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Author Topic: MDD 1.25 Uni, chime but no video output  (Read 118 times)

G4 MDD Steve

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MDD 1.25 Uni, chime but no video output
« on: May 13, 2026, 11:58:21 AM »

Hello, I've just dug out of storage and attempting to resurrect a 2003 MDD 1.25 single processor G4.

I've bought new RAM (2x 512Mb), a new clock battery, reused an old 640Gb iMac HD with an adapter card. The monitor is connected with a DVI to DP cable. When I turn it on I hear the chime, which suggest the motherboard is OK, but the monitor does not detect an input signal, so I see nothing. I was expecting the flashing question mark for no OS present.

Is there a fault-finding sequence I could follow to narrow down the problem? I know the monitor is OK because I used it on my Raspberry Pi, which I just sold. So, to me, that suggests the video card or the cable, which is brand new. The card is the 64Mb version

Any help appreciated.
Steve
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blazer1878

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Re: MDD 1.25 Uni, chime but no video output
« Reply #1 on: May 14, 2026, 08:03:27 AM »

Some DVI-DP cables are one side only, i have cable that can only be used to connect dvi monitor to DP
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68K: PowerBook 165c
PPC: Powermac G4 400mhz Sawtooth, Powermac G4 MDD 1.25 Single 2002, iBook G3 2002, iBook G4 m2005, Powermac G5 2003 dual
Intel: iMac 20 l2006, Apple TV 2007, MacBook Pro m2007, MacBook 13 e2008, MacBook Pro 15 l2008 Unibody, MacBook Air 13 2014, MacBook Air 11 2010
Apple Silicon: MacBook Air M2

G4 MDD Steve

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Re: MDD 1.25 Uni, chime but no video output
« Reply #2 on: May 14, 2026, 12:06:08 PM »

Oh, thanks. Would you recommend DVI to HDMI?
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GaryN

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Re: MDD 1.25 Uni, chime but no video output
« Reply #3 on: Yesterday at 02:31:45 PM »

A quick rant regarding “standards”.

In the beginning (lol) cables/connectors were described based on the direction of signal flow. So, if your computer had a DVI OUT and the monitor had a DP IN, the cable would be a “DVI-to-DP”. All good, right? It seems however, that somewhere along the line, the logic got reversed so that the cable is now described as “this cable connects device to” so that it’s backwards.
A “DVI to DP” cable NOW means the DVI is the destination (the monitor) and DP is the source (the computer) to connect a DVI monitor to a DP computer.
So, it’s likely that your cable is connected backwards from the way it is supposed to work and that’s why there’s no signal on the monitor. There’s stuff inside the connector to enable the process so it will only work in one direction.

You described everything except the make/model of the monitor. That might be useful info.

Your last post seems to suggest that the monitor might also have a HDMI input. If you go looking for a “DVI-out to HDMI-in” cable, you’ll immediately notice that most of them will say they’re bi-directional. That’s because an HDMI monitor-in can be directly connected to a DVI source if you just get the correct wires on the correct pins.

So, that’s probably a good thing to try.

Ain’t this fun?
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G4 MDD Steve

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Re: MDD 1.25 Uni, chime but no video output
« Reply #4 on: Today at 12:45:27 PM »

You're absolutely right, the cable was sold DVI to DP, which I assumed was what I needed. If the retailer can't exchange it I'll get an HDMI cable.

My monitor is a 19" Lenovo with 3 input ports, HDMI, DP and VGA
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