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From: rubywand@swbell.net
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Subject: Apple II comp.sys.apple2 FAQs: Monitors, Part 16/23
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The comp.sys.apple2 Usenet newsgroup Apple II FAQs originate from
the Ground Apple II archive, 1997-2000. Administrator: Steve Nelson

Csa2 FAQs-on-Ground ref: Csa2MONITOR.txt  rev028 1 July 2000






Monitor


 001- How can I fix an unstable display?
 002- I'm using a TV + IIc RF module. How can I improve the display?
 003- What monitor repair Safety precautions are recommended?
 004- How do I discharge the High Voltage anode?
 005- How do I open my RGB monitor's case and get set for repairs?
 006- What tools and solder should I use for repairs?
 007- What's the fix for a flickering, Jumping, display?
 008- How can I fix an all-red, all-blue, etc. monitor display?
 009- Is there any more RGB Adjustments info?
 010- How do I adjust Centering on my GS RGB color monitor?
 011- How do I adjust Focus & Intensity on a blurry GS RGB Monitor?
 012- What is a replacement for the RGB "flyback" power transistor?
 013- How do I fix sporatic Shrinking and Flicking in-out of Focus?
 014- How do I fix a serious case of shimmy on my GS monitor?
 015- I need a new RGB monitor for my GS. Which monitors can I use?
 016- What is the pinout for Commodore's 1084s monitor?
 017- What is a "composite video monitor"?
 018- Why doesn't hires look as good on my GS RGB monitor?
 019- How can I to do the "Color Killer Mod" on a //e?
 020- My A2 display doesn't work with a "TV/Game Switch". How come?
 021- Can I use a color TV with my IIc+?
 022- What is the IIc+ video pin configuration?
 023- Where can I buy a replacement RGB monitor for my GS?
 024- What kind of RGB monitors will work with a IIc?
 025- Can I replace my GS RGB monitor with one from a PC?
 026- What are the specs and pin-out for the GS RGB monitor?
 027- Do I need monochrome monitor to get a clear 80-col display?
 028- Is there a high-quality replacement for RGB monitors?
 029- Can I use a GS RGB monitor with my IIc?
 030- Why does a composite monitor I added show a fuzzy dim display?
 031- Is my SecondSight board the cause of increased system crashes?
 032- Why do Inwords and PublishIt bomb on my SecondSight board?
 033- How many dots are actually sent to the GS monitor per line?
 034- My GS RGB monitor takes a long time to get bright. A fix?
 035- Where can I get a GS RGB monitor cable?




Monitor RepairMini-Manual  (Q&A 001-014) 4/98 version

     This mini-manual describes Repairs & Adjustments which usually involve removing the case. Before removing the case, check to see that the your problems are not due to a poorly connected monitor cable or misadjusted monitor controls.


From: Rubywand

001- My display is sharp but it seems to be unstable. Is there
     a quick, easy fix for this?

     Maybe. First, check your cable connections to make sure they are solid. Also, try diddling the side and back controls. Sometimes, these become dirty or develop bad spots.

     If diddling a control seems to cure or nearly cure an unstable, jumping, etc. display, you can be fairly sure that a squirt of Control Cleaner will help. The cleaner needs to reach the control's resistance element-- the place where the wiper touches the carbon track in a potentiometer-- and you should turn the control back and forth after squirting the cleaner. Probably, you will need to remove the case to get a good shot at the dirty control.

= = = = = = = = = = = = = =


002- My Apple IIc has the IIc RF modulator module and is connected
     to a color TV through a TV/Game switch. The color is okay but
     the display is more or less ragged depending on where I run
     the cable. Is there a way to get a better, more stable display?

     If you are using a plain hi-fi type cable to connect from your IIc modulator to the TV/Game switch, then, changing to a video cable may help.  If you are using a much longer cable than necessary, try a shorter cable.

     Another popular trick is to form any unused length into one or more loops (use wire ties or tape to hold the loops together).  Wrapping unused cable length around a ferrite or iron core (e.g. from an old transformer) is a

variation on the same idea.

= = = = = = = = = = = = = =


003- What Safety precautions should I take when working on my monitor?

     Basically: unplug the monitor and let sit for a day, wear goggles, work on a non-conductive table surface, do not stress CRT neck.

     Unplugging the monitor and letting it sit for a few hours reduces the danger of shock from stored charges; it does not eliminate it. The usual warning for this kind of work is AVOID touching two different circuit points at the same time. Like, don't touch the metal chassis and the conductive surface of the CRT at the same time.

     WEAR protective GOGGLES. If you should, somehow, bump or stress the CRT neck-- as in jumping when you get shocked-- it may break. The result may be a peaceful THOOP! or the CRT may implode in a spray of glass. (Avoid using the CRT's neck to support the monitor in any position.)

