How to get inside a TDK boombox!
- Thread starter blu_fuz
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Anyone find a replacement power switch + pot for this? Finding various B503 D type switches that would work for volume but would have to bridge the power connector so its always on unless unplugged.
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Regarding my 3-speaker issue: I bought this unit second-hand, so I have no idea what its brand-new condition should be.
The problems are as follows:
If it can be confirmed that the problem lies with the volume potentiometer, I plan to try replacing it. But I haven't removed the volume knob yet, so I don't know the exact model of the 3-speaker's volume potentiometer, nor whether I can find a potentiometer with a built-in switch. So far, I've seen in this thread that the 2-speaker model uses a B503 potentiometer, but I've tried searching and haven't found this model with a switch.
Additionally, I found the teardown photos provided by blu_fuz in this post extremely helpful, and I'm very grateful for that. I had an idea: since a full teardown is quite troublesome, and the Boombox has a large inner cavity that appears mostly empty with few obstructions on the upper left side, if I only need to replace the volume potentiometer, could I just remove the left speaker, reach into the Boombox's inner cavity through the speaker mounting hole, use a screwdriver to remove the PCB board screws, and take the volume potentiometer and PCB board out through the speaker opening? This would save a lot of effort. As for not being able to see the screws clearly, I can insert a camera with a light into the inner cavity, connect it to a monitor for a live feed, and perform the screw removal that way.
The problems are as follows:
- When the device is running and playing audio via USB or radio, even if the volume knob is turned to the minimum position, the sound is still very loud — louder than a person speaking at a normal volume. If you turn the volume knob slightly higher, the sound becomes extremely loud, to the point that it feels unbearable for the ears, so I never dared to turn it up further.
- When I play audio through the line input, the sound can be fully muted when the volume knob is at the minimum position. As I turn the knob up, the volume increases gradually. However, once the knob is rotated to roughly a quarter of its total travel, further turning of the volume adjustment knob no longer makes the volume any louder.
If it can be confirmed that the problem lies with the volume potentiometer, I plan to try replacing it. But I haven't removed the volume knob yet, so I don't know the exact model of the 3-speaker's volume potentiometer, nor whether I can find a potentiometer with a built-in switch. So far, I've seen in this thread that the 2-speaker model uses a B503 potentiometer, but I've tried searching and haven't found this model with a switch.
Additionally, I found the teardown photos provided by blu_fuz in this post extremely helpful, and I'm very grateful for that. I had an idea: since a full teardown is quite troublesome, and the Boombox has a large inner cavity that appears mostly empty with few obstructions on the upper left side, if I only need to replace the volume potentiometer, could I just remove the left speaker, reach into the Boombox's inner cavity through the speaker mounting hole, use a screwdriver to remove the PCB board screws, and take the volume potentiometer and PCB board out through the speaker opening? This would save a lot of effort. As for not being able to see the screws clearly, I can insert a camera with a light into the inner cavity, connect it to a monitor for a live feed, and perform the screw removal that way.
I have a 3 speaker also.
Funnily I have the exact same issue as you on the USB / Raido input. I have not tested line in yet. In my earlier post I found a B503 potentiometer, but alas, without a switch. If you gently pull off the volume knob, you can see its also a B503 on the 3 speaker too.
There are incorrect 50k ohm pots with switches that exist, but the shaft only comes in flower shape, and they lack the metal prongs to solder into the board itself to account for rotational torque.
I currently see the best route for repair (if it is the pot) as relacing it with a non-switch B503, hardwiring the power ON by bridging the pins, and then using a wall switch / unplugging the device to power it off from the socket instead.
Funnily I have the exact same issue as you on the USB / Raido input. I have not tested line in yet. In my earlier post I found a B503 potentiometer, but alas, without a switch. If you gently pull off the volume knob, you can see its also a B503 on the 3 speaker too.
There are incorrect 50k ohm pots with switches that exist, but the shaft only comes in flower shape, and they lack the metal prongs to solder into the board itself to account for rotational torque.
I currently see the best route for repair (if it is the pot) as relacing it with a non-switch B503, hardwiring the power ON by bridging the pins, and then using a wall switch / unplugging the device to power it off from the socket instead.