dplatt@coherent.com (Dave Platt) (06/18/88)
Last week, I found the following tidbits on my local EchoMac bulletin-board
system:
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From: James Brigman
To: Howard Berman Msg #313, 29-May-88 08:50pm
Subject: Re: A Quieter Macii!
Howard;
You can reduce the noise level of a Mac II by replacing the nasty little
Panaflo 12V .45A unit with an equivalent part from Radio Shack. It's Cat. No.
273-243A, a 3" DC Brushless Fan. This is a 12V, .16A BALL BEARING unit that is
about 70% quieter than the original. I am preparing a procedure for the
"upgrade", but it should be relatively straightforward if you have had any
reasonable electronics hobbyist experience.
ONE NOTE: The radio shack unit is rated 27CFM, while the oem unit is rated
31CFM. I expect this to make a difference only for a fully loaded Mac II
system. I have operated my Mac II in this altered state for two months now,
and have had no problems whatsoever.
Additionally, if you can mail order an equivalent unit at a better price, do
so. I'm not endorsing RS, it
just the most accessible source for most people.
Someone else out there on Fidonet has reported a successful upgrade via this
method, with a dramatic decrease in noise level. I forget his name.
Please let me know if you need more information, if you will attempt the
upgrade and when you successfully complete the project.
--- TBBS v2.0
* Origin: Micro Message Service NCRTP (919)779-6674 Multiline TBBS (151/102)
*** This is a reply to #82.
From: Andrew Stone
To: Howard Berman Msg #286, 31-May-88 07:26pm
Subject: Re: A Quieter Macii!
Hi,
I quieted my MacII with James' suggestion of replacing the .45a fan with
the .15 Radio Shack #273-243A fan {$14.95} in the power supply. Very
straightforward, if you like getting your feet wet.
Probably not recommended if you are driving 4 monitors and running 2 16meg ram
nubus cards!
--andrew
--- TBBS v2.0
* Origin: The BMUG BBS - home of MUGADMIN - Berkeley, CA (161/444)
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This was too impressive a suggestion to pass up. I popped my II open,
examined the innards of the power supply, and decided that I could
fumble my way through the fan-swap without difficulty even in the
absence of detailed directions. Fortunately, I was correct... the whole
job took me about 45 minutes. The Mac II runs _much_ quieter with the
new fan; the airflow doesn't seem to have been noticably diminished,
and the case and "exhaled" air seem to be no warmer than before.
For the benefit of those of you who may wish to undertake a similar
fanectomy and transplant, here are the steps involved. NOTE: I don't
guarantee that this sequence is entirely correct or complete (I'm
working from memory rather than from notes), and I specifically disavow
any responsibility for the outcome (short- or long-term) of a fan-swap
according to these or any other directions. Do it at your own risk!
Please note James Brigman's cautions above about the fact that the
replacement fan has a lower maximum airflow than the OEM fan... if your
Mac has lots of NuBus cards or is operated in a hot room, switching fans
might cause problems. This mod will certainly void the warranty on your
power supply!
The Radio Shack fan suggested for this modification is rated at .16
ampere maximum (about a third of the Matsushita Panaflo OEM fan), at
27 CFM maximum (cubic feet of air moved, per minute... about 10% less
than the OEM fan), and 35 dbA maximum (I don't know the sound rating of
the OEM fan). Many similar fans are available... a brief glance through
the EE Master Catalog showed more than a dozen manufacturers listing fans
that could be used in this application. There are many different
tradeoffs possible between current required, airflow delivered, noise
level, and bearing type; if you have the energy and opportunity, you
could pick the specific fan best for your Mac II. If you're like me,
you'll go to Radio Shack...
------------------
PARTS AND SUPPLIES NEEDED:
* 3" DC Brushless Fan. Radio Shack part #273-243A, or equivalent.
* 2" of small-diameter (1/8" or so) heat-shrink tubing, or a roll of black
electrical tape
* 2 plastic wire ties or equivalent (I used waxed dental tape!)
