I have received two Computer Apricot F1e without accessories and aesthetically destroyed so i have decided to recover all that was possible.

This gallery shows some stages of the repairing of the Floppy Drives of the Commodore SFD-1001 & Commodore CBM 8296D.

Defects found on the Floppy Drives:

• Floppy drives had the capacitors that leaked acid on the motor control pcb.

The difficulty was rebuild the tracks of the pcb and remove the most of the leaked acid of the capacitors. Unfortunately on the aesthetic level this type of repair are not perfect, but i’m glad that all drives now work.

To test the correct operation of the Floppy Drives i have used a working SFD-1001 with a ZoomFloppy Interface through the IEEE-488.

Replacing bad capacitors (Floppy Drive #1):

Replacing bad capacitors (Floppy Drive #2):

Replacing bad capacitors (Floppy Drive #3):

The reason of the replacement is the leaky capacitor.

The Aluminum Electrolytic Capacitors (SMD) used in these machines eventually exude their conductive contents onto the mainboard causing short circuits and corrosion of the pcb tracks.

Replacing the capacitors on an Apple Macintosh Classic II:

As you can see from the first photo i had to replace the cathode ray tube (CRT) of a Macintosh SE/30 because has a “ghost image”.

The replacement is very simple but you have to replace also the deflection yoke because the yoke connector is different between Classic and SE/30.

The replacement of the deflection yoke obviously also involves the calibration of the image. The calibration of the image is not  simple and should be done with the computer on. Be careful there are very high voltages on the cathode ray tube (CRT).

Gallery of the replacement:

Below a short description of the repair.

Commodore PET 2001 (1977) Chiclet Keyboard (#1)

Defect:

• Garbage Screen on boot and partially in a working state.

Diagnosis/Repair:

• The Multiplexer 74LS157 (position D2) had an output (pin 4) always been in low state.

Gallery of the repair:

Commodore PET 2001 (1978) Chiclet Keyboard (#2)

Defect:

• Garbage Screen on boot.
• Memory Problems (1018 Bytes are missing)

Diagnosis/Repair:

• The garbage screen on boot was caused by a poor contact of the sockets where reside the ROMs. Temporarily fixed by inserting a precision sockets above the original socket (very bad quality sockets).
• The problem of the missing memory was fixed by replacing a RAM MPS 2114 (position J1) with a new one.

Gallery of the repair:

Jean-François DEL NERO (who’s behind the HxC SD Floppy Emulator) recently has released a version of the HxC emulator firmware that is compatible with the STM32 chip used in the Gotek floppy emulators.

This means that the great functionality of the HxC SD emulator is now available on cheaper and more widely available hardware.

The bootloader to convert the Gotek floppy drive in HxC compatible must be purchased on the website HXC 2001 by sending an email to Jean-François DEL NERO. The price of the bootloader is one-off 10 Euro per Gotek that you want to update. Future updates of the software are free and can be made from a USB stick

The HXC Usb (Gotek) firmware supports:

Flashing the Gotek floppy emulator with HxC firmware:

Gotek floppy emulator with HxC firmware (Testing on Amiga Computer):

Gotek floppy emulator with HxC firmware (Testing on Amstrad CPC computer):

Gotek floppy emulator with HxC firmware (Testing on Atari ST Computer):

Gotek Audio Track Loader:

The schematics is here

Components:

• 1 x Buzzer.
• 1 x BC547 or similar bipolar transistor.
• 1 x 1k resistor.

I have to thank Jean-François DEL NERO for the support that he gave me for the bootloader programming.

source: hxc2001.com

Defect:

• The backup system not using correctly the on-board memory and don’t load any games.

Diagnosis/Repair:

• Broken pcb track under the GAL (position U9). The battery acid has corroded some pcb tracks.
• GAL (position U9) completely dead.

Note1:

• The glitches on the screen that you see in the photo are caused by a failure on my Super Famicom. I have to fix it. ;-D

Note2:

• I don’t have the .JED code of the GAL and however i have sold many years ago my PAL/GAL programmer so i cannot replace the faulty component.

Download:

• Super Wildcard 2.8CC ROM & 2 x GAL16V8 (421)
• Super Wildcard DX (EPROM & EEPROM DUMP) (549)

Explanation of how it work the program “RAM3_RAMFAIL_BAS” written by Dominic Brown in the 1990 in Super Basic for the Sinclair QL which is used to calculate what the RAM on the Sinclair QL is broken, you need to use the MINERVA ROM (RAM PassCheck).

I tried to explain how it work and i have rewrote the software in a “language” a bit more modern ;-D

MINERVA OUTPUT EXAMPLE:

——————————————
WRITE: 5 4 8 C 4 8 7 8
READ: 5 C C D 5 C C D
ADDRESS: 0 0 0 3 2 0 0 0
——————————————

HEX WRITE: 54 8C 48 78
HEX READ:  5C CD 5C CD

Convert the numbers in decimal:

DECIMAL WRITE: 84 140 72 120
DECIMAL READ:  92 205 92 205

You have to make a xor in pairs (write & read)

XOR: 84 XOR 92 = 8
XOR: 140 XOR 205 = 65
XOR: 72 XOR 92 = 20
XOR: 120 XOR 205 = 181

Now you need to do an OR with the result of the XOR starting with “0″ and continuing with the result of every OR

OR: 0 OR 8 = 8
OR: 8 OR 65 = 73
OR: 73 OR 20 = 93
OR: 93 OR 181 = 253

Convert the final result of the OR in Binary.

