10-04-2022, 01:51 PM
(10-04-2022, 01:21 PM)amy Wrote: So I started work on Dad's old 32IC. I can get 5V out of the 7805 on the core board, but the ones on the motherboard (under the keyboard) are dead. I've replaced D14 and the electrolytic cap, but I'm not sure if I can get at the 7805s without taking the keyboard off. Also when I desoldered them a couple of the solder pads lifted off the motherboard. Is there a way to re-solder the regulators without taking the keyboard off?
I ordered some switch-mode replacements for the voltage regulators but I was wondering, if I have to take the keyboard off is it worth waiting for a new keyboard replacement kit?
Lifting PCB pads? It sounds like you're using a vacuum pump desoldering tool, too much heat both. If you are, stop right now.
The regulators are easily removed without the need to remove the keyboard bracket.
Affordable and acceptable desoldering stations are available. After a bit of practise, components can be easily removed without any tugging whatsoever.
As as side note, why is it everyone's fascination with TO-220 switchmode voltage regulator replacements? Someone just uses bog standard linear ones.
If you're worried about the heat being dissipated, then run the bee from a lower voltage. Use LDO versions if you want to run from even lower voltages but this may require adjustment to the voltage good sensing resistor network resistors.