Radio Shack TRS-80 Model 1 (#2) Repair.

Defect:

• Black Screen.

Replaced parts:

• Replaced 1 x CD4069 HEX Inverter (Z6)
• Replaced 1 x CD4069 HEX Inverter (Z57)
• Replaced 1 x 74LS00 QUAD 2-INPUT NAND GATE (Z5)

Radio Shack TRS-80 Model 1 Repair.

This is the second time that this computer was repaired within 2 years.

Defect:

• Video Sync issues (Horizontal Driver) and then … garbage on the screen.

Replaced parts:

• Replaced 1 x CD4069 HEX Inverter (Z6)
• Replaced 1 x MM2102 RAM (Z62)

Repair Commodore Amiga 3000 Motherboard with Battery leakage

There was once a motherboard of an Amiga 3000/25 devastated of the Battery acid where missings all the socketed components and others are unsoldered and recovered for other things.

The situation was not exactly the best one, in other words … was going into the box of spare parts.

I made the impossible, i have cleaned, scraped and rebuilt many tracks of the pcb corroded by the battery acid and i must say that with lot of patience i have repaired the motherboard giving a new life to this Amiga 3000/25 that he had no many chance to come back to work

Apple IIe Power Supply Repair.

Defect:

• Dead with clicking noise in background (This power supply works even without load)

Replaced parts:

• Replaced 1 x 200uF 10V Electrolytic Capacitor.

Removed as a precaution the RIFA filter capacitor.

Gallery:

Epson PX-4+ Easy Repair

Defect:

• Dead.

Replaced parts:

• Replaced 1 x Fuse 3A

Removed the internal Backup Battery (RB 301) 4.8v 90mA.

Commodore VIC-20 Repair

Defect:

• Black screen … then black and white image.

Replaced parts:

• Replaced 1 x 901486 KERNEL ROM (U12)
• To fix the problem of the image in black and white i have adjusted the “RED” trimmer (C48)

Commodore 16 Power Supply Repair

Defect:

• Output voltage in short circuit.

Replaced parts:

• Replaced 1 x 4700uf / 16v Electrolytic capacitor.
• Replaced 1 x 800mA Bridge rectifier.

Atari 2600 Repair

Defect:

• The second joystick port doesn’t works properly.

Replaced parts:

• Replaced 1 x 6532 RAM-I/O-Timer (RIOT)

Commodore CBM 4032 (40 Columns) Repair

Defect:

• “Device not present” error when using the IEEE 488 port (Example Floppy Drive)
• Sometimes the computer show the prompt of the TIM monitor (Machine Language Monitor program)

Replaced parts:

• Replaced 1 x IC 6522 VIA (UB15)
• Replaced 1 x IC 6520 PIA (UB16)

This Commodore PET 2001-8C also includes a homemade Power Amplifier to hear the sound of some games that use the pin CB2 of the User Port as audio output.

Also is included a reset button and two mini-led (Red / Green) that display the data (Save / Load) when using the tape recorder.

Some photos of the Commodore PET 2001-8C:

Copyright label on the motherboard:

Some photos of the repairing and cleaning:

Commodore PET 2001 (Chicklet) Repair datassette.

Defects:

• Doesn’t load any more.

Repair:

• Replace motor.
• Replace belt.
• Azimuth adjustment.

Thanks to Manosoft for the spare parts (white datassette, the same model of the black one)

Commodore PET 2001 (Chicklet) Repair.

Defects:

• Wrong chars on the screen.
• Memory problems.

Repair:

• Replaced all MOS 6550 main ram with an 6550 Ram Adapter by xAD & Manosoft (only 2 x MOS 6550 was faults)
• Replaced 1 x MOS 6550 Video Ram with a spare one from the main ram.

Video of Galaxy Invaders with Sounds:

from Wikipedia homepage:

The Commodore PET (Personal Electronic Transactor) was a home/personal computer produced in 1977 by Commodore International. A top-seller in the Canadian and United States educational markets, it was Commodore’s first full-featured computer, and formed the basis for their entire 8-bit product line.

Read more…

Gallery:

This adapter replaces all ram installed in the Commodore PET 2001 with a 6264 Static Ram and is useful when one or more ram are faulty. These type of ram are no longer available to purchase.

NOTE: This adapter will only work to replace a chip with a part number starting with MPS 6550. They will NOT replace other RAM types used in Commodore computers other than the original Commodore PET 2001.

The original design was done by Donni of the VCF forum (Vintage Computer Forums).

Unfortunately these pcb have a design problem, below the fix which needs to be done (i always forgot to post this fix, sorry)

Download: Original printable version by Donni (1374)

Gallery:

Restoration the external case of the Micro Peripherals Ltd Floppy Disk Drive that was eaten by rust.

Gallery:

Cleaning the keyboard keys is really tedious.

Gallery:

12►

Commodore CBM(PET) 4032 (FAT40) / 8032 Cathode Ray Tube (CRT) Replacement.

The cathode ray tube was taken from the Amstrad GT-65 (Monochrome monitor)

The CRT Tube Orion 310GNB31 (Amstrad GT-65) is fully compatible with the Amperex M31-334GH (CBM 4032/FAT40 – 8032).

NOTE: The same CRT work perfectly for the computer Radio Shack TRS-80 Model 3 and Model 4.

Gallery:

Commodore 16 ASSY 251789-01 REV B Empty PCB