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Silencing Macintosh II

finkmac

NORTHERN TELECOM
So, I have a Mac II but… Man, the fan is rather VOOSHy, almost like a vacuum cleaner!

Anyone had success replacing the PSU fan with something quieter? I understand that the PSU fan is the only thing cooling the entire system, but I'd still like to make it quieter…

The Mac II uses a Panaflo FBK-08A12H fan, these are the specifications according to this page.

 80x25mm  1.56W  37.1 CFM   4.5 mmH2O    35 dB-A   FBK-08A12H

I don't see any Noctua  fans that output the same mm H20 for example, any recommendations? I'm really not sure where to go here.

 

blitter

Well-known member
Yeah I replaced the PSU in my II with a IIfx PSU and it made a noticeable difference. I'm also interested if there are further improvements to be made.

 

Byrd

Well-known member
I'd try cleaning it first, and re-lubricating the fan.  If you must replace, I'd go for a unit which has similar CFM qualities over the existing fan, not a ultra quiet slow model.  The fan is important in circulating air in the entire case, not just the PSU.

 

finkmac

NORTHERN TELECOM
Not seeing too many around 37.1 CFM, I wonder if 31 CFM would work?

The thermal design of this thing isn't exactly advanced…

 

finkmac

NORTHERN TELECOM
So, thanks to somebody else's post on one of Larry Pina's books, I took a look through the "Macintosh II Repair and Upgrade Secrets" book for information on fans and such.
 
It seems there was a fan controller upgrade sold by "Nova International", which connected between the fan and power supply, and used a temperature probe on a long wire to adjust fan speed.
 
Of course, nowadays… That particular fan controller upgrade is basically unobtanium.
 
 
So, as a substitute… I've been looking at various cheap temperature fan controller boards on eBay and aliexpress, and settled on one that features a temperature probe on a wire, and has screw terminals for power input (From the PSU) and power output (to the fan), as well as a dial that can adjust when to start ramping up fans.

$_57.JPG

I will test it out, and report back with findings!

 

Compgeke

Well-known member
That's pretty close to the same kind of setup I have in my HP 6632A power supply, mine controls PWM rather than voltage though. It works quite well, the hardest part is just finding somewhere to mount it.

 

dr.zeissler

Well-known member
How did it turn out? Did you change the fan or did you put a fan-controler in the power supply?
I am also thinking about reducing the noise and the fan is very noisy in my macintosh II.
I currently have the color-graphics-card in my setup. The 3,5" SCSI-HDD will be changed to SCSI2SD, so no heat either.
I will also put a soundcard in it (PAS16NUBUS) and a ethernat-card. If everything turns out well, I get a P33-Nubus accelerator and an NUBUS-PC Board. So that machine will be fully equiped :)
 

EIMS

Member
I've been exploring options for this. The Mac II power supplies I have, both the Sony and the Astec, have Panaflo FBH-08A12H fans. This is not the FBK, the FBH has a larger hub motor with small stubby fins, and probably has to spin faster to get the same air flow as a result. The Mac IIfx power supply I have has a larger 92mm fan, Panaflo FBK-09A12H, which won't physically fit the Mac II power supplies.

All the power supplies seem to have variable speed fan controllers. The power supply seems to be designed to pull air out of the computer, and blows it over a thermistor that controls the fan speed. For the Sony Mac II power supply, I measured the fan voltage at 9V when started up at room temperature. For the Astec I measured the fan voltage at 10V. I removed one of the fans and put it on a variable bench power supply, at 9V it draws 0.23A, about 2W. If I turn it up to 12V it is even louder and draws about 0.35A, 4.2W, so it is running at about half power at 9V.

I've replaced one of the fans with an NMB 08025SA-12N-EL-D0, which is rated at 41.3CFM and is variable voltage from 6.0V to 13.8V. It is a vast improvement over the old fan, I can barely hear the fan over the noisy old hard drive. Currently in stock at Mouser.

The Sony Mac II power supplies have a rib mount fan, where the Astec has a flange mount. The flange mount version fits both, I just wouldn't go crazy tightening the screws, but if you want to get a rib mount version there is the NMB 08025SA-12N-AA-D0.

Delta have a 37.43 CFM fan that could also be a good option, Delta AUB0812HH flange, or AFB0812HH for a rib mount version. There is also a VH version rated at 42.02 CFM. I went with the NMB fans as they seem to be a more modern design, and the specifications say they are only 30dB noise at 41.3 CFM. The specs for the Delta are 34.0dB for the HH and 38.0dB for the VH.

