from GS WorldView

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[:                         Apple IIE Repair Guide                           :]
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                                Written By:
                              Double  Density

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INTRODUCTION
------------

I bring this series to all of the Apple //E users who have experienced the
unfair and outrageous prices that repairmen of computers (especially at
Computerland) charge for their services, only to replace a $0.50 chip. I myself
have been charged $75 to have a $2.50 chip replaced, not to mention it took them
two weeks to get to my computer to replace the damn thing.  At the end of this
series, most repairs on your computer you should be able to do on your own, and
most for less than the cost of a movie.

Before I get heavily into this discussion, may I make a small suggestion? Print
this out NOW! If you don't and your computer breaks down, then what are you
gonna do?  Yup, you are gonna pay big bucks.

Open your computer and take a look at the motherboard. Looks confusing, eh? Not
really. The big black things are called integrated circuits, and these are what
break down or fail most often. The other things we will not worry about at the
moment.

Up and down the left side of the motherboard you will see letters A-F, and along
the bottom the numbers 1-14. This is the way Apple locates their chips on the
board - much like a city map with grids. Here are the names, and locations, and
the approximate costs for each of the chips on the board. Don't let the names of
the chips scare you or anything on this chart. It is mainly for information, and
you won't need to know anything about the chips on the board (aside from the
fact they are broken, which will come later).
 

IC #       Location        Approximate $     Description        Notes
-------------------------------------------------------------------------------
74LS02        B8              0.78          Quad 2-input NOR
74S10         C5              0.78          Triple 3-input NAND
74S109        C1              1.34          Dual JK Flip-flop
74LS125       E1              1.12          Tri-state quad buffer
74LS138       B5              1.22          Expandable 3/8 Encoder
74LS154       C10             2.80          4-16 decoder/multiplexer
74LS166       F5              1.84          8-bit serial in,
                                            parallel out shift register
74LS244      B1,B3            2.80          Tri-State octal line driver
74LS245       B2              1.70          Tri-State octal bus receiver
74LS251       C11             1.55          Tri-State 8-input multiplexer
74LS374       D3              1.98          Tri-State octal-D flip-flop
NE558         A12             2.00          Quad 555 timer
MC741         A11             0.75          Operational Amplifier
ULN2003    Analog Card        ????          7-channel input       (from Apple)
                                            driver
LM3146     Analog Card        ????          Transistor Array      (from Apple)
MC3470     Analog Card        ????          Floppy disk           (from Apple)
                                            read amplifier
MC3764      F6-F13           20.00          64k x 1 bit RAM
6502B         B4             14.00          8 bit microprocessor
KB ROM        D12             8.00          Keyboard ROM
VID ROM       F4             12.00          Video ROM
CD ROM        D10            20.00          Applesoft ROM
EF ROM        D8             20.00          Monitor ROM
HAL           D1             56.00          Programmed Array      (from Apple)
                                            logic
IOU           D6             56.00          I/O unit              (from Apple)
MMU           D4             56.00          Memory Mgmt Unit      (from Apple)
AY3600        D14            16.00          Keyboard Decoder
 

Ok, that's all of the chips on the motherboard, and a few from the Analog card,
that is the one inside your disk drive (apple drives only). If you need to order
one of these chips from Radio Shack or some other local electronics store, then
you ask for the chips by the number in the left hand column. For example, if
your paddles were not working and the cables were good, you would need to start
with the NE558 chip, and that is what you order. More about that later, though.
Don't worry about the big costs of the ROM chips or the CPU. Most computer
breakdowns are of the 74LSxxxx series and you will most normally have to deal
with those only.

Now, before you go poking around your motherboard popping out chips and sticking
them back in, a few tips and reminders to keep your apple running right, and how
not to screw anything up...

1) Never touch ANYTHING in or on your computer, including your disk drives,
   before grounding yourself on something. Static electricity, especially in
   the wintertime can reach as high as 10,000 volts - enough to fry any of the
   delicate chips inside your computer.

2) Buy a chip puller. They are cheap, and you will save your fingers from
   getting pins from the chips stuck in them, and blood all over everything.

3) Always note the orientation of the chip you pull out, so that you can put
   the new chip in the same way. There is a notch in one end of the chip, or a
   dot at one end. Either way, be sure the new chip has the notch or dot in the
   same place as the old one.

4) Use power strips and surge protectors. The surge protector for obvious
   reasons, and the power strip for preventing wear and tear on the switches.
5) Keep your coke off the keyboard. Liquids can blow every chip they touch.
6) Take special care about static electricity when messing around with the CPU,
   the ROM chips, the MMU and the IOU chips. These are quite sensitive to
   static charges.

7) Don't open your monitor. This is stupid, xrays and 30kV's are running around
   inside and if you don't know what you are doing, you will have radiation
   damage, or worse yet, your parent will smile when they collect life
   insurance on you.

