Blown diode i have a blown diode on a lap top its on the charging side,i have found which one it is i was woundering if i could solder a low amp fuse wire across to mend the problem?

Hi Charles
I haven't seen an Alternator with a Fuse.
They Generate 35-55 or more Amps and are usually connected directly to the Battery Positive. Check at Alt. Main Terminal with MultiMeter. Check for Good Ground.


The small wire on the back of the alternator often comes from Ignition Key + to control the charge rate.
The Modern Alt. also has an internal Regulator Circuit to control charge rate.

If trying to save money.... Alternators can be split open on the Bench and repaired. Just put a mark across joint before opening.
Use a brush hook (make one) to hold brushes back while re assembling.

Items to watch for:
Brushes Worn Out - no juice to Rotor to excite (generate)
Diodes Blown - (Multimeter Test on Diode Function for shorts / open. Simple Unsolder, Press out & replace
Regulator Blown - Buy replacement
Stator Coils Corroded or Shorted/Open or bad solder joints.

Remove Alternator & Bench Test.

Good Luck
Alternator automotive

How to diagnose and repair bad alternator in your car or truck

The most probable cause is a blown fuse on the circuit board. It is a cylindrical glass component with two chrome colored ends, located near the AC cord wires soldered to the circuit board. It can be checked with a volt-ohm meter, it should read minimal, close to zero ohms, across the ends. This fuse is soldered to the circuit board, mine is a 2A fast blow fuse with one lead attached to each end. If the fuse is OK or a replacement does not fix the problem, the bridge rectifier is probably bad as mine was. I rigged up 4 power diodes rated at 120 Volts AC and 2 Amps current as a replacement.

Do you like your radio medium or well done?

You may have hooked your power wire up backwards at some point and blown the polarity protection diodes.

This requires opening the radio and using a soldering iron to remove and replace the blown diode.

You will need:

1. Soldering Iron
2. Solder
3. De-soldering braid
4. N1004 diode or better.
5. Phillips head screw driver.

Using the phillips head screw driver to take the bottom cover of the radio off being careful of the speaker wires. Using the soldering iron, heat the solder on the tabs of the speaker and pull off the wires. No need to use the de-soldering braid to remove the solder. You should do this to make it easier to handle the radio, and to avoid damage to the speaker or wires etc.

Now take the cover off the top of the radio. This will reveal the "Trace" side of the board. This is where all of the components are soldered to the board.

Now flip it to the other side where you can see all of the components and wires etc. Look at the back right of the radio by where the power socket is. Look for D23. its a big black diode. It will most likely be black and burnt. Some times it may not be.

Here is the tricky part. You need to locate the points at which this component marked D23 is soldered to the trace side of the board. Some times you can use a bright light and look at the trace side of the board while the light shines on the other side to locate the part.

Once you have located the points at which the diode is soldered too, do not de-solder it yet. Make note of which side of the diode the white band is on. This is important, putting the diode in with the wrong polarity will make the radio not work.

After you take note of the white band you may now use the de-soldering braid to remove the solder from the trace side of the board. To do this, place the braid over the solder point. put the tip of the soldering iron on the braid and press it down to the solder point. You will see it **** the solder into the braid.

Once the solder is off both solder point, flip the radio and remove the bad diode.

Put the new diode in, making sure the white band is on the same side as the original diode.

Once again flip the radio over to trace side of the board and solder the new diode in. To do this place the tip on the solder point, making sure to touch both the solder point of the board and the wire from the diode. take the solder and touch it to the solder point, not the soldering iron tip. Once enough solder is on the point you can remove the soldering tip. Don't use too much solder.

Once both points have been re-soldered, solder the speaker wires back to the speaker. Red is positive, it connects to the tab marked by the positive symbol "+". The white wire is negative. It goes to the negative symbol, "-". You can just reheat the tab, and put the end of the wire into the melted solder and remove the solder tip while holding the wire in place until it cools enough harden again.

After the speaker is re-soldered, Put the covers back on. Now be very careful hooking up the radio to power. If you hook it up backwards again it will blow the diode again. Once the power wire is connected, turn on the radio, it should work fine at this point.

Good Luck!

You have hooked your power wire up backwards at some point and blown the polarity protection diodes.

This requires opening the radio and using a soldering iron to remove and replace the blown diode.

You will need:

1. Soldering Iron
2. Solder
3. De-soldering braid
4. N1004 diode or better.
5. Phillips head screw driver.

Using the phillips head screw driver to take the bottom cover of the radio off being careful of the speaker wires. Using the soldering iron, heat the solder on the tabs of the speaker and pull off the wires. No need to use the de-soldering braid to remove the solder. You should do this to make it easier to handle the radio, and to avoid damage to the speaker or wires etc.

Now take the cover off the top of the radio. This will reveal the "Trace" side of the board. This is where all of the components are soldered to the board.

Now flip it to the other side where you can see all of the components and wires etc. Look at the back right of the radio by where the power socket is. Look for D10. its a big black diode. It will most likely be black and burnt. Some times it may not be.

