ever, a d efective c o m p o n e n t else­
where in th e in s tru m e n t can appear as a p o w e r-su p p ly
tro u b le and m ay also a ffe c t the o p e ra tio n o f o th e r c irc u its .
Table 4-2 lists the tolerances o f the p o w e r supplies in th is
in s tru m e n t. I f a p o w e r-su p p ly voltage is w ith in the listed
TABLE 4-2
Power Supply Tolerance and Ripple
Power
Supply
Tolerance
Maximum Ripple
(Peak-to-peak)
Line
Frequency
25
Kilohertz
—15 v o lt
W ith in 0 .113 v o lt 10 m V
4 0 m V
+1 5 v o lt W ith in 0 .2 2 5 v o lt 10 m V 4 0 m V
+ 1 1 5 v o lt W ith in 4.6 vo lts
0.5 v o lt 0.5 v o lt
+ 250 v o lt W ith in 10 volts 1 v o lt 1 v o lt
—75 v o lt W ith in 2.2 5 vo lts 1 v o lt
1 v o lt
to le ra n ce , th e s u p p ly can be assumed to be w o rk in g
c o rre c tly . If o u tsid e th e to le ra n ce , the s u p p ly m ay be
m isadjusted o r o p e ra tin g in c o rre c tly . Use th e procedure
given in th e C a lib ra tio n section to ad ju st the pow er
supplies.
A fte r the d e fe ctive c irc u it has been lo ca te d , proceed
w ith steps 6 th ro u g h 8 to locate the de fe ctive c o m ­
p o n e n ts ).
6. Check Circuit Board Interconnections.
A fte r the
tro u b le has been isolated to a p a rtic u la r c ir c u it, check the
p in co n n e cto rs on th e c ir c u it board fo r c o rre c t c o n n e c tio n .
Figs. 8-1 th ro u g h 8 -23 show th e c o rre c t c o n n e ctio n s fo r
each board.
The p in c o n n e cto rs used in th is in s tru m e n t also p ro vid e
a c o n v e n ie n t means o f c ir c u it is o la tio n . F o r exam ple, a
s h o rt in a p ow er s u p p ly can be isolated to th e p o w e r su p p ly
its e lf by d isco n ne ctin g the pin co nnectors fo r th a t voltage
a t th e rem aining boards.
7. Check Voltages and Waveforms.
O fte n th e d e fe ctive
c o m p o n e n t can be located by checking fo r th e c o rre c t
voltage o r w a ve fo rm in th e c irc u it. T y p ic a l voltages and
w a ve fo rm s are given on the diagrams.
N O T E
Voltages a n d w a ve fo rm s given on the diagram s are
n o t ab so lute a n d m a y vary s lig h tly b e tw e e n in s tru ­
m ents. To o b ta in o p e ra tin g c o n d itio n s s im ila r to
those used to take these readings, see the fir s t
diagram page.
8. Check In d iv id u a l Components. The fo llo w in g p ro ­
cedures described m ethods o f checking in d iv id u a l c o m p o ­
nents in th e 43 4 . C o m ponents w h ic h are soldered in place
are best checked b y d is co n ne ctin g one end. T h is isolates the
m easurem ent fro m th e e ffe cts o f su rro u n d in g c irc u itry .
A . T R A N S IS T O R S . T h e best check o f tra n s is to r opera­
tio n is actual p e rfo rm a n ce u n d e r o p e ra tin g c o n d itio n s . I f a
tra n s is to r is suspected o f being d e fe c tiv e , it can best be
checked b y s u b s titu tin g a new c o m p o n e n t or one w h ic h has
been checked p re vio u sly. H ow ever, be sure th a t c irc u it
c o n d itio n s are n o t such th a t a re placem ent tra n s is to r m ig h t
also be damaged. I f s u b s titu te transistors are n o t available,
use a d y n a m ic tester (such as T e k tro n ix T y p e 5 7 6 ). S ta tic-
ty p e testers are n o t recom m ended, since th e y do n o t check
o p e ra tio n u nder sim ulated o p e ra tin g c o n d itio n s .
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