I have finally decided to document the repair of these speakers. I discovered that they sound even better than the old Cyber Acoustics MMS-20 speakers.
A couple years ago, I realized that the sound quality of these speakers was very poor. High frequencies were so loud and distorted that I had to keep the volume low to prevent my ears from being
ed. I thought that it was a combination of small, cheap speakers and the poor sound from the computer they were connected to. I also noticed that the volume control was noisy. I decided to clean the volume control and found bad caps. The two output coupling caps were both bulging and leaking. I also discovered that the amplifier runs very warm and these two caps were next to the heatsink.
To open the case, remove the one screw on the back, then the two screws below the driver and the top two screws holding the driver in the enclosure. These last four screws are under the grille, which can be pulled off easily. The top two corners and the bottom edge are glued, so you will need to pry the case open.
These are the caps that need to be replaced:
2x 1000uF 16V 8x16mm, 770mA ripple current
2x 100uF 10V 5x11mm, 165mA
2x 100uF 25V 5x11mm, 190mA
4x 0.47uF 50V 5x11mm, 14mA
1x 470uF 25V 8x16mm, 530mA
Every electrolytic cap needs to be replaced. They are all poor quality and had failed or were close to the lower end of their tolerances. When I removed the 1000uF caps, I discovered that they were bulging from the top and bottom and one had leaked from both ends as well.
Strangely, the 0.47uF caps were still good. In my speakers, these were Fujicon RA series.
I used cheap metal film caps to replace the 0.47uF caps, but any type of cap can be used to replace them. The rest should be replaced with high quality 105°C caps. I found that low ESR caps must be used to match or exceed the ripple current ratings of the old caps. Pictures of the amplifier can be found here and here. I posted pictures of the power supply here.
After recapping, I was surprised that the little 3" full range drivers could produce so much bass. The tinny sound with insanely loud treble was gone. They even make everything on the desk vibrate.
A couple years ago, I realized that the sound quality of these speakers was very poor. High frequencies were so loud and distorted that I had to keep the volume low to prevent my ears from being
ed. I thought that it was a combination of small, cheap speakers and the poor sound from the computer they were connected to. I also noticed that the volume control was noisy. I decided to clean the volume control and found bad caps. The two output coupling caps were both bulging and leaking. I also discovered that the amplifier runs very warm and these two caps were next to the heatsink.To open the case, remove the one screw on the back, then the two screws below the driver and the top two screws holding the driver in the enclosure. These last four screws are under the grille, which can be pulled off easily. The top two corners and the bottom edge are glued, so you will need to pry the case open.
These are the caps that need to be replaced:
2x 1000uF 16V 8x16mm, 770mA ripple current
2x 100uF 10V 5x11mm, 165mA
2x 100uF 25V 5x11mm, 190mA
4x 0.47uF 50V 5x11mm, 14mA
1x 470uF 25V 8x16mm, 530mA
Every electrolytic cap needs to be replaced. They are all poor quality and had failed or were close to the lower end of their tolerances. When I removed the 1000uF caps, I discovered that they were bulging from the top and bottom and one had leaked from both ends as well.
Strangely, the 0.47uF caps were still good. In my speakers, these were Fujicon RA series.I used cheap metal film caps to replace the 0.47uF caps, but any type of cap can be used to replace them. The rest should be replaced with high quality 105°C caps. I found that low ESR caps must be used to match or exceed the ripple current ratings of the old caps. Pictures of the amplifier can be found here and here. I posted pictures of the power supply here.
After recapping, I was surprised that the little 3" full range drivers could produce so much bass. The tinny sound with insanely loud treble was gone. They even make everything on the desk vibrate.
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