Picture 1
Shows the EPROM (Erasable Programmable Read Only Memory) fitted with a
label marked JAF7. EPROM's can be erased by removing the sticker and
exposing the device to strong ultraviolet light. I incorrectly refer to
it as a PROM (Programmable Read Only Memory. Below it is the old leaking
PLL backup battery.
Wikipedia article about EPROM’s (Erasable Programmable Read Only Memory)
Link / example of a Fluke 77 DMM (Digital Multi Meter) I mention that I used it to check the battery voltage of the original PLL backup battery which I think was manufactured around 1984. I was very surprised to find that the battery which is likely 40 years old had a battery voltage of 3.2V which is a healthy voltage. The battery still needed changed due to liquid (probably acid) which can be seen in picture 1 being present on the top surface of the battery.
Picture 2
Shows me extending the new battery terminal using the leg of a 1.8 kilo
ohm resistor. Note that the resistor leg is shiny because this time I
scraped away the surface oxidation using pliers prior to soldering it in
place. This improves the final solder joint.
Part 5 deals with the removal of the original 40 year old PLL backup battery.
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