Texas Instruments Magic Wand Speak & Learn Fixed

Defect:

• Doesn’t always turn on.The power button doesnt work properly.
• Battery acid leak.

Fix:

• Cleaning the Battery acid leak in the battery compartment.
• Cleaning the strange power-on button with a spray Contact Cleaner R-11.
• Inserted a thicker on the power-on button because the plastic pin that pressing the contact has deteriorated.

Note:

• External power supply 6v (TIP POSITIVE)

Gallery:

Cartridge shell for FinalGROM 99 – TI-99/4A

I have fit in a best way the pcb of the FinalGROM 99 inside a standard cartridge shell of a TI-99/4a game.

As you can see from the photos the final result is good, there are still some minor imperfections but i’m very satisfied.

I have made three cartridges shells, one for me and two for my friends Ciro Barile of  TI-99 Italian User Club, Andrea Pierdomenico.

Some things about the FinalGROM 99:

The FinalGROM 99 supports ROM images, GROM images, and mixed images of up to 1 MB in size that use the write-to-ROM bank switching scheme. The cartridge does not require the Peripheral Expansion Box and runs on both PAL and NTSC consoles, including modified consoles with an F18A. It will also run on v2.2 consoles and enables those to run ROM-only programs.

The cartridge offers some advanced modes that provide RAM and GRAM to programs. It also allows a running program to reload another program from SD card or to dump its state to SD card. All firmware of the FinalGROM 99 can be updated by SD card.

FinalGROM 99 is released as Open Source Hardware under the CERN OHL license and the GNU GPL license. Both hardware design files and firmware sources are available on GitHub.

For more information about this project please visit the project homepage hosted at GitHub.

Gallery of the works that have been made:

12►

Download:

• FinalGROM99 SD CARD Utility/Games Compilation (827)

Commodore 128D Repair #1

Defect:

• Black Screen.
• Garbage Screen.

Replaced parts/Fix:

• 9v AC line Fuse of the PowerSupply.
• Made a bridge of a pcb trace interrupted.

Gallery of the repair:

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Commodore 128D Repair #2

Defect:

• Garbage Screen.
• Memory Problems.

Replaced parts:

• Replaced 74LS08 (U61)
• Replaced OKI M3764A [RAM] (U43)

Gallery of the repair:

Commodore Floppy Drive 1541 (ASSY 250442) Repair

Defect:

• Drive access problems (IEC): drive resets but the computer freez with a “searching for”

Replaced parts:

• Replaced EL74S14 with a 74LS14 (UA1)

Gallery of the repair:

Commodore 16 Power Supply Repair

Defect:

• Dead.

Replaced parts:

• Replaced Electrolytic Capacitors of 4700uF/16v
• Replaced Fuse of 250v/1A Retarded.

Gallery of the repair:

Commodore 16 Repair #1

Defect:

• Black Screen.

Replaced parts:

• Replaced RAM TMS4416 (U6).

Gallery of the repair:

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Commodore 16 Repair #2

Defect:

• Black Screen.

Replaced parts:

• CPU Socket (U2).

Note:

I took advantage of this repair to install the ic sockets on the entire motherboard and use it like a “test board” for repairs.

Catweasel Z-II Mk2 (Urine CAT Cleaning)

Defect:

• The card is not recognized by the computer.

Cleaning:

• The Catweasel has traces of cat urine that with time has crystallized causing corrosion and short circuits.  I used the KONTACT PCC & Toothbrush to clean. I also checked the continuity in holes between pcb layers and traces in general.  Now it seems to work properly.

Gallery of the repair:

Peggy Plus (Scala MD100) v1.1 Recap

This Z2 card for Amiga has a problem of audio distortion on one channel. I have replaced all the tantalum capacitors, two of them in the Audio section.

Unfortunately i could not try this card, i did consider that could be also a problem of the NE5532  a Dual Low-Noise Operational Amplifier so i preferred put it on a socket, so it’s easy to replace if it is needed.

Gallery:

Commodore 64 Repair

Defect:

• Drive access problems (IEC): drive resets but it freez with a “searching for”

Replaced parts:

• Replaced EL7416 with a 7406PC (U8)

Note:

I have also removed a nasty connector welded directly on the c64 userport.

Gallery of the repair:

Commodore 128 Repair

Defect/Missing Parts:

• Two Electrolytic Capacitors have detached and the pins are gone…
• Garbage Screen.

