Troubleshooting the Equipment

A TV studio is vastly more complicated than even our largest and most complicated computer. Consequently, there is a lot more that can go wrong. This document provides information about the most common problems, how to diagnose them, and what to do to correct them.

The Best Uninterruptable Power Supply (UPS)

The entire TV studio gets it's electricity from a Best corporation FE5.3KVA Uninterruptable Power Supply. This filters out power glitches, and prevents master tapes from being ruined when the external electricity fails in the middle of an edit. The battery is large enough that the entire studio can run for 20 minutes without external power, so that an orderly shutdown can be arranged. By switching off all unnecessary equipment it is sometimes possible to stretch the runtime to more than an hour, which may be enough time to finish a "rush" project in the dark.

The UPS is programmed so that if the power feed remains off for so long that the UPS battery runs out, the UPS will not restart when the power is restored. Once the equipment is safely off, there is no point in bouncing things on and off again. Everything is left off until some human shows up to use the studio again.

As a result, it is not uncommon to find that the UPS has shut off over the weekend. To turn it on again, ensure that the green AC LINE and READY indicators are lit. Then on the front panel press the red CONTROL button, then the "2" (two) button, then the blue ENTER button. The system should power up with a loud snap.

If the green AC LINE indicator is not lit, there is no electricity. The UPS gets it's electricity from the power distribution unit (PDU) in Room 100, which has it's own power-fail trips and emergency power off (EPO) circuit, as well as a circuit breaker for the UPS. (Breaker #???). Ensure that the PDU is operating normally.

If the graphics lab is going to be unused for a long time, the best way to shut everything down is by simply shutting off the UPS. On the front panel, press the red CONTROL button, then the "1" (one) button, then press the blue ENTER button twice. The whole graphics lab (including most of the UNIX workstations) will immediately power down.

The Tektronix Sync Generators

There are two identical Tektronix TSG-170 NTSC Television Generator units. The one mounted over the Abekas only affects the operation of the Abekas, the one mounted in the middle rack is the house master sync generator, and affects every single piece of equipment in the racks.

For some reason, when first turned on, the sync generators sometimes don't power up properly. The green power indicator (labeled "SELECT TEST SIGNAL") is glowing, but there is no output signal. The best way to check for this condition is to examine the front of the VPE-251 edit controller; if the red "NO SYNC" indicator is lit then there is a problem, if it is not lit then the master sync generator is probably fine. As a further check, press the red COLOR BARS button on the video switcher program bus; the color bars pattern should be visible on the program video monitor.

If the sync generator is not operating properly, go to the back of the rack and power cycle the unit. Next to the power cord on the back of the sync generator, there is a pushbutton power switch. Pushing it once will cause the button to pop out to the OFF position. Wait 3 seconds, then push it again, making sure that it latches in the ON (depressed) position. So far, this has always cured the problem.

Occasionally, someone fiddles with the buttons on the front of the master sync generator, and selects one of the other test patterns. If pressing the red COLOR BARS button on the video switcher yields a different test pattern on the monitor, press the leftmost button on the front of the sync generator (under the icon of the SMPTE colorbars). The green indicator light over top of the icon should illuminate.

The Primary Monitors

In the center of the control table there is a block of four primary monitors. Ensure that all four are turned on. They should all be set to input "A" except for the upper right monitor, which should be set to RGB. The function of these monitors is this:

	+------------+   +------------+
	|            |   |            |
	| Abekas Ctl |   | Edit Ctlr  |
	|            |   |            |
	+------------+   +------------+

	+------------+   +------------+
	|            |   |            |
	|   Preview  |   |  Program   |
	|            |   |            |
	+------------+   +------------+

If the Abekas or edit controller are switched off, their monitors will remain dark.

When finished for the day, it is best to select "BLACK" on the program and preview bus on the video switcher, turn off the Abekas, and change inputs on the Edit Controller monitor to VTR, so that the screen goes black.

The Video Switcher

The Grass Valley GVG 200-1N video switcher exists in two parts. The large control panel has it's own power supply behind the table. All the video processing is done in the large aluminum electronics frame mounted in the 4th rack from the left. The frame has a power supply in the bottom of it; the three green indicators should all be lit.

In order to conserve bulb life, the control panel has a "screen saver" mode. When dozing, the word "OFF" is displayed on the four LED displays, and all the illuminated buttons are dark. The processing of the video signal is not affected, only the control panel is dozing. To wake it up, press any key, once. That one keypress causes the control panel to "wake up" and light all the indicators. As a good practice, it is best to press the BLACK button on the preview ("preset background") row; that way if you accidentally press it twice nothing bad will happen, even if an edit is underway.

The switcher has a lot of state. Usually people don't mess with portions of the switcher that they are not using, but in case some curious button-pusher has been by, here are the "normal" settings. (When the unit was first delivered it took me hours to get things into the right settings).