* Optional: a small plug of the sort used to terminate the ends of the
fan wires in the Mac II power supply. I have no idea where to locate
such a plug... but if you can find one, you need not cut the plug off
of the OEM fan wires.
TOOLS NEEDED:
* Medium-sized Phillips-head and flat-head screwdrivers
* Diagonal cutters
* Needle-nose pliers
* Standard pliers
* Soldering iron (I used a 35 watt unit) and rosin-core solder.
* Code-approved grounding strap or pad, if available. If not, work
where you won't generate static charges, and discharge any static
buildup on your body by touching a grounded object (WHILE TOUCHING
NOTHING ELSE!) before opening the Mac II case, and frequently
thereafter.
CAUTIONS:
* Read through all of these instructions before starting. After you
open the power supply, examine it carefully and make sure that you
understand what is to be done in each step, before you actually
remove any components or clip any wires.
* These procedures worked with the power supply in my Mac II; if my
descriptions don't match up with what you see in your Mac II, do
what's right for your machine!
* Use all standard precautions against zapping your Mac II with static,
and against zapping yourself with 120-volt power! If you don't know
what you're doing, DON'T DO IT!
* If something goes wrong or doesn't work properly... it's your
problem, not mine.
INSTRUCTIONS:
* Shut down your Mac II, and let it rest for at least 5 minutes before
proceeding.
* Unplug all cables and wires from the Mac II chassis.
* Remove the cover-retaining screw at the center of the back side of
the Mac II cover; press the cover-release buttons at each back
corner, pivot the cover up and towards you until the catches at the
front of the case disengage, and set the cover aside. [This procedure
is pictured on page 8 of your Mac II owner's manual]
* Touch the case of the power supply with one hand, while keeping your
other hand clear of all electrical thingies. This will equalize any
static-electricity potential between you and the Mac II.
* If your Mac II was configured in the standard fashion, the video card
is probably mounted in Slot 1, immediately to the right of the power
supply. This isn't really an optimal position... the card restricts
the airflow somewhat, causing the fan to work harder and raising the
noise level. It's also in your way, now that you want to remove the
power supply. I'd recommend moving the card over to Slot 4 or Slot 5
(putting it in Slot 6 might interfere with the cables for an internal
SCSI hard disk). BE SURE to touch the power-supply case, and thus
discharge any static electricity on your body, BEFORE touching the
video card... some of its components are said to be extremely
static-sensitive. Also, be careful to plug the card back into the
motherboard correctly... don't bend the pins or the card. [See pages
9 through 11 of your owner's manual]
* A multi-wire cable comes out of the power supply and plugs into the
Mac II motherboard. Disconnect the plug by pulling it gently towards
the front of the Mac II until it disengages the motherboard pins.
* There is a single screw near the motherboard power-supply plug, which
fastens a metal "foot" of the power-supply case to the Mac II
cabinet. Remove this screw and set it aside.
* Slide the power supply towards the front of the Mac II case (it moves
about an inch). This will disengage it from slots and pins in the
case. Raise the font end of the supply towards you, and then lift
out the entire power supply module.
* Set the Mac II case aside where you won't drop anything into it.
* The power-supply has a U-shaped cover which is fastened with two
screws (one at either end) and which has slots that engage retaining
ridges on the sides of the power-supply case. Remove the screws and
set them aside. Disengage the cover slots from the retaining ridges;
this can be done with firm finger-pressure, or by prying gently with
a flat-blade screwdriver. Slide the cover off, and set it aside.
* Set the power supply down, with the open side up and the fan towards
the right.
NOTE: in subsequent steps, I'll use the following conventions:
"top" and "bottom" refer to the open side of the power supply, and
the side that's now sitting on the desk/table/floor. Other
directions will be specified as if the fan were a clock: "9-o'clock"
refers to the direction to the left of the fan, "12-o'clock" refers
to the far side of the power supply, and so forth.