     Work on a wooden or plastic-topped table with plenty of space. Try to position yourself, tools, and the monitor so that when you get 'stung', the chances of breaking something are reduced.

     As much as posible, avoid using heavy tools of any kind. An inadvertant tap from a mini-screwdriver is much less likely to crack the CRT than a bonk from a full-sized screwdriver or pair of pliers.

     Rubber gloves are probably a good idea so long as they do not get in the way. Of course, pointy connections and components can puncture gloves.

     It's a good idea to clip a wire to the chassis and touch the other end to the conductive surface of the CRT a few times before doing any work in order to drain off any charge there.

Note: Several places in a monitor or TV carry high enough voltages to deliver an uncomfortable shock. Draining the charge from one point does not guarantee that other points have been discharged.

===========================


From: Joe Walters

004- How do I discharge the High Voltage?

The HV charge (20,000+ volts) might not be much reduced by just waiting a few hours (or days), especially if you are in a low humidity location and the tube, etc., are of good quality. You can, probably, _reduce_ the shock hazard by discharging the High Voltage at the anode. You can not, really, expect to eliminate the shock hazard. (See WARNING below.)

1. There is a long wire (called the anode) that goes from the high
   voltage power supply to the top of the tube where it is snapped
   into a hole. You can't see the hole because there is a rubber
   shield built onto the wire. The end of the wire goes to a metal
   clip which, without the rubber shield, looks somewhat as below.
   One squeezes the clip so the end slips into the hole in the tube.

   ---     ---
  ==  \   /  ===== back of CRT
       \ /  <-- metal clip (This is what your grounded
        |                      screwdriver needs to touch.)
       [|]
       [|]  insulated Anode lead going to HV module
       [|]

   Needless to say, UNPLUG the monitor before beginning. Simply
   turning it off isn't good enough.

2. Get a clip lead and clip one end to a long slender screwdriver

3. Clip the other end to the metal chassis of the TV  (i.e the
   metal frame parts)

4. Carefully! slip the screwdriver tip under the rubber flap on the
   top of the tube until it touches the internal wire that both
   holds the anode wire in place and conducts electricity.

Step 4 may result in a somewhat loud "SNAP" as the tube is discharged. Be prepared so you don't jump and break something.

WARNING: After "discharging", do _not_ assume that no High Voltage is present. Almost certainly, some High Voltage remains or may reappear over time.


===========================


From: Rubywand

005- How do I open my RGB monitor's case and get set for doing
     internal adjustments or repairs?

     Whatever it is you plan to fix, if you remove the monitor case, you will probably need to unplug the cable running from the circuit board to the Controls/Switch Module on the side of the case. Use 'whiteout',  nail polish, etc. to mark the position of the plug. In more detail ...

   1. Unplug everything from the monitor & let it sit for a day.

   2. Put on protective GOGGLES. Place the unit face down on a wooden or plastic-topped surface with lots of space and good lighting. Remove the screws. Place the unit in nomal position.

   3. Have a fat magazine ready. Slide the case off until you are able to see the control leads plugged into the main board on the right side of the case. Mark the plug position with 'white-out', nail polish, etc.. Unplug the connector.

   4. Slide off the case while supporting the monitor and slide the fat magazine under the circuit board to prop up the monitor from behind.


   5. Discharge the HV (optional, but, generally, a good idea).

   6. <Do adjustments, fixes on Monitor>

   7. When done, reinstall the control assembly.

   8. Still wearing GOGGLES, support the monitor, remove the magazine, slide on the case, reconnect the plug, finish sliding on the case, replace screws.

= = = = = = = = = = = = = =


006- What tools and solder should I use for repairs?

     For any soldering use a good quality pencil-style iron rated at 25-40 watts with a holder and sponge. Use high quality (60/40 tin/lead or better) rosin core solder (e.g. Kester "44" 20 gauge).

= = = = = = = = = = = = = =


007- How do fix a Flickering, Jumping, display which sometimes
     collapses to a line?

     If  the monitor exhibits major flickering, periodic collapse of the display to a line, etc., then it may help to know that a common source of such problems is one or more bad connections where the High Voltage module is joined to the main circuit board. (This module is the black thing with a HV lead running to the CRT-- it's near the left, back. The slotted nub controls in its case set Focus and base Intensity.)  Often these connections look okay because it is hard to see the small fractures in the so

lder surrounding the pins.

     The cure is to resolder all of the pins coming from the module (on the under-side of the circuit board).  Before doing the soldering, clip a wire to the metal chassis and touch the other end to each HV module pin and other points in the area. While soldering, avoid touching anything conductive on the monitor with anything but the iron and solder.

= = = = = = = = = = = = = =


008- Suddenly my monitor has an all-blue (all-red, etc.) screen!
     How do I fix this?

