I have repaired an motherboard of a Commodore CBM 4008 for a friend. The computer at the start-up shows only a black screen
The components that have been replaced are:
- 1 x Video Ram 2114
- 2 x SN74LS244
- 1 x 6520
The computer after the repair works perfectly. You can see from the Photo.
I have repaired an Enterprise 64 (SixtyFour) for a friend. The defect via Composite or RF was a Black Screen but with the RGB output you could see a video signals without vertical sync.
The components that have been replaced are:
- 1 x BC337
- 1 x 74LS86 (HSync/VSync to Csync)
- 1 x 74LS32 (HSync/VSync to Csync)
The computer after the repair works perfectly. You can see from the Photo.
Download: Enterprise 64/128 Schematics (1112)
source: enterprise.iko.hu
Console Amstrad GX4000 Repaired.
The fault is was caused by a wrong power connection. It was ‘resting’ the power plug of 11v on the power plug of 5v (monitor input).
Replaced parts:
The components have been recovered from the Amstrad 464+
TI-99/4A MBX Expansion System Repaired.
The interface MBX Expansion System was dead and the power voltage was in short-circuited. The failure was caused by the filter between the power supply and the 7805.
Video:
A few things to repair for a friend.
- Enterprise 64
- Archimedes 310
Defect: unknown.
I have repaired an Atari 800XL for a friend. The failure was caused by a faulty cpu, the computer freezes after 10 minutes of operation, using an oscilloscope i have noticed that the clock pin of the cpu did not give me more signal but when i have used the synthetic ice spray on the cpu has resumed to work.
This type of cpu (Atari customized 6502 – C014806-12 Sally) is not easy to find but fortunately a friend of mine (Carlo) has found a spare part for me.
Kernel JiffyDos Installation and Keyboard Repair for my friend Damiano (manosoft.it). To repair the keyboard you must clean the contacts very well on the pcb.
I received this computer to be repaired for a friend some days ago. The computer displays only a black screen and some times a random character without any sound beep at the startup boot.
I have replaced the PLA IC 324745-01 (UE5) and 324744-01 (UE6) with two EPROM 27C512 70ns (suitably programmed), the Universal PLA adapter was kindly donated by Manosoft.
The computer also had another defect, apparently the fault was not only in the two PLA. The computer starts with the classic beep but the screen remain black, the faulty is the IC 6545 (CRTC) and that was replaced.
This model uses a ROM daughterboard instead of a single 23128 ROM (EPROM 27C128 pinout compatible). I have made an adapter to preserve the original state of 8296 and allow the insertion of the daughterboard after the replacement of the two PLA that are different (in size) to the original one.
Have been replaced 4 tantalum capacitors short-circuited with 4 electrolytic capacitors. The computer has been tested and works perfectly.
I have gathered all photos of some phases of the work that i have done on the Atari 1200XL.
Below the descriptions:
- SIO 5v Enabled (you have to short-circuit the resistor R63 to get the 5v on the SIO of the Atari 1200XL)
- Repairing Keyboard (i have stretched the springs of a few keys for make the right pressure. The work must be completed using the liquid graphite where the contacts are more ruined)
I have gathered all photos of some phases of the work that i have done on the Tatung Einstein TC01.
Below the descriptions:
- Replaced 2 x 74LS157 (IOO6/IOO7) Multiplexer.
- Replaced UK Power Connector.
- Repaired some not working keys.
- External Floppy Drive 3.5″. Yes, it’s better than 3″ ;-D
Todo:
- Repair the defect of the vertical sync of the Monitor Tatung TM01
I have received this computer Commodore CBM 8296-D 1 year ago. The computer has never worked, it only displays a black screen without any sound beep at the startup boot.
The repair it was very simple, i have replaced the PLA IC 324745-01 (UE5) and 324744-01 (UE6) with two EPROM 27C512 70ns (suitably programmed). The Universal PLA adapter was kindly donated by Manosoft.
Download:
Sorry, this entry is only available in Italian.
I was very lucky in this repair, the fault is a broken belt that is used for the operation of the Floppy “Quick Disk”.
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I post some screenshots and a video of the repairing of a NEC PC-Engine LT console.
Defect in the console:
Some capacitors have leaked acid on the pcb, i had to clean with the right product made especially for cleaning the pcb before proceeding with the replacement operation. The LCD screen is was disassembled to remove the dirt inside.
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