VISTEK V1626 User manual

1
VISTEK V1626
DIGITALTOANALOGUE
CONVERTERUSERGUIDE
www.pro-bel.com

VISTEKV1626digitaltoanalogue
converter
2Issue 1
Contents
1. OVERVIEW..............................................................................................................3
2. INSTALLATION........................................................................................................4
2.1 Introduction.............................................................................................................4
2.2 Installing Modules..................................................................................................4
2.3 Rear Panel Connections........................................................................................5
2.4 Front Panel Controls..............................................................................................6
3. ONBOARD CONTROLS &ADJUSTMENTS..........................................................7
3.1 Main Board..............................................................................................................7
3.2 Matrix Sub-board....................................................................................................9
4. CALIBRATIONOF V1626 DAC MODULE.............................................................10
4.1 Introduction...........................................................................................................10
4.2 Test Equipment.....................................................................................................10
4.3 Environmental.......................................................................................................10
4.4 Calibration Procedure..........................................................................................11
4.4.1 Power Distribution Check..............................................................................11
4.4.2 Clock Centre FrequencyCalibration..............................................................11
4.4.3 Y, Pb,Pr DCOffsetAdjustment.....................................................................11
4.4.4 N10/SMPTE leveladjustment (including syncs)............................................12

VISTEK V1626 digital to analogue
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1. OVERVIEW
The V1626 10 Bit Monitoring DAC Module provides10 bit conversion between aComponent SerialDigital
input signal to RGB or YPbPr output (N10/SMPTElevels), adedicated re-clocked Serial Digital output as DA
and a separate SyncO/P isalso provided.
Three auxiliaryoutputsare available. These maybe configured aseitheran extraset ofY,Pb, Pr or three
spare serial SDI outputs.
Remote control interface isavailable for communication between moduleswithin the frame, and others
outside it.
With the optional matrixboardfitted, the unit can be configured to provide RGB output, or YPbPr with
Betacamlevels.
Near 601 performance filters are employed.
Main Features
• Full 10 Bit Precision
• NearCCIR 601 Performance Filtering
• User selectable configuration
• RGB or, with optional matrix board, YPbPrOutputs (N10 or Betacamlevels)
• 4x Serialoutputs

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2. INSTALLATION
2.1 Introduction
Thissection givesinformation on installing the V1626 DAC modulesinto the V1601 and V1603 interface
framesand detailson the connectionswhich can be made to it. Information is alsosupplied on the function
ofeach Preset adjustment and switch which are made available to the user on the front panel.
2.2 Installing Modules
The V1601 and V1603 framesare normallysupplied with modulesfitted. However,if further modulesareto
be fitted to a part loaded unit follow the instructionsbelow.
Rear (I/0) modules
Removethe screwsfromthe blanking plate covering the spare position at the rearofthe equipment and
removethe plate. Place the newrearmodule in frameand slide into the unit until the connector(s)mates.
The connector panel on the rear module should be seated flush with the rearcrossextrusionsofthe frame
when inserted correctly. Screwthe module to the rear cross extrusionswith the screwsprovided.
Front modules
Withdrawthe front panel ofthe frameand fold it down. Place the new front module in the card guides(take
care to insertthe circuit board into the runnersand not the screen plate)and slide into the frameuntil it
mates with the rearmodule. Close the front panel.

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2.3 Rear Panel Connections
AII the input and output connectionsare available on the rear panel asshown below.
SerialDigital Input:
SD (IN)
ThisBNC connectoris internallyterminated with 75 Ohms.The Serial
Digital Input should be connected to this BNC.
SerialDigital Output:
SD1 (OUT)
Active loop through output fromSD (IN).
SerialDigital Outputs:
SD2 (OUT) - SD4 (OUT)
Serialdigital outputs to SMPTE T14.22/082.
OR
Additional Y, Pb, Pr outputs, see SW5, SW6 &SW7.
Component Outputs/Digital Outputs:
Y/G/SD5, Pb/B/SD6, Pr/R/SD7.
Sync Output:
S/SD8
Thisisa separate sync supplied separatelyfor component outputs.

