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Cb radio reverse polarity damage

I have a cobra 29 that was reverse polarized,should i junk it or attempt to repair the diode?

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The diode is there to protect against rev polarity. Simply replace it with soomething like a 1n4007.

Geno

Posted on Mar 11, 2008

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Am/fm tuner no power


Try changing the cable/transformer for a new one. you should be able to find a new cable online easily enough, or maybe a friend has one you could borrow.

Try a different power outlet.
Make sure your multi-plug (if you're using one) is functional.
Try plunging something that you know works, in the outlet, to see if you have power at that plug.

Isolate your power supply from the mains switchboard.
Switch off and Unplug your appliance from the wall socket before attempting any repairs.
It could be a fuse in the Tuner, replace the fuse for a new one.

Get your Multi-meter and do some tests...
Test the flexible cord connections
Electrical tests included, visual inspection, Earth continuity, Polarity and Insulation resistance.

Examining cord for Damage
Disconnect flexible cord from power supply.
Check cord along the whole length for obvious damage

1: Visual Inspection
A visual test is necessary before using test instruments to ensure that all specific safety requirements are meet.
Check the general condition and safety of the cord, plug, cord anchorage, terminations and of the appliance itself.

2: Earth Continuity.
The earthing system of an electrical installation must be installed in a manner that will allow circuit protection devices to operate if there is a fault between live parts (other than Neutral) and the mass of earth.
What to check: For class (one) 1 protectively earthed appliances only, test for very low resistance between exposed appliance metalwork and the earth pin of the plug. this resistance should be as low as possible and must not exceed 1 ohm. Note: the Exposed metal parts of a class 2 double-insulated appliance must not be earthed.
Equipment requirements:
A Multimeter (Digital or analogue) Set on a ohm scale or an insulation tester that also has a continuity scale.
A set of leads.

3: Polarity
Why is this test necessary:
An incorrect connection of phase and neutral conductors to fittings and appliances is extremely dangerous and has been the cause, either directly or indirectly of many shocks and fatalities.
What to check:
Polarity tests are carried out to ensure that every single-pole switch operates in the active conductor or the circuit in which it is connected.
Equipment requirements:
A Multimeter (Digital or analogue) Set on the resistance scale when the SUPPLY is NOT connected.
or a voltage indicator set on a suitable voltage rating when the supply is not connected.

4: Insulation Resistance
Why this test is necessary:
All live conductors (including Neutrals) and live parts must be insulated to prevent - Electric shock hazards from inadvertent contact.
- Fire hazards and equipment damage from short circuits.
What to check:
Insulation resistance tests must be made between:
- Active conductors of a poly-phase circuit
- Active and Neutral
- Active and Earth
- Neutral and Earth
The insulation resistance between appropriate components shall be not less than 1 mega-ohm minimum
Equipment requirements:
An insulation resistance tester which maintains an output of 500 volts when loaded with a 1 mega-ohm resistance.
A set of leads.

Different countries adhere to spicific Electrical (safety) Regulations and standards

This information is only intended to enlighten the novice, guide and remind someone already in the field of electrical installations.
DO NOT attempt any electrical repairs unless you have the appropriate background or training.

Feb 10, 2014 | Sony Audio & Video Receivers

1 Answer

Wiring


Check your power cord and power supply, check the plug is clean and free from corrosion or dirt.
Plug another appliance into the same socket to check there is power at the socket.

Note: Electricity can cause serious injury even Death.
Isolate your power supply from the mains switchboard.
Switch off and Unplug your appliance from the wall socket before attempting any repairs.

If its still under warranty, take it back to the store or manufacturer for replacement.
Call a serviceman to test the appliance for you,

If not you could...
Check your fuse in the device, you will have to dismantle the appliance.

Get your Multimeter and do some tests...
Test the flexible cord connections
Electrical tests included, visual inspection, Earth continuity, Polarity and Insulation resistance.

Examining cord for Damage
Disconnect flexible cord from power supply.
Check cord along the whole length for obvious damage

1: Visual Inspection
A visual test is necessary before using test instruments to ensure that all specific safety requirements are meet.
Check the general condition and safety of the cord, plug, cord anchorage, terminations and of the appliance itself.

2: Earth Continuity.
The earthing system of an electrical installation must be installed in a manner that will allow circuit protection devices to operate if there is a fault between live parts (other than Neutral) and the mass of earth.
What to check: For class (one) 1 protectively earthed appliances only, test for very low resistance between exposed appliance metalwork and the earth pin of the plug. this resistance should be as low as possible and must not exceed 1 ohm. Note: the Exposed metal parts of a class 2 double-insulated appliance must not be earthed.
Equipment requirements:
A Multimeter (Digital or analogue) Set on a ohm scale or an insulation tester that also has a continuity scale.
A set of leads.

