Unplugging CRT monitor

I have a G4 PowerMac mirror drive door running 10.4. I was using a mac CRT studio monitor and then got a LCD monitor to replace it. It worked for a while and then wouldn't start up. I tried plugging in the CRT monitor simultaneously and the computer powered up. Now I'm running both monitors and it's been working fine like this for several months but the CRT monitor is wasting energy.

The Question:

Can I unplug the CRT monitor after I start up without doing any damage?

Yes.
I also have a old apple crt monitor and a powermac g4 but sawtooth. You can plug in the CRT monitor when the computer is on. I've done it many times. But depending on your video card it could fry.
It's not recommended though unless you must. Because it can do damage to the computer, monitor and you.

Hope this helps!

Please tell us how you're running two monitors.
1. Do you have a PCI card fitted for the extra one?
2. Are you using the original graphics outlet for the CRT or the LCD?
3. Does your G4 have two outlets from the native video card (I'm not familiar with that model)?

Agreed, you can indeed plug and unplug a CRT monitor (VGA or Apple connection?) but you risk causing a power surge or short if the pins don't dis/connect simultaneously. If you're practised and competent, you can do the power-on plugging thing successfully 9 times out of 10, but it's that one time that's the danger factor. It's up to you whether or not you wish to take the risk. Unplugging is safer than plugging.

Edit: if your LCD monitor will only work if the CRT one is plugged in, why don't you simply switch the CRT monitor off. Sure, it's going to 'standby', but it will use a lot less power in that mode.

The original native graphics card has two outlets, one VGA and one DVI. That's where both monitors are plugged in.

The computer will only power up if CRT monitor is plugged in. If I try to start up with only the LCD monitor, the computer wont power up.

How do I switch off the CRT monitor, only? Holding the power switch shuts down the computer also. If I push the button with the sun icon, it just opens a dialog box with monitor settings.

Okay, so the CRT monitor is connected via VGA - right? And the LCD is connected via DVI. That second factor has me just a little puzzled.

After posting yesterday, I checked Mactracker and EveryMac, and read that the second video connector is ADC, Apple's own type of interface. What appears to be happening is some sort of crossover at the video card, causing the two monitors to be interdependent, but how it is happening I cannot explain.

Solutions:
1. Boot your G4 from the original install disk
2. From Disk Utilities, run a hardware check. I have a feeling, but cannot be sure, that you have a hardware fault in the video card.
3. If faulty, and a native video card is unavailable or too expensive, invest in a third party PCI card to run the LCD monitor. Dispose of the faulty Apple video card.

To your question: most CRT monitors have a power button at the lower right area of the front face. There's usually a little green LED light in it. Pressing that switch turns the monitor screen off (the LED light goes out) but does not turn the monitor off 'inside', ie. it goes to standby. You should always power the monitor screen on at the front switch before starting your computer (same with the LCD monitor).

I have already installed a third party LCD video card and plugged the LCD monitor into it thinking that would solve the problem. No luck, but I haven't tried taking the native card out. Will that make a difference? Others have told me the problem due to a fault in the CPU and for some reason the CRT monitor signals the computer to start up.

The apple CRT studio monitor only has the power up switch that also turns on the computer unlike third party CRT monitors.

telecarver1 said:

I have already installed a third party LCD video card and plugged the LCD monitor into it thinking that would solve the problem. No luck, but I haven't tried taking the native card out.

Click to expand...

What do you mean by "3rd party video card"?

If it's a video card meant for a Windows computer...it will not work...you can only use "Macintosh version" video cards.

- Nick

I mean it was not purchased from apple. it is made for and intended for use in a mac

telecarver1 said:

Now I'm running both monitors and it's been working fine like this for several months but the CRT monitor is wasting energy.

The Question:

Can I unplug the CRT monitor after I start up without doing any damage?

Click to expand...

I guess that I'm really confused by is the whole point of this question!!! If you're so concerned about the CRT monitor wasting energy...why not unplug the CRT monitor permanently??

Sorry...I read your 2nd post about the computer not starting up properly without the CRT monitor plugged in.

This really should not be a problem, just plug in the LCD monitor...and start up your computer "twice". The first time will be for the computer to properly "sense" the LCD display, and the 2nd startup may get things working properly.

