[HECnet] DEC GIGI - Power Supply Replacement Success

[Mark Wickens]

Folks,

Always nice when you've got a piece of good news ;)

I replaced all the mains filtering capacitors in the original DEC GIGI power supply when one blew only to find that the power supply lasted another 10 minutes before losing power completely. At this point I decided given the relatively standard power outputs (5V 3A, 12V 1A, -12V 0.3A) I would source a replacement power supply.

This arrived and was installed yesterday. It I guess unsurprisingly is substantially smaller and lighter than the original. The original cooling fan was removed as it was basically transformed directly from either the mains directly or one of the windings of the main transformer. I used the fan out of an external SCSI enclosure as a replacement, although I look to source a high quality brand new one. To me it looks like the fan primarily is for cooling the PSU only - given the fan location and the location of the plate that the PSU is mounted on it looks unlikely that the main circuit board would benefit much.

The machine now happily powers on and I had an hours playtime last night with the local BASIC monitor.

The GIGI now only exhibits one minor trait, and I'm yet to determine whether this is down to the LCD panel it is driving being at limits or whether there is a slight issue with the video generation circuit. Once in a while, every couple of minutes or so the LCD looses sync and the picture is dropped. This only happens for a fraction of a second, then the picture is restored as was.

If anyone has any ideas I'm all ears. For reference I'm using a Iiyama AS4637UT, an old but extremely capable 18.1" 1280x1024 native panel. If anyone is interested I can post the horizontal and vertical frequencies it is being driven at.

I plan on scanning the GIGI brochures I have for inclusion on bitsavers shortly.

Regards, Mark