Make sure the EDITOR button is the only button illuminated in the "Enables" row.

Make sure that the white PST/DSK button is the only button illuminated in the "Preview" row.

On the Program Transition unit, ensure that the BKGD light is ON, and the DSK light is OFF. If the green indicator "DSK ON" is lit, press the "BLACK" input select on the Program Background output bus to cancel it.

In normal video editing, the program bus is assigned to "M/E 1", and the preview bus is assigned to monitoring VTR-R. Both the white and yellow Key bus should be set to the BLACK input. The edit controller will modify the yellow A and B bus selections via RS-232 commands.

The Audio Mixer

The Soundcraft DELTA AVE audio mixer is a 24-input stereo mixing console of very high quality. You may have seen others of it's ilk in the control rooms of recording studios and at concerts. It is easily the most complicated piece of equipment in the studio, having more than 300 knobs.

The most important controls are on the right-most column, the master unit. The red-top MONITOR LEVEL knob controls the volume of the speakers. Set it to position 1 until you are sure you have a good signal.

The yellow and red faders should always be up at their maximum (zero attenuation) setting.

Please do not alter the setting of the red-top OSC LEVEL knob. This has been precisely set. If you need 1 kHz tone to go with your color bars on the leader of your tape, simply turn the MONITOR LEVEL knob to position 1 and press the ON button directly below the OSC LEVEL knob. This routes the standard test tone to the speakers and to all recorders.

For normal use the "AVE" button should be up (unlit). When doing audio fades and dissolves the "AVE" button needs to be pressed in and lit. This delegates control of the mixing board to the edit controller. Note that all the inputs will go dead except when commanded by the edit controller, so you want to make sure the AVE button is off while you are getting set up.

The Three Audio Buses

The video switcher has two video buses, program and preview. The audio mixer has three audio busses, with unlikely and confusing names. The equivalent of "preview" is called MIX. The equivalent of "program" is called "1-2". The "3-4" bus is used only when mixing stereo programs down to monaural.

Whatever is sent to the MIX bus is routed to the "L" and "R" LED display, and to the control-room stereo monitor speakers. The MIX bus does not get sent to any of the recorders.

Whatever is sent to the 1-2 bus is routed to the 1-2 LED display, and a copy is sent to every record-capable VTR in the rack. In addition to VTR-R, this includes VTR-A, VTR-B, VTR-C, VTR-G, VTR-J, VTR-K, VTR-L, and the DAT audio recorder. Be aware that if you have the input column for any of those machines assigned to output to the 1-2 bus this can set up a feedback loop, which is painfully loud.

Listening to a VTR

To listen to audio from a particular VTR, find the corresponding column on the audio mixer for that input.

  1. Move the blue fader up from -infinity to the 0 (zero) mark.
  2. Press the ON button to the in position; it will light up in green.
  3. Press the MIX button to the in position, to send a copy of this input out onto the MIX bus.
  4. Ensure that the yellow "MIX" faders are all the way up.

You should now hear the audio from that VTR. Adjust the red-top MONITOR LEVEL knob (rightmost edge of the mixer, halfway up) for a pleasing volume; typical settings are in the 2-5 range.

If the headphones are plugged in, the speakers will be disabled.

Recording audio from a source VTR onto VTR-R

To use the audio mixer for audio editing, a more complex setup is required. First, set up the so that we can listen to VTR-R, the Betacam recorder, on the control-room speakers (MIX bus).

  1. On the mixer column marked "R", move the blue fader up to the 0 (zero) mark.
  2. Press the ON button to the in position; it will light up in green.
  3. Press the MIX button to the in position.
  4. Ensure that no other input has the MIX button pressed in. (Important!)

Second, set up the mixers input column for your audio source, such as VTR-D.

  1. Move the blue fader up to the 0 (zero) mark.
  2. Press the ON button to the in position; it will light up in green.
  3. Press the 1-2 button to the in position.
  4. Ensure that no other input has the 1-2 button pressed in. (Important!)
  5. Double check that the MIX button on this column is not pressed in.
This two-bus setup helps prevent audio feedback loops, and ensures that what you hear on the speakers is what the recorder is hearing. (If you just routed the source column to the MIX bus, you would be listening to what you thought the recorder was hearing, but if the recorders level controls or cables were not set right, the signal wouldn't arrive there, and you wouldn't know it.)

Normal Settings for one Input

Each of the 24 input "columns" on the mixer operates similarly. There are two types: stereo line-level inputs, which have blue sliders, and monaural microphone-level inputs, which have white sliders. The signal enters on a connector at the top (back) of the column, and runs down towards the front (bottom) of the column.

The red GAIN knob is used to adjust for variations in voltage used by the different types of VTRs. These are carefully aligned, please do not change them.

