Tektronix 494AP service manual DBO DB5-DBO, Extmixer, Rfinput

Table&13 {cont)

Maintenance- 494A^l494ApServiceVot. 1

Table&13 (cont)

DataBlts

7 6 5 4 9 2 1 0

D.Digital Storage (cont)

Deseription

DataEits

7 6 5 4 3 2 1 0

F. Crt Readout

DB7-DBO

DB7-DBO

Ver$calDigltal Storage Board

FA

Datavaluesfrom digitalstorage.

A writeto 78 initializesoutputto beginat the left of the trace and proce€dto the right

FB

Alwayshighto indicatethat it is frornthe VerticalDigital Storage board

7A

Data valuesfor digital storage.

A writeto 78 clearsthe address

counterso valuesare storedfor

l x x x x x x x

0 x x x x x x x x l x x x x x x x 0 x x x x x x x x l x x x x x x x 0 x x x x x x x x x l x x x x x x x 0 x x x x x x x x x l x x x x x x x O x x x x x x x x l x x x x x x x 0

D84

oB2

Crt Controt(5F)

Spectrumchopenable

Spectrumchopdisable

32characters/line

40characters/line

2lines

16 l i n e s

Max spandot on Max span dot ofr

Address2F containsan address Address2F containsdata Readoutenabted

Reacloutdisabledto load readout A8 (addressbit 8)

A9 (addressbit 9) Address/Data(2F)

pointson the displaystartingat

the left and proceedingto the

rightin order

7B

DB7.DB6 l f D B l i n 5 F - 1 - A 7 , A 6 o f address.With Ag and A9 in 5F, they specify the line number (0-F).

DB5-DBO l f D B I i n 5 F - 1

x 1 ' l x x x x x

x l 0 x x x x x

x 0 l x x x x x

x x x ' t x x x x x x x 0 x x x x

E. Z-Axls & RF Interfaee

Peak/Averagecursor in knob position

Peak/Averagecursor in peak position

Peak/Average

cursor in Average

position Max Holdon Max Holdoff

Z-Axis& RFAttenuator{4F)

D87

DBO

DB5-DBO

A5-40 of address. This specifiesthe characterposi- tion in a line.

l f D B l i n 5 F - 0

1 - Characteris a space

0 - Characteris not a space l f D B l i n 5 F - 0

1 - S k i p a l i n e

0:Don'tskipa tine lf DBl in 5F :0

l x x x x x x x 0 x x x x x x x x 1 x x x 1 x 1 x 1 x x x 1 x 0 x 0 x x x 1 x 1

Baselineclipperon Baselineclipperoff

0 dB RF attenuation

10 dB RF attenuation

20 dB RF attenuation

G. Sweep

Charactercode (lower6 bits of ASCII)

1 F

x 1 x x x 0 x 1 x 1 x x x 0 x 0 x 0 x x x 0 x 1 x 0 x x x 0 x 0 x x l x x x x x x x 0 x x x x x x x x l x x x x x x x 0 x x x x x x x x O x x x

x x x x x x l x x x x x x x 0 x

30 dB RFattenuation

40 dB RF attenuation

50 dB RF attenuation

60 dB RF attenuation

829MHz2nd converter

2 GHz2ndconverter

EXTMIXER

RFINPUT

100ms to switchattenuator

PowerSuppliesStatus(CF)

Fault

Suppliesokay

l x x x x x x x x l x x x x x x x x l x x x x x x x x x l x x x x x x x x l x x x x x x x x l x x x x x x x x l

Extended Address 1 and Address 2

ExtendedAddress1

ExtendedAddress0

MarkerDAC/RampGenerator

TriggerSingleSweep

DisableSweepGate

DisableTrigger

Abort Sweep

Subaddressbits for Port 0F giv- ing subaddresses3-0. Subad- dresses0 and t havethe rest of the control bits not on Address lF. Subaddresses2 and 3 receive the 12 bits to set the DAC.

6-59