There's no real reason why your computer should not be able to operate with just the LCD display plugged in...I do it on my old "Sawtooth" all the time. Assuming your LCD monitor is not unusual in some way.

- Nick

Aren't we all confused Nick! Either one or the other of the displays is faulty, or the graphics card which you will not tell us what it is, is not compatible.

harryb2448 said:

Aren't we all confused Nick! Either one or the other of the displays is faulty, or the graphics card which you will not tell us what it is, is not compatible.

Click to expand...

Very true Harry!

Something could be something defective "hardware-wise" making a diagnosis more difficult!

- Nick

I wish it were that easy. The problem is not that the computer doesn't recognize the LCD monitor. It does that fine. The problem is that the computer will not power up unless the CRT monitor is plugged in. No light, no noise, no nothing. It's as if the power cord were unplugged. If the CRT monitor is plugged in, with or without the LCD monitor, it starts up normally. If I try to start it up with just the LCD plugged in, nothing happens. I then have to unplug and re-plug the power cord before it will start up with the CRT monitor. As long as the CRT monitor is plugged in, everything functions normally. The same thing happens whether the LCD is plugged into the native video card or the Radeon 7000 video card I installed in the hope that it would solve the problem. Both the native video card and the Radeon 7000 video card recognize the LCD monitor fine. The computer just won't start up with only the LCD monitor plugged in.

Having posted the question about the start-up problem before and consulting with two local mac technicians, the conclusion has been that it is, indeed, a hardware problem. Being that I can't afford a new mac at this time, I have learned to live with it. I was just hoping that I could unplug the CRT monitor after I start-up.

telecarver1 said:

The problem is that the computer will not power up unless the CRT monitor is plugged in. No light, no noise, no nothing. It's as if the power cord were unplugged. If the CRT monitor is plugged in, with or without the LCD monitor, it starts up normally.

Click to expand...

This is a very very unusual problem...one I have not heard of before...but also a very interesting problem to look into further.

Is there any chance that this is a Apple CRT monitor, and if so...does it have an ADC video connector on it? It looks like this...the plug on the right:

Also...does the monitor have a video cable & a power cord...or just a video cable?

Thanks,

- Nick

Nick - you've echoed almost exactly what I mentioned to Harry 'offline', ie. this most unusual problem. I commented in an earlier response that the G4 MDD's video card had an ADC outlet.

As a 'sparkie' of limited experience, this situation suggests that there's a strange, and possibly dangerous, re-routing of the power supply through the CRT monitor, when it should be isolated. It should, in theory, be irrelevant to the computer<>LCD circuit.

Question: telecarver, are all your computer setup devices powered from a multi board, or power board - whatever it's called where you live?

I'm wondering if in fact there is a fault in the power supply, ie. arcing, bleed. With absolutely everything in the setup switched off, including the power at the wall socket, try swapping the various devices into different sockets in the power board - most importantly the computer itself and the CRT monitor - and then power them back on, monitors first [but I don't believe the LCD is involved in this problem].

If you are using a power board, and have a spare backup, try that as well.

hughvane said:

Nick - you've echoed almost exactly what I mentioned to Harry 'offline', ie. this most unusual problem. I commented in an earlier response that the G4 MDD's video card had an ADC outlet.

As a 'sparkie' of limited experience, this situation suggests that there's a strange, and possibly dangerous, re-routing of the power supply through the CRT monitor, when it should be isolated. It should, in theory, be irrelevant to the computer<>LCD circuit.

Click to expand...

Hughvane,

Not sure if you're thinking the same thing I'm thinking (sounds like you may be)...I was going to wait for the "OP's" answers to my questions above before speculating further.

- Nick

Yes, piggo3

That is the type of plug, on the right, in the photo, that plugs into the computer. The other end of the cord is permanently attached to the Apple CRT monitor. There is no other power supply to the CRT monitor, only the video cord. The CRT monitor came with an older G4 400 Mghz. computer that I have. When I got the newer setup, I transferred the CRT to the new computer, that had the same ADC connector. This problem didn't arise until I tried to upgrade with a LCD monitor on the newer computer. The older computer still works fine using only a LCD monitor and the newer one works fine using only the CRT monitor.

telecarver1 said:

Yes, piggo3

That is the type of plug, on the right, in the photo, that plugs into the computer. The other end of the cord is permanently attached to the Apple CRT monitor. There is no other power supply to the CRT monitor, only the video cord. The CRT monitor came with an older G4 400 Mghz. computer that I have. When I got the newer setup, I transferred the CRT to the new computer, that had the same ADC connector. This problem didn't arise until I tried to upgrade with a LCD monitor on the newer computer. The older computer still works fine using only a LCD monitor and the newer one works fine using only the CRT monitor.

Click to expand...

Here's the deal with the ADC plug (Apple Display Connector). The ADC cable carry's both the video signal AND the power for the monitor...that's why it only has one cable...instead of two cables (one for video & one for power) that almost all other monitors have.

So...what I'm thinking is something is wrong with this computer...since the computer should work fine regardless if you have your CRT or LCD monitor connected to it.

What I'm guessing is...your computer only works when you have the CRT monitor (with the ADC connector) plugged into it...and it doesn't work with the LCD monitor...since the CRT monitor gets it's power from the computer...there must be some sort of "weird" thing going on between your:

- CRT monitor
- video card
- and the computers power supply

I think that you mentioned earlier that nothing happens when you press the computers power button when you have the LCD monitor connected (by itself)...but the computer works fine if the CRT monitor (ADC connector) is plugged in.

Here's a very important additional point...even with no monitor connected to your computer...if you push the power button the computer should still start up normally. The power button will light up, the hard drive will spin up...you just won't get any video since you don't have a monitor hooked up.

So...if you unplug all monitors from your computer, and then push the power button...if nothing happens something is wrong with the computer...and it's nothing to do with the monitors.

I'm going to suggest two things are possibly wrong either:

- the power supply is bad (more expensive fix)
- or possibly the PRAM battery is dead (much less expensive fix)

Dead PRAM batteries can really cause certain model Macs to act really really weirdly...so I would say try replacing the PRAM battery first. Since the computer seems to work fine with the CRT monitor plugged into it.

Here's the battery you need:

3.6v Newer Technology Lithium 1/2 AA PRAM Com... (3.6VPRAM) at OWC



Sorry for the long post..but I was sort of thinking "out loud" and wanted you to have as much detail as possible regarding my logic/thought process.

Hope this helps,

- Nick

Good advice Nick. What's got me whacked is that old (computer) works with new (LCD), new (computer) works with old (CRT), and never the twain shall meet. A thought from left field - are these two computers networked?

hughvane said:

Good advice Nick. What's got me whacked is that old (computer) works with new (LCD), new (computer) works with old (CRT), and never the twain shall meet. A thought from left field - are these two computers networked?

Click to expand...

Are we talking about more than one computer in this thread?...if so maybe I'm getting confused! I thought that we were talking about one computer...a G4 PowerMac mirror drive door...and two monitors (an LCD & an Apple CRT with an ADC connector).

I think that what helps an old computer work with newer hardware (like an LCD monitor) are newer versions of the Mac OS...like OS 10.4 which the OP has on their computer.

- Nick

hughvane said:

Good advice Nick. What's got me whacked is that old (computer) works with new (LCD), new (computer) works with old (CRT), and never the twain shall meet. A thought from left field - are these two computers networked?

Click to expand...

If a new PRAM battery doesn't fix the "OP's" problem...this is going to get to be a real perplexing problem!

- Nick

pigoo3 said:

Are we talking about more than one computer in this thread?

Click to expand...

Yep, see post No 17.

An LCD monitor is an LCD mon ....... you know how it goes. It should just work, whatever computer it's hooked to. I've had a Philips LCD working off my old tower G3 with Panther via VGA without any hiccups.

Rhetorically ... so
1. why won't the LCD work with TC's new(er) computer?
2. what role is the CRT monitor ('scuse capitals) - which DOES work with the new(er) computer - playing in all this? The power supply provided via the ADC cable should NOT prevent ANY computer starting up. The cable is simply a conduit FROM the computer TO the monitor, there should be no reverse feed.

Unfortunately, there has been a confusing amount of information provided in paragraph form, which makes it difficult to extract salient points, so I'd like to ask TC to post some pics of his setup and LIST the way in which devices are connected.

A question to someone who knows more than I do about the hardware involved - is it actually permissible/possible, in hardware terms, to run two video cards in the one machine, as TC's post No 6 states.

Hugh