     You probably have a blown choke on the little chroma board mounted to the back of the CRT. The choke will be connected to one of the larger, R/G/B output transistors. Use an Ohmmeter to find the open choke. Replace the bad choke with 'one like it' or brew your own: wind about 25-30 turns of #30 wire on a small ferrite core.

     A more detailed procedure is presented below ....

1. The part that causes the problem when it fails is a "choke" or "inductor" , it is mounted on a small circuit board attached to the back of the monitor tube itself. This part looks like a small blue ceramic ball with two leads coming out the bottom, and is color coded for 10 microhenries.

2. There are three of these items on that circuit board, and if any one of them fails, the symptom is a screen all of one color, with total loss of any controls of the monitor. The parts are identified by number, and what color the screen is will tell you which one to replace.

       L6R2 for a Red screen
       L6G2 for a Green screen
       L6B2 for a Blue screen

3. You can probably get a 10 microhenry choke at Radio Shack, or it is available for $1.28 (plus a $5 Handling charge) from Digikey Corporation at (800) 344-4539.  They take Mastercard, Visa, and C.O.D.. The Digikey part number is M8025-ND.

4. After replacing this part, the monitor colors may need to be readjusted via the small color trimpots on the same circuit board.

===========================


From: David Fretz

009- Any more RGB Adjustments info?

R13- RGB Intensity
C86- Horizontal Position on RGB
C85- NTSC Color Hue Adjustment
C45- NTSC Frequency Adjustment

===========================


From: James Poore

010- How do I adjust Centering on my GS RGB color monitor?

     Color monitors do vertical and horzontal centering differently than do monochrome monitors.  Almost all color monitors have either a jumper arrangement or actual centering controls, sometimes both. Centering adjustments are usually located on the PCB with no access holes, so the back will most likely have to be removed to get to them.

     If your monitor uses jumpers, there should be 3 tabs that each jumper can be connected to. For vertical adjustment the tabs should be marked as 'up', 'down', and center.  If your pix is too high, then you would connect the jumper to the down tab. For horizontal adjustment the three tabs should be marked 'left', 'center', and 'right'.

     If your monitor has centering controls, then adjust for best centering.


     Many GS monitors use small tab switches to adjust centering. These are located near the back of the main circuit board.


     Adjustment of Vertical Size, etc. via shafts on back of GS monitor can affect centering. For small changes, these adjustments may get the job done.

     Adjustment of Intensity and Focus (see below) can affect centering.

===========================


From: Rubywand

011- How do I adjust Focus and Intensity on a blurry GS RGB Monitor?

     These adjustments may also help cure display "bowing", etc..

     Intensity and Focus controls are on the High Votage Module (black module near back of circuit board) inside the case.

     Follow procedure outlined earlier for safety (e.g. unplug, wait, wear goggles, ...) and removing the case.

     Note the position of the two controls on the HV Module (at the left, back). Mark the back of the cover where handy access hole should be. Take the case cover to another area (i.e. away from the exposed CRT neck). Remove the control assembly from the right side of the case.

     Using a Dremel tool, hole saw, ... cut an approx. 1" diameter hole in the back of the case. Use this opportunity to give the case interior a good cleaning. (If you wash it, be very sure it's dry before continuing.)

     Reinstall the control assembly.

     Put everything back.

     Reconnect cable and AC cord. Turn on the computer & monitor. Let it sit 10-20 minutes. Use the normal side of case controls to get the brightest, 'decent-focus' picture you can obtain.

     Using a plastic TV technician's tool (and flashlight if necessary) adjust the Intensity and Focus controls (through the hole in back) on the HV module to get a good looking display.

     Work back and forth between the back and side controls. What you're aiming for is a display with good brightness and sharp focus when the side controls are near their middle positions.

     Cover the back hole using a piece of duct tape, a large sticker, etc.. (The opening is a potential shock hazard, especially if the monitor is within reach of children.)

===========================


From: "John F. Reeves" and Sam Goldwasser

012- I need to replace the High Voltage "flyback" power transistor
     in my Applecolor monitor. The part bears no manufacturer's
     mark, just two lines of text:

     D1650
       7A

     What part should I get?


     The transistor is part Q502 on the PCB of the Applecolor RGB monitor, manufactured in 1987. This is the only power transistor in the HV section, the only one which is on a heat sink. ...."

     D1650 is a 2SD1650 which crosses to an ECG2331. You should be able to pick one up at your local electronics shop. Try MCM Electronics, Dalbani, etc..

===========================


From: Rubywand

013- How can I fix sporatic Shrinking and Flicking in-out of Focus?

     Arcing from the metal brace to the HV module can cause the display to momentarily shrink and flick out of focus.

     Follow safety and setup procedures outlined earlier.

