The EC-130 is fully operational after a complete disassembly and rebuild.
This machine was acquired from a thoughtful individal who had rescued it from his workplace shortly after it was superseded. He had recognised that it was something special in its time and acquired it, rather than see it discarded. He had kept it in clean dry storage for over thirty years before deciding to pass it on for continuing preservation.
Restoration 1 Cleaning, Physical & Safety
General condition was very good, consistient with its excellent storage history. It was briefly demonstrated when acquired but as is DoPECCs standard practice, it was not powered up again until it had been partly dismantled for inspection and cleaning.
Standard practice was well justified in this case as a nasty and very dangerous fault was uncovered. The main power wiring from the input socket to the main switch was overheated and burned, live wires at mains potential could easily have contacted the metal case (fortunately, the earth connections had remained sound). See Mains Fault Pictures in the pictures section.
The source of the overheating appeared to be within the actual wiring, perhaps a dry joint at the mains switch. The actual mains switch was somewhat overheated with loose contacts and this may also have contributed to a high resistance junction. Fortunately, the switch could be restored. The damaged wiring was replaced and an IEC socket was substituted for the obsolete original socket, allowing a modern mains lead to be used.
Restoration 2 Power Supply Test
The EC-130 was has a transformer based power supply with series pass regulation of logic levels. The transformer has primary taps for international voltages and there were verified for local levels.
The low voltage circuits appeared to be in good condition, in particular the filter capacitors showed no sign of deterioration. Increasingly, DoPECC prefers to replace all old filters, especially if it is easy to conceal the replacements. In this case it was decided to use the original capacitors and observe the outputs carefully
Powerup with dummy loads was successful and all voltages were close to specification with satisfactory ripple.
Restoration 3 Keyboard Faults - Teardown and Repair
The EC-130 has a very special keyboard which appears to be at least in part inspired by a desire that the keys have a particular quality of movement.
The keyboard mechanism is an intricate arrangement of parallel bars with machined ramps which are pressed on by blades attached to each key. The pressure on the ramps causes the bars to slide in a pattern that is unique to each key and small magnets attached to each bar are moved into a unique pattern that is then sensed by a series of reed switches.
Inspection showed that one magnet had come loose and further inspection suggested that this was a more general design flaw - two other magnets had been glued and/or wired back into place in the past. With this in mind it was decided to dismantle the entire keyboard, clean all parts and moving surfaces, inspect and secure all magnets and rebuild.
This was done successfully and the keyboard is now reliable with a consistent feel across all keys.
Restoration 4 Startup
After high voltage power inspection and repairs, followed by low voltage power inspection and tests, it was time to consider a full startup.
All circuit boards had been inspected, the edge connectors were in good condition but were cleaned with DeOxit.
The initial startup was not accompanied by any suspicious smells or sounds but was a little anxious because there was no display for some time. Fortunately, this proved to be just slow heating of the CRT and finally there was a very nice four-line display. All keys and calculations operated as expected and it seemed that this 40+ year old machine was back to full operation.