COMPACT MACS 

Compact Macs include the Plus's, SE's, SE30, and the Classics. Compact Macs are all very similar in the way they are designed inside.
One nice thing about these machines is that they take a licking and keep on computing.  If they don't they can be easily repaired at not a too great expense with rebuilt parts. They are virtually immortal.  These computers although slow and limited in memory by today's standards are still working hard in offices and homes. They make great word processing machines and the SE30's are in demand as used machine small network servers.

Adjusting Screen Size

Look at the screen. Does it look the right size? You may have been looking at it so long that it always looks right.  The screen can tell you a lot about the status of your computer.

Measuring
The lit up part of the screen on your Mac should measure exactly: 

Length: 7.11 inches
Height to menu bar: 4.47 inches.

If it is a little off you may not care. If it is a lot of then it can be annoying.  The nine inch screens will shrink as they age because of the deteriorating nature of capacitors on the analog board. But, there is an adjustment for this that can solve the problem within limits.

Adjusting vertical and horizontal linearity
With the case off, find the width and height adjustments on the white fiber shield on the outside of the analog board. (On a classic they are located on the back edge of the board facing the back of the computer.)

 

Using a small plastic video alignment screwdriver, adjust the width or height until it comes up to specifications on the screen. If you adjust with the computer turned on use extreme caution as there is a lot of high voltage here.
If you can't adjust the screen to the desired height then the easiest thing to do is replace the analog board.  See the later for Analog board removal and for places to get a rebuilt board at reasonable cost.

Scan Line Adjustment

If your compact mac suddenly develops scan lines but the computer works (see diagram below) then you have one of two problems. Either a resistor on the analog board has gone bad or your cut-off resistor is out of adjustment. Sometimes moving the computer or taking it apart can cause this to happen.  If the problem is the resistor then you will have to replace the analog board. To find out, you need to try adjusting the cut-off on the analog board. Refer to the section (opening compact Macs).

   Scan Lines

 

Locate the cut-off and  adjust it using the plastic alignment tool until the brightness is just right and the scan lines disappear.  You may have to work in conjunction with the  brightness control on the front of the SE and Plus.  The Scan lines should disappear when the brightness is set about half way.

If this does not solve the problem the a new analog board is probably in order.

Focus Problems

When the screen is out of focus one possible cause could be the out of focus adjustment. Turn the focus knob with the plastic alignment screwdriver until focus is sharp(er). If this does not work then a new analog board is probably in order.

Strange Sounds

The compact Macs will sometimes make a strange sound that will indicate an analog board problem. The sound will come from inside the computer and not from the speaker. When this happens the only thing besides a component level repair is to replace the analog board.  (See analog board replace).

The range of sounds

Mac Plus's
High pitched loud whistling at startup: Things will get worse eventually but nothing dangerous. You will need an analog board eventually. The problem is with a faulty coil used in early Plus's

High pitched buzz at any time: The flyback transformer is going. You will need a new analog board soon. If you see the display go dark during one of these sounds you will soon smell smoke as the flyback transformer begins to fry.

Hum and no startup:  Replace the analog board, you have component failure on it.

Growl and no startup:  Replace the analog board, you have component failure on it.

Screeching tires and no startup:  Replace the analog board, you have component failure on it.

Cricket chirps and no startup: Replace the analog board, you have component failure on it.

A flapping noise and no startup: Could be the analog board or the power video cable is disconnected. It is one of the bundle of wires plugged into the center of the analog board.

Mac SE and SE30

A loud computer and possible shaky screen: This only affected the earliest SE models. They had a fan that interfered with the video circuits. You can replace the fan (good luck finding one) with a newer brushless one or replace the analog board.

Hissing and no startup: Replace the analog board, you have component failure on it.

Continuing flapping sound: Power Supply problem. Replace the power supply or entire analog board and power supply unit.

