jansweij@swivax.UUCP (Wouter Jansweijer) (02/23/89)
I can buy 2 MByte memory expansion (2 SIMMS, low-profile, 100 nsec)
for a good price.
o Can I mount them myself in my Mac+ ?
o Which two 256K memory chips do I have to remove?
o Do I have to set some dip-switches?
o Do I need to re-adjust the voltage-level?
o What pre-caution (static electricity) have to be taken?
o Is there an Apple-technote that descibes the procedure?
o ... ... ... etc
Any information on the procedure to follow will be greatly appreciated.
--
Wouter Jansweijer Phone: (31)-20-525.2152 (.... 525.2073)
EMAIL: jansweij@swivax.UUCP {seismo,decvax,philabs}!mcvax!swivax!jansweij
SNAIL: Department of Social Science Informatics, University of Amsterdam,
Herengracht 196, NL-1016 BS Amsterdam, The Netherlands.alen@crash.cts.com (Alen Shapiro) (02/25/89)
In article <934@swisun.swivax.UUCP> jansweij@swivax.UUCP () writes: >I can buy 2 MByte memory expansion (2 SIMMS, low-profile, 100 nsec) >for a good price. > > o Can I mount them myself in my Mac+ ? > o Which two 256K memory chips do I have to remove? > o Do I have to set some dip-switches? > o Do I need to re-adjust the voltage-level? > o What pre-caution (static electricity) have to be taken? > o Is there an Apple-technote that descibes the procedure? > o ... ... ... etc > I've seen 2 such messages so here's a post of the reply rather than mail. procedure... 1) buy an earth strap (folklore but who dares go against that!!), a long handled allen-key of the type that will fit into the "star" screws on the mac (apple will sell you a "star" key for about $50 - the allen key can be bought for about $5) and a case cracker (the case cracker can be done without if you dare to face the mac on its screen and shake it as you pull up on the case with ALL 5 (yes 5) screws undone (2 screws under the handle, 2 in plain sight and 1 UNDER the battery flap (crafty apple)). 2) undo screws 3) pry off programmer buttons (they will crease the mother-board protector paper). 4) pull case from rear of machine with screen face down (case cracker comes in useful here) the plastic/foil mother board protector may fall off at this point - take it off anyway and save for reassembly. 5) mother board is the board nearest the base of the machine. Pull off 2 cables attached to mother board (1 = floppy 2 = power - note which way they should go back on (no harm in being careful)) 6) carefully slide out mother board towards the rear of the machine (NOTE if you have an accelerator board you won't want to slide this board anywhere since it will probably scrape off the add-on board (not much clearance)). 7) with the board chips up and the external plugs nearest you (rear of the board), the simms are far away from you mounted at an angle to the horizontal with side-catch fasteners. Remove the 2 simms nearest you (the 2 nearest the center of the board) 8) replace these with new simms (chip side up, board notch same as all the other simms). 9) locate and remove the resistor jumper marked 256kbit which will be towards the right side of the board if the previous orientation (back towards you) is maintained. The jumper is about 1/4 of the board length away from you. 10)All done - slide mother board back in, replace plastic/foil protector, connect 2 leads, slide case back on (careful - no force is necessary here if it seems to stick then find out why and correct), replace screws (you should still have 5!!), replace programmer switch and power-up. NOTES: 1) do not be alarmed if 10-15 secs go by before the grey screen becomes the smiley face - testing 2.5Mbytes take a while 2) simms must be fitted in like pairs - start with 4*256k = 1M, upgrade to 2*1M + 2*256k = 2.5M or 4*1M ( = 4M). I don't believe any other combinations are legal. 3) replacing memory is fun - it'll take 10 mins or less when you've had some practise. 4) if the smiley face is bordered by a black screen then you forgot to remove the resistor jumper (or snipped the wrong one - woops). (the former should not cause any damage, the latter is anyone's guess). 5) I replaced my memory while wearing an earth strap I suggest you do the same just in case the folklore is soundly based. DISCLAIMER - (guess what comes here). Sorry if I got it wrong guys - I don't believe I did - I've done it a load of times now with no problems but I won't be responsible for problems due to following these instructions which are given in good faith etc etc. --alen the Lisa slayer (it's a long story) ....ucsd!ncr-sd.uucp!asdev2!alen
mfi@beach.cis.ufl.edu (Mark Interrante) (02/27/89)
After one cuts the 256k resistor and installs 2.5m, what process is needed to convert the machine BACK to a 1m machine? (if I sell it I might want to keep the 1m simms) ----------------------------------------------------------------------------- Mark Interrante Software Engineering Research Center mfi@beach.cis.ufl.edu CIS Department, University of Florida 32611 ----------------------------------------------------------------------------- "Imagine what it would be like if TV actually were good. It would be the end of everything we know." Marvin Minsky
twakeman@hpcea.CE.HP.COM (Teriann Wakeman) (02/28/89)
Just a suppliment to the previous how to install RAM reply.
