Freaks Macintosh Archive/Freaks Macintosh Archive.bin/Freaks Macintosh Archives/Textfiles/Quadra700ClockMods1.45.txt

Text File | 1996-06-04 | 23KB | 453 lines

Newsgroups: comp.sys.mac.hardware
Subject: quadra-700-clock-mod-145 (long FAQ)
From: [e-mail] (Guy Kuo)
Date: 7 Jun 93 06:22:48 GMT
Organization: University of Washington
Keywords: Quadra,700,clock,oscillator,FAQ
Summary: Update of FAQ on accelerating Quadra 700 motherboards
NNTP-Posting-Host: carson.u.washington.edu


Version 1.45 of FAQ

This FAQ describes a technique for changing Quadra
700 clock speed. This version includes cooling fan installation, custom
speed oscillators, thermal data, caveats regarding socket pins, and
performance data. At the time of posting, the author has reports of 33
Q700's modified in this way. Some have been running this way for months
without additional cooling. Three machines required cooling for
accelerated operation.

----------
This procedure should only be attempted by users experienced in circuit
board fabrication and repair. You must desolder a component on a
multi-layer motherboard. Such boards are fragile and expensive to
repair. This is NOT a good first soldering project. The process
voids your warranty. If you are not dissuaded by the above, read on
and see how a $5.00 part can bring your Quadra 700 up to Quadra 950
performance.

The Quadra 700 has been successfully accelerated by exchanging its
CPU clock oscillator for a higher frequency unit. The original
oscillator is a 50 MHz unit from which is derived the 25 MHz and
50 MHz clocks used by the 680RC40 processor. Speeds up to 33 MHz
are usually attained with new oscillators. Higher speeds are
attainable by some individual motherboards. One can reasonably expect
to attain 30 MHz. Higher speeds are likely but not guaranteed. There
is a small chance that your particular motherboard is incapable of
higher speed.

Of the 33 Quadra 700's reported to or modified by myself the results
are:

35 MHz    2 machines (custom Fox electronics 70 MHz clocks)
33 MHz   17 machines. Two of which reported as unstable until
               cooling fan added
32.5 MHz 12 machines (had 65 MHz clocks available at low cost)
31.5 MHz  1 machine required cooling fan to operate. Higher speed
               testing pending.
Failed    1 machine failed at 33 MHz. Lower speeds not yet tested
          1 machine with a clip on clock oscillator failed at 32
               MHz to properly access floppy drive

Motherboard destructions: 0

Motherboard damages: 2 episodes of plate through hole damage which
    the users managed to solder through.

Unusual problems: 1 motherboard shorted against the case during
          reassembly. A piece of paper between the motherboard and
          case solve the problem.


33 MHz exceeds the manufacturer expected performance of the Newer
Technology Variable Speed Overdrive. Newer guarantees 30 MHz as
attainable by all. Of the five VSO's in Seattle I know about, 31 MHz
has been the recommended speed. Personally, I have run a motherboard
with full stability (except 24 bit video) at over 35 MHz. 24 bit video
instability at accelerated speeds prompted me to swap motherboards. My
second motherboard has a top stable speed of 30.5 MHz with a VSO. 24
bit stability was not attained until I slowed to 30 MHz. This very same
motherboard is running rock solid at 33.3 MHz & 24 bit video is working
very well. Apparently, the machine finds a true clock oscillator more
palatable than the VSO's synthesized clock. This suggests that speeds
over 30 MHz will be more easily attained using true clock oscillators.
This observation is confirmed by two other user reports.

The VSO is more expensive but does not require warranty voiding
board modifications. I also market a clip on clock modification which
uses a true clock oscillator which has a solder free installation.
However, I recommend a true soldered installation for highest
reliability. Clip on mounts are primarily for users wary of voiding
their warranty. One user of my clip on had floppy access problems.
It is unknown if that machine would have done better with a soldered
installation, but I would not be surprised.