Here is the tricky part. You need to locate the points at which this component marked D10 is soldered to the trace side of the board. Some times you can use a bright light and look at the trace side of the board while the light shines on the other side to locate the part.

Once you have located the points at which the diode is soldered too, do not de-solder it yet. Make note of which side of the diode the white band is on. This is important, putting the diode in with the wrong polarity will make the radio not work.

After you take note of the white band you may now use the de-soldering braid to remove the solder from the trace side of the board. To do this, place the braid over the solder point. put the tip of the soldering iron on the braid and press it down to the solder point. You will see it **** the solder into the braid.

Once the solder is off both solder point, flip the radio and remove the bad diode.

Put the new diode in, making sure the white band is on the same side as the original diode.

Once again flip the radio over to trace side of the board and solder the new diode in. To do this place the tip on the solder point, making sure to touch both the solder point of the board and the wire from the diode. take the solder and touch it to the solder point, not the soldering iron tip. Once enough solder is on the point you can remove the soldering tip. Don't use too much solder.

Once both points have been re-soldered, solder the speaker wires back to the speaker. Red is positive, it connects to the tab marked by the positive symbol "+". The white wire is negative. It goes to the negative symbol, "-". You can just reheat the tab, and put the end of the wire into the melted solder and remove the solder tip while holding the wire in place until it cools enough harden again.

After the speaker is re-soldered, Put the covers back on. Now be very careful hooking up the radio to power. If you hook it up backwards again it will blow the diode again. Once the power wire is connected, turn on the radio, it should work fine at this point.

Good Luck!

You have hooked your power wire up backwards at some point and blown the polarity protection diodes.

This requires opening the radio and using a soldering iron to remove and replace the blown diode.

You will need:

1. Soldering Iron
2. Solder
3. De-soldering braid
4. N1004 diode or better.
5. Phillips head screw driver.

Using the phillips head screw driver to take the bottom cover of the radio off being careful of the speaker wires. Using the soldering iron, heat the solder on the tabs of the speaker and pull off the wires. No need to use the de-soldering braid to remove the solder. You should do this to make it easier to handle the radio, and to avoid damage to the speaker or wires etc.

Now take the cover off the top of the radio. This will reveal the "Trace" side of the board. This is where all of the components are soldered to the board.

Now flip it to the other side where you can see all of the components and wires etc. Look at the back right of the radio by where the power socket is. Look for D23. its a big black diode. It will most likely be black and burnt. Some times it may not be.

Here is the tricky part. You need to locate the points at which this component marked D23 is soldered to the trace side of the board. Some times you can use a bright light and look at the trace side of the board while the light shines on the other side to locate the part.

Once you have located the points at which the diode is soldered too, do not de-solder it yet. Make note of which side of the diode the white band is on. This is important, putting the diode in with the wrong polarity will make the radio not work.

After you take note of the white band you may now use the de-soldering braid to remove the solder from the trace side of the board. To do this, place the braid over the solder point. put the tip of the soldering iron on the braid and press it down to the solder point. You will see it **** the solder into the braid.

Once the solder is off both solder point, flip the radio and remove the bad diode.

Put the new diode in, making sure the white band is on the same side as the original diode.

Once again flip the radio over to trace side of the board and solder the new diode in. To do this place the tip on the solder point, making sure to touch both the solder point of the board and the wire from the diode. take the solder and touch it to the solder point, not the soldering iron tip. Once enough solder is on the point you can remove the soldering tip. Don't use too much solder.

Once both points have been re-soldered, solder the speaker wires back to the speaker. Red is positive, it connects to the tab marked by the positive symbol "+". The white wire is negative. It goes to the negative symbol, "-". You can just reheat the tab, and put the end of the wire into the melted solder and remove the solder tip while holding the wire in place until it cools enough harden again.

After the speaker is re-soldered, Put the covers back on. Now be very careful hooking up the radio to power. If you hook it up backwards again it will blow the diode again. Once the power wire is connected, turn on the radio, it should work fine at this point.

Good Luck!

You have hooked your power wire up backwards at some point and blown the polarity protection diodes.

This requires opening the radio and using a soldering iron to remove and replace the blown diode.

You will need:

1. Soldering Iron
2. Solder
3. De-soldering braid
4. N1004 diode or better.
5. Phillips head screw driver.

Using the phillips head screw driver to take the bottom cover of the radio off being careful of the speaker wires. Using the soldering iron, heat the solder on the tabs of the speaker and pull off the wires. No need to use the de-soldering braid to remove the solder. You should do this to make it easier to handle the radio, and to avoid damage to the speaker or wires etc.

Now take the cover off the top of the radio. This will reveal the "Trace" side of the board. This is where all of the components are soldered to the board.

Now flip it to the other side where you can see all of the components and wires etc. Look at the back right of the radio by where the power socket is. Look for D93. its a big black diode. It will most likely be black and burnt. Some times it may not be.

Here is the tricky part. You need to locate the points at which this component marked