These are old school unregulated DC supplies, just a transformer, rectifier and a capacitor. When unloaded the output voltage is higher and you have losses in the transformer itself, so you still get heat. With the supply loaded the voltage drops to the nominal rated voltage. They are a quite inefficient supply as well.
Jeff Birt From: M100 <[email protected]> On Behalf Of dano none Sent: Sunday, February 14, 2021 7:13 AM To: [email protected] Subject: [M100] Fw: New Knowledge to me. I didn't see Jeff Birt mention it, but he now has a new take down video of the stylish Olivetti M-10. https://www.youtube.com/watch?v=tq8DnnvOAy8 I left my Model-100 plugged in to an original Tandy transformer/power supply, it got a bit warm, so I said... Hum.. What happens if I unplug the transformer - it will probably go cold, as there is nothing to complete the circuit. I was surprised, the little bugger actually got warmer, not being plugged into the Model-100. I've determined, I need to build it a little pig tail with an on/off rocker switch on the AC side of the circuit.
