How to Fix Squeal in Casio Digital Horn
Casio digital horns, introduced in the late 1980s, allow musicians to produce a variety of impressive effects. The horns come in four models, and although each model offers different features, they all share a common fault: after prolonged use, an essential capacitor tends to fail. When this happens, blowing into the digital horn produces a high-pitched squeal. Replacing the failed capacitor with a new one eliminates the squeal.
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Things You'll Need
- Phillips screwdriver
- Pliers
- Rubbing alcohol
- Cloth
- 33uF electrolytic capacitor
- Soldering iron
- Solder
Instructions
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DH-100, DH-200 and DH-500
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1
Turn off the Casio digital horn, open the battery compartment and remove the batteries. Take off the mouthpiece.
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2
Remove all screws using a small Phillips screwdriver. Separate the horn into two halves to reveal two stacked circuit boards.
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3
Take out the screws holding the two circuit boards together. Lift up the top board and flip it over. In the DH-100 and DH-200 models, look on the far left side of the board for a capacitor labeled "C39." In the DH-500 model, look at the center of the board to find the capacitor labeled "C37."
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4
Use small pliers to wriggle the offending capacitor until it detaches from the circuit board.
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5
Cut off or unsolder the legs left behind by the capacitor, if necessary.
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6
Moisten a cloth with rubbing alcohol and clean the circuit board if you see any corrosive fluid left by the capacitor.
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7
Locate the two feed holes nearest to the capacitor's original location. In the DH-100 and DH-200 models, find the rectangle printed on the left side of the circuit board. The first feed hole touches the upper right tip of the rectangle; the lower right corner points at the second feed hole. For the DH-500 model, find the positive hole next to the "+" mark on the board. Find the negative hole above "R37" printed on the board.
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8
Slide the legs of a 33uF electrolytic capacitor through the feed holes and solder them in place. On the DH-100 and DH-200 models, slide the short, negative leg through the bottom hole and the long, positive leg through the top hole. For the DH-500 model, slide the long, positive leg through the hole next to the "+"; the short, negative leg goes through the hole above "R37."
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9
Insert the batteries and blow into the horn to test it. If the squeal remains, ensure that the capacitor is securely attached to the circuit board.
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10
Reattach the circuit boards and reassemble the two halves of the horn. Refasten all screws.
DH-800
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11
Remove the batteries, mouthpiece and screws. Take apart the two halves of the horn.
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12
Look for the C20 capacitor, labeled "33 6V," in the center of the green circuit board. The C20 capacitor sits between the ribbon cable and the "VR3" marking.
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13
Remove the C20 capacitor using a pair of small pliers.
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14
Use a cloth dipped in rubbing alcohol to clean the solder pads below the capacitor.
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15
Slide the replacement 33uF electrolytic capacitor's short, negative leg through the hole next to the ribbon cable. Solder the leg in place.
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16
Bend the capacitor's long, positive leg into an "L" shape. Solder the tip of the positive leg to the solder pad directly below the negative leg.
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17
Replace the batteries and blow into the horn. If you still hear a squeal, make sure that the capacitor is securely soldered to the circuit board. When the squeal disappears, reassemble the horn.
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1
Tips & Warnings
If you do not want to try this repair yourself, some electronics stores and musical instrument shops will fix the horn for you.
If the horn's circuitry is not properly handled, permanent damage may result.