     The cure is to bend the brace up enough to increase the arc path and clean the surfaces involved. Apply HV dope to the brace and module where distances are small.

     If the case interior seems pretty clogged with dust and gunk, it's a good idea to remove the side-mounted Controls/Switch (C/S) Module and give the case a good washing. (Be very sure it is well dried before replacing.) You should also clean the two controls on the C/S Module with spray-in Control Cleaner.

     Before putting the case back, this may be a good time to adjust base Intensity and Focus (the two nub controls on the HV module).  Position the monitor so that screen is easy to see and the nub controls are accessible.

     Plug in the the C/S Module. Adjust the C/S Module controls to center positions. Plug in the monitor to the computer. Get a Desktop display with some text and icons. Use an insulated tool to adjust the nub Intensity and Focus controls for maximum sharpness at 'normal' viewing intensity. A magnifying glass is helpful to obtain max pixel sharpness.

= = = = = = = = = = = = = =


014- Suddenly my GS monitor exhibits a serious case of display
     shimmy which sometimes degenerates into jagged lines. How
     can I fix this problem?

     Side-to-side shimmy indicates that Horizontal lock is not stable.

     A good fix try is to adjust Horizontal Hold (the "<- ->" knob/stub) until the shimmy stops. This usually works unless  1- The HH control is already at its extreme setting,  2- The HH control has 'dirty' or burn spots at the position which would, ordinarily, be the correct setting,  3- The display stabilizes but ends up moved too far to the left or right side of the screen.

     If, adjusting Horizontal Hold does not fix the problem, you will probably need to remove the case. For starters, this will let you squirt some Control Cleaner into the HH control.

     With the case removed, you will have access to some other controls which may help solve the shimmy problem. Two are on the black High Voltage module: one nub controls base Intensity; the other controls Focus. There are also a couple small tab switches located near the back edge of the main circuit board. One sets Horizontal position; the other sets Vertical position.

     If you reconnect the side controls and power cord, you will be able to experiment with adjustments.

     Working with monitor adjustments with the case removed requires constant awareness of potential hazards. For example, you would connect the AC power cord to the monitor _before_ plugging it into an AC socket. The monitor needs to be on a plastic or wooden table with nearby clutter removed. It may be easiest to support with the rear of the circuit board resting on a thick magazine.

     You should have one or two plastic TV technician tools. These are rods with ends for turning slotted controls.  (A whole set will cost a few dollars at Radio Shack.)  Such tools are handy for adjusting the controls on the back of the HV module, for flipping the tab switches, for tapping components you suspect may be loose, etc..

Note: If the HH control seems to have serious burn spots-- e.g. you notice a crunchy feel when turning the knob-- you may have to get it replaced in order to achieve a correct setting. Replacing such a control is a job for someone with experience in working with monitors or TV's. If you decide to do it, be sure to check safety and setup suggestions listed earlier. De-solder the control, remove it, and take it to an electronics parts seller to get a replacement.

     Working with Horizontal Hold, the Horizontal tab switch, and the Intensity control on the HV module, (and, maybe, the Focus control and Vertical Size) you should be able to eliminate any shimmy and end up with a properly sized and positioned display.

Note: On some monitors, you may have to trade-off Vertical Size in order to get a stable display which retains good linearity.

     Once the shimmy problem is cured and the display is the right size and

positioned correctly, work back and forth between the side controls and Focus to get a sharp display.

=======  End of Monitor Repair Mini-Manual =========



From: Michael Hickey

015- I need a new RGB monitor for my GS. Which monitors can I use?

     I have good information that the Commodore Amiga 1084s monitor will work with the Apple IIgs. I have no information on the quality of the output. I've seen some Amiga displays that look no better than your average colour TV. Perhaps the local WAL-Mart will have a few in stock at a low price.

You will need to build your own DB9 to DB 15 cable.

1084s  to  IIgs
DB9        DB15

1          13
3           2
4           5
5           9
7           3


----------------------------


From: G. Utter

     Magnavox equivalents for the Commodore monitors exist. 8CM515 is one model number and there is at least one more. 

----------------------------


From: Steve Jensen

     I just tried a Sony CPD 1302 multisych monitor on a GS and it works perfectly. Very crisp picture. I used a standard cable from a Mac II.


----------------------------


From: Jeff Blakeney

     You should keep an eye out for any analog RGB monitor that can 
horizontally sync down to 15.75 kHz. These include:

     AppleColor RGB Monitor (model A2M6014, the IIgs monitor) 
     Commodore 1084 (and variants such as the 1084S) 
     Commodore 1902 (although most of these only do digital RGB) 
     Tandy CM-8 (not sure about model but it was used with the Coco3) 
     Atari monitors used with the ST series (don't know models) 
     Some TVs


----------------------------


From: Ruud


     Here's a different approach: my Powermac 7500 is right next to my IIgs; so, I plugged its composite video output into the video-in port of the 7500, started Apple Video Player, and lo and behold, it *is* possible to use your 1024*768 multires RGB Powermac monitor as a IIgs monitor, in a pinch. Color is all washed up, but mono is OK.