* Make a sketch of the fan's position. You'll note that a pair of
wires (red and black) leaves the fan case at the 1-o'clock position,
runs along the 12-o'clock side of the fan, is bundled with another
red-and-black pair of wires, and terminates in a plug that's
connected to a small circuit-board which is mounted above and on the
9-o'clock side of the fan. The second pair of red-and-black wires
runs from an LED mounted above the fan on the 3-o'clock side, and
runs to a plug connected to a circuit board below the fan at about
the 10-o'clock position. [To make matters even more confusing, the
LED wires plug into the 10-o'clock circuit board at a point
misleadingly labelled "fan"!. Be sure you don't confuse the wires,
plugs, or plug-in locations!]
* The fan and LED wires are fastened together with a plastic wire-tie.
Cut this tie with diagonal cutters, and discard it. Also cut and
discard a second, larger tie that fastens the outgoing power-supply
wires to the 4:30-o'clock corner of the fan.
* Unplug the fan leads from the circuit-board at the 9-o'clock
position. There's a small retainer that engages a ridge on the plug;
pull the retainer gently away from the pin with a fingertip to
release the plug. Separate the fan wires from the LED wires, and
make sure that the LED wires are routed clear of the 12-o'clock side
of the fan.
* Turn the power supply so that the "bottom" (the air-intake side) is
accessible. Loosen and remove the four Phillips-head screws that
hold the fan in place, and set the screws aside. Return the power
supply to its original position.
* You should now be able to reach down and remove the fan from the
power supply. You'll find it necessary to raise the 6-o'clock edge
of the fan first, then rotate the fan slightly as you work it
upwards. Be careful not to force the fan against the LED, circuit
boards, or against the capacitors mounted above the 6-o'clock edge.
It _is_ possible to remove the fan without removing or damaging any
components!
* Below the fan's position is a spacer, which held the fan about 3/8"
above the bottom of the power supply (the air-intake grill). Leave
this spacer in place.
* Examine the fan. You'll see that the four retaining screws were held
by small brass nuts that are pressure-fitted into the fan's
plastic case. If you want to leave the original fan entirely intact,
you'll need to scrounge up four nuts of the same size and thread.
Otherwise, remove these press-fit nuts from the fan, by turning the
fan upside down, setting it on a firm surface, inserting the point of
a pair of needle-nose pliers through the mounting holes (so that they
fit inside the threaded portion of the press-fit nut), and applying
gentle and increasing pressure downwards. The press-fit nuts will
pop out of the fan case after a few seconds, leaving the fan intact.
* Mount the press-fit nuts into the new Radio Shack fan. This can be
done by placing them into the mounting holes by hand, and squeezing
them into the fan's case with a pair of pliers. Remember that you
want them mounted in the same places, and in the same way, as they
were on the original fan.
* Cut the wires that run from the original fan to the plug at the
wires' end. Be sure to leave a couple of inches of wire attached to
the plug.
* Cut the wires on the new fan to a suitable length... leave them an
inch or so longer than the wire stubs that remain on the original
fan.
* Strip about 1/2" of insulation off of the two leads coming from the
plug, and from the two leads coming from the new fan.
* If you have some narrow-diameter heat-shrink tubing, cut two 1"
pieces, and thread them over the ends of the wires from the new fan.
* Twist the red wire from the plug to the red wire from the new fan.
Twist the black wire from the plug with the blue wire from the new
fan. Solder both connections. After the connections cool, bend the
twisted and soldered portions down against the wires themselves.
* If you placed heat-shrink tubing on the wires, move the tubing up to
cover the soldered regions, and heat it above the soldering iron (or
with another heat source) until it shrinks and secures the solder
splices. If you don't have heat-shrink tubing, insulate the solder
joins with black electrical tape.
* Lower the new fan into the power supply, reversing the turns and
contortions that were necessary to remove the old fan. Make sure
that you place it in the same orientation as the original fan... the
wires will leave the top of the fan case at the 1-o'clock position.
Double-check this using the sketch you made earlier.
* With a flat-bladed screwdriver, move the fan spacer (now below the
new fan) into proper alignment with the fan itself. Ideally, you'll
be able to look down through the fan's mounting holes, through the
spacer, and through the holes in the power-supply case itself.