8) Don't pull cards out or put cards in when the power is on. You will kill
   either the card or the computer, I promise.

9) Check everything outside of the computer before you start fiddling around
   inside.  Usually cables, switches or other shit like that are the cause of
   the problem.
 

Now: I am dividing up this series into 5 parts as follows:

                        1) Start-Up Problems
                        2) Run Problems
                        3) Display Problems
                        4) Keyboard Problems
                        5) Other I/O Problems

And I will release them as I type them. Don't hold your breath, as I am in
school and hardly have lots of time...
 

Part I - Start-Up Problems
--------------------------

This section covers all problems that occur at the time you turn the power on,
or at start up, including no power, no boot up, no beep and no display...
 

1) No power light, no beep, drive won't run:
        Probable defect:    1) 74LS125 at E1 is bad  (replace and test)
                            2) 74S109  at C1 is bad  (replace and test)
                            3) 74S02   at B8 is bad  (replace and test)

2) Power light on, no message, no beep:
        Probable defect:    1) 74S02   at B8 is bad  (replace and test)
                            2) 74S109  at C1 is bad  (replace and test)

3) Power light on, message, no beep:
        Probable defect:    1) (experts only) PAL 16R8/8323T at D1 is bad

4) System won't boot, power light on, drive won't run, garbage on screen:
        Probable defect:    1) Bad EF ROM at E10 (replace and test)
                            2) Bad 6502B at C4 (replace and test)

5) System won't boot, power light on, message on screen, drive won't boot:
        Probable defect:    1) Clean connector pins
                            2) Clean or replace ribbon cable
                            3) Bad ULN2003 on analog card (replace and test)
                            4) Bad regulator on analog card (replace card)

6) System won't boot, everything on, drive keeps running:
        Probable defect:    1) Reseat disk, check disk, check cable, reseat
                               card. (coming later if this doesn't work)

7) System won't boot, disk drive runs and then stops:
        Probable defect:    1) Bad DOS
                            2) Bad Disk
                            3) Bad RAM chip on motherboard (f6-14) replace
                                                and test

8) System boots and then stops, no display:
        Probable defect:    1) Video cable bad (replace and test)
                            2) Video connector bad (replace)
                            3) Brightness knob on monitor?
                            4) 74LS02 at B8 bad (replace and test)
                            5) 74LS10 at C5 bad ("""""""""""""""")
                            6) 74LS166 at F5 bad (replace and test)
                            7) 74LS374 at D3 bad (replace and test)
                            8) IOU at E5 bad (replace and test)
                            9) 2732 ROM at F4 bad (replace and test)

If you need advance help, you can reach me at my board by chat or by mail. If you have questions or suggestions, also call my board.
 

Part II - Run Problems
----------------------

1) Disk drive will not read (I/O error or disk just runs on and on)

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Bad Disk                              Replace Disk
     b) Wrong DOS                             Try another disk
     c) Disk not seated                       Reseat disk
     d) Read head not reading                 Replace head
     e) Cable loose or bad                    Reseat or replace cable
     f) Bad chip on analog card               Replace Analog Card

2) Disk drive will not write (read is OK)

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Write protected                       Remove tab
     b) Protect switch bad                    Replace switch
     c) Disk not formatted                    format disk
     d) Cable bad or loose                    Check/Replace cable
     e) Corroded connectors                   Clean connectors
     f) Bad 74LS125                           replace (analog card)
     g) Bad CA3146                            replace    "    "
     h) Bad MC3470                            replace    "    "
     i) Bad ULN2003                           replace    "    "
     j) Bad Write head                        replace
     k) head alignment off                    realign head

3) Disk reads or writes occasionally

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Cable corrosion                       clean connector pins
     b) Connector corrosion                   clean connector pins
     c) noise interference                    good luck
     d) disk tracking off                     realign head

4) Occasionally keyboard locks up and computer locks up

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Program error                         debug program
     b) no keyboard out put                   coming later
     c) bad RAM chip                          replace and test
     d) bad MMU chip                          replace and test
     e) bad CPU at C4                         replace and test
 

Part III - Display Problems
---------------------------

1) No Display - Screen all White

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) shift register latch-up               replace 74LS166 at F5 and test
     b) ROM data hung up                      replace 2732 character ROM (F4)

2) No Display - No Video

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Bad Cable                             Replace and test
     b) low signal                            adjust brightness
     c) Bad monitor                           test monitor
     d) Bad 74LS02 at E8                      replace and test
     e) Bad 2N3906 at A14                     replace and test
     f) Bad 2N3904 at A14                     replace and test
     g) Bad 74LS10 at C5                      replace and test
     h) Bad 74LS166 at F5                     replace and test
     i) Bad 2732 ROM at F4                    replace and test
     j) Bad 74LS374 at D3                     replace and test
     k) Bad IOU at E5                         replace and test
     l) Bad PAL 16R8 at D1                    replace and test

