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Macintosh LC to VGA adaptor settings

Hey everyone,
Thanks for all the help! Here is what I have tried so far: I tried the quick turn on, turn off trick, but nothing new happened. I then set my monitor to the 640X480 at 66 Hz setting, when I plugged the mac into the monitor, the monitor displayed a message saying: Auto Config. Then the same thing happened, the screen turned black, but then when I unplugged the mac the monitor displayed a message saying: no input.

I know this is a stupid question! But on a PC you don't need to have the keyboard and mouse plugged in, in order to see if it will boot up. I was assuming the same principle with the mac LC. Am I correct in assuming this? Do you need to have the keyboard and mouse plugged in, in order to have it boot up correctly?

Do you guys think there may be a problem with the VRAM or just the "normal" RAM?

I used to have a DB15 to VGA adaptor (the cheap kind where it doesn't have any pins selections) and it worked fine with a previous mac I had. I'm thinking it might be worth a shot to get another DB15-VGA adaptor? I found this on ebay and it has not settings like my previous one here is the link: http://www.ebay.com/itm/271123155495?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

What do you guys? Think this is worth a shot, or am I just beginning to be too desperate!
Thanks again for all of your help! Any advice would be very much appreciated!
 
Do you have access to a regular CRT instead of an LCD? That would help you narrow down if it's the computer or the LCD screen. I've found that most LCDs won't work on an older Mac because they want to run at either 60Hz or 120Hz, but nothing else. Older LCDs that still used analog input often supported frequencies common on CRTs such as 70Hz, 72Hz, and 75Hz in addition to 60Hz.

That has been my experience, anyway.

Also, Macs use Sense on Boot. You may have to shut down the computer completely before connecting a monitor or making any changes if you want to see a picture on the screen.
 
Hello olePigeon,

I tracked down a friend who has a CRT monitor. I will try it with their monitor and let you know how it goes.

Thanks
 
So, I tried using it with a CRT monitor, and the same thing happened.... The monitor detected a signal, but there was no picture. So I'm pretty sure we can rule out the monitor has being part of the problem. I guess the problem is the mac its self... What could be the culprit on the mac? The VRAM? Or the motherboard its self?

Many Thanks
 
habibrobert said:
So, I tried using it with a CRT monitor, and the same thing happened.... The monitor detected a signal, but there was no picture. So I'm pretty sure we can rule out the monitor has being part of the problem. I guess the problem is the mac its self... What could be the culprit on the mac? The VRAM? Or the motherboard its self?

Many Thanks
Click to expand...

How long have you been waiting for picture to appear on the screen? I have a beige G3 that takes a full 90-120 seconds to display anything on bootup, press its power button, chime, wait 90-120 seconds of blank screen and then it starts booting. My G3 does this because its crammed full of the maximum amount of RAM as it can handle, maybe it's something similar on yours?

Also, the chimes you hear, are they normal chimes, or are you getting death chimes, maybe there's something else wrong with your LC?
 
You don't seem to have noted the importance of the ID sense lines described in my earlier post. The Mac video adapter will not provide the right signals if it does not identify a compatible monitor type USING THOSE THREE LINES. This is all set out quite clearly in Apple's Developer Notes, which again I recommend.

Rick
 
You need to short pins 7 & 10 on the Mac side for the LC to enable VGA mode. The highest resolution you can do is 640x480. 16 colors with stock VRAM, 256 colors with 512 VRAM.

If you're still playing with that adapter, try the codes for the Apple 13" RGB monitor instead of the ones for a VGA monitor. One of those should short pins 7 & 10.
 
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I use the setting '2367' (also mentioned by digress) to connect a 15" iiyama lcd panel to a Macintosh LC475 and it works fine.
The adapter has 10 switches that have two positions, 'on' or off.
'2367' simply means that switch 2, 3, 6 and 7 are 'on' and the others are off. That goes for the other combinations as well, of course.
habibrobert shows a scheme that has all the different settings on it but it's a thumbnail so rather hard to read.
Here's a link to the document: http://myoldmac.net/FAQ/RGB-VGA-DIP-switchconfiguration.htm

IMPORTANT: The Mac only reads the settings at start-up so for each different setting you have to RESTART your Mac!

Herman
 
The original LC only supports 512x384 and 640x480. The LC 475 had a re-designed video card and supports 512x384-1152x870. The 475 also has twice the VRAM. You can do VGA on the LC, but only at 16 or 256 colors.
 
olePigeon said:
I've found that most LCDs won't work on an older Mac because they want to run at either 60Hz or 120Hz, but nothing else. Older LCDs that still used analog input often supported frequencies common on CRTs such as 70Hz, 72Hz, and 75Hz in addition to 60Hz.
Click to expand...

After a lot of disappointments I have found one of my LCDs that will work with VGA adapter settings 2,4,5 on a IIsi.
It is a Benq FP737s, which has both VGA and DVI inputs.

This monitor is very common. Made in Taiwan or China, it also appears under other OEM names including HP and I think perhaps a Dell model. It is one of those that often needs a couple of capacitors replaced in the board that supplies current to the backlight tubes. I've found a couple at landfill salvage shops.

Rick
 
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