Olivetti/Programma 101/Revive/LetterSandroGraciotti 20130709 1107

Re: Olivetti P101: Circuit diagrams?

Date: Sun, 9 Jun 2013 11:07:21 +0200

From: Sandro Graciotti ...

Dear Thorkil,

Congratulations for the work done on the 101. Most of the documentation we have is in italian and is based on symbols that were used in Olivetti during the '60s: quite hard to interpret.

Enclosed is a schematic drawing of the P101 power supply (Fil:OlivettiProgramma101 Alimentatore P101.pdf). The part enclosed in the blue line is the small board with the lamps, the other components are installed in the cooling block.

The power supply cannot be turned on without load because the output voltage would be not regulated (the leakage current of the series regulator transistors is pretty high) so the electrolitic capacitor on the small board may have suffered.

If you want to check the power supply before inserting the electronics, you should connect a suitable load (10 Ohms 40W): the easiest way is a couple of car headlights connected in series (or a 24V headlight).

With the load you should have about 20V, the voltage can be regulated by the pot that is on the board but is not critical at all (anywhere between 18V and 22V is OK).

Keep me informed of any progress or problem.

Ciao, Sandro