Philips GM5659-01 oscilloscope (1957)

The GM5659-01 is an average laboratory oscilloscope that can display signals in the frequency range of 1 Hz to 1 MHz.

This scope uses a DG7-32 CRT, a bit more modern than the original GM5659. It has 12 other valves: 4 EF80's in the horizontal amplifier, 4 in the vertical amplifier, 2 ECC40's in the time base, and 2 AZ41 rectifiers. I cannot date it precisely, but the service manual I have, is from 1959. The GM5659-01 has real printed circuit boards, unlike its predecessor, the GM5659, that has hand-made circuit boards.

I bought this one in March 2006 as non-functional. The hammered metal finish case has a little rust. Some glue stains on the face plate where an inventory label used to be, show the outline of the letters "PTT" showing it must have been used in the PTT workshops. This means it has probably been used quite a lot. Someone has awkwardly dropped this fine instrument. The silent witnesses of that accident are the shattered mains receptacle on the back, a number of broken screws on the back, a few pieces of the frame that have been bent, and one of the circuit boards that is broken in two. One of the switches on the side has been removed. These switch the deflection plates from the vertical amplifier to the input receptacles on the back, for direct deflection. Both cover plates around these switches have disappeared. But all the valves are in one piece (but why has the mu-metal screen around the CRT disappeared?). So I will have some work to do before this scope will show its neat green traces on the screen again.

To be continued.