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Noopy2014 · 31st Jul 2018, 9:56 pm

You are right! The power supply is a little bit tricky.

The main problem of the time was the low voltage rating of the power FETs at the time of the development. The solution for Gould was the construction of a switching power supply working with something around 70V (the upper supply).

To get the 70V-Supply the lower supply was developed. This supply is a step down regulator which has lower voltage requirements.
In detail the ground of the upper supply is connected to the inductor L1 and the lower supply transistor switches in this way that the upper supply get´s 70V.

To make it a little bit more confusing the regulation of the output voltages at the secondary side is realized over the lower supply. It monitors the auxiliary winding 9-5-10. This voltage is distributed to the 3524 over D19 and D20.
(D21 and D22 are for synchronisation of the to supplys. The upper supply works with 19kHz while the lower supply works with 38kHz.)

31st Jul 2018, 9:56 pm	#21
Noopy2014 Tetrode Join Date: May 2014 Location: Eichstätt, Germany Posts: 88	Re: Gould 4072 bad PSU You are right! The power supply is a little bit tricky. The main problem of the time was the low voltage rating of the power FETs at the time of the development. The solution for Gould was the construction of a switching power supply working with something around 70V (the upper supply). To get the 70V-Supply the lower supply was developed. This supply is a step down regulator which has lower voltage requirements. In detail the ground of the upper supply is connected to the inductor L1 and the lower supply transistor switches in this way that the upper supply get´s 70V. To make it a little bit more confusing the regulation of the output voltages at the secondary side is realized over the lower supply. It monitors the auxiliary winding 9-5-10. This voltage is distributed to the 3524 over D19 and D20. (D21 and D22 are for synchronisation of the to supplys. The upper supply works with 19kHz while the lower supply works with 38kHz.)