____________________________



From: Stefan Voss

016- What is the pinout for Commodore's 1084s monitor?

pin assignment of 1084S monitor:

        pin #           analog RGB signal
         1                 ground
         2                 ground
         3                 red
         4                 green
         5                 blue
         6                 not used
         7                 composite sync.
         8                 horizontal sync.
         9                 vertical sync.

             ____________________
            \ 5   4   3   2   1 /
             \                 /
              \ 9   8   7   6 /
                -------------

I can't give any garantee!

____________________________



From: Rubywand

017- What is a "composite video monitor"?

     A composite video monitor is a display which requires a composite video signal such as that output by an Apple II computer. The signal is called "composite" because it is a mix of Video, Horizontal Sync, and Vertical Sync signals. A color composite video signal will, also, include Color Burst. These signals are separated inside the monitor.

     The cable for connecting such a monitor is a single wire surrounded by insulation with an outer shield (usually braided copper) covered by insulation. The inner wire carries the signal, the shield is at 'ground'. Often, each end of the cable has a standard RCA plug-- so; the cable looks much like a normal audio hi-fi cable. (In fact, a decent hi-fi cable will, often, work fine for connecting your Apple II to a composite color monitor.)

     The main differences between a hi-fi cable and one intended to carry video signals are  1) the video cable usually has a better, tighter shield;  2) the video cable is characterized for impedance matching at, usually, 50 or 75 Ohms; and  3) the video cable exhibits lower capacitance between the center lead and the shield.

     You can connect your Apple II to a Monochrome or Color composite video monitor.

----------------------------


018- When I play old hires games on my GS the RGB monitor display
     does not look as good as my old Amdek Color-1 connected to
     the II+. What's wrong?

     Most hires displays look better on a composite color monitor, such as the Amdek Color-1, than they do on the GS's RGB monitor. The difference is even more striking for double-hires displays. (King's Quest and Air Heart look much better on a Color-1 connected to a IIc+ than on an RGB monitor connected to the GS.)

     What's wrong is that the GS's display circuits do just a passable job of translating hires and double-hires into RGB form.

----------------------------


019- Does anybody know how to do the "Color Killer Mod" on a //e?

     It looks like you should be able to do a full-screen color-killer on a IIe by using a general purpose NPN  transistor (2N3904, 2N2222, etc.) to shunt the Color Burst signal. The transistor's collector would connect to the junction of R15 and R13; the emitter lead would go to Ground. The transistor should be connected directly to the R15-R13 junction and ground.

     The base lead would go through a 2k-3k Ohm resistor to an annunciator output, such as An-3 at pin 12 on the 16-pin J-15 Game connector. PEEKing the appropriate addresses should flip Color OFF and ON.

     The reason for qualifiers such as "looks like", etc. is that I have not actually tried a mod like this on a IIe. Monitors are remarkably sensitive to Color Burst. If the transistor does not do a good job of shunting the signal, enough may get through to trigger Color-ON.

     A more positve (but less easy) technique is to use a 74LS32 OR gate to control flow of the 3.58MHz signal. The IC could be tack-soldered onto U88 via its +5 and GND pins. U88 is the 74S02 which has the gate which produces Color Burst.

     Pin 12 of the 'S02 would be bent up and connected to the output of an 'LS32 OR gate (e.g. pin 3). One of the OR gate's inputs (pin 2) would go to Pin 12 of the 'S02 socket. The other (pin 1) would go to an annunciator output.

     Turning ON the annunciator forces the OR gate output to "1" and eliminates Color Burst. Turning OFF the annunciator lets the OR gate output follow the 3.58MHz signal and enables Color Burst.

----------------------------


020- I connected my IIe to a color TV using a Radio Shack
    "TV/Game Switch" but it doesn't work. How come?

     A "TV/Game" switch is, usually, intended to switch RF (radio frequency) signals. For example, in the "TV" position it connects the TV's VHF antenna input to the VHF antenna (e.g. the long "rabbit ears").  This way, you can watch TV.

     In the "Game" position it connects the TV's VHF antenna input to a game machine's or computer's CH 3 or CH 4 output. To see the computer's display, you need to set the TV Channel selector to the channel being output by the computer.

     The reason your setup does not work is that the IIe does not output an RF signal. (In fact, no Apple II has built-in circuitry for outputting an RF signal.) The IIe outputs composite video. Composite video is pure video information like the kind output by a VCR through the standard 'Yellow' cable. It produces a better, sharper image than video which is converted to RF and fed into a TV's antenna input.

