/diy/ - Do It Yourself

>>908330
Well, the board and the copper, being different materials, expand and contract under heating at different rates. This is not problem in low temperature environments, but for a PCB that is mounted above the globes this will be a big issue. Over time the difference in expansion and contraction rates causes the copper (or whatever metal the tracks are made of) to separate from the board. Another factor is the adhesive they use to fix the copper to the board failing over time, leading to the same outcome.

Pic related is a perfect example, a power supply board from a 50's era mainframe terminal. Over the years the constant heat and cool cycling caused by those chunky, high watt resistors has caused the tracks to lift away from the PCB. Circled is an example of a fractured solder joint that I referred to in my other post. This board is toast, and I plan to etch my own replacement board to get the device working again.

>>908332
Looks like the transformers leads come out underneath the chassis. Pop the base plate off and take a photo of the underside of the unit and i'll see what I can find.