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1. F4GRX Sébastien (f4grx@chaos.social)'s status on Friday, 10-Jan-2025 07:17:02 JST F4GRX Sébastien

   in reply to

   @altomare starting analysis of the second board. As suspected, the coax shield is connected to the positive supply, so this oscillator is actually powered by -24VDC to ground... Or, output signal is referenced to +24V. Weird.

   • polprog68k likes this.
   • F4GRX Sébastien (f4grx@chaos.social)'s status on Friday, 10-Jan-2025 07:17:03 JST F4GRX Sébastien

     in reply to

     @altomare Calling all EE engineers, specifically ones that were designing stuff in the seventies. Does this look like a typical heat regulation circuit that would work? I suspect this is the power part, and the other PCB is a kind of oscillator to drive this. it has 3 transistors and I have not looked at it yet.

     I'm not posting a bitmap as it's unreadable

     I am working on page 3 of this PDF.

     I imagined what a transformer could be but the second one is a mystery.

     https://cloud.f4grx.net/index.php/s/JtSfTx4rmwZfS7W

   • F4GRX Sébastien (f4grx@chaos.social)'s status on Friday, 10-Jan-2025 07:17:04 JST F4GRX Sébastien

     in reply to

     @altomare reversing reversing. No idea what this crap does.

   • F4GRX Sébastien (f4grx@chaos.social)'s status on Friday, 10-Jan-2025 07:17:06 JST F4GRX Sébastien

     in reply to

     @altomare a few more pics while disassembling for cleanup.

   • F4GRX Sébastien (f4grx@chaos.social)'s status on Friday, 10-Jan-2025 07:17:07 JST F4GRX Sébastien

     in reply to

     @altomare the insides are quite complex, two transistors heat the box that I understand as an outside oven. Inside there are circuits, includind two transformer-like units, and a big cylindrical plastic box that should be the inner oven. Interestingly the ground seems connected to the +24v line. Full reverse engineering and restoration will happen!

     If it was used for a long time, this crystal should have aged like good champaign and will be quite stable.

     edit: alt incoming - done

   • F4GRX Sébastien (f4grx@chaos.social)'s status on Friday, 10-Jan-2025 07:17:08 JST F4GRX Sébastien

     Thanks @altomare for this very interesting antique oscillator. It's massive! It's from 1971, made in France by "Quartz et Electronique" a dead company that was acquired by Alcatel.