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2.4 Front Panel Controls
A view of the front panel indicatorsand controls is shown below.
Front Panel Indicators
The +V lamp indicatesthat powerisapplied to the module.
The REM lamp indicatesthat the module/control systemcommunications link
is accessing the module.
The 525 lamp indicatesthat the unit is working in 525 mode and islocked to 270
Mb/s serial digital input signal.
The 625 lamp indicatesthat the unit is working in 625 mode and islocked to 270
Mb/s serial digital input signal.
Front Panel Controls
3 variable resistors for gain output adjustment.
These adjustmentsare set at the factory. It isrecommended that these are
not adjusted without the correct monitoring/test equipment.

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3. ONBOARD CONTROLS &ADJUSTMENTS
3.1 Main Board
Locations ofswitchesand Preset potentiometersare shown in the figure below.
Togain accessto these controls and adjustmentsthe boardmust be removed fromthe chassis.If the
adjustmentsneed to be made while the unit ispowered up, an extendercard needsto be used.

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When reference isgiven to the direction /position ofswitch settings, it assumes that the module isin the
verticalposition as in the rack with its control panel on the left.
Switch Setting Function
SW1/1 Off
On
8 bit operation
10 bit operation
SW1/2 Off
On
Blackclip enabled
Blackclip disabled
SW1/3 Off
On
Not used
SW1/4 Off
On
VITC passed
VITC blanked
SW2To the rear, a-b
To the front, b-c
Sub module output if fitted
YPbProutputsfrommain board
SW3To the rear, a-b
To the front, b-c
Sub module output if fitted
YPbProutputsfrommain board
SW4To the rear, a-b
To the front, b-c
Sub module output if fitted
YPbProutputsfrommain board
SW5Up, b-c
Down, a-b
Spare Y(N10)output
Spare re-clocked SDI output
SW6Up, b-c
Down, a-b
Spare Pb (N10) output
Spare re-clocked SDI output
SW7Up, b-c
Down, a-b
Spare Pr(N10) output
Spare re-clocked SDI output
The following potentiometersare calibrated at the factorybefore delivery, the unit will need to be re-calibrated
if the settings are altered (see calibration section).
Y,Pb,Pr DC offsetadjustment.
VR1, VR4 and VR8 adjust DC offset ofthe Y, Pb and Pr channels respectively.
Y,Pb,Pr Gain Potentiometers
VR2, VR3, and VR6 adjust the gain ofthe Y, Pb, Pr channels respectively.
Deserialiser VCO centre frequencyadjustment. (Test point TP4)
VR5 adjustsforcentre frequencyon TP4 the deserialiser PLL voltage test point.
Sync Amplitude Adjustment
VR7 adjustsoutput syncamplitude.

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3.2 Matrix Sub-board
The matrix sub-board is designed to convert aY,Pb, Prcomponent N10 level signal into an RGB output. By
means of switches on the sub-board, it is alsopossible to by-pass the matrix section and provide the Y,Pb,
Pr output signal at N10 or Betacamlevels.
VR1 adjuststhe Ygain for525 Betacamlevel. Pb and Pr are not adjustable on the sub-board.
VR5 adjuststhe pedestal on the 525 Betacamsignal.
VR2, VR3 and VR4 adjust the G, B, R output levels.
Switch Position Function
SW1b-c
a-b
Syncs on Green in RGB mode
No syncs on green
SW2b-c
a-b
Syncs on Blue in RGB mode
No syncs on blue
SW3b-c
a-b
Syncs on Red in RGBmode
No syncs on red
SW4-1 ON
OFF
RGB outputsselected
YpbPr outputsselected
SW4-2 ON
OFF
625 BetacamYpbPr output level
625 N10 YpbPr output level
SW4-3 ON
OFF
525 BetacamYpbPr output level
525 N10 YpbPr output level
SW4-4 ON
OFF
Remote Control

