How to Repair my Osborne 1
I have recovered a Osborn 1 in pretty nice cosmetic conditions but broken ;-(
List of broken stuff:
- Startup Garbage screen.
- Long startup beep.
- Reset works 1 times out of 20.
- Modem port desoldered.
- Powersupply ripple.
- Some screws missing.
Solutions & Fixes:
- Powersupply Ripples: Replaced some capacitors.
- Modem Port de-soldered: Fixed the cold solder.
- Startup garbage screen/long beep/reset: I have replaced a broken 4116 RAM.
- Screws missing: Replaced with a new one.
I have to thank Terry ‘Tezza’ of Classic Computers Blog for the piggyback ram guide.
I used an oscilloscope to find the faulty ram cause all ram in my motherboard seemed to work well. In the photo #9 you can see the signal of the pin 2 (data in) of a faulty ram, while in the photo #8 the same signal of a working a ram.
Grande!