texasguitarslinger
Mo Cow Bellologist
I've been a technician for 20 years and I want to emphasize the danger of working on instrument amplifiers.
Amps have lethal voltages and current running through them. Without basic safety precautions your next mod could be your last one. Please use these basic precautions WHENEVER you are working on your amp.
ALWAYS UNPLUG your amp! No one can accidentally turn it on if it's unplugged.
1. As a general rule you NEVER want to put both of your hands near a circuit board. This could complete a circuit across your chest and kill you. Electricity is always going to take the path of least resistance to ground. "A hand in the pocket" is a habit you should get into.
2. Don't wear metal rings, bracelets or anything else which can conduct electricity while working near circuits.
3. The large capacitors (filter caps) on your amp's circuit board MUST be drained before working on your amp. These caps can store a lethal dose of electricity. Using a Digital Multi-Meter (DMM), put your black lead into any chassis screw hole and with ONE hand in your pocket put the red lead on the positive side of one of the filter caps. If you read anything above 10V then I recommend draining your caps. Since the filter caps are wired in parallel draining one should drain them all but noones going to say anything if you want to check each cap individually. Better safe than sorry. To drain the caps you will need a resistor (I use a 5W 330 ohm cement resistor) with a least 1 1/2" to 2" of lead on each end. Bend the leads so that they will make contact with the capacitor's leads easily. Grip the resistor with a pair of insulated pliers (thick rubber handles) and with one hand in pocket place the resistor leads across the positive and negative capacitor leads. Hold it there for about 30 seconds. Take another reading with your DMM. Repeat this until you have gotten the caps below 10 volts.
4. Anytime you are working with high voltages you should wear safety glasses. A high voltage arc can throw out small bits of metal just like a grenade. Better to look like a nerd than to be blinded.
5. If you are EVER unsure of a procedure or modification take it to a professional. It's cheaper to pay for technical service than a funeral service.
Amps have lethal voltages and current running through them. Without basic safety precautions your next mod could be your last one. Please use these basic precautions WHENEVER you are working on your amp.
ALWAYS UNPLUG your amp! No one can accidentally turn it on if it's unplugged.
1. As a general rule you NEVER want to put both of your hands near a circuit board. This could complete a circuit across your chest and kill you. Electricity is always going to take the path of least resistance to ground. "A hand in the pocket" is a habit you should get into.
2. Don't wear metal rings, bracelets or anything else which can conduct electricity while working near circuits.
3. The large capacitors (filter caps) on your amp's circuit board MUST be drained before working on your amp. These caps can store a lethal dose of electricity. Using a Digital Multi-Meter (DMM), put your black lead into any chassis screw hole and with ONE hand in your pocket put the red lead on the positive side of one of the filter caps. If you read anything above 10V then I recommend draining your caps. Since the filter caps are wired in parallel draining one should drain them all but noones going to say anything if you want to check each cap individually. Better safe than sorry. To drain the caps you will need a resistor (I use a 5W 330 ohm cement resistor) with a least 1 1/2" to 2" of lead on each end. Bend the leads so that they will make contact with the capacitor's leads easily. Grip the resistor with a pair of insulated pliers (thick rubber handles) and with one hand in pocket place the resistor leads across the positive and negative capacitor leads. Hold it there for about 30 seconds. Take another reading with your DMM. Repeat this until you have gotten the caps below 10 volts.
4. Anytime you are working with high voltages you should wear safety glasses. A high voltage arc can throw out small bits of metal just like a grenade. Better to look like a nerd than to be blinded.
5. If you are EVER unsure of a procedure or modification take it to a professional. It's cheaper to pay for technical service than a funeral service.
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