As new user reports arrive, I shall add them to this info file.

Although machines will run more rapidly, this modification pushes the
circuits beyond normal operating speeds. Although no reported, long
term failures have occurred on Quadra's due to higher speed operation,
there is a possibility of shortening the lifespan of components on
the motherboard. I have run my Q700 at accelerated speeds for almost 10
months and have not had a board failure. Others have run their VSO's
longer. Given this, I doubt this is a very high risk. On the other
hand, the machine may be more prone to system crashes. In my experience,
this has not been the case. For safety reasons, do not perform this on any
mission critical Macintosh.


PARTS

    Clock Oscillators (4 pin TTL or CMOS in 14 pin DIP form factor)
            Check that you are not receiving the half size package!
            Obtain speeds beginning at 50 MHz and higher as you wish
            to attempt. Reasonable values would be 55, 60, 62, & 66.66 MHz
            units. You might try higher speeds as well. The oscillators are
            typically less than $5.00 each mail order.

            You should include the 50 MHz clock in case you damage the
            original oscillator or wish to plug a 50 MHz unit into your
            socket. The original Apple clock oscillator has an Output
            Enable control on pin 1. The units listed below always have
            output enabled. This is not a problem unless you try to use
            a Variable Speed Overdrive with one of the below clocks.

            I obtained my clock oscillators from DigiKey 1-800-344-4539
            Some of their part numbers are:

                50 MHz TTL Clock Oscillator  (part # X121)
                55 MHz CMOS Clock Oscillator (part # SE1509)
                60 MHz CMOS Clock Oscillator (part # SE1510)
                64 MHz TTL Clock Oscillator  (part # X136)
                66.66 MHz TTL Clock Oscillator (part # CTX137)

            Speeds above 66.66 MHz and up to 70 MHz are difficult to find.
            If you wish to try higher speeds, Fox Electronics 1-813-693-0099
            can make 70 MHz clock oscillators on their "Fast Fox" program in
            15 working days. The cost is about $12 each.In ten weeks their
            factory can make any value you wish. Reasonable values to try
            would be 69, 70 and 71 MHz. Ask for TTL in a 14 pin DIP sized
            four pin can.

    Socket: Obtain a 4 pin socket which is in the same form factor as
            a 14 pin DIP package. If you try cutting the extra
            pins off a regular 14 pin socket, be absolutely sure
            no remnants of unused pins can short traces on the
            motherboard. Marc A. Tamsky helpfully suggests using a
            needle nose plier to push the pins out of a machine pin
            socket. It tried it and it work well.

            I used 4 machined socket pins cut from a screw machined
            socket. This allows easier removal should need arise.

    Cooling Fan?: A small, 12 volt muffin fan can be mounted on top of
            the CPU heat sink. Obtain one which has dimensions about
            40 mm square for easier mounting.

            Newer Technology's Variable Speed Overdrive includes a
            cooling fan. However, most machines with modified clock
            oscillators have survived without a cooling fan.
            James MacPhail measured a 4 degree increase was noted at
            33.3 MHz. See later in this document for more thermal
            information. Additional cooling may not be absolutely
            necessary, but one Quadra 700 which I upgraded to 33 MHz
            failed at that speed after two hours of operation. Adding
            a cooling fan allowed that machine to operate reliably.
            If your machine crashes or locks up after several hours of
            operation, you may improve reliability by adding a cooling
            fan.

            WARNING: Do not let your Quadra 700 run too long with
                     the cover off. It needs the cover on to properly
                     direct air past the CPU heat sink. One Apple
                     source stated that the motherboard is known to
                     die after 20 minutes of open air operation.


PROCEDURE

1)  Insert usual disclaimer and anti static warnings here. I can take
    take no responsibility for damage you do to your own machine.
    Undertake this modification only if you are well qualified.
    PROCEED AT YOUR OWN RISK.

2)  Back up your hard drive. If your Mac is incapable of operating at
    the speed you select, it may trash the data on your drive. See
    the warning by Rainer Menes at the end of this document.

