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 double triodes 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 circuit boards using solder posts (turrets?) like the older version GM5659.

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, reveal 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, some parts 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 and the switch covers on both sides are missing. These switch the deflection plates from the vertical amplifier to the input receptacles on the back, for direct deflection.

This allows the user to connect the output voltage of a GM2886 sweep generator. But none of the valves is broken. I wonder why has the mu-metal screen around the CRT has disappeared? So I though I would have some work to do before this scope will show its neat green traces on the screen again.

But that never happened. Shortly after this one, I acquired another GM5659 in excellent condition. A few years later, I found another GM5659 complete with visor, that was missing some parts. So this scope became donor of components. Finally, I traded it to someone who was in need of the power transformer.