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. I mention I have an EC2000 Weller Electronically controlled soldering station. Here is a link to an example I found
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. I mention I have an EC2000 Weller Electronically controlled soldering station. Here is a link to an example I found