RE: the static wrist band- This is a conductive bracelet & conductiveline
that has an allagator clip {or equiv.} at the other end.Somewhere between
the wrist band and theclip is a 1 meg resistor or equiv. The object is to
equalize the voltage potential between you & the circuit that you are working
on with a low level of current {hense the large resistance}. Dosn't matter if
you buy one or make one. You will need it as soon as you remove the enclosure.
Put the bracelet on your wrist & connect the other end to the chassis.
Once the board is removed, you will want to move the clip to a ground point
on the board, probably one of the metal flanges. Revers procedure when
replacing board.
RE: the resistor to be clipped. The plus has coordinates marked on it.
The resistor to be clipped is R8 located at C1. It is in a white rectangle
drawn on the board. It is a 150 carbon comp resistor {colour bands brown,
green, brown, gold{5% tolerance marking}}
On a SE, the 150 ohm resistor is R35, & I believe it is located near the
RAMS. Look for a white rectangle labled RAM size.
RE: repacing the SIMMS. The SIMMs are latched into their sockets. There are
socket pins sticking up through holes in the SIMMs {one on each side} and
a clip arm on eather side of the SIMM holding it into the socket. What you
need to do: Carefully slide each arm of the socket off the side of the board.
the SIMM will pop up with the arms off. remove the SIMM. Lay the new SIMM
into the socket woth the SIMM holes over the socket pins & gently press
down. Clip the arms over rhe edges of the SIMM board & its in. The socket
is spring loaded with the socket pins acting as the spring. Be careful with
the arms, Force them too hard & you will need another socket. If you have
SMT SIMMs there should be no fit problems. Problems may occur with DIP
SIMMs. Here leads go through the board & are soldered on the bottom side.
The pins closest to the socket may interfere with the SIMM socket & not allow
the SIMM to fit low enough in the socket for the arms to lock. This has been
a problem with MacProducts USA SIMMs for instance.
RE: What the previous peply did not say: Disconnect the power cord before
opening the Mac. There are some capacitors that may pack a powerful jolt
inside the Mac. You can avoid the problem by letting it sit overnight with
the power off before opening the Mac. Otherwise, stay away from the
board on the side of the Mac.
Put the enclosure back on before turning the Mac back on unless you are an
"expert" and know what can hurt you & how to avoid it.
Best of luck!
TeriAnntwakeman@hpcea.CE.HP.COM (Teriann Wakeman) (03/02/89)
RE: Going back to 1 Meg.
If you, like me are thinking of taking your RAM with you to your next
Mac platform, whatever or whenever it is, only clip one end of the 150 ohm
resistor, lift the free end off the board, & if you want, put a wrap of
electrical tape around the resistor covering the free end. Pack your old
256K SIMMs into the anti static packaging that your 1 meg SIMMs came from
& pack them away.
When & if it ever comes time to pull up 1meg SIMMs and move on, just repeat
the installation process, resoldering the lifted lead {use a low wattage
solder iron with grounded tip}.
About this resistor- it is 150 ohms, R8 on a +, located at board
coordinates C1 {far away from the SIMMs on a +. There is a white rectangle
printed on the board areound R8 and R9 locations.
On an SE,the 150 ohm resistor to be cut is R35, which also lives in a small
white printed rectangle labeled "RAM SIZE". There is a label near the
resistor that says 256K but this referes to SIMMs & not the resistance of the
resistor. The resistor is a small brown cylinder with leads coming out each
end and colour bands. The colour bands tells the resistance and tolerence of
the resistor {tolerance band optional, %20 iff missing}. The bands are read from
the band closest to the edge. R8,on a +, R35 on a SE, is brown{1},green{5},
brown{0}, gold {5% tolerence}. If you cut if competely off, you can
replace it at any electronics store.
CAUTION: Solder suckers are sources of high static charges and may destroy
CMOS circuitry.
TeriAnn