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Grundig W4/7 oscilloscope restoring Part One - Part Two - Part Three Recently I've come along an dusted and dirty tube oscilloscope Grundig type 51 W4/7 serial 1954. It was made in 1964. From outside it looked really poor, but under layers of dirt, nice gray paint shined through. After first power-up I've noticed bad wave shapes and horizontal trace wasn't stable. Opening the housing showed nice inner construction, so typical for this once famous german brand. Built to last, but with so many dust inside, it screamed for restoring. And the accuracy was compromised. Tubes held in place by wire buckles may indicate this instrument was intended for a field work, not only in a lab. Grundig logo on nearly all components... Apart from tubes, I cannot guess if they are original or already replaced. Fabric-insulated wires, bent in 90 deg angle before soldering - one cannot see this in today's made electronics. This fine piece of gear, made 42 years ago had typical problem for a device of such age - dried electrolytic capacitors. Measuring their ESR confirmed my doubt. Caps lost part of their capacity and ESR went up. Close-up look around + terminal revealed cracked and swollen rubber end. Quick and simple solution was replacing all electrolytic caps with new ones. Part One - Part Two - Part Three Images (C) 2006 Tomislav Kordaso, 9A5TT