HMV 1628 1959 radiogram (valved) repair & overhaul - pt1 скачать в хорошем качестве

HMV 1628 1959 radiogram (valved) repair & overhaul - pt1

Richard Shireby discusses & demonstrates the service work needed to bring a 1959 HMV 1628 valved (tube) radiogram (mono) back into working order. The Ebay vendor said it last worked 10 years ago. We automatically changed all the electrolytic capacitors & this brought the amplifier back into working order. Fault finding with the service manual & multimeter found three o/c resistors & a couple that had gone very high resistance. There was also a short circuit caused by a cart just touching another in AM mode. I found that altering the wavechange switch position brought the radio into operation & suspected the switch just needed cleaning, which I did. It turned out that the slight mechanical movement of the switch assembly temporarily relieved the s/c. It was eventually tracked down & full normal operation was then achieved. I forgot to mention that we usually put valved chassis through the company dishwasher, which is why it looks so clean. This is done in a carefully controlled way. The dishwasher is set to the quickest cycle in our case it takes 35 mins. The chassis is then put across a convector heater we have which has a carefully set digital thermostat & the heater set to 700W . This takes place in a room with air conditioning & this is carefully set up as well. The idea is that the air conditioning sucks out the moisture, helped by the gentle heat from the 700w heater. I leave them like this for 24hrs. Sometimes extra sensitive components are protected from water in the dishwasher by sealing them in a plastic bag. My nearest neighbour 1/2 mile up the road has access to date expired condoms which he will always let us have for this purpose too, Richard