Replaced parts:

• Replaced Electrolytic Capacitors of 220uF/50v and 330uF/50v.
• Replaced 74LS00 (U31)

Gallery of the repair:

This computer is of a dear friend; Paolo Cognetti.

Short story of the repair:

I have checked the voltages and are correct, although a couple of capacitors on the power stage need to be replaced.

I have tried to turn on the computer and i have see immediately a problem, the screen is full of random characters, with the oscilloscope i have tried to see if i have data stream on the CPU (Z80), interrupts and so on.., nothing, it seemed completely dead, replaced.

The computer has started better then before but with some video glitches, raster lines scrolls from bottom to the top and some characters scattered on the screen. I double checked the voltages and i have realized that the 12v are gone and the 7812 warmed a lot, about 80 degrees after 2 minutes.

Almost all tantalum capacitors of 1uf and 33uF on the 12v line are shorted, i have decided to replace them all (22 pieces)

After the replacement of all tantalum capacitors and two electrolytic capacitors on the power supply stage the computer has started to work correctly but with some video problems, characters scattered on the screen, after replacing two Static RAM 2114 everything works perfectly, including the Basic Cartridge that until now had never worked.

Works that have been made:

• Fixing broken Fuse Holder.
• Fixing a cold welding of a capacitor on the power supply stage.
• Testing Voltages.
• Replaced CPU Z80.
• Replaced 12 x Tantalum Capacitors (1uf)
• Replaced 10 x Tantalum Capacitors (33uf)
• Replaced 1 x Axial Electrolytic Capacitor (470uf)
• Replaced 1 x Axial Electrolytic Capacitor (1500uf)
• Replaced 2 x NMOS 2114 Static Ram.
• Fixed the botton cover with two missing screws.
• Cleaning the top cover using only water and a sponge.

Exidy Sorcerer II Repair Gallery:

Exidy Sorcerer II Gallery:

source: wikipedia

Sinclair ZX Spectrum 128k (Toastrack) Repair

Defect:

• Garbage screen on bootup.

Repair:

• Replaced 7404 (74LS04)

Note:

• Missing one HEX Inverter between Pin 11 and 10.

Gallery of the repair:

I have exhumed my old Macbook Core 2 Duo 13″ (late 2007) to install a Linux OS (Linux Mint) but before doing this work i wanted to give a nice internal cleaning and replacing the thermal paste of the cpu.

Gallery:

Commodore Floppy Disk Drive 1541 Repair (#1)

Defect:

• Motor runs continuously.
• Loading a Program or a Directory freeze the computer.
• Misaligned.

Repair:

• Replace 901229-05 (UB4)
• Replace 7414 (UA1)
• Head Alignment.

Gallery of the repair:

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Commodore Floppy Disk Drive 1541 Repair (#2)

Defect:

• Write Protect Problem.

Repair:

• A wire of the infrared LED was broken. The problem is remove the glue and the heat shrink tube around the LED.

Gallery of the repair:

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Commodore Floppy Disk Drive 1541 Not Repaired (#3/#4/#5)

Defect:

• Don’t read anything.

These Floppy Disk Drive have the Read Head interrupted. This seems to be the most common problem in the Mitsumi (Newtronics) drives.

Gallery:

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Commodore Floppy Disk Drive 1541 Repair (#6)

Defect:

• Loading a Program or a Directory freeze the computer.

Repair:

• Replace VIA 6522 (UC3)

Gallery of the repair:

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Commodore Floppy Disk Drive 1541 Repair (#7)

Defect:

• Loading a Program or a Directory freeze the computer.

Repair:

• Replace 7414 (UA1)

Gallery of the repair:

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Commodore Floppy Disk Drive 1541 Repair (#8)

Defect:

• Motor runs continuously.
• Loading a Program or a Directory freeze the computer.

Repair:

• Replace CPU 6502 (UC4)
• Replace 7414 (UA1)

Gallery of the repair:

Commodore 64 [ASSY 250407] Repair (#1)

Defect:

• Startup screen Scrambled/Garbage.

Repair:

• Replaced the IC socket of MOS 6569 (VIC-II) oxidized.

Gallery of the repair:

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Commodore 64 [ASSY 250407] Repair (#2)

Defect:

• Garbage Graphics.

Repair:

• Replaced MOS 6569 (VIC-II).

Gallery of the repair:

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Commodore VIC-20 [ASSY 250403] Repair

Defect:

• Black Screen.

Repair:

• Replaced MOS 6502 (UE10).

Gallery of the repair: