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Use your flat screen monitor with your Apple IIgs

My first computer was an Apple II. I progressed to an Apple IIgs and then to Mac. But I still have my Woz Signature Apple IIgs and a box full of floppies with games and AppleWorks data.

If you are like me and no longer have the IIgs monitor, you may find it difficult to find one again.
But all you need is about $50 in parts and you can make your flat screen monitor work with your Apple IIgs. Sure, you could use the RCA jack output to your TV to get a lousy picture. But you will not be able to read 80 column text with that picture.
Using the following information, you can use the RGB output of the IIgs for a nice sharp picture.

What you will need:

1. Flat screen monitor with a VGA input.

2. Mac DB15 Male to VGA HD15 Female Adapter

3. SainSmart GBS-8220 RGB/CGA/EGA/YUV to VGA Arcade HD Video Converter Board

4. 5 VDC power supply for the SainSmart board.

5. Jumper wire and soldering iron.

First an explanation for the jumper...

The reason that you need a jumper on the Apple IIgs motherboard is to redirect the composite sync signal to a different pin so it can get to the SainSmart board.

And an explanation for the SainSmart board...

You need the SainSmart board because it converts the 15 khz sinc signal to your flat screen frequency which is in the range of 31 khz to 83 hhz normally.

If you do not use the SainSmart board with the motherboard jumper, you will get a black screen and may see a message on the screen that says the frequency is out of range.

What you need to do:

1. Remove the motherboard from your Apple IIgs. It is quite easy to remove because it is just held in place with plastic clips that you push to release the board.

2. Solder a jumper from pin 3 to pin 15 on the RGB video connector.
The jumper takes the composite sync from pin 3 and redirects it to the unused pin 15. Then the adaptor redirects pin 15 to pin 13 in the VGA cable.

The motherboard and adaptor are shown below:

The photo above shows the Apple IIgs motherboard with jumper going from pin 3 to 15.
You can get the adaptor from Cables to Go for about $15.00


3. Re-install the motherboard and plug the adaptor into the motherboard.

4. Connect a standard VGA cable from the adaptor to P 10 on the SainSmart board
(That is the RGBHV Signal input).

5. Connect a standard VGA cable from one of the Db15 VGA outputs on the SainSmart board (either one should work) to the VGA input on your flat screen monitor.

The SainSmart GBS-8220 RGB/CGA/EGA/YUV to VGA Arcade HD Video Converter Board is shown below and can be purchased from amazon for about $25.00...

It does not come with a power supply, so you will also need a 5V DC power supply. If you are like me, you have one laying around the house somewhere (in a box all tangled up with other power supplies).

This SainSmart board is fantastic. You can just plug it in and it will work. The only thing I did was adjust the brightness and contrast (the default settings were much too bright). When you press on the General Menu Button, you will see all of the settings you can change.

Note that the tiny tiny manual that comes with it is impossible to read. You will need to download the pdf. It is in many places on the web and here...



Here are the pin-outs for the motherboard RGB video port on the IIgs


Mac DB15 Male to VGA HD15 Female Adapter Pin-outs
P2 is the larger end of the adaptor.


Rich Love is President and owner of Carnation Software

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