New fans for my Micro PDP11/23

[peclark]

The cooling fans on my Micro PDP11/23 were wearing out - the bearings in one were failing and the fan would no longer spin, and the other one was getting loud and rattling a bit so I wanted to replace them. After looking around a bit I found a 12v fan that has slightly lower CFM, but is much quieter.

I installed them today and they are so much quieter - here's what I used:



And as installed:



The fans come with power adapters for various types of plugs, I ran the wires to the front, and used the power connector that used to be used for the MFM hard disk (which has been replaced by a ZuluSCSI...

 

[leegleason]

This looks great. I've been wanting to do something like this - I have two BA23s under my desk and the fans are pretty loud. Do you have the airflow specs of the old fans and these?

 

[peclark]

This looks great. I've been wanting to do something like this - I have two BA23s under my desk and the fans are pretty loud. Do you have the airflow specs of the old fans and these?

My old fans were Torin TA450 - which according to a catalog I found, seems these models are 106cfm.



They don't seem to spec fans like this anymore, the specs for the fan I got is here - https://noctua.at/en/products/fan/nf-s12a-flx/specification

Seems the airflow of this model is listed like this:

From conversion charts I found online, I believe these new fans are around 63 cfm... If what I found is correct, the conversion is as follows:

One m³/h equals ~0.589 CFM and one CFM is ~1.699 m³/h

I've run the computer for about 2 hours straight since I put in the new fans, and so far so good. The exhaust flow seems really good and the computer doesn't seem to be getting hot... I'll keep a close eye on it for some time to be sure.

 

[leegleason]

My old fans were Torin TA450 - which according to a catalog I found, seems these models are 106cfm.

View attachment 1276983

They don't seem to spec fans like this anymore, the specs for the fan I got is here - https://noctua.at/en/products/fan/nf-s12a-flx/specification

Seems the airflow of this model is listed like this: View attachment 1276984

From conversion charts I found online, I believe these new fans are around 63 cfm... If what I found is correct, the conversion is as follows:

One m³/h equals ~0.589 CFM and one CFM is ~1.699 m³/h

I've run the computer for about 2 hours straight since I put in the new fans, and so far so good. The exhaust flow seems really good and the computer doesn't seem to be getting hot... I'll keep a close eye on it for some time to be sure.

Thanks!

 

[commodorejohn]

Nifty! This has been on my to-do list for forever; the fan noise is a big reason I don't run my -11 very often.

 

[hush]

fantastic find, thank you! uploaded a quick before and after, in this video you're only hearing the fans in the two power supplies making up forum user alegend's h7864-c, the noctua fans are essentially silent. inside the ba23 deskside enclosure with covers on i think this should be quiet enough to run where it belongs! i'm running a 4.3bsd kernel build to make sure the temps stay good, about halfway through and it seems happy so far even with a half loaded backplane! :>