Tweeting sound:  This could indicate a  SIMM problem, see Appendix, RAM chips and Chapter, Sad mac screens for replacing the SIMMS

MAC CLASSIC SPECIFIC

Symptom: Your Mac Classic arcs and smokes a bit and you can smell smoke. The computer may stop working. 
The Mac Classic has what I consider to be a design flaw. The power cord socket is soldered to the circuit board on the lower back edge of it.  If you plug and unplug the board many times some sockets become loosened at the solder joints. The loose joint has 120 volts going through it and the arcing burns the board. Usually this eventually breaks the connection to the board and the computer doesn't work afterwards.  What I have done to some models to save the owners the approximately $100+ cost of a new analog board is to chip away at the burned board and solder a wire to the burned pin of the socket to the trace on the circuit board. It isn't really that difficult to do but I recommend you check your connection with a meter before powering up. Look, it doesn't work now so what have you got to lose? If it doesn't work you will have to order a new logic board.  Too bad because nothing is wrong with it except you can't get electricity in to it.

Opening Compact Macs

Opening the case of compact Macs refers to SE's, SE30's, Plus's, and the Classics

To open the case you will need the long hex wrench, and spring clip (or other clever device) described in hardware tools of the appendix.

There are four screws on the back of the case. Two easy ones are located at the bottom corners and the deep ones are in the handle. (see diagram below). Note: On the plus there will be a small screw in the battery compartment.

Place the computer face down on a folded bath towel.

Using the prying tool insert it into the seam near the front of the computer and pry evenly around the case. The first time the case is removed it will take some work. After that it will separate easier.
It may help to push on the on/off switch to help force the case off.

Warning
There are several places on the analog board (vertical one) and the video tube that can have lethal voltages. The case should never be opened with the power on and the computer should be left setting over night without plugging it in to allow any condensed electricity to dissipate.  If you feel uncomfortable even with this then don't go any further. (please refer to the disclaimer in the introductions chapter.) There is a way to bleed voltage from the video tube using a screwdriver and large ohm resistor. You may wish to look into this further if you are interested.

 

Compact Mac Inside

The Compact Mac models have the same basic configuration
Please read the warning in appendix "Opening compact Macs"

  The Logic board is the
computer. It contains all
of the processing chips
and memory chips. If the
computer doesn't compute
this is usually the problem.

  The Analog board is the
power supply and video
circuits.  If the video
doesn't light up or otherwise
goes wacky it is usually the
problem

Analog Board Removal

The analog board of a compact Mac is the power supply and video circuit board.  Replacement may be required and removal is not that much or a chore but you must be carful.  Please read the warning in the in "Opening compact Macs".

The analog board has similarities in all compact mac models. Common sense will be needed if the description here is not exactly like yours. This is a general removal description. Basically, for whatever model you have, disconnect all cables connected to the board.

High voltage cable disconnect
This is the cable that has a suction cup at the end. and the other end leads to the flyback transformer on the analog board.
Be sure you let the Mac set over night unplugged to allow any built up charge to leave the video tube. If you are not satisfied with that there is a way to discharge the tube with a high ohm resistor. If you feel uncomfortable with this then don't mess with it.  Please read the disclaimer in the introduction. The cable can be disconnected at the suction cup by placing a thin screwdriver under the suction cup and pushing the spring clip together so it lifts out. (be careful not to hit the tube neck it could implode.)

Screws
Before you can remove the screws you need to remove the high voltage protective shield on the side of the board. Most models use small black locking pins. The best way to remove them is to grab them with needle nose pliers and gently lift them out.  Once the card is removed locate any screws that hold the analog board in place and remove them. Notice how some Macs use a press fit within the edge of the case to help hold the board in place. This is important in replacing the board.

SE Brightness knob
You must remove the brightness know on an SE. It pulls down and out.

Voltage Cables
Remove the cable located near the center of the analog board. Pull straight out. Likewise remove the other cable(s) located on the board. New ones only assemble one way so you don't have to worry about how they connect. These cables supply various voltages to different areas of the computer.

Ground Wire
There may be a ground wire near the power cord socket. If so remove the screw that holds it.

Logic Board Removal
Logic boards remove fairly easily. On the Mac Plus the board slides out of rails. On the SE the board must be slid back far enough to line up the board tabs with cuts in the rails. The board simply swing away. Both boards have two or three cables attached to them and as usual they only reconnect one way so you don't have to worry about that.
Logic Boards are particularly prone to static damage so wear your grounding strap when working on them.