3)  Remove the top lid of the machine. You will see the floppy disk and
    hard drive mounted in a plastic tower. Follow strict anti-static
    precautions and make sure the machine is OFF. Unplug ALL cables,
    wall and monitor power supply cords from the back of the Mac.

4)  Remove the power supply by pulling the plastic interlocking tab on the
    tower forward and simultaneously pulling the power supply straight up.
    The tab is a piece of plastic from the left posterior aspect of the
    tower which extends downward to hook on to the power supply. You may
    also feel a horseshoe shaped piece at the right portion of the power
    supply. Leave that alone. The plastic tab from the tower is all you
    need release.

5)  Look at the rear of the tower assembly. You will see the flat ribbon
    SCSI connector to the hard drive, a power cable and a flat ribbon cable
    leading to the floppy drive. Disconnect all these from the motherboard.
    The hard drive power cable connector has a tab which must be squeezed
    to release it.

6)  Unplug the drive activity LED from its clear plastic mount

7)  Look down the posterior, cylindrical section of the plastic tower. A
    Phillips head screw is at the base. Remove it, taking care not to drop
    it into the case. A bit of gummy glue on your screwdriver is helpful
    here.

8)  Remove the tower assembly by pulling medially the plastic tab on the
    rear right side of the tower. This tab prevents the tower from sliding
    posteriorly. Slide the entire tower assembly 1 cm posteriorly then
    lift the tower assembly straight up and out of the case.

9)  Remove the interrupt switch assembly. It is a strangely shaped plastic
    device at the left, front edge of the motherboard. Pull the middle,
    rear plastic prong up and forward. The entire device will release.

10) Unplug the speaker cable. Squeeze the plastic tab on the speaker to
    free it. Swing the fan backwards to free it from the case.

11) Remove the motherboard from the case. Lift the front right corner of
    the motherboard about 1 mm. This allows it to clear the clear plastic
    light guide. Slide the motherboard forward about 1 cm. Be very gentle
    You should not require great force. Once slid forward, the motherboard
    lifts easily out.

12) Locate the 50 MHz clock crystal. It is a small metal box near the
    CPU chip. Note and remember its orientation. The new clock oscillators
    must be aligned with pin 1 (the square corner) in the same orientation.
    Plug an oscillator in backwards and it will be destroyed.

    For your information the pin assignments are:


             --------------
            | 14         8 |           1  Ouput Enable
            |              |           7  Gnd/Case Gnd
            |              |           8  Output
            | 1          7 |          14  V dc (+5)
            L--------------

    Very carefully desolder and remove the old clock oscillator. Some of
    the pins may be bent over. Simply desolder then unbend them. Pin 7
    is directly attached to the metal can and absorbs a great deal of
    heat before melting. Be sure your desoldering iron is hot enough
    before doing pin 7. It is reasonable to desolder the other pins
    first. NEVER use any force on the motherboard. The oscillator should
    practically fall out on its own.

    Tip: Put a small amount of soldering flux on the joints before
    desoldering. This can greatly speed the process, especially on pin 7.

13) Install your socket or socket pins where the old oscillator once was.
    If you are using socket pins, simply put them on an oscillator and
    use the oscillator to hold them in place while you solder the pins.

    WARNING: If you use plain socket pins, leave the leads of your clock
    oscillators long enough to keep the can from touching the pins and
    shorting out the circuit board!

14) Put a 50 MHz clock oscillator into the new socket. You could use the
    old clock but it has solder on its pins. This can come off inside the
    socket and cause corrosion problems later. I suggest using a new
    50 MHz clock. NEVER plug the old clock oscillator into plain socket
    pins. The leads are too short to keep the can off the pins.

    Again, watch the orientation of the oscillator when you plug it in. It
    goes in the same orientation of the other clock oscillator next to
    your new socket. Reversal will destroy the clock oscillator.

