Hey everyone,
I have this portable vacuum cleaner that works just fine, except for the attached brushes that are completely dead. The vacuum motor has 3 speeds, but the brushes always worked at the same speed regardless. After a quick check I realized that the brushes are not getting a way to ground when the cleaner is on.
I accessed the motherboard and started probing around. Unfortunately, I didn't fully remove the motherboard because my iron is not powerful enough to melt the solder connection to the motor (vacuum) in the center of the board. The board was just soaking all the heat and I felt like I could possibly damage things even more if I persisted, but there are components on the other side as well.
The circuitry for the brushes seems simple enough (see attachment), Q16 seems like the brushes' way to ground, maybe an N-channel mosfet or an NPN transistor. I googled the numbers with little results. While on, it's not receiving any signal on its base/collector (0v). I couldn't troubleshoot any further since the trace goes to the other side of the board, but it measures about 60k (rising up to 90k) to B+.
There might be more to the mystery, but with no schematic and no access to the other side there's no way to tell.
The battery measures around 27v and has its own separate protection and charging circuit. I also tested the brushes with an external constant voltage power supply, they seem to work just fine at around 8-9v, I could imagine they'd go crazy with 27v, that's why I tend to believe that Q16 could be a transistor.
Now here for the questions:
1. Would it be safe to soak the board with heat in an effort to desolder the motor connections and access the other side of the board for further troubleshooting?
2. If I could identify Q16, would it be crazy to just cut the trace to the original signal and feed it an external one with the appropriate resistor configuration?
Thanks for any help and suggestions, if you need any more info or pictures just ask.
I have this portable vacuum cleaner that works just fine, except for the attached brushes that are completely dead. The vacuum motor has 3 speeds, but the brushes always worked at the same speed regardless. After a quick check I realized that the brushes are not getting a way to ground when the cleaner is on.
I accessed the motherboard and started probing around. Unfortunately, I didn't fully remove the motherboard because my iron is not powerful enough to melt the solder connection to the motor (vacuum) in the center of the board. The board was just soaking all the heat and I felt like I could possibly damage things even more if I persisted, but there are components on the other side as well.
The circuitry for the brushes seems simple enough (see attachment), Q16 seems like the brushes' way to ground, maybe an N-channel mosfet or an NPN transistor. I googled the numbers with little results. While on, it's not receiving any signal on its base/collector (0v). I couldn't troubleshoot any further since the trace goes to the other side of the board, but it measures about 60k (rising up to 90k) to B+.
There might be more to the mystery, but with no schematic and no access to the other side there's no way to tell.
The battery measures around 27v and has its own separate protection and charging circuit. I also tested the brushes with an external constant voltage power supply, they seem to work just fine at around 8-9v, I could imagine they'd go crazy with 27v, that's why I tend to believe that Q16 could be a transistor.
Now here for the questions:
1. Would it be safe to soak the board with heat in an effort to desolder the motor connections and access the other side of the board for further troubleshooting?
2. If I could identify Q16, would it be crazy to just cut the trace to the original signal and feed it an external one with the appropriate resistor configuration?
Thanks for any help and suggestions, if you need any more info or pictures just ask.
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