The next 4 black and grey topped knobs control that input's 3-band equalizer. This is normally not used. The equalizer can be disabled by ensuring that the EQ button is in the up position.

The next 4 blue topped knobs are used to send copies of this input to the 6 AUX output busses. These are unused in our installation; the 4 blue knobs should all be set to zero.

The yellow topped BAL knobs should be left in the center (zero) position, for the stereo inputs. The yellow topped PAN knobs should be left in the extreme left or right position for the monaural inputs.

The PFL button should not be depressed in normal use. It's a debugging aid; when pressed, it routes a full volume copy of the input to the L+R LEDs and to the monitor loudspeakers. This tends to be very unpleasant.

The ON button should be pressed (lit) only on those inputs which are being actively used. The signal to noise ratio of the mixer is improved when unused inputs are left offline.

The MIX, 1-2, and 3-4 buttons are used to send copies of this input to each of the three output busses. Each button is independent, but in general only one of them should be pressed for any one input column.

The blue or white fader is used to adjust the volume of the source material to the appropriate level for the program being prepared for the master tape. Typically the "right" setting will be very close to the zero mark. If the source tape has a 0dB 1kHz tone on the front of it from timecode 20;00 to 40;00 as per recommended practice , use this fader once at the beginning to adjust the LEDs to read +0 VU, and nothing more than perhaps a slight tweak should be required after that.

Controlling Audio "Dissolves" from the Edit Controller

Ensure that the Soundcraft VSA24II unit is powered on. It's located to the right of the left control-room loudspeaker. Ensure that the "Fade Law 2" is pressed, that the "Fade Start" mode is set of "Auto", and that the "Outputs" button is not pressed in, i.e. not set to "Stereo". (The "Stereo" mode is a hack for 8-input monaural units, activating it only confuses our 24-input stereo mixer).

Set up the audio mixer the way you want it.

Press the "AVE" button to the IN position to surrender all control of the audio mixer to the edit controller. The indicator light will glow green. It's located to the right of the yellow MIX faders. Until you deactivate the "AVE" button, the mixer will not respond to manual adjustments in a rational way -- because the VPE-251 edit controller has control. Before you panic, ensure that the AVE button is OFF.

Perform dissolve operations using the edit controller, either audio+video or audio-only (select mode with dark blue keys), and the audio mixer will respond just like the video switcher's dissolve unit. What video people call a "dissolve to black" audio people call a "fade out", and what video people call a "dissolve" audio people call a "cross-fade", "segue", or "mix".

Be certain to deactivate the "AVE" button when you have completed your audio fades/dissolves, or you'll get frustrated!

The Edit Controller

Kick-Starting the raw hardware

There is a PDP-11/73 inside, be prepared for almost unlimited complexity.

Examine the indicators on the front panel of VPE-251 Video Production Editor in the leftmost rack. The green POWER and RUN indicators should be lit, and the other (red) indicators should be dark.

If the red NO SYNC indicator is lit, the problem is upstream. Reset the Tektronix sync generator. If that does not correct the problem, ensure that the "Sigma Series 2100" distribution amplifier has it's dim green ON indicator glowing. (Center rack).

If the monitor has an RT-11 command prompt RT>, enter the command MENU and press return.

If the monitor has a blue menu system on it, select "restart" (?) (usually the default) and press RETURN.

If the monitor has a yellow title message which says "GVG Super Edit V7.01 VPE-251 S23653 Aberdeen Proving Ground #1" across the top, then the edit controller program ("Super Edit") is alive and well. Conversely, if that message isn't displayed, the next section won't do you any good.

Configuring Super-Edit

Press Shift-RESET (shift-"/") and look at the bottom of the monitor for any messages about "switcher not responding". Ensure that the "EDITOR" button is glowing on the GVG-200 Video switcher's "ENABLES" section.

Selecting the BIN with your presentation in it.

Make sure all the videotape machines to be used are in REMOTE mode.

The Abekas

The Abekas is a complex beast. For starters, make certain that the upper left monitor is turned on and set to input "A", so that you can see the Abekas's control panel. In general, the Abekas should be powered on at all times. Just the disks should be spun down whenever the Abekas is not in use, this keeps the battery charged and the configuration settings in memory. The switch for the disks is on the board labelled "A60 Computer", near the front right hand side.

The Abekas's battery is getting old, so it often forgets it's configuration settings. When you turn it on, you may need to re-configure it.

Return the menu system to normal operation by pressing "NORM_PLAY". Keep pressing the MENU button until you highlight "1) Setup" and press ENTER. These are the correct settings:

  1. Coarse Hphase: +22 pixels (adjust with trackball)
  2. Fine Hphase: +0 ns
  3. Interp on/off: OFF
  4. Freeze: FRAME
  5. Machine Mode: AUTO FRAME
    (set this while on an even field, or get stuck halfway between two frames. Temporarily go to FIELD mode to fix.)
  6. Time Display: FRAMES
  7. Frame Offset: 0
  8. PVW Display Position (no adjustment)
  9. Input Select: INPUT-1

The COARSE HPHASE value of +22 pixels, and that the FINE HPHASE of +0 pixels shifts the position of the first pixel to the left so that the maximum number of pixels are in the visible area of the screen.

