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A Homebrew MicroVAX II

Alegend

Alegend

Experienced Member
Joined
Jun 13, 2017
Messages
88
Location
Israel
Hi All,

For years I wanted to have a MicroVAX II that would be livingroom-friendly, i.e. quiet and nice to look at.
After about a month of construction, two power supplies, three custom PCBs and six quiet fans, the homebrew MicroVAX II is ready.

The machine currently runs its own HTTP server, hosting a (basic) web site that tells its story, how it was constructed, what software is installed on it, and lots of general MicroVAX II facts and anecdotes.

It is quiet, interesting (especially for kids), and also functions as a [power hungry] clock: the display is a POS VFD 2x20 character RS232 display hooked up directly to the console port, with very accurate time as the machine runs NTP.

The elongated custom panel PCB seen on the side of the machine is a combination DHV11 cabinet kit, dual Ethernet AUI cabinet kit, a BA23 front panel LED & switch interface (not used on this machine) and FUNCT SEL/SLU holder (also not used, as the SLU is mounted facing the front).
I will post the manufacturing files and bill of materials for this board, in case someone ever wants to build one.

To save a very long post - you can go to the web site on the machine itself and check it all out.
The web address appears on the POS screen in one of the attached photos below, just add "http://" in front and ":50224" at the end.

-Alon.

20200424_152627.jpg20200424_152701.jpg20200424_152740.jpg20200511_131216.jpg20200511_131625.jpg20200512_184431.jpg
 
Quite different. I’m sure your idea of livingroom friendly is different from my wife’s though!
 
bobaboba said:
Quite different. I’m sure your idea of livingroom friendly is different from my wife’s though!
Click to expand...

On my side this conflict (along with many others) has been resolved. The mechanism is called Divorce;)
 
Interesting! Had a look at your microvax2 museum site. I am quite interested in the replacement TOY board. Did you just make the one PCB? Or do you have any to sell? I am in the UK, if there are others in the UK who are interested it might be worth seeing if we can get a few PCBs made? I have no idea how easy or hard that might be though.
 
That is really cool.

I am currently on a secret quest to setup one vintage computer in each room of the house. So far I am 2/10 and still married ;)
 
Very nice :D What's the noise level like? Part of me would almost consider migrating my 11 out of the BA-23 if it meant I could run it in the house...
 
I would have some serious concerns about the airflow between the cards there.
The BA23 was designed so that the fan(s) are pulling air over all the boards in the box. This design seems to have lost that detail.
It does look very nice, though.
 
commodorejohn said:
Very nice :D What's the noise level like? Part of me would almost consider migrating my 11 out of the BA-23 if it meant I could run it in the house...
Click to expand...

All the fans are low noise, around ~26dBA so the machine is barley audible, six fans and all. With four fans sucking air out of the enclosure, its inside is only 2-3C above ambient.
The 20cm fan on the left of the card cage is the biggest and quietest fan, it blows air horizontally through the cards. The most problematic issue I think is the two KA630 chips that normally get too hot to touch (CPU and FPU), so they are fitted with BGA-type heatsinks, as seen in the photos, as well as their own 12cm fan right above them. The rest of the cards (DELQA, two MS630 RAM boards, and UC07) enjoy a reasonably cool breeze, not as strong as the original BA23 fan but it's definitely there. No chips get above 50C as far as I can tell, so I think this setup should be OK. All the details and part numbers are on the machine's own web site...
20200515_185543.jpg
 
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