Here is a picture of the old Panaflo beside the new NMB:
Mac II fans.jpg
 

beachycove

Well-known member
Yes, I had a Macintosh II that had been upgraded to a IIfx, but the machine still had what I took to be the original power supply in there. Certainly that fan did not slow down on idle. Oh no. It was lift-off all the way. Another of our lot on here bought it from me and loves the machine, but I have to say that I was not impressed, and thought the machine almost unusable. I can’t stand loud fans, drives, etc.

The cooling system in the machine was indeed primitively conceived, which I find very surprising given the care taken in design elsewhere at HQ.

I would have thought the fan replacement route sh/would work best, but another little trick I learned after selling on the IIfx is to solder a small resister onto (into?) one of the leads of a jet-engine-esque fan, which slows things down nicely, enough to make OEM fan noise far less irritating. I’ve been running a Color Classic Mystic like that for years with no ill effects. The resistor, by the way, gets cooled by the fan.
 

Trash80toHP_Mini

NIGHT STALKER
Great info gang, thanks much. Fan tech has come a long way in the past 30+ years! Time to do the fourth in my schedule of five year overhauls of the pet IIfx and this looks like a great thing to do. :)
 

Concorde1993

Well-known member
but the machine still had what I took to be the original power supply in there
Probably was/is, it's an ASTEC unit, but I thought it was recapped at some point?
Certainly that fan did not slow down on idle. Oh no. It was lift-off all the way.
Can confirm it is somewhat loud, almost the same as the fan on my SE SuperDrive. The winner in my collection is my HD20 which houses a 5.25" Seagate ST-225N and its equally audible fan (I think it's a Sony).
Another of our lot on here bought it from me and loves the machine
Definitely the best $100 I ever spent, and still going strong after 8+ years of use.
 

beachycove

Well-known member
I am glad to hear that it is still doing its duty!

The ps wasn’t recapped, but it was thoroughly cleaned out. I used a handheld shower and hot, hot water. Lots of brown water emerged. Gallons. Fish died in the Thames.

It had to done, though, as the fellow I got it from was a chain smoker, had owned it from new, and the machine was literally brown. I exaggerate only slightly when I say that the thing was coated inside and out with about a quarter inch of cigarette tar. It was as if someone had rubbed it down with moly lube. The ps was especially bad, as it had sucked all the smoke in and had the first crack at it, as it were. When the fan was running and the fan was pushing through all that air, well, the place smelled like an ashtray. It was disgusting. So the whole thing got a long, hot wash, what could get scrubbed got scrubbed, etc., etc.

It cleaned up wonderfully, though. I have a theory that the tar preserved the plastics, because they were unusually good.

I think you should do something about that fan, now that we are on the subject. This would also give you a good opportunity to take a look at the caps.
 

LaPorta

Well-known member
Interestingly, it appears that my IIfx has a II PSU, as there is never any speed throttling. It is also loud as all get-out. At this point, since it is recapped and works perfectly, I am reluctatnt to just find a IIfx one to pop in. Maybe the replacement fan option would work. I believe it is a Sony; did anyone find a good replacement for this?
 

Concorde1993

Well-known member
Lots of brown water emerged
Holy crap.
I have a theory that the tar preserved the plastics, because they were unusually good.
Probably. The plastics are still in decent shape; just some minimal yellowing on the top cover and some minor rusting on the metal shielding but nothing to get excited about. I bought a IIx on eBay awhile back and both the plastics and the shielding were in relatively the same shape as the IIfx.
I think you should do something about that fan, now that we are on the subject.
Unlikely that I will. Working in auto manufacturing for 10+ years I've become accustomed to loud fans and sometimes it's best to leave things alone (Murphy's Law and so forth). Plus it does keep the internals cool.
This would also give you a good opportunity to take a look at the caps.
The only thing I noticed about the power supply is that it makes a rapid click-click noise if I connect the 8.24 GC video card. It used to work with the IIfx up until my LaCie Electron IV went haywire about a year or two ago and said that the resolution was out of range. I had a thread about it but I think it was lost during the recent forum crash.
 

Quantum

New member
I've been exploring options for this...

Thank you, EIMS, for sharing your findings! The fan in my Mac II's power supply is about as irritating as it gets. Glad someone has done the research to find a viable replacement. I'll likely be purchasing the very model of fan you suggested using, and I'll eventually update the thread with my observations.
 

Quantum

New member
An update...

I picked up the same model of NMB fan recommended by EIMS, and I promptly installed it. It is quieter than the stock Panaflow, but not dramatically quieter. (Like the stock fan, this one is still plainly audible over the noisy HDD.) Of course, it is substantially more efficient than the Panaflow. In fact, I would assume that it could safely run at a lower voltage and near silently keep the Mac cool. (I would need to determine the ideal voltage and RPM, about which I am currently unsure.) For now, it's at least a bit quieter than the stock fan.
 
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