14-12-2016, 01:37 PM
Sorry for the thread resurrection, but here goes ...
A lady contacted me yesterday asking if I could repair her 'amp' (it turned out to be an Aiwa TPR-3001 receiver with built-in cassette recorder, but that's another matter). Apparently she and/or her partner had unplugged it, moved the piece of furniture underneath it, replaced the receiver/cassette, plugged it back in and it was dead. They'd tried it in another socket and it didn't work there either. They'd replaced the fuse in the plug and looked at the fuse in the unit itself (glass-bodied, so she could see the wire wasn't blown) to no avail. I said yes, bring it over and I would have at least a quick look.
It was scary. The receiver/cassette (inherited from her father) had a two-wire mains lead and a single-pole internal mains switch. The unswitched mains lead core was wired to the plug's neutral pin. So far, so good. But the switched core was wired to the earth pin ! "Was the plug taken off and put back on when you moved things around ?" I asked. "No" she said "we just unplugged and replugged it". Looking more closely I could see that the metalwork in the plug which makes up the terminal for the wire and the spring clip for one end of the fuse was not the original piece. The current one had been fitted into the plug body 'end up' and the fuse pushed into it at 90 degrees from its normal orientation. In this position the metal piece was just about in contact with the top of the earth pin and thus the wire to the receiver/cassette. This contact seemed to have been completed by a good deal of scorching and a small amount of arc-spattered metal on the inside of the plug body !! Obviously plugging and unplugging had disturbed this. I rectified the situation by fitting a replacement plug with the correct fuse so now all is well with the receiver/cassette.
The really scary thing, of course, was that for all the time that this had been working at her home (a long time, apparently), the earth pin of the plug must have been at high enough volts to power the receiver/cassette. I recommended that she get a competent electrician to look at the wiring in the corresponding wall socket as a matter of urgency !
VB
A lady contacted me yesterday asking if I could repair her 'amp' (it turned out to be an Aiwa TPR-3001 receiver with built-in cassette recorder, but that's another matter). Apparently she and/or her partner had unplugged it, moved the piece of furniture underneath it, replaced the receiver/cassette, plugged it back in and it was dead. They'd tried it in another socket and it didn't work there either. They'd replaced the fuse in the plug and looked at the fuse in the unit itself (glass-bodied, so she could see the wire wasn't blown) to no avail. I said yes, bring it over and I would have at least a quick look.
It was scary. The receiver/cassette (inherited from her father) had a two-wire mains lead and a single-pole internal mains switch. The unswitched mains lead core was wired to the plug's neutral pin. So far, so good. But the switched core was wired to the earth pin ! "Was the plug taken off and put back on when you moved things around ?" I asked. "No" she said "we just unplugged and replugged it". Looking more closely I could see that the metalwork in the plug which makes up the terminal for the wire and the spring clip for one end of the fuse was not the original piece. The current one had been fitted into the plug body 'end up' and the fuse pushed into it at 90 degrees from its normal orientation. In this position the metal piece was just about in contact with the top of the earth pin and thus the wire to the receiver/cassette. This contact seemed to have been completed by a good deal of scorching and a small amount of arc-spattered metal on the inside of the plug body !! Obviously plugging and unplugging had disturbed this. I rectified the situation by fitting a replacement plug with the correct fuse so now all is well with the receiver/cassette.
The really scary thing, of course, was that for all the time that this had been working at her home (a long time, apparently), the earth pin of the plug must have been at high enough volts to power the receiver/cassette. I recommended that she get a competent electrician to look at the wiring in the corresponding wall socket as a matter of urgency !
VB
Ampregen Ltd http://www.ampregen.com
