3]RAM ON/OFF SWITCH (For A500 with A501) Cut the PCB track from pin 32 of CNX1 and connect pin 32 to a SPST toggle switch. Connect the other terminal to ground. 3]INTERFERENCE SUPRESSION for A520 modulator. This reduces some of the interference that the A520 suffers from. Solder a piece of short wire from the hole in the PCB next to the crystal to the top of the crystal. 3]LONG MOUSE CORD Go to Tandy's and get: 1 female 9 pin plug (NUMBER 276-1538 ) plus cover. 1 male 9 pin plug (NUMBER 276-1537 ) plus cover. About 8 to 9 inches of 9 core wire. Just solder the male plug on one end and the female plug on the other end and now you have an extended lead and you don't have to keek unplugging the mouse to play a joystick game, this will prevent possible damage to the pins in th socket on the Amiga. 3]EXTERNAL DRIVE SWITCH It's quite easy to install an on/off switch if you have an external drive without one. Just locate the correct lead for PIN 21 (SEL1) on the drive cable, (refer to the pinout diagram in your Amiga instruction book) and just cut that wire and solder an SPST switch between the two ends. 3]JOYSTICK BUTTON If you have a joystick plugged into PORT 1 (the mouse port) the fire button is the same as the mouse button. 3]CONNECTING DIFFERENT MONITORS Some monitors have problems with the screen synchronising with the video output of the 500 and 2000. This is because the output of the video gate- array is 4 or 5 volts instead of 1 volt.and is too high for these monitors. It appears that the problem can be solved by inserting a 390 ohm resistor into the sync-signal lines of the video cable from pins 11 and 12. 3]DISK DRIVES The Amiga, IBM, and ST all have the same 3.5" Disk Drives and so an ST or IBM disk drive with the right cable can be used with the Amiga! All you have to do is get the right cable! 3]RESET SWITCH This allows you to reset with one button instead of three. Connect pin 18 of the 68000 to a SPST NO momentary pushbutton. Connect the other terminal to ground. 3]PRINTER RESET SWITCH This allows you to reset any parallel printer. Connect pin 16 of the parallel connector (on the A500 and 2000) to a SPST NO momentary pushbutton. Connect the other terminal to ground. 3]LOSING MEMORY FROM YOUR A501 If your A501 seems to lose bits of memory on your A500 with a rev. 5 main board, it could be that the power supply pins are getting hot because they have a small heat dissipation area. Volts are lost, and you'll see a blackening around the pin area, nearest the front of the bunch of pins that connect to the A501. Solution is to resolder around the pin landings, providing a good coating. 3]JOYSTICK PORT The joystick port on the A500 is linked directly to the CPU (central processing unit, ie the 68000) so don't touch it with anything, or you may develop serious problems. If you do, such as the screen going green it means that your Agnes chip or your memory could be damaged, and it's important not to keep re-booting or you may damage other components. 3]CONNECTING TWO AMIGAS The number of games grows where you can connect two Amigas to play against each other. There are 3 ways in establishing a connection: 1. Simply through the modem, if you can afford the telephone bill. With this one, you only have to make sure that your partner uses the same baud rate. 2. The so-called Null modem where you have to solder your own cable in the following way: 2-------- --------2 \ / / \ 3-------- --------3 7-------------------7 The only important thing is that receive and transmit (2 and 3) are crossed. 3. The third option works when you've got 2 MIDI-interfaces, you simply put the cables "IN" into the other computer's "OUT" and vice versa. Now you can transfer in full speed of 32500 baud. 3]PAUSE SWITCH This allows you to stop the computer and then restart it. Connect pin 17 of the 68000 to a SPST toggle switch. Connect the other terminal to ground. 3]A2000 REAL-TIME CLOCK ADJUSTMENT Take the top off the 2000 and find the coprocessor slot, which will be next to the disk and power supply assembly. At the front end of it, you should see a small trimmer capacitor. Turn it counter-clockwise to make it run slower. The only thing is, that you'll have to calibrate it by trial and error. 3]A2000 REAL-TIME CLOCK ADJUSTMENT Take the top off the 2000, look for the coprocessor slot, next to the disk and power supply assembly. Looking at the front end of it, you'll see a small trimmer capacitor - turning this counter-clockwise makes it run slower. The best way to calibrate it is to use trial and error, unless you can find a jeweler's watch calibrator. 3]DISK DRIVE CLEANER DISKS To get the most out of these (available at Electronics shops), cover the hole on the diskcleaner and then do a DISKCOPY to it. This will clean the drive fully. Normal use of the diskcleaner doesn't allow much cleaning time. Cleaning the drives will reduce the incidence of read/write errors and related problems. 3]FAT AGNES PROBLEM If your A500 has a tendency to develop a green screen and flash the power light, put it down to a design fault in the computer. It happens when the Fat Agnes chip (or Blitter) is loose in its socket. Commodore should have put a clip there to hold it in, but cut a little corner. So push it back it firmly, or get a technician to do so for you. Nothing to do with a virus! 3]MODEM PINOUTS Thought I would pass this along to Amiga users wishing to hook up a modem. First off, check your Amiga users guide for the pinouts on the rs-232 cable. There are a few non-standard pins that carry voltage. These can ruin your modem and the Amiga itself if you plug them in. CHECK THE AMIGA USERS GUIDE. Next, pin 20 on the connector is supposed to carry a data-terminal ready signal to tell the modem that you are on-line. This would normally be +5 volts, but on the Amiga, there is no such signal. In fact, the line tests out at -5 volts. If your modem requires the DTR signal, then you should check to see if it has a DTR bypass switch somewhere inside (mine did), and switch it on. Otherwise the modem will ignore the Amiga. 3] REPAIRING A MOUSE First Unplug your mouse. Remove the two screws underneath, then open it up and turn it the right way up. Peel back the clear sticky tape covering the two silver buttons that you see making sure you don't lose the centres stuck to the tape. Use a cotton bud dipped in a methylated spirits or similar and thoroughly clean the silver buttons and the tracks on the exposed circuit board. Relace the silver buttons back where they were making sure that no part of the button touches the metal contacts on the circuit board. Plug the mouse back in and try it before you screw the top back on. Now screw it back together and then clean the ball and rollers as described in your Amiga manual.