Tektronix 2445, Instruction Manual

Page: 127 / 351

Adjustment Procedure— 2445 Service
AUTOMATIC CALIBRATION CONSTANTS, HORIZONTAL AND VERTICAL
GAIN, CENTERING, AND TRANSIENT RESPONSE ADJUSTMENTS
N O T E
Within the follow ing procedure, the calibration constants fo r timing, vertical gain, an d trigger level a re g en erated b y the
system m icroprocessor an d are sto red in nonvolatile m em ory. The adjustm ents in CAL 01, 02, 03, an d 0 4 should be
p erform ed in num erical sequence, i.e., CAL 01 should be done before CAL 02, CAL 0 2 should be done b efore CAL 03,
etc. P erform ing p a rtia l procedures (i.e. only one o r tw o o f the CAL step s) is n o t recom m ended an d should only b e done if
the calibration constants th a t w ould have been s e t in the preceding steps a re know n to be correct.
The CAL functions are available only if the C A L /N O CAL ju m p e r (P 501 on the C ontrol B oard) is in the CAL position
(betw een pins 1 an d 2 ) when p o w e r is turned on. When the auto m atic calibration procedures are com pleted, return the
ju m p er to the N O CAL position to p reven t en try into the calibration routines.
Equipment Required (see Table 4-1)
Calibration Generator (Item 3) Dual-Input Coupler (Item 10)
Time-Mark Generator (Item 5) 5X Attenuator (Item 16)
50 BNC Cable (Item 9) Digital Multimeter (DMM) (Item 18)
Alignment Tool (Item 19)
S ee
ADJUSTM ENT LOC ATIO NS 4
a t the re a r o f this m anual fo r te s t p o in t an d adjustm ent locations.
Initial Control Settings.
CAL/NO CAL jumper CAL position (between
pins 1 and 2) prior to turn­
ing on power
N O T E
When perform ing the au tom atic CAL steps, in itial set­
ting o f the front-panel controls is n o t required.
CAL 01— HORIZONTAL
b. CHECK—Top line of the readout display says:
“DIAGNSTIC. PUSH A/B TRIG TO EXIT”.
N O T E
The “m en u ” o f calibration, test, a n d exercise routines
a re in a loop th a t m ay b e scrolled through in single
steps, e ith e r fo rw ard o r backw ard. Pressing up o r
dow n on the TR IG G E R M O D E sw itch a n d releasing it
respectively increm ents o r decrem ents the m enu posi­
tion b y one. A s each routine is selected, its nam e
appears in the to w er le ft co rn er o f the read o u t display.
1. Check/Adjust Horizontal Timing, X I Gain
(R860), X I 0 Gain (R850), Hrz Ctr (R801), and Trans
Resp (R802).
push buttons, then press and hold the SLOPE switch. Hold
all three switches in for approximately one second, then re­
lease them.
W hen perform ing a calibration siep , touch oniy ih e
specific control o r controls called o u t in the procedure.
M ovem en t o f o th e r controls m ay cause erroneous cal­
ibration results.
c. Scroll to CAL 01.
5-9