06-01-2015, 11:07 PM
Lovely old things. I have a small collection up in the attic - every time I dig them out, they continue to work perfectly. Even the 30 year old floppy discs still seem to be OK (I keep those downstairs, just in case).
Those Riva caps are *everywhere*, and are a right pain! But although they are dramatic when they let go, normally the damage stops with them. They made their way into those nice filtered mains inlets from the likes of Schaffner, and are starting to fail now. Just recently I had one fail in a Philips counter/timer, and unusually the capacitor went short-circuit (and as this inlet was unfused, it took out the fuse in the mains plug).
High-value resistors with lots of volts across them (say, >100k and >100V) are prime suspects - the classic cause of start-up problems in switchers like this. I usually replace with metal oxide resistors. We discussed resistors last summer: http://golbornevintageradio.co.uk/forum/...8#pid46468
It has to be said that those power supplies have been pretty reliable over the years. I did manage to blow one up once by power-cycling it far too quickly, but that might have been just the fuse; at the time I didn't investigate it, but simply swapped it with a spare.
Cheers,
Mark
Those Riva caps are *everywhere*, and are a right pain! But although they are dramatic when they let go, normally the damage stops with them. They made their way into those nice filtered mains inlets from the likes of Schaffner, and are starting to fail now. Just recently I had one fail in a Philips counter/timer, and unusually the capacitor went short-circuit (and as this inlet was unfused, it took out the fuse in the mains plug).
High-value resistors with lots of volts across them (say, >100k and >100V) are prime suspects - the classic cause of start-up problems in switchers like this. I usually replace with metal oxide resistors. We discussed resistors last summer: http://golbornevintageradio.co.uk/forum/...8#pid46468
It has to be said that those power supplies have been pretty reliable over the years. I did manage to blow one up once by power-cycling it far too quickly, but that might have been just the fuse; at the time I didn't investigate it, but simply swapped it with a spare.
Cheers,
Mark
