Most, but not all, modern consumer electronics today discharge the large filter capacitor after it has been unplugged from the AC wall socket after a few minutes.
My first encounter with something that did not discharge the large filter capacitor by itself was a LG 22 inch monitor (made in 2009). I recently encountered my second one.
I left an "used, but working" Motorola DCT3416 (made in 2008), where it obviously had 12 bad capacitors, unplugged for nearly 4.5 weeks while waiting to get a special security screwdriver to remove the outershell screws.
After I took out the power board and before desoldering the 3 bad caps on the power board, I measured the DCV across the main filter capacitor. My multimeter reported 166.67VDC.
In other words, the main filter capacitor did NOT lose its charge after 4.5 weeks of being unplugged from an AC wall socket.
Here is where things can go wrong. Imagine not knowing that the filter capacitor/components was fully charged, a 350C soldering station and working alone.
3 obviously bloated Lelon capacitors were on the power board and 9 Teapo SEK were on the main/logic board (all circled in red). United Chemicon KMG caps, a known bad series here, were non bloated on the main board, but I don't have an ESR meter and wasn't willing to desolder each one to test it so I left them.
Some other random observations.
1) The Teapo 470uF 10V cap closest to the A/V inputs was impossible to desolder on the negative leg presumably due to the large copper common ground. Even with my solder station turned up to 425C and a 3.2mm chisel tip and generous amounts of new 60/40 solder, I could not get the negative leg out. All the other ones on the main board came out okay.
2) The power supply outputs 12V, 5.0, 3.3V and -5.0V according to the silkscreen legend (obscured in the picture). Without the main board connected, the 12V rail flucates crazily from around 3 to 9V. Once everything is reconnected, the 12V is a solid 12.11V.
3) The security screwdriver needed is known as the Nintendo torx 4.5mm. I got mine off ebay "sort by lowest price + shipping" for about $3 CDN, but it takes about 30 days+ to arrive from China.
4) The unit is under going testing over the next 48 hours to see how well it works.
My first encounter with something that did not discharge the large filter capacitor by itself was a LG 22 inch monitor (made in 2009). I recently encountered my second one.
I left an "used, but working" Motorola DCT3416 (made in 2008), where it obviously had 12 bad capacitors, unplugged for nearly 4.5 weeks while waiting to get a special security screwdriver to remove the outershell screws.
After I took out the power board and before desoldering the 3 bad caps on the power board, I measured the DCV across the main filter capacitor. My multimeter reported 166.67VDC.
In other words, the main filter capacitor did NOT lose its charge after 4.5 weeks of being unplugged from an AC wall socket.
Here is where things can go wrong. Imagine not knowing that the filter capacitor/components was fully charged, a 350C soldering station and working alone.
3 obviously bloated Lelon capacitors were on the power board and 9 Teapo SEK were on the main/logic board (all circled in red). United Chemicon KMG caps, a known bad series here, were non bloated on the main board, but I don't have an ESR meter and wasn't willing to desolder each one to test it so I left them.
Some other random observations.
1) The Teapo 470uF 10V cap closest to the A/V inputs was impossible to desolder on the negative leg presumably due to the large copper common ground. Even with my solder station turned up to 425C and a 3.2mm chisel tip and generous amounts of new 60/40 solder, I could not get the negative leg out. All the other ones on the main board came out okay.
2) The power supply outputs 12V, 5.0, 3.3V and -5.0V according to the silkscreen legend (obscured in the picture). Without the main board connected, the 12V rail flucates crazily from around 3 to 9V. Once everything is reconnected, the 12V is a solid 12.11V.
3) The security screwdriver needed is known as the Nintendo torx 4.5mm. I got mine off ebay "sort by lowest price + shipping" for about $3 CDN, but it takes about 30 days+ to arrive from China.
4) The unit is under going testing over the next 48 hours to see how well it works.
Attached Files