DECIMAL: 253
HEX: FD
BINARY: 11111101

Follow the table to find the faulty ram. Pay attention to the memory address.

1: BAD Ram
0: GOOD Ram

BINARY = 1     1     1     1     1     1     0     1

IF < $30000 (ADDRESS) = IC8  ,IC7  ,IC6  ,IC5  ,IC4  ,IC3  ,IC2  ,IC1

IF > $30000 (ADDRESS) = IC16 ,IC15 ,IC14 ,IC13 ,IC12 ,IC11 ,IC10 ,IC9

IF > $40000 Faulty ram is in expansion memory.

The Original Program (ram3_ramfail.bas) was written for the SINCLAIR QL in SUPER BASIC language by Dominic Brown (1990).
Documentation of how it work by Xad/Nightfall (2015).
Thanks to my friend for the support.

Faulty Ram Decoder Changelog:

• v0.1: First Release.
• v0.2: Added a message (Faulty ram is in expansion memory) if the Address > $40000.

Faulty Ram Decoder Online: http://www.nightfallcrew.com/minervaram

Download:

• Faulty Ram Decoder v0.1 PHP Script (1057)
• Faulty Ram Decoder v0.2 PHP Script (1105)

Photo of cleaning (before and after):

To clean the power supply i have used compressed air and a media bristle brush.

Click to view original size

I have repaired the Commodore Amiga 2000 with a Black Screen for a dear friend.

Defect:

• Black Screen.

Diagnosis:

• The Battery Acid has corroded some pcb tracks (not visible to the naked eye) connected to the pin of the resistor packs RP900.

Repair:

• I have made three small bridges between the points on the solder side of the pcb and the problem was fixed in a short time.

I have repaired the Sharp Twin Famicom AN-500R for a dear friend.

Sharp Twin Famicom AN-500R Repair.

Defects:

• Black screen.
• Distorted sound.

Fix:

• Cold solder joints.
• Cleaning the volume slider on the second Joypad.

The microphone is mixed into the output signal, if the contacts of the volume slider are dirty you hear a background noise which disturbs the in game audio.

Gallery:

Repair Apple II EuroPlus.

This computer has taken a lot of moisture and temperature changes, it can be seen because the connectors (Apple BUS) have dried up and the plastic tends to break. In addition, some pins of the ICs are rusty, fortunately few.

The main problem of this computer, as well the removal of the usual filter capacitor inside the power supply, was that don’t accepts some basic commands (see photo)

The problem was caused by the malfunction of the PROM 341-0014. (E8)

The owner will have to decide whether to purchase the original PROM (current price €13,90 + Shipping) or use a horrible adapter to insert an EPROM 27C16 (2716) in place of a PROM.

This adapter in addition to changing the aesthetics of the original motherboard brings with it some problems.

• 16k language card don’t work.
• Long cards which extend to the part of the circuit board cannot be used.

Gallery of the repair:

source: willegal.net classic-computers.org.nz

This Floppy Drive, but probably also other models, suffer of a quite annoying problem.

The little box in aluminum placed over the head of the Floppy Drive comes off, this happens because the bioadhesive foam rubber that was used to fix the “box” on the head will dry.

This piece of aluminum that at first thing can seem absolutely useless, however it is not, because it is a balancer, without this little piece of aluminum the floppy drive head vibrates and consequently don’t read / write properly.

The replacement of the bioadhesive foam rubber is very simple.

• Remove the top of the Floppy Drive (3 screws)
• Look for the little box that are detached and wanders inside the Floppy Drive.
• Thoroughly clean the remains of the bioadhesive foam rubber inside the box and on the upper side of the head (see photo). Don’t make much pressure on the head.
• Use another piece of foam rubber with the same thickness (see photo). For this purpose you can use a thousand of way to fix this box, the important thing is that must remain raised and  don’t touch the Floppy Disk (see photo)
• Fix the foam on both sides with a glue, i suggest a small amount of Bostik or Loctite – Super Attak.
• Wait for it to dry.
• Close everything.

I finally found a time to do the replacement of all the electrolytic capacitors of my Amiga 1200 that was beginning to have serious problems of stability.

Since I had disassembled the amiga i took the opportunity to do the E127R fix that solves some problems of graphics glitches with the interface Indivision AGA 1200.

The fix is very simple to do, you need to short the E127R resistor with a jumper.

I have also replaced the original power supply of the Amiga with a ATX power supply can supply more ampere and is a little stable than the original.

Commodore Amiga 1200 Recapped:

Commodore Amiga ATX Power Supply:

E127R Amiga 1200 Indivision Fix:

This Commodore 64 was found in the trash from a friend, although aesthetically in a good state, the computer doesn’t work.

Defect: