Inside a 1960s Medical Device - Unistom G-9

Teardown of an old Polish dental pantostat made by FAMED (Medical Apparatus Factory), which interestingly was located a few hundreds meters away from my old home. I saw the factory everytime I looked out the window. The Unistom G-9 was made in the 1960s/70s, it was used for several types of dental procedures: electro-surgery (electrotomy and electro-coagulation), endoscopy, sample viewing, ionophoresis and dental pulp testing using Faradic current. The device runs on two EL81 pentodes in parallel as a HF current generator for electro-surgery and a TG0,1/1,3 thyratron for generating current spikes at up to 10% duty cycle on the dental pulp test setting which uses Faradic currents. The 110V DC power supply on the terminal board on the side is used for ionophoresis, with the milliammeter for measuring the current. The voltmeter is used in pulp test to set the voltage low enough to be relatively comfortable to the patient, but high enough to be felt when inflammated tissue is stimulated.