Today a friend, that i thank him immensely, gave me a large amount of chips.

The donation amounts to:

• 70+ Z80 CPU.
• 14+ Z80 CTC (Counter / Timer Channels)
• 200+ 74XXX TTL chips.

I ran the repair of the membrane that had a micro interruption, i have used a micro-drop of vinilic glue mixed with the graphite that i have scraped from the pencil ikea, i made a thin film on the microfracture and now it works.

There were other problems, including: graphite consumed in some keys and the keyboard connector (pcb side) don’t work very well.

I have received this motherboard of a CBM 8032 to repair from Rossano T.

The motherboard was devastated by rust, many components are short-circuited due to rust that was abundant on the pins side of the chip. Unfortunately the computer was turned on to test it, causing the total breakdown of more components.

I have installed 40 socket because some components are rusty other are dead, however some traces under the chips are eaten by rust and and i had to rebuild.

The repair and cleaning took me a very long time and a lot of patience, it took me about 10+ hours.

Components Replaced:

• 1 x 4650 (6845P) CRT Controller
• 3 x 4116 RAM
• 2 x 2114 Video RAM
• 5 x 74LS244
• 3 x 74LS74
• 1 x 74LS02
• 1 x 1uf 100v Capacitor

Phases of the repair:

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This gallery shows some stages of cleaning the computer Apple IIe and the Apple Monitor ///.

I have also made minor repairs which i describe below:

• Fixing the keyboard connector on keyboard side (some keys not working)
• Adjusting the yoke of the CRT tube (the screen is lightly rotated)
• Replaced the LED of power-on (CR1) of the Apple IIe (LED was off)
• Removing the RIFA filter capacitor (the capacitor was exploded)

The failure was due to a cold solder on the ram socket and a bent pin on the ic MOS 8276.

I have disabled the mod to make the screen in reverse (white chars on black background), i have also made the composite mod with the right resistor value for the best quality video output.

Replacement:

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Simple steps to replace the keyboard Membrane of the Sinclair ZX Spectrum 128k (heatsink).

• Buy a new Sinclair Spectrum 128k Keyboard membrane.
• Unscrew the eight screws on the bottom.
• Kindly disconnect the keyboard from the connectors on the main pcb.
• Remove the back of the keyboard.
• Unscrew the block that holds the cable.
• Remove the old membrane.
• Clean the keyboard with air-spray and a soft brush.
• Install the new membrane.
• Close the back of the keyboard.
• Very kindly put the block of the flat cable and screw in.
• The keyboard is ready to be connected.
• Very kindly insert the flat cable into the connector.
• Your Sinclair ZX Spectrum 128k is like new.

source: rwapsoftware.co.uk

I thank my dear friend for the donation of the motherboards.

• Commodore Dual Drive Floppy Disk CBM 8250
• Commodore CBM 8296

A dear friend sent to me a few things to repair or test, i will see to do my best.

Things to repair/testing:

• Commodore 64/128 – 1764 Ram Expansion (dead)
• Commodore 64 Power Supply for the Commodore 1764 Ram Expansion (pcb broken)
• ZX Spectrum Plus (7805 over burned)
• Texas Instruments TI-99/A (black screen)
• Amstrad 464 + (replace case and keyboard)
• Kung-fu Master Jamma pcb Board (no audio)
• Arabian Sinclair Spectrum 2+ (dead + tape problem + keyboard problem)
• Sinclair ZX81 (video problem / testing)
• Sinclair ZX80 (video problem / testing)
• Sega SC-3000 (cpu bad socket)

Things for spare parts or to keep:

• Sinclair ZX80 Original Power Supply.
• Commodore VIC-20 Boxed cartridges.
• Sega SC-3000 Basic cartridge.
• Commodore Dual Floppy Drive 8250 motherboard (spare parts)
• Commodore CBM 8296 motherboard (spare parts)
• Sharp CE-510F Dual Floppy Drive for Sharp PC-5000 (Boxed)
• Chalkboard Powerpad + Expansions (Boxed)
• Tape Recorder for Commodore (spare parts)

Replaced a old yellowed Amiga 1200 keyboard with a new one.

I have made some works for a friend and i didn’t want money, the friend then wanted to contribute to my Electronic Lab with this Hot Air Desoldering Station. Thanks, i appreciate it.

Video demostration:

source: aoyue.com

I have repaired an Commodore VC-1541 Floppy Drive donated by Alessio. The Floppy Drive doesn’t take any commands via IEC.

The components that have been replaced are:

• 1 x 7406
• 1 x 74LS14

Material donated:

• Commodore VC-1541 (need to fix it)
• Microcomputer Data Recorder Klain for Commodore 64/VIC20/PET.
• Some IC.

Thanks Alessio for the donation.

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I had several problems with the repair of the Hewlett-Packard HP-85.

The first problem was the way to reconstruct the pinch roller using a latex tube, this is a very bad choice, then i have used a 10mm heat shrink, this choice instead is very good.

The second problem was the rubber parts of the pinch roller are literally dissolved and the rubber is went to cover the optical diode and part of the pcb and of course nothing has worked and the tape drive was always in stalled state.

After cleaning, the drive started to work perfectly. The last problem are the magnetic tapes 3M DC-1000 instead of HP DC-100, for the correct operation you must perform a modification by adding a resistor of 2kohm in parallel to the already present on the pcb. After this mod you need to format the tape with the “erasetape” command.

I must also thank John of the site vintagecomputers.freeserve.co.uk for the support.

Download:

• 3M Data Cartridge Compatibility List (1604)
• Athana DC100A / 3M DC-1000 Fix (1365)

source: voidware.com/calcs/hp85rep hp9845.net vintagecomputers.freeserve.co.uk

Replacement:

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Simple steps to replace the keyboard Membrane of the Sinclair ZX81. The removal of the old keyboard is not illustrated but it is a very easy job.

• Open the Sinclair ZX81.
• Place the membrane.
• Remove the adhesive protection.
• Place the membrane and press firmly.
• Check the Membrane Connector.
• Gently insert the connectors on the pcb side.
• Close the Sinclair ZX81.
• Enjoy.

source: rwapsoftware.co.uk