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TheShortTimer

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I've picked up a Mac Mini G4 and it definitely works ok but I cannot get it to output a signal to HDMI on a monitor or an HDTV. I'm met with a black screen or the "no signal" warning respectively. Through a process of elimination, I have already ruled out any issues with the DVI to HDMI cable: I have two and they both work perfectly with my other Macs that feature DVI ports (with the exception of my Sawtooth) and also my 2007 HP desktop.

If I use the DVI to VGA option, it happily displays an image (and my Sawtooth has the same affliction) but trying HDMI brings no joy. To troubleshoot, I have reset the NVRAM with CMD, Option and P and R, I have tried forcing a detect with CMD and F2 and various scenarios of unplugging and reconnecting the cable at both ends. From Googling, this appears to be a notorious problem with the MM G4. Am I stuck with VGA only or is there something that I've overlooked?

Thanks as always. :)
 

Project Alice

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I've picked up a Mac Mini G4 and it definitely works ok but I cannot get it to output a signal to HDMI on a monitor or an HDTV. I'm met with a black screen or the "no signal" warning respectively. Through a process of elimination, I have already ruled out any issues with the DVI to HDMI cable: I have two and they both work perfectly with my other Macs that feature DVI ports (with the exception of my Sawtooth) and also my 2007 HP desktop.

If I use the DVI to VGA option, it happily displays an image (and my Sawtooth has the same affliction) but trying HDMI brings no joy. To troubleshoot, I have reset the NVRAM with CMD, Option and P and R, I have tried forcing a detect with CMD and F2 and various scenarios of unplugging and reconnecting the cable at both ends. From Googling, this appears to be a notorious problem with the MM G4. Am I stuck with VGA only or is there something that I've overlooked?

Thanks as always. :)
I can't help with your problem, but I'd like to add that I have a MacMini G4 that cannot output to VGA, only DVI (I haven't tried HDMI but after seeing this thread I'd like to test that).

I would still try another adapter, even if it works on another machine. It couldn't hurt.
 

TheShortTimer

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I can't help with your problem, but I'd like to add that I have a MacMini G4 that cannot output to VGA, only DVI (I haven't tried HDMI but after seeing this thread I'd like to test that).

Do you want to swap machines? :D

I would still try another adapter, even if it works on another machine. It couldn't hurt.

Another DVI to HDMI cable? I already have two, remember? Neither of them worked with it.

Or were you thinking of something like this instead?

 

Project Alice

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Do you want to swap machines? :D



Another DVI to HDMI cable? I already have two, remember? Neither of them worked with it.

Or were you thinking of something like this instead?

Yeah I was thinking of one of those. I've got one, it worked on my 2009 Mini, Haven't tried it on the G4 though. DVI and HDMI are literally the same thing, so it should work. And if it doesn't, I'd suspect its something weird with the cable.

My issue with VGA is most likely that the analog pins on the Mac are bad for whatever reason. HDMI however uses the same digital connection DVI does. If you can output DVI, you should be able to output HDMI.
 
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DearthnVader

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Could be the display you are using.

What is the native resolution of the display?

The Mini G4 has a 135Mhz pixel clock limit for non-coherent displays. If you display's native resolution exceeds that, you won't get any picture.
 

TheShortTimer

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Could be the display you are using.

What is the native resolution of the display?

Apparently it's 1920 x 1080. The model is the Panasonic TX-P50ST50B.

The Mini G4 has a 135Mhz pixel clock limit for non-coherent displays. If you display's native resolution exceeds that, you won't get any picture.

Ah. Does this segment from the manual provide any clues?

eTLLmLe.png
 

Amethyst1

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The 135MHz pixel clock limit is indeed the culprit here, as 1920×1080 at 60Hz happily exceeds that (I think it's 148.5MHz). See if you can lower the resolution to, say, 1280×720 or alternatively, while staying at the higher resolution, lower the refresh rate until you get a stable picture. You may have to use Screen Sharing from another system into the mini to do that as you get no picture.
 
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TheShortTimer

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I've plugged the Mini into another HDTV that has a VGA port and it automatically configured to 1920 x 1080 at 60hz.

ARjWVyP.png


Is this because VGA is an analogue system and so different rules apply? Please excuse my ignorance in this field.
 

Amethyst1

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@TheShortTimer: You nailed it. This 135MHz pixel clock limit for non-coherent displays only applies to DVI; VGA has higher limits. I've been able to drive 2560×1024 at 60Hz from my G4 mini's VGA output. According to my calculator, that's a pixel clock of 218MHz using CVT or GTF timings. For that matter, I've also been able to drive 3840×2400 at 13Hz from my G4 mini's DVI output but that's only 125MHz using CVT-RB timings and thus, safely within the mini's limit.
 

DearthnVader

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Apparently it's 1920 x 1080. The model is the Panasonic TX-P50ST50B.



Ah. Does this segment from the manual provide any clues?

eTLLmLe.png
Unfortunately most display manufactures don't advertise if the display is coherent or not.

It's sort of luck of the draw, the only safe bet is the Apple LCD's built around the time the G4 Mini was, except the 30" as the Mini can't do Dual-Link DVI.

I had luck setting my Mini G4 to 1280x720@60 for my non-coherent HDTV, then rebooting so the changes were saved to Open Firmware and OS X's display preferences.

You'll have to enable Screen Sharing in 10.4 or later then VNC in to make changes. If your running an older OS 10.3.x you'll need a 3rd party way to setup a VNC host.

I think I used an older version of Vine VNC Server for that before.

Not sure what version:

 
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Bug-Creator

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A few facts/experiences:

- a MacMini will do 1920x1200 on DVI, but thats really the limit (was my main MorphOS system years ago)

- the digital part of the video output has a relativ high failure rate (still not sure wether that 1920x1200 monitor killed DVI on my Mini or the other way round :oops: ) Know of at least 2 Mini having the same issue (without ever going to or beyond FullHD)
 

Amethyst1

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@Bug-Creator: The limiting factor is the pixel clock alone. If you lower the refresh rate to stay under this limit, much higher resolutions are possible. I can post a screenshot of my G4 mini flawlessly driving my IBM T221 supermonitor at 3840×2400 and 13 Hz.
 
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TheShortTimer

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Unfortunately most display manufactures don't advertise if the display is coherent or not.

It's sort of luck of the draw, the only safe bet is the Apple LCD's built around the time the G4 Mini was, except the 30" as the Mini can't do Dual-Link DVI.

I had luck setting my Mini G4 to 1280x720@60 for my non-coherent HDTV, then rebooting so the changes were saved to Open Firmware and OS X's display preferences.

You'll have to enable Screen Sharing in 10.4 or later then VNC in to make changes. If your running an older OS 10.3.x you'll need a 3rd party way to setup a VNC host.

I think I used an older version of Vine VNC Server for that before.

Not sure what version:


Thanks. This also explains why I was unable to get my Sawtooth to work with the Panasonic using DVI to HDMI. The Mini is running under 10.4. I'll have a go with Screen Sharing and VNC and report back with the results. Just to confirm, this could all be set up across Ethernet with the other Mac running El Capitan?

@Bug-Creator: I can post a screenshot of my G4 mini flawlessly driving my IBM T221 supermonitor at 3840x2400 and 13 Hz.

Please do, I'd like to see it! :)
 

Bug-Creator

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Must admit that I never before heard about (non)coherent displays.....

@Bug-Creator: The limiting factor is the pixel clock alone. If you lower the refresh rate to stay under this limit, much higher resolutions are possible. I can post a screenshot of my G4 mini flawlessly driving my IBM T221 supermonitor at 3840×2400 and 13 Hz.

Wellsuremaybewhatever...

I do know that the Samsung I used for getting 1920x1200 all those years ago would simple fail to sync anything below 59Hz on VGA and it was even worse for DVI where it would sometimes stay synced when I dropped the rate while it was running only to fail on the next boot...

On the hand I did get 1024x1008 out the RGB output of an Amiga500, while others had 24bit colors. Both needed HW on the other end capable of displaying ultra-low refresh signals with a few WTFs thrown in.....

None of this should get the "no signal" error OT complains about, hence my assumption of the digital out being defective (which is not uncommon for the Mini).
 

TheShortTimer

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On the hand I did get 1024x1008 out the RGB output of an Amiga500, while others had 24bit colors. Both needed HW on the other end capable of displaying ultra-low refresh signals with a few WTFs thrown in.....

A stock A500 (OCS?) running at 1024 x 1008, delivering 24bit colour? ?
 

Bug-Creator

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Neither offcourse, notice „others“ and „needed HW“.
I had a A2024 doing a whooping 4 shades of grey while for 24bit you needed something like a Grafitti.

But both did indeed work on a stock A500, C= even shipped a „JumpStart 1.4“ floppy so one could use the A2024 with KickStart 1.3..
 

Amethyst1

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Wellsuremaybewhatever...

You said the Mini's limit is 1920×1200 over DVI but it is not. That was my point. It's obvious that you need a monitor capable of dealing with very low refresh rates if going for higher resolutions over single-link DVI.
[automerge]1571830057[/automerge]
Wow. 13 Hz... And here I thought my 2012 MacBook Pro running a 4K display at 30 Hz was bad...
Been there, done that. :) However, the 2012 MBP should be able to do 40 Hz if the pixel clock limit has been patched away.
 
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TheShortTimer

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Success!?

With Chicken of the VNC and Vine Server set up on the Mini and some fiddling from my MacBook, I was able to produce a display via HDMI! I think you'll find the results to be very interesting.

These are the resolutions that are available to me on my Polaroid LED HDTV:

CjGJls4.png


Every resolution option shown works, with the unsurprising example of 1920 x 1080: due to the TV being a non-coherent display.

Moving onto my Panasonic plasma that previously had a no signal issue...

Only two resolutions from this list appear to work and they are: 1280 x 720 and also 1920 x 1080! (1080i) :oops:

nAJ7Xih.png


I do not understand why 1920 x 1080 works now but it does and whilst 60hz is possible, it seems a tad unstable and so I'm sticking with 50hz. I found that similar to what @DearthnVader had described with his own experiences, when I rebooted with the Panasonic connected, the Mini used 1920 x 1080 as the default resolution.

Thanks for your help everyone. ?
 
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