     If your TV has a "Video In" plug, that is where you want to plug in the IIe's video output. An alternative is to plug the IIe output into a VCR's "Video In" and let the VCR take care of interfacing to the TV.

     Getting an "RF Converter" ("TV Converter", etc.) module is another way to go. For about $30 Radio Shack sells a box which will convert an Apple II's video signal to RF on CH3 or CH4.

     One thing to consider when looking for ways to connect to a color TV is that you could end up wasting time and money better spent on just getting a standard composite color monitor (like the Amdek Color-1) at a local Apple II swap meet.

----------------------------


021- Can I use a color TV with my IIc+?

     Yes. You can use one of the methods described above or you can use the RF Modulator module especially designed for the IIc series.

     The IIc RF module is formed to fit the IIc case and has a "CH3-CH4" slide tab on the top. Once the module is plugged in and a cable run to the TV's antenna inputs or to a TV/Game switch, you can get very nice, colorful on-TV hires and double-hires displays.

____________________________



From: David Empson

022- I have a friend with an Apple IIc+ who wants to connect
     an RGB monitor. What is the IIc+ video pin configuration?

     First, I should correct a misconception: the video port on the back of the IIc+ is _not_ an RGB port.  It is a video expansion port, which provides all of the internal video generation signals used by the IIc/IIc+ which can be used to generate an alternative video output signal.

The actual functions of the IIc video port are as follows:

1   TEXT     Indicates text mode is active (spcl fn in DHR mode)
2   14M      14 MHz clock sigal
3   SYNC     Horizontal and vertical sync
4   SEGB     Vertical counter signal from IOU, or lo-res indication
5   1VSOUND  Sound output (one volt peak-to-peak)
6   LDPS     Video shift load enable
7   WNDW     Active area display blanking
8   +12V     +12 volts DC
9   PRAS     RAM row address strobe
10  GR       Graphics mode enable
11  SEROUT   Serialized character generator output
12  NTSC     Composite NTSC video output
13  GND      Ground reference
14  VIDD7    Bit 7 of video shift latch (hires mode col shifting)
15  CREF     Colour reference timing signal

These come from the IIc Technical Reference, both first and second editions.


     You cannot connect a monitor directly to the IIc video port (with the possible exception of the the LCD display, or an NTSC monitor). To produce RGB output (or anything else) from this port, you need an external adaptor box.

     This adaptor is not simple: it has to decode the colour information from the NTSC video signal (or generate it by detecting the graphics mode and monitoring bit patterns), generate appropriate sync signals, etc.

     I believe there is (or was) an RGB output adaptor for the IIc, which should also work on the IIc+.

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From: James Stafford

023- Where can I buy a replacement RGB monitor for my GS?

     Alltech Electronics sells RGB monitors that they specially set up for the Apple II for arround $150.00 I believe. These monitors were Atari monitors that they fixed to work on Aplle II's. Alltech also has used llgs RGB monitors.
----------------------------


From: Rubywand


     Intrec has been listing used "good" condition IIgs monitors for around $60.00. Click on the "Used" stuff on Intrec's main Store page at http://www.intrec.com/intrec/intrecdox/store/store.html . For other sources, see the Vendors listing in the Main Hall.

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From: David Empson

024- What kind of RGB monitors will work with a IIc and a Laser 128?

I don't know about the Laser.  The IIc doesn't have built-in RGB output.  Its video port provides several low-level timing signals which allow RGB data to be decoded from the composite video signal (which is also provided on the port), but this requires external hardware.

The "standard" IIc RGB adaptor (assuming there was one) would probably have produced digital RGB output, the same as the Apple III and the Apple IIe memory expansion cards with RGB output.  With a digital RGB monitor, standard digital logic levels (TTL) indicate whether a colour (or colour weighting) is present or absent.  One wire is required for each bit of each primary colour.

The IIgs, on the other hand, produces an analog RGB signal - a voltage on the Red, Green and Blue outputs represents the intensity of each primary colour. Any number of shades of each colour can be supported, by providing a finer resolution digital to analog converter within the computer.  The IIgs has 4-bit D-to-A for each primary colour.  High-end video cards on the Mac and PC (SVGA) use 8-bit D-to-A for each primary colour.

Digital RGB monitors cannot be used with an Analog RGB signal (unless comparators are used to generate a digital signal from the analog one).

Analog RGB monitors cannot normally be used with a Digital RGB signal, but generating an analog signal is possible with a resistor network (an example of this is given in the Apple III Owner's Guide).  In some cases, it may be possible to plug an Analog RGB monitor into a Digital RGB output, but it won't produce the correct colours (when compared with a Digital RGB monitor).