3) No Display - Screen Black

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Brightness bad                        Adjust
     b) Bad monitor                           test monitor
     c) Bad IOU at E5                         replace and test
     d) Bad 2732 ROM at F4                    replace and test

4) No Color

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Bad IOU at E5                         replace and test
     b) Capacitor C32 shorted                 replace (soldering required)
     c) Inductor L3 Bad                       replace (soldering required)

5) No Syncronization

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Bad IOU at E5                         replace and test
     b) Bad monitor                           replace or repair

6) Bad cursor or no cursor

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Bad EF ROM at E10                     replace and test
     b) Bad 2732 ROM at F4                    replace and test

7) Bad inverse or flash

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Bad 2732 ROM at F4                    replace and test

8) No text

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Bad 2732 ROM at F4                    Replace and test
     b) Bad IOU ROM at E5                     Replace and test

9) Video - Bad color

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Bad HAL at D1                         Replace and test

10) Bad Graphics (lo and Hi bad); text ok

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Bad IOU at E5                         Replace and test

11) Bad Graphics (HI), low and text ok

     Probable Defect:                         Remedy:
     ---------------                          -------
     a) Bad IOU at E5                         replace and test
 

Part IV - Keyboard Problems
---------------------------

1) Bad key action - some keys or no keys work

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Bad Key                               replace key
     b) Bad or loose cable                    check and replace cable
     c) Bad AY3600 at E14                     replace and test
     d) Bad 2716 ROM at E12                   replace and test

2) Bad key action - prints wrong characters

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Bad 2716 ROM at E12                   replace and test
     b) Bad AY3600 at E14                     replace and test

3) Bad key action - unwanted repeat

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Bad AY3600 at E14                     replace and test
     b) Bad capacitor C71                     replace (soldering required)

4) Repeat key won't work

     Probable Defect:                         Remedy:
     ----------------                         -------
     a) Bad Key                               replace and test
     b) Bad AY3600 at E14                     replace and test
     c) Bad Capacitor C70                     replace (soldering required)

5) Key top pops off

     Well, just glue that fucker back on or get a new keyboard.
 

Part V - Other input/output problems
------------------------------------

1) Speaker - volume too low

     Probable Cause:                          Remedy:
     ---------------                          -------
     a) transistor Q5 marginal                replace (soldering required)

2) Speaker - won't click

     Probable Cause:                          Remedy:
     ---------------                          -------
     a) Bad speaker                           Replace speaker
     b) speaker wires bad or loose            check or replace
     c) Bad transistor (Q5)                   replace (soldering)
     d) Bad IOU at E5                         replace and test

3) Cassette - can't load data

     Probable Cause:                          Remedy:
     ---------------                          -------
     a) Bad cable                             Replace and test
     b) Volume not set pproperly              Retry at different volume
     c) No signal on tape                     Replace tape
     d) Bad LM741 at A11                      Replace and test
     e) Bad 74LS251 at C12                    Replace and test
     f) Bad 74LS154 at C10                    Replace and test

4) Cassette - Can't write data

     Probable Cause:                          Remedy:
     ---------------                          -------
     a) No signal to tape                     reconnect or replace cable
     b) Tape bad                              replace tape
     c) Bad IOU at E5                         replace and test

5) Game paddle - does not work at all

     Probable Cause:                          Remedy:
     ---------------                          -------
     a) Bad cable                             Replace
     b) Bad 558 timer at A12                  Replace and test
     c) Bad 74LS251 at C12                    Replace and test
     d) Bad 74LS154 at C10                    Replace and test

6) Game paddle button won't work

     Probable Cause:                          Remedy:
     ---------------                          -------
     a) Button bad                            Replace button
     b) Broken wire                           Replace wire

7) Game Paddle - knob does not work correctly

     Probable Cause:                          Remedy:
     ---------------                          -------
     a) Bad pot in paddle                     Replace pot
     b) Broken wire in cable                  Replace wire

8) Card in peripheral slot does not work

     Probable Cause:                          Remedy:
     ---------------                          -------
     a) Bad 74LS138 at B5                     replace and test
     b) Bad 74LS154 at C10                    replace and test
     c) Bad 74LS10 at C5                      replace and test
 

Additional hints:
-----------------

Look and smell and feel the chips in your computer for things that seem to be
bad or out of place. Feel for hot spots, smell for blown capacitors, etc etc.
Notice anything out of the ordinary and replace it if it doesn't look, smell or
feel right. You can search for heat-blown chips by cooling each chip one at a
time with freon from a can and examining the results on the operation of your
computer. I f you find a chip that allows the computer to work cold, but when it
warms up, p hooey, replace it. If all fails, take it to Computerland. Their
prices are unreasonable, but i f you couldn't fix it from what I typed, you can
be sure that you are going to g et your money's worth from them as they try to
track down the problem, and cry t he whole way.