3: Polarity
Why is this test necessary:
An incorrect connection of phase and neutral conductors to fittings and appliances is extremely dangerous and has been the cause, either directly or indirectly of many shocks and fatalities.
What to check:
Polarity tests are carried out to ensure that every single-pole switch operates in the active conductor or the circuit in which it is connected.
Equipment requirements:
A Multimeter (Digital or analogue) Set on the resistance scale when the SUPPLY is NOT connected.
or a voltage indicator set on a suitable voltage rating when the supply is not connected.

4: Insulation Resistance
Why this test is necessary:
All live conductors (including Neutrals) and live parts must be insulated to prevent - Electric shock hazards from inadvertent contact.
- Fire hazards and equipment damage from short circuits.
What to check:
Insulation resistance tests must be made between:
- Active conductors of a poly-phase circuit
- Active and Neutral
- Active and Earth
- Neutral and Earth
The insulation resistance between appropriate components shall be not less than 1 mega-ohm minimum
Equipment requirements:
An insulation resistance tester which maintains an output of 500 volts when loaded with a 1 mega-ohm resistance.
A set of leads.

Different countries adhere to spicific Electrical (safety) Regulations and standards

This information is only intended to enlighten the novice, guide and remind someone already in the field of electrical installations.
DO NOT attempt any electrical repairs unless you have the appropriate background or training.

Jun 11, 2013 | Yamaha RX-V757 Receiver

1 Answer

The Encore 4050A is a guitar amplifier. It's going thorugh batteries verty fast and, although it has a 12V power input, I don't have the power adaptor for it. Have searched a lot but can find no...


It will be best to have a good 12volt/5 amps adapter that will suit your amplifier.There are many model with SMPS units. This will give a clean supply and all you need will be to make the connections with the correct polarity.
Double check when you connect as a wrong polarity can damage the amplifier.

Oct 28, 2010 | Audio & Video Receivers

1 Answer

Constant buzzing sound in all speakers


Sounds like either a transformer or amplifier problem. You haven't reversed polarity on the speaker connections? or changed the speaker sizes, Ohms, ect? Probably a resistor, diode, or condenser in the amplifier causing feedback through the speaker system. It's doubtful both speaker coils went out at the same time. Possible, but doubtful.And you mention that the volume "SPIKES" from time to time. Could be as simple as corrosion on the volume "pot". Basically a Rheostat that allows more signal the farther you turn the knob. If so, you can clean that yourself with a spray product available at any Radio Shack. It is for cleaning electonic components and leaves no residue. You could have this checked at any competant electronics shop, but BEWARE, the "Bench Fee" to test may be more than the value of the system. I would ask what the "bench fee" was to determine a problem, and then what the labor costs would be to repair either a transformer or amplifier with resistors, diodes, capacitors, ect. Electronic equipment tends to "break down" over time and use, and sometimes you can replace a component cheaper than repair. If part of a rack system, then you may want to retain this sub-part and repair may be your choice. I would ask about the fees to test, and the costs of labor to repair, before turning it over. How old is the system?

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1 Answer

Radio Panasonic RF-4900 - no power


Just spent the afternoon with an RF4900 with a power problem. The set was intermittent. Found on the back of the set where the ac plugs in, there is a switch that is ingaged when the ac plugs into the set. If the ac cord is old it might not be engaging this switch when the cord is plugged into the set. The switch controls ether battery power or ac power.

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2 Answers

Damage due to reversed polarity


hello unless you know something about electronics of course you may repair it ...this kind of equipment are so sophisticated take extremely care....i think it would be better to get a estimated cost.......saludos

Nov 21, 2008 | Audio & Video Receivers

1 Answer

Probably too simple to be true .. but I have a 'record player' in an old car, and the small motor that drives the turntable is running in reverse (incorrect) direction. Is thi simple a matter of...


Hi,

I agree, it is old. None the less, yes on reversing the wiring of the motor. All DC motors are polarity affected.

Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information.

Good luck and kind regards. Thank you for using FixYa.

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1 Answer

300 watt invertor reverse polarity damage


Some units have a diode across the input leads that blow and short out if reverse polarity is applied. It's a safety device to protect the unit. If your's has one, replace it.

Geno

Mar 10, 2008 | Audio & Video Receivers

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