There are two common types of digital RGB monitor: one type will work with the Apple III, Apple IIe (with RGB card), Apple IIc (with RGB adaptor) and CGA on an IBM PC (different cables or adaptors are required).  This type has intensity and one bit each for red, green and blue (16 colours in total).

The second type is usable with EGA.  This has two bits each for red, green and blue (64 colours in total).  These monitors also have a higher scan frequency than the first type, and cannot be used with an Apple II (unless a card has been specially designed to use them).


Analog RGB monitors are mainly classified by the scan frequency and resolution. The IIgs RGB monitor (A2M6014X) operates at similar frequencies to television - around 15 kHz.  Macintosh and VGA/SVGA RGB monitors do not support such low scan rates, and typically work at about 30 kHz or higher.  The Mac cannot use the IIgs RGB monitor, and the IIgs cannot use Mac/VGA RGB monitors.

Some third-party multisync monitors will work on the Mac/VGA and IIgs, but these are very rare now.  Most multisyncs do not go as low as 15 kHz.

"15 kHz" and "30 kHz" refers to the horizontal scan frequency - Apple II video output has a horizontal retrace roughly 15,000 times per second.

Vertical retrace is a different issue (it is much slower - usually 50 to 100 retraces per second), and most monitors are very flexible in the supported vertical retrace rate, as far as I know.

This is also where "interlacing" comes in.  Interlacing is a technique which doubles the effective vertical resolution of the monitor, by performing two vertical scans (fields) per frame, with a slight vertical shift in the second field.  The scan lines for the second field are interleaved between the scan lines for the first field.

An interlaced display has more noticeable flicker than a non-interlaced display with double the frame rate, because the phosphor is only lit half as often.

For example, the Second Sight card will support a 400 line interlaced mode with the IIgs RGB monitor.  There will probably be noticeable flicker in this mode (especially out of the corner of your eye).

This mode will have 60 fields (i.e. 30 frames) per second, whereas the standard IIgs video output is non-interlaced with 60 frames per second (but only 200 lines vertical resolution).

(I'm assuming 60 Hz mode - the IIgs also support 50 Hz mode, for use in countries with 50 Hz mains supplies and TVs.)

Television also uses interlacing - with NTSC, there are 525 lines per interlaced frame and 30 frames per second, with alternating lines being scanned on each pass of the electron beam (262.5 lines per field, 60 fields per second).

PAL uses 625 lines per frame, usually at 50 frames per second (312.5 lines per field, 25 fields per second).

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From: Rubywand

025- Can I replace my GS RGB monitor with one from a PC?

     Modern PC monitors generally have a Horizontal scan rate which is too high to be compatible with the GS. Some users report success using some old PC VGA monitors with a special adapter cable. (See Q&A 015 above.)

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026- What are the specs and pin-out for the GS RGB monitor?

Max Resolution:    640 Horizontal dots x 200 Vertical dots/lines


Dot Pitch:        .37mm

CRT Size:          12"/  11.5" viewable

Video Bandwidth:   6.5MHz   (+/- 1.5DB)


Scanning Frequencies

               60Hz model            50Hz model

Horizontal:    15.734kHz             15.696kHz
Vertical:         60Hz                  50Hz


 Pin    Function

  1     Red video ground
  2     Red composite video
  3     Composite sync
  4    (not used)
  5     Green composite video
  6     Green video ground
  7    (not used)
  8    (not used)
  9     Blue composite video
 10    (not used)
 11    (not used)
 12    (not used)
 13     Blue video ground
 14    (not used)
 15    (not used)
Shell   Shield ground


----------------------------


From: Mitchell Spector

     The above specs show only maximum resolution when used with a plain Apple IIgs. It has an interlaced mode which allows you to display 640x400, though it isn't going to be easy to look at for long periods of time. You can see the interlaced mode if you have a VOC or Second Sight card.

     The viewable area on an Apple IIgs is probably a fair bit less than 12"/ 11.5" viewable when you take into account all the space reserved by the border in all display modes. That probably makes it about 10" viewable or so. If you hook up another video source (e.g. a SuperNintendo) then you can use the entire 11.5", including what would be the border area.

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From: Rubywand

027- Do I need to connect a monochrome monitor to my IIe to get
     readable 80-column text?

     Maybe not. Try turning down the "Color" control to get a B/W display and adjusting Brightness and Contrast. This will, possibly, make 80-column text readable on your composite color monitor. Just how readable will depend upon the particular monitor. On the popular Amdek Color-1, readability is marginal at best. According to some user reports, readability is decent on Apple's composite color monitor.


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From: Jim Krych (ab453@cleveland.Freenet.Edu)

028- Is there a high-quality replacement for RGB monitors?

     Yes. It's called the "VideoTurtle." (What follows comes from a Video Turtle advertisement.)

     The VideoTurtle is a product that converts your RGB signal, known as TV RGB-15.75KHz scan rate for NTSC, into S-Video!  S-Video is an enhanced form of TV with better clarity and resolution than the "TV" we are all familiar with.

