W
Walter Harley
Guest
I'm trying to repair a fried switching power supply (it's for a satellite
downlink receiver at a radio station). The supply appears to produce +15V
and +5V at unknown current levels. (Curiously, it does not appear to
produce -15V.) I have three component-related questions that maybe y'all
can help with:
First, there are two components I'm trying to identify. They are in a
TO-220 case. They have a logo that looks like two diodes back to back
(cathode in the middle), and are marked "0984" (probably a date code?) and
"K2475". Anybody know what these might be? They are not heat-sinked.
Second, each of those same two components was encased in a little rubber
"boot." The rubber is some sort of soft, beige material; feels a bit slick,
like surgical tubing, but it's opaque. It's about 1/16" thick. The rubber
is pretty crumbly, and both boots fell apart trying to get them off. The
TO-220 cases themselves are completely plastic, no exposed metal, so I don't
think they need to be insulated further; the boots are not an extremely
tight fit; what the heck *are* these things? And where can I find
replacements?
Third, there are what look like five relatively large (1206?) surface-mount
resistors, each marked 20R, all in parallel with each other. Each one is
obviously blown up. Am I right that these are probably just what they seem,
that is, 20 ohm resistors? (There are no others like them on the board, so
I can't compare with a working one.) And that they're just in parallel in
order to distribute the power? Is this a common technique for
surface-mount?
Thanks for any help!
-walter
downlink receiver at a radio station). The supply appears to produce +15V
and +5V at unknown current levels. (Curiously, it does not appear to
produce -15V.) I have three component-related questions that maybe y'all
can help with:
First, there are two components I'm trying to identify. They are in a
TO-220 case. They have a logo that looks like two diodes back to back
(cathode in the middle), and are marked "0984" (probably a date code?) and
"K2475". Anybody know what these might be? They are not heat-sinked.
Second, each of those same two components was encased in a little rubber
"boot." The rubber is some sort of soft, beige material; feels a bit slick,
like surgical tubing, but it's opaque. It's about 1/16" thick. The rubber
is pretty crumbly, and both boots fell apart trying to get them off. The
TO-220 cases themselves are completely plastic, no exposed metal, so I don't
think they need to be insulated further; the boots are not an extremely
tight fit; what the heck *are* these things? And where can I find
replacements?
Third, there are what look like five relatively large (1206?) surface-mount
resistors, each marked 20R, all in parallel with each other. Each one is
obviously blown up. Am I right that these are probably just what they seem,
that is, 20 ohm resistors? (There are no others like them on the board, so
I can't compare with a working one.) And that they're just in parallel in
order to distribute the power? Is this a common technique for
surface-mount?
Thanks for any help!
-walter