15) Install your (optional?) cooling fan system to complete the
    modification. I used two 1 1/4 inch sheet metal screws through the
    fan's mounting holes and into the gaps between the fingers of the
    heatsink to hold the fan in place. Power was tapped from the hard
    drive's 12 volt line on its power cable. This is the yellow or orange
    wire on the harness. Ground is either of the middle, black wires.
    If the fan is too noisy, try tapping the +5 supply (red) instead.
    The fan will run quietly and slowly but will move enough air to
    cool the CPU. Some of the very low profile fans will not run on +5.
    I place four 1/4 watt resistors which have been wired in parallel
    with each other in series with the fan's 12 volt supply for that
    type of fan.

16) Reinsert the motherboard and slide it into place.

17) Snap in the interrupt switch assembly and speaker to lock the mother
    board firmly. Plug the speaker wire back into the motherboard.

18) Reinstall the tower assembly by first placing the right wall of the
    tower against the right wall of the case with the tower assembly about
    1 cm posterior of its intended position. Lower the tower assembly into
    place while maintaining contact with the right wall of the case.
    Once fully down, slide the tower assembly anteriorly until it clicks
    into place.

19) Reconnect the motherboard ends of the cables. DON'T FORGET THE
    FLOPPY DRIVE CABLE.

20) Replace the Phillips head screw

21) Drop the power supply straight down into place until it clicks in.

22) Plug the hard drive activity light back into its clear plastic mount.

23) Reattach your cables and power cords. Cross your fingers and turn
    on the Mac. It should make the usual power on chord. If it doesn't,
    immediately turn of the power and recheck your work. If all is not
    well, you have my sincere condolences. Please report your failures
    to the network. The information may help someone else.

    Hopefully, all will work normally. Turn the machine back off and
    replace the 50 MHz clock oscillator with a faster one. Reboot and
    be astounded.

    You must run the machine for many hours before deciding
    a particular speed is truly usable. With my VSO, a machine lock-up
    could take 8 hours of operation to occur. In the brief time since
    modifying my clock oscillator (one week) I have not had a single
    problem.

Thanks to Rainer Menes, whose comp.sys.mac.hardware article prompted me
to try this modification. Thanks also to the following for submitting
reports allowing me to summarize the success rate of this procedure:

    Guido Paccagnella <[e-mail]>
    James MacPhail <[e-mail]>
    Charles Grosjean <[e-mail]>
    "Stuart R. Harper" <[e-mail]>
    Rainer Menes <[e-mail]>
    "Eric D. Kemp '94" <[e-mail]>
    Dan Winkler <[e-mail]>
    Rick Botman <[e-mail]>
    Mark Newman <[e-mail]> Holy Smokes!
    [e-mail]
    Dustin Boyette <[e-mail]>
    "Marc A. Tamsky" <[e-mail]>
    Yushi Kaneda <[e-mail]>

Good Luck to all who attempt this modification. There is a small but real
risk, but you will likely reach Quadra 950 speeds or higher with less than
$50 in parts. My personal Q700 at 33.3 MHz with an external memory cache
benchmarks faster than a 950. I pass this information along as a very
pleased techie.

Guy Kuo <[e-mail]>

BTW: This same type of mod works for the IIsi, IIfx, Q900, Q950, Centris 610
and Centris 650.
---------------------------------------------------------------------------
And now an important caveat from Rainer Menes

From: [e-mail] (Rainer Menes)
Subject: WARNING: Q700 clock upgrade to 33MHz
Keywords: test your machine very carefull!!!!
Date: 10 May 93 08:43:41 GMT
Organization: Technische Universitaet Muenchen, Germany

Hi all,

Yesterday I have encountered on the Q700 of a friend of mine some very strange
problems. It looks as if the RAM on the motherboard (80ns DRAM) isn't able to do
33.33 MHz) Sometimes it fails and may damage your hard disk or what ever. This
problem varies from board to board. Mine works perfectly under any tested condition
with 33.33 MHz.