     With your computer, the VideoTurtle, and an S-Video equipped TV, you get equal or better display quality, than your old RGB monitor. Not only that, you get a much bigger and eye-pleasing display, and a TV to boot!

     The VideoTurtle, from Turtle Enterprises, can be purchased for $149.95 from one of it's authorized distributors, such as Tex Comp Ltd. To order all 1-800-846-3474. For technical information on TV RGB systems we haven't mentioned, or general technical help, call 1-626-967-3341. Turtle Enterprises can be reached via email: videoturtle@hotmail.com

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From: Tony Cianfaglione

029- Can I use a GS RGB monitor with my IIc?

     I use a IIc with a GS RGB monitor constantly through a Video 7 cable and it works fine. The 80 column text is crystal clear plus you can make it 4 different colors by flipping switches on the Video 7. A digital RGB displays 16 colors on a IIc but the GS RGB still displays 8.


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From: Rubywand

030- I connected a composite monitor to my GS at the standard "RCA
     plug" output but I get a fuzzy dim display. The monitor worked
     fine on my II+. What's the problem?

     When a composite monitor is known to be okay, a fuzzy/dim display usually indicates that the video output level is too low. (A too-bright, whitish, faded look could indicate the output is too high.)

     You can adjust video output on a II+ via the small on-motherboard knob near the Game I/O socket. There does not seem to be any way to adjust composite video output on the GS. If your monitor has a video input level adjustment, try changing the setting.

----------------------------


031- Ever since adding a SecondSight video board it seems like my
     GS is always crashing. Is the SS board causing problems?

     SecondSight adds some nice features; but, it is known to be a power hog. Most likely, your system is crashing due to noise glitches on the +5V and/or +12V power busses. The fix is to fatten power supply leads and, probably, add on-motherboard +5V and +12V jumpers to a couple Slots. Details are supplied in the POWER FAQs (csa2POWER.TXT).

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From: James D. Keim

032- My SecondSight board bombs every time I try to run Inwords or
     PublishIt. What's wrong?

     Inwords and PublishIt use the DHR display. The SecondSight cannot emulate the DHR display and locks up the system.

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From: Eric Jacobs

033- Including the left and right borders, how many dots are
     actually sent per line in 320 and 640 modes on the GS?

     Including the left and right borders, plus the horizontal retrace, the video sends out more than 320 or 640 "dots" before the screen begins scanning the next line. Here's a quick summary of the Apple II video that's been used throughout the whole series (assuming 60 Hz video here). It's a slightly modified NTSC signal, though the differences are small enough for most monitors to accomodate.

     Everything in the Apple II is derived from a 14.31818 MHz master clock. This runs both the video and the processor/memory subsystems. The cycle time is therefore 69.8 ns. For 640-mode (or 80 cols, or double-hires) the dots are sent out at simply this rate. In 320-mode (40 cols or single-hires) the dots are sent out at half that rate, 7.15909 MHz (one pixel every 139.6 ns). The NTSC standard calls for 227.5 cycles of color reference (3.579545 MHz) per horizontal line, for a horizontal scan rate of 15.7

34 KHz (3.579545/.2275). The Apple II rounds this up to 228 cycles of 3M, so the horizontal scan rate is 15.699 KHz (3.579545/.228). This is well within the tolerance of most monitors. So therefore in 320-mode 228*2 = 456 "dots". In 640-mode there are 912 "dots". I put dots in quotes because, obviously, only 320 or 640 of them are actually seen as part of the screen.

     When the GS is outputting a composite video signal, each horizontal line must contain a horizontal sync pulse and color burst, and there can't be a border during this time, or else the TV won't register a sync. On the RGB, the GS puts the border color on. So, the answer to your question is 456-320 or 136 pixels in 320-mode and 912-640 or 272 pixels in 640-mode. This includes both borders and the horizontal sync. Of course, a good proportion of this time is not visible; this depends on the overscan set

tings of the particular monitor.


----------------------------


034- I picked up a IIgs RGB monitor at a garage sale. The focus is
     off and it took several minutes until the display got brighter
     but it's still not very good. Are there any adjustments that can
     be made?

     The problem you describe is consistant with low B+ going to the flyback transformer which results in low brightness level, poor focus, and blooming when the brightness and/or screen level is turned up. More than likely if this monitor has been sitting around for awhile, the filter capacitors have gone to mush. Sometimes they can be revived by leaving the monitor on for a long period of time <over 24hrs> but, usually, they require replacement.

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From: Wayne Stewart

035- Where can I get a GS RGB monitor cable?

     You can try a store selling Mac supplies and get a Mac 15 pin cable. I'm using one right now where I needed a longer than standard cable
