Algemeen's Electronics and Bicycle Tinker Blog

A quick update, since next weekend I’ll be in Vienna again so I won’t be tinkering for a while. Today ordered the electrolytic capacitors and checked how to remove the knobs from the pot shafts. It was a bit of an unpleasant surprise to me, since I was expecting just a hex nut under the plastic cover cap as most of these style knobs have them. But instead there is some slotted rounded nut, some bespoke SAFIM brand brass nut it seems. SAFIM Collet knob Found out by some googling, the SAFIM Collet knobs are also used in designs by SSL and the likes. SAFIM sells a special tool for this, but I’ll just make my own tool. It clearly doesn’t follow DIN546 spec for slotted nuts so I guess there is no alternative “standard screwdriver” anyway. Added some cheap-ish 8mm slotted 1/4inch hex drive screw bits for the purpose to the order, and I’ll just grind or file my own “snake” style bit with an approximate shaft gap of about 5mm. Meanwhile thinking about the enclosure design. Cheers fro...

Electrolytic capacitors have a wet dielectric which degrades with age and temperature. As a result the extremely thin oxide layers may become less isolating when stored over decades. Either the capacitor shorts or opens at some point, or just doesn't perform as good when it was new. Re-capping is the usual procedure to replace (all) electrolytic caps in restoring old audio equipment. The most common coupling capacitor value in these modules is 15uF / 40V. These smaller values might be replaceable with solid foil capacitors, though it largely depends on the space on the circuit board if this is possible and the cost involved. High-end audio nut cases (no relation to this blog) may spend top dollar/euro/yen on such things. Here it just has to be in line with the actual value of these units. So we will only use foil if the costs are limited. Otherwise just stick to cheap but good quality electrolytic caps. The likes of Nichicon, Panasonic, Vishay. Vishay bought a lot of the old Eur...

This is a restoration project I’ve been procrastinating around since about 2015. This will be quite some work, but then if one doesn’t start at least it will not happen at all. This will be a step by step project, and see how far we get with this Kaizen like approach. So first a short intro of the four audio modules made by Audio & Design (Recording) Ltd, in the mid 70s based in Shinfield Green, Reading, Berkshire UK. The company still exists to this date and is still active in pro-audio and is now in a different location but still in Reading. These modules can be dated to the mid 1970s, more precisely found the E900 Equaliser unit quality checklists to be dated 12 November 1976. There are two E900 equaliser modules, and two F760N Compressor/Limiters. A picture of the now dismantled mixing desk with the four modules. The mixing desk was in a quite dusty and sorry state. The desk was too space consuming and heavy to keep and many other parts were sold as separate items. ...