Press "NORM_PLAY". Keep pressing the MENU button until you highlight "7) Miscellaneous" and press ENTER. If the IP address is displayed as zero, Keep pressing the MENU button until you highlight "4) IP Address". Key in 128.063 and press ENTER. (The 0 is significant). Key in 016.015 and press ENTER. It's a 12-digit shift register, accepting 6 new digits at each press of the ENTER key.

While under the #7 MISCELLANEOUS menu, ensure that the message "SYNC ADVANCE ON" is displayed. If not, turn dip switch 3 on the Abekas computer board DIP position 18K to the ON position.

Now check the network connectivity of the Abekas by running "ping" from some host, preferably a host on Subnet 16. If the IP address is correct ( on the display but there is no response, check the ethernet cable on the back of the Abekas. It is prone to falling out. (A pox on whomever invented the feeble slide-lock for the DB-15 AUI connector). Also, sometimes the Abekas's 68000 CPU overloads after a sustained burst of broadcast traffic on the ethernet; try pressing the square RESET button on the front right corner of the A60 CPU board, wait 10 seconds, and try again. (Also recheck the config menus, to make sure the configuration didn't alter during the reset).

Sometimes the disks don't spin up properly, or you have the switch in the wrong position. Press "NORM_PLAY". Keep pressing the MENU button until you highlight "4) Diagnostics" and press ENTER. In normal operation, the bottom two lines of display should read:

        drv 0Y: up      drv 0C: up
        drv 1Y: down    drv 1C: down

If you cannot get the Abekas to function by using any of the above techniques, there is still hope. Power off the Abekas and slide out the "computer" board (be sure to use the little plastic handle for pulling out the board). There is a dip switch towards the rear left side of the board. Its settings should be:

  1. switch 1: may be on or off
  2. switch 2: on
  3. switch 3: on
  4. switch 4: off
  5. switch 5: off
  6. switch 6: off
  7. switch 7: off
  8. switch 8: off

Flip switch #1 to the opposite of whatever it is now. Replace the board and power the Abekas back up. The Abekas keeps track of that switch setting and will clear all its configuration settings when that switch is in a different position from last power-up. Now you need to go back and set all the configuration parameters as described above. If that doesn't help, try calling Abekas at 1-800-777-9787. A Mr. Rob Stevens or Mr. Bruce Williams have been very helpful in diagnosing problems.

When digitizing live video and recording it onto the Abekas, it is important that every unit along the chain be configured properly:

To record a full load of video onto the Abekas, select your source on the PROGRAM bus of the GVG switcher, and select "DISK 1" on the PREVIEW bus (so you can see what the Abekas is up to). On the Abekas control panel press the VIDEO_IN button; it should light up red. Then press: 0 GOTO 750 RECORD. The red light inside the RECORD button will start blinking, indicating that the record circuit is armed. Press PLAY to start recording. Note that pressing almost any other button on the Abekas will dis-arm the record circuit.

To view what you just recorded, press the VIDEO_IN button again to extinguish the red light inside. This changes the Abekas's video output from the digital input to disk playback. Now use the controls as usual. (0 GOTO PLAY, for example.)

The SGI 4D/240 (Vertex)

Vertex's NTSC video output shows up as "Graphics Factory 1", after an encoding pass through the Truevision VidI/O box.

The SGI Indigo (Whistle)

The video output of WHISTLE's Galileo board shows up as "Graphics Factory 2". Before this signal is valid, you need to run /usr/sbin/vcp to get the video control panel. The Galileo board has a separate framebuffer memory for the NTSC video output, so the NTSC output need not correspond to anything that is on the main screen.

The normal settings are:

Next, go to the menu bar on the top of the VCP display, pull down the "Utilities" menu, and select "Live Video Output". A small "Live Video Output" window will pop up. Put the cursor inside that window, press and hold the right mouse button. Select either "Send Screen" or "Send Full Screen". I recommend that you check (enable) the "Flicker Filter" item, too.

If you select "Send Screen", there is a frame that you can move around which delimits the borders of the NTSC signal being sent. It can be helpful when planning your frame layout to select "Graphics Factory 2" on the PREVIEW bus, then activate the (physical) CENTER and BOX buttons on the "Safe Title" unit of the GVG switcher. Then view your video signal on the NEC monitor (on table behind Whistle's monitor) to get an idea of how few pixels will make it to the end-users TV screen. The NEC can also be a convenient monitor to use as your recording progresses, as it's easy to see while using the keyboard of Whistle.