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4. CALIBRATIONOF V1626 DAC MODULE
4.1 Introduction
Thissection is intended to provide sufficient information to allow an engineer to calibrate the DAC system.
Calibration should onlybe carried out if the unit has been mal-adjusted, or ifdrifthas occurred over an
extended period oftime.
It should be appreciated that calibration isnot aduplication ofthe alignment procedure whichshouldbe
referred to ifa repairhasbeen carried to the module.
4.2 Test Equipment
100 MHzdual channel oscilloscope.
TektronixTSG-422 10 bit serial test signal generator.
TektronixWFM601i Serial signal analyser.
Tektronix1781 test set
Digital multimeter
Standard RS trimtool
4.3 Environmental
The calibration should be carried out at a nominal temperature of20 degrees Celsius.
TestEquipment Connection
Connect the serial digital outputsof the TSG422 to inputs ofthe unit under test.
Connect one ofthe serial digital outputsfrom the unit under test to the VFM601i via acable clone. Initiallyset
the cable clone to zero metres.
Connect the YPb, Proutputs of the unit undertestto TEK1781 set. Use cablesof the sametype and equal
length (this is necessaryfor luma-chroma delaycalibration).

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4.4 Calibration Procedure
Initial Set-up: Ensure the following switchesare set as detailed before starting calibration.
Switch Setting Function
SW1-1 ON 10 bit operation enabled
SW1-2 ON Black clip disabled
SW1-4 ON Vertical interval data blanked
SW5, 6, 7 a-b Auxiliaryoutputsconfigured forSDI
SW2, 3, 4 b-c Main outputs configured for YPbPr (N10/SMPTE)
4.4.1 Power Distribution Check
Using a Digital Multi Meter, check the following pointsforthe specified dcpotentials:-
TP2 +5V +/-0.2 V VCC
TP3 +5V +/-0.2 V P5V A
TP1 -5V +/- 0.3 V N5VA
TP6 maybe used as the ground reference
4.4.2 Clock Centre FrequencyCalibration
Set the TSG422 generator to provide the SDI matrix check field.
Whilstmonitoring the 601i and TP4 (oscilloscope)adjustVR5 (VCO centre frequency)until lock is achieved
without data errors.Amethod for setting the VCO centre frequencyisdescribed in the Gennum1994 Data
book(page 2-47):
"Tune the potentiometer (VR5)sothat the PLL loseslock at the lowend (lowestloop filter voltage at TP4).
Increasethe potentiometer slowlyuntil the loop re-locks. Record the loop filtervoltage at this point as Vcl.
Nowadjust the potentiometer(VR7)so that the loop filter voltage (TP4)is200mV above Vcl."
Remove and then re-applythe serial input signal. Confirmthat the card re-locks.
4.4.3 Y,Pb, Pr DC Offset Adjustment
Set the TSG422 generator to provide 625 100% colour bars.
Monitorthe Youtput using the oscilloscope.
Adjust VRl for a dcoffset of0V +/-10mV on the displayed signal.
Monitorthe Pb output using the oscilloscope.
Adjust VR4 fora dcoffset of 0V +/- 10mV on the displayed signal
Monitorthe Pr output using the oscilloscope.
Adjust VR8 fora dcoffset of 0V +/- 10mV on the displayed signal

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4.4.4 N10/SMPTE level adjustment(including syncs)
Set the TSG422 generator to provide 625 100% colour bars.
Monitorthe Youtput using the 1781 measurement set. Adjustthe front panel Ygain control pot (VR2) for an
amplitude of 700 mV blackto peakwhite.
Adjust the syncsamplitude pot (VR7) for 300 mV p-p of syncs.
Monitorthe Pb output using the 1781 measurement set. Adjustthe front panel Pb gain control pot (VR3)for
an amplitude of700 mV peakto peak.
Monitorthe Proutput using the 1781 measurement set. Adjustthe front panel Pr gain controlpot (VR6)for
an amplitude of700 mV peakto peak.
Set the TSG 422 generator to provide 525 100% colourbars.Checkthat the Y,Pb, Pr levelshave not
deviated fromthose set above.
Thiscompletes the V1626 DAC Module calibration.