So here my warning:

TEST your upgraded Quadra 700 very carefully. Run it under full load a minimum
of 24 hours with, for example, a POVRay picture, which uses most of the
components in your Quadra 700 (CPU, FPU, SCSI, DRAM, VRAM ...). After that run a
memory test for another 12-24 hour. If your Quadra doesn't show any problems you can
be 99% sure that it runs at 33MHz. 1% is left over sorry, but no risk no fun.

To be 100% on the safe side make your room a little hotter than normal when you run
the tests. This gives you more security and the 1% probability of problems is now
smaller than < 1%.

Another tip, if you have not done a backup of your harddisk do it now before
you upgrade. This will give you a better sleep with out nightmares.

Good luck for all how have or think about upgrading to 33MHz,

Rainer
---------------------------------------------------------------------------
I include an informative temperature & performance report from James MacPhail

Date: Thu, 22 Apr 93 21:53:49 -0700
From: James MacPhail <[e-mail]>
Subject: Quadra 700 osc upgrade temp results


I have done some Q700 CPU temperature measurements using an HP 34401A
DMM with a Fluke 80TK temperature adapter. I placed the temperature
probe on the case of the CPU where it is exposed beside the heat sink,
as this is certainly not the place to measure the temperature most
accurately, the actual conditions are probably a bit hotter than
indicated.

Synopsis: The Q700 has a large design margin for CPU heat dissipation.
Increasing the clock speed by 33% increases the CPU case temp about 4
degrees, indicating an increase in power dissipation of 25%.

Machine configuration: Base machine + four 1M SIMMUs, Quantum LP52 drive.
(no additional cards or VRAM).


With the box closed in the upright orientation, the equilibrium CPU

temperature was 37 degrees C at 25 MHz, and 41 degrees C at 33.3 MHz.

The temperature rose rapidly when the cover was removed: it was up 8
degrees in 5 minutes (and still rising). Room temp was 21 C (69 F).

The 68040 designer's handbook predicts Theta(JC) as 2.7 degrees C/Watt.
Their calculations use figures of 3 and 5 watts dissipated (typ).
Using 5 watts gives a junction temperature of 55 degrees C, so we have
oodles of margin (max rating is 110 degrees C).

For those of you who also asked about performance numbers, I did more
accurate comparison runs with Speedometer 3.1:

Synopsis: Except for SCSI I/O (the Disk test), 33.3 MHz machine is 33%
faster than 25 MHz as expected (including on-board video).
            faster than 25 MHz as expected (including on-board video).




Extensions off, 24 bit mode, 1 bit two page display, AppleTalk off,
System 7.1, Quantum LP52, after quitting Finder (no other applications
running):


                KWhet   Dhry    Towers  QSort   Bubble  Queens  Puzz.
Q700 @ 33.3     205.479 27.247  24.960  22.391  23.823  24.105  28.804
Q700 @ 25       155.078 20.390  18.909  17.166  18.000  18.320  21.721

                Perm.   FFT     FPMM    MM      Sieve   BMAve   PRGraf
Q700 @ 33.3     27.170  172.661 154.452 30.250  25.602  63.912  28.347
Q700 @ 25       19.892  127.619 115.839 22.891  19.071  47.908  21.489

                PRDisk  PRMath  PRCPU   PRAve   FPUMM   FPKWhet FPUFFT
Q700 @ 33.3     1.897   136.210 21.898  31.264  13.416  14.827  7.636
Q700 @ 25       1.807   101.943 16.320  23.530  10.733  10.750  5.600

                FPUAve  Mono    2Bit    4bit    8bit    ColorAve
Q700 @ 33.3     11.960  6.134   6.527   6.785   0.000   6.482

Q700 @ 25       9.027   4.615   4.878   5.036   0.000   4.843



32 bit mode (with 8 Mb) tests about 5% faster for video
MacsBug, AppleTalk, and a bunch of inits hits video about 20%

[EOF]