* Lift the power supply up vertically without turning it, and insert the
four fan-retaining screws from beneath. They should slide through
the spacer, and engage the press-fit nuts mounted in the new fan's
body. Finger-tighten each screw a few turns before inserting the
next one. Once all four screws have been inserted into their nuts,
turn the power supply on its side and tighten the screws with a
screwdriver. Tighten them firmly, but not too hard (don't want to
break the fan case). Set the power supply back down in its original
position.
* Reinsert the plug on the fan leads into the pins on the circuit board
at the 9-o'clock position. Make sure that you plug it in correctly;
the retaining clip on the circuit board should engage the ridge on
the plug.
* Dress the fan and LED leads neatly, by folding any excess fan wire
into a "Z" shape, and fastening the wires together with a plastic
wire tie or insulated thread of some sort (I used Tom's waxed dental
tape... I doubt that the mint flavoring will cause problems). Make
sure that the fan rotates smoothly and doesn't strike any of the wires.
* Fasten the outgoing power-supply leads to the 4:30-o'clock corner of
the fan with a wire tie, per the original arrangement. [Actually,
this seems rather superfluous, as the leads are dressed to the case
less than an inch away with a screw-mounted cable tie. I didn't
bother to re-dress them...]
* Place the power-supply cover back on the case and press it back into
position. Make sure that the retaining slots and ridges all line up
properly. Replace the cover-retaining screws at either end of the
case, and tighten.
* Return the power supply to the Mac II cabinet. Lower it into the
cabinet with the front (fan) end raised slightly, to permit the pins
at the rear of the cabinet to engage. Then, lower it into its
horizontal position, slide it gently towards the rear of the case to
engage the slots near the front end of the supply, line up the
retaining "foot" with the proper hold in the case, and reinsert and
tighten the hold-down screw.
* Plug the power supply back into the motherboard. Make SURE that you
plug it in properly... double-check this, or you could quite possibly
damage your machine when you turn it on!
* Put the cabinet cover back on... engage the slots at the front of the
case first, then lower the rear of the cover into position and press
down until the cover-retaining catches engage. Reinsert and tighten
the cover-retaining screw. [See page 11 of your Mac II owner's
manual.]
* Reconnect the monitor, keyboard, and other peripherals and
accessories.
* Reconnect the power cord, and plug the Mac II back in.
* Push the "Power on" button, and hear the reassuring chord. If the
Mac doesn't power up, emits the four-note "I'm sick" chime, or lets
out a hail of sparks and smoke... well... you have my sympathies!
* Stare at the Mac and see if you believe that it has actually powered
up... the buzzing WHOOSH of the old fan will have been replaced by a
quiet breeze.
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If you use this procedure, I'd enjoy hearing about the results. If you
can suggest any changes to the procedure to make it easier or more
effective (or to correct any errors on my part), please let me know!
[I'll be away on business through 6/26; please forgive any tardiness in
responding to your comments.]
Best of luck!
--
Dave Platt VOICE: (415) 493-8805
USNAIL: Coherent Thought Inc. 3350 West Bayshore #205 Palo Alto CA 94303
UUCP: ...!{ames,sun,uunet}!coherent!dplatt DOMAIN: dplatt@coherent.com
INTERNET: coherent!dplatt@ames.arpa, ...@sun.com, ...@uunet.uu.netsierra@ati.tis.llnl.gov (Frankie Sierra) (06/18/88)
I could not resist the temptation any longer, and went to Radio Shack and bought the replacement fan for my Mac II (cat no. 273-243A, $14.95). I read the instruction, took the appropriate precautions, and proceed to the fanectomy on instinct (not actually following the step by step procedure). It took nearly an hour (I took my time with a snack in mid-processing). If I have to do it again it would not take me more than 20 minutes. The results, as described. I was surprised to hear for the very first time the noise produced from my internal hard disk (PL90i-Turbo). I thought this was a quiet hard disk, but now I am concerned on how to quiet this one too (it is noisier than the new fan). The noise reduction has been very noticeable (I use the Mac in a very quiet environment - Home). And, as described, the fan only produce a calm breese type of noise. It works! Frankie Sierra sierra@ati.tis.llnl.gov