MaciNap: Modern power management for your SE[/30]

[ymk]

MaciNap is a small PCB which shuts down the analog board and slows down PWM fans when the screen is blanked.



Screensavers prevent CRT burn-in, but won't save your analog board or flyback transformer.

MaciNap monitors the video signal and shuts down the analog board once the display has been blank for about three seconds. When resuming from sleep mode, the video signal is suppressed until the sweep circuitry stabilizes, to avoid bright lines on the CRT. Power consumption is typically reduced by half during sleep mode.

A single amber LED on the board indicates status:

• Bright - Video is active and the analog board is powered.
• Two flashes - Video signal is dark and analog board is shut down.
• Dim - CRT protect: analog board is starting with video signal suppressed.

MaciNap generates two fan PWM signals which have a duty cycle of 100% when video is active. During sleep mode, they're reduced to 50% and 75% duty cycle, reducing airflow and noise.

The PCB intercepts the red wire on the PSU/AB harness (12V sweep). The video signal is tapped from the back of the analog board with a black/white twisted wire pair. The yellow and black pair shown here powers the Noctua PWM fan. The fan's blue PWM wire is soldered to the MED pad for speed reduction:




Basic through-hole soldering skills are required for installation.
Any screensaver which completely blanks the screen will activate MaciNap's sleep mode.
Basic Black is a lightweight screensaver recommended for System 6 and 7.

Available on Tindie.

 

[David Cook]

Very cool (pun intended).

Have you found that power usage drops significantly when the screen is blank? And thus, the fan is needed less?

I wonder whether it would be better to monitor temperature instead.

 

[MacintoshSE1987]

MaciNap is a small PCB which shuts down the analog board and slows down PWM fans when the screen is blanked.

View attachment 91034View attachment 91038

Screensavers prevent CRT burn-in, but won't save your analog board or flyback transformer.

MaciNap monitors the video signal and shuts down the analog board once the display has been blank for about three seconds. When resuming from sleep mode, the video signal is suppressed until the sweep circuitry stabilizes, to avoid bright lines on the CRT. Power consumption is typically reduced by half during sleep mode.

A single amber LED on the board indicates status:

• Bright - Video is active and the analog board is powered.
• Two flashes - Video signal is dark and analog board is shut down.
• Dim - CRT protect: analog board is starting with video signal suppressed.

MaciNap generates two fan PWM signals which have a duty cycle of 100% when video is active. During sleep mode, they're reduced to 50% and 75% duty cycle, reducing airflow and noise.

The PCB intercepts the red wire on the PSU/AB harness (12V sweep). The video signal is tapped from the back of the analog board with a black/white twisted wire pair. The yellow and black pair shown here powers the Noctua PWM fan. The fan's blue PWM wire is soldered to the MED pad for speed reduction:

View attachment 91035View attachment 91037


Basic through-hole soldering skills are required for installation.
Any screensaver which completely blanks the screen will activate MaciNap's sleep mode.
Basic Black is a lightweight screensaver recommended for System 6 and 7.

Available on Tindie.

This is actually ingenious.

 

[ymk]

Have you found that power usage drops significantly when the screen is blank? And thus, the fan is needed less?

Yes! On an SE with no spinning drives or cards, power consumption drops from 36W to 14W.

I wonder whether it would be better to monitor temperature instead.

Without a remote probe, the PCB isn't in a great place to sense flyback heat, which is fairly constant when powered.

Fan RPM goes to maximum immediately when there's a video signal, before the flyback heats up.

 

[shirsch]

Just ordered mine

 

[zigzagjoe]

Nice idea! One caution: you should check your voltages while the screen is off. Without a HDD and screen off there will be nearly no load on 12v.

With recapped OEM PSUs, the 12v voltage may increase problematically if you have a lot of cards in your system and especially if you have adjusted the PSU voltage to compensate. Seasonic retrofits may have the inverse problem where 5v sags unacceptably without sufficient +12v load.

Meanwell retrofits like the Babyface PSU won't have an issue as each rail is fully independent.

 

[ymk]

Nice idea! One caution: you should check your voltages while the screen is off. Without a HDD and screen off there will be nearly no load on 12v.

Thanks! I measured my SE with Hitachi PSU at the analog board:

Active: 12.58V / 5.36V
Sleep: 12.83V / 5.31V

Also, this machine is passively cooled, so there's not even a 12V fan.