greg kimnach

towerizing an a4000, using a Supermicro SC750A tower case

updates

this project is not yet complete, as of 2 january 2000, but i have a few moments to add to these pages.

2 july 2000--first update in a long while! i recently purchased a long sought after conceirto module for my picasso iv, and this led to a system tear-down and modification of the case. not much of a mod, mind you. i just refused to lose an expansion slot; therefore, i cut an opening in the case's rear and mounted the conceirto there.

much of the metal working is as in the 2000 tower projects. here, however, i used a slightly different approach because the onboard 4000 daughter card has zorro/video slots, which are parallel to the a4000 motherboard. also, because i was tackling this project due to the towerhawk case's shortcomings as a toaster/flyer solution, i needed additional db-19, db-15, db-25, and scsi connector openings. to this end, i used an a2000 cover which i modified to become the back and mounting plate for the a4000 mother board. (note that the side of the a2000 cover becomes the back plate, and the top of the a2000 cover becomes the motherboard mounting plate.)

the openings in the a2000 cover were located as follows:

the a4000 mounting plate was placed within the a2000 cover, and the openings for the video/floppy/audio/keyboard and serial port were traced out on the inside face of the a2000 cover. these openings were also traced out on heavy construction paper. (the astute reader will realize that, by aligning the a4000's mounting plate as i did, the a4000base plate will be used in the final assembly. also, the mounting plate was placed within the a2000 cover such that the onboard 4000's stand-offs would be epoxied to the cover.)
reference points (i.e., the corners of the openings and the center of the stand-off openings) were drilled out on the case, and the elongated openings were cut out and filed.
the db-9/db-15, db-25, and high density scsi openings were laid out on the construction paper. the two elongated openings were cut out, as well, on the paper.
the construction paper was aligned atop and taped to the a2000 cover.
the db- and scsi-connectors' stand-off holes were drilled out, and the construction paper removed.
aligning the appropriate mounting bracket for each opening, brackets were aligned with the respective mounting holes and scored. (it's best to afix the bracket to the case with a pair of nuts and bolts, while scoring the metal.)
each hole in the a2000 cover was cut short of and then filed to the score line. the zorro expansion slot "opening" has yet to be cut at this stage.
the a4000 mounting plate's front and rear panels were then cut off.
having cleaned all metal flakes off, the a4000 motherboard was fastened to the original a4k base plate, and this was installed in the a2000 cover. the required "fine-tuning" of the openings were marked and made.
the a2000 cover was then cut to the appropriate width and depth to fit within the supermicro tower.

the supermicro case then had to have openings cut to accept the original a4000 power supply and the a2000 cover/mounting bracket. these were straightforward and will not yet be detailed. the a2000 cover was then test fitted within the supermicro case.

to determine the exact width of the required zorro slot opening, the a4k motherboard was installed on the mounting bracket and the onboard 4000 expansion card was installed. an expansion card was installed in each of the extreme zorro/video slots: this provides proper vertical and horizontal alignment of the card guide openings. the supermicro's expansion slot plate, having been cut to have only the expansion slot openings, was slipped in and screwed to the expansion cards. the required opening was then marked, and the back plate was then modified accordingly. the resulting two "sub-assemblies" are shown here.

the expansion slot cover was then bonded to the mounting plate with j-b weld metal epoxy. epoxy was placed on the appropriate contact surfaces, and the onboard 4000/expansion cards + expansion slot plate sub-assembly was installed. after 24 hours of curing, the daughter cards & the onboard 4000 were removed and epoxy placed in the three locations where the onboard stand-offs sit upon the a2000 plate. the daughterboard sub-assembly was then re-seated and the epoxy allowed to cure. (it should be noted that i had to use a 1/4" and 3/8" stand-off, epoxied together, to attain the correct hieght to support the onboard 4000 expansion card.) this chassis subassembly is then be epoxied in and riveted to the server case, and the results of a 3/4 rear view and side view are shown. (note that the original a4000 power supply case is atop the pc power supply, and that it does not have the bigfoot electronics installed.)

once all of the epoxy and the silver paint, which protects the filed & cut metal, have set and dried, the next item is a test-fit of the a4000 motherboard and the motherboard with the cyberstorm ppc installed. the yellow, green, and black wires on the lower left of these previous pictures are soldered to the serial port on the trace side of the motherboard. (i did this many years ago to avoid using the "less than elegant" external serial connector for the personal v-scope.) also, the battery holder for three, rechargeable ni-cad batteries is seen in the lower center of the picture.

modifying the power supplies

the two power supplies (a bigfoot 4000 and an atx ps) were next modified. because i decided that the bigfoot 4000 would be used solely to power the a4000 motherboard and all of the expansion cards in the onboard 4000, the harddrive and floppy power harnesses on it were expendable. i opened the case (again, care must be taken: the capacitors may still be charged!), removed the pc-board and de-soldered all of the harnesses used for the hd's and floppies. all that remains is this. a bit neater, huh?

next came the atx power supply. again, this was going to power only the harddrives, floppies, cd-rom, tape drive, etc. therefore, the atx connector was summarily removed and in its place i put an additional set of harddrive and floppy power harnesses. check out the menagerie. one caution about the atx supply: because it provides a 3.3vdc bus and because this is sensed at power-on, the sense line must be maintained, else the ps will shut-off automatically after a few milli-seconds. you'll recognize this lead in the atx power connector because it's the only pin with two wires connected to it. trace the thinner wire to its source within the ps box, and solder a small jumper to the point from which the other power lead emanates.

install the expansion boards....

it's quite nice having two video slots! the expansion slots are filled, from top to bottom, with:

toaster 4000
picasso iv
flyer
dps personal component adapter
ad516
gvp i/o extender
ariadne ethernet

the system has a number of fans--all available from 3dfxcool--installed. three case fans are installed on the front of the case (behind the facia, of course) and blow air over the expansion cards and csppc ram, and the rc060/50 has an "rtho-fan" installed to keep it cool.

time to start installing s/w and get that flyer running!:-)

come back again, ya hear.......see the pictures page in the mean time.

questions, comments, concerns?

This site developed and maintained by greg kimnach.

Experience is something you don't get until just after you need it.