In <1ema25d.110cduy1mflxykN%dempson@actrix.gen.nz>, dempson@actrix.gen.nz (David Empson) writes:
>Allen Bong <sfbong@tm.net.my> wrote:
>
>> What are the differences between a GS rgb monitor and a PC SVGA monitor?
>
>The IIgs RGB monitor uses TV-compatible scan frequency: about 15.75 kHz.
>
>VGA and higher resolution monitors operate at a higher scan frequency:
>at least 30 kHz.
>
>The IIgs can only output video at 15.75 kHz, and modern RGB monitors
>cannot synchronize to such a slow signal, so they won't display the
>image correctly.
>
>> I ask this because I want to mail order a used IIgs without monitor from
>> ebay and modify a SVGA monitor to work with it.  Could it be done?
>
>In theory, you could get a scan doubling device which would take the
>IIgs video signal as input and produce a double speed video signal as
>output.  This would work with many current monitors.
>
>For some monitors, it is possible to modify their internals to work with
>the lower frequency, but I don't know the details.

An easier and cheaper solution is to pick up an old VGA monitor at a flea market or surplus
store that can scan down to 15 kHz.  I found the following list of monitors so capable:

    Model Manufacturer
    Size
    Horiz (inch)
    Hz Vert
    Frequency
    KHz
    Frequency

    7015 ACER
    ?
    ?
    ?

    AML-1402
    Adara Technology
    14
    15-36
    45-90

    MS-8431
    Amazing Tech.
    14
    15-36
    ?

    CM-324 AOC
    International
    14
    15-36
    50-90

    CM-324H/M
    AOC International
    14
    15-36
    50-90

    CM-326 AOC
    International
    14
    15-38
    50-90

    Auto-Trak
    714 Conrac Display
    13
    15.5-37
    45-80

    Auto-Trak
    9250 Conrac Display
    13
    15-37.5
    48-90

    Model 7126S
    Conrac Display
    26
    15-32
    48-75

    Model 7211
    Conrac Display
    13
    15-37.5
    47-80

    Model 7211
    Conrac Display
    19
    15-37.5
    47-80

    Model 7241
    Conrac Display
    19
    15-37
    47-80

    Model 9214
    Conrac Display
    13
    15-38
    50-80

    Multiscan
    3436 CTX International
    14
    15-38
    50-90

    TSM-1431
    Darius Technology
    14
    15.5-39
    50-90

    ECM 1410
    Electrohome, Ltd.
    14
    15-40
    45-90

    ECM 2010
    Electrohome, Ltd.
    20
    15-38
    45-120

    Eversync
    Color Everex Systems
    14
    15.5-35
    50-70

    FMS Falco
    Data
    14
    15-38
    47-90

    MTS-9608S
    Forefront Technology
    14
    15-38
    50-90

    TY-1411
    Golden Dragon
    14
    15.5-30
    50-120

    Idek
    MF-5017 IDEK/Iiyama North Amer.
    17
    15-40
    50-90

    Idek
    MF-5021 IDEK/Iiyama North Amer.
    21
    15.5-38
    50-90

    C21LV-65MAX
    Image Systems Corp.
    21
    15-65
    55-90

    C24LV-65MAX
    Image Systems Corp.
    24
    15-65
    55-90

    CM-1403
    Intra Electronics USA
    14
    15-38
    40-100

    GD-H4220US
    JVC Information
    19
    15-37
    45-87

    CMON M
    Leading Edge
    14
    15.75-39
    50-90

    MagicVIEW
    20 Mac
    20
    15.75-36
    50-100

    Model
    2014/LP Microvitec
    14
    15-40
    45-100

    Model 2020
    Microvitec
    20
    15-38
    ?

    Model 710MH
    Mitsuba Corp.
    14
    15-38
    50-90

    Diamond Pro
    26M Mitsubishi Electronics
    25
    15-38
    45-90

    HC-3505SK
    Mitsubishi Electronics
    26
    15.7-38
    45-90

    XC-3315C
    Mitsubishi Electronics
    33
    15-38
    40-120

    XC-3715C
    Mitsubishi Electronics
    37
    15-36
    45-120

    AM-2752A
    Mitsubishi Electronics
    27
    15.6-36
    45-90

    AM-3151A
    Mitsubishi Electronics
    31
    15.6-36
    45-90

    AM-3501R
    Mitsubishi Electronics
    35
    15-35.5
    45-70

    MG-3430
    Modgraph
    9
    15-35
    50-70

    DM-2710 NEC
    Technologies
    27
    15-38
    40-100

    NEC 2 NEC
    Technologies
    ?
    ?
    ?

    NEC 3D NEC
    Technologies
    ?
    ?
    ?

    PanaSync
    C1391 Panasonic Communication
    13
    15.5-36
    40-80

    Ultra 1200
    Princeton Graphic Syst.
    12
    15-38
    45-120

    Ultra 1400
    Princeton Graphic Syst.
    14
    15-38
    45-120

    Ultra 1600
    Princeton Graphic Syst.
    16
    15-38
    45-120

    CN4551
    Samsung
    ?
    ?
    ?

    AlphaScan
    Sampo Corp. of America
    14
    15.75-36
    50-87

    CE-8
    Sceptre Technologies
    14
    15-38
    50-90

    CM-3
    Sceptre Technologies
    14
    15.5-36
    50-70

    CPD-1302
    SONY Corporation of Am.
    13
    15.75-36
    50-100

    GVM-1310
    SONY Corporation of Am.
    13
    15.75-36
    50-100

    GVM-2020
    SONY Corporation of Am.
    20
    15.75-36
    50-100

    Tuff/CRT
    Talon Technology Corp.
    14
    15-35
    47-73

    Omniscan
    CM-1495H Tatung Co. of America
    14
      15-37
    40-120

    MultiVision
    770+ TAXAN America
    14
    15-37
    50-90

    MediaScan
    3+ TVM Professional Monitor
    14
    15-38
    46-100

    TM-5414 TW
    Casper Corp.
    14
    15.5-35
    50-70

    MM20E45
    Toshiba
    ?
    ?
    ?

I have a Sony 1302-CPD and an NEC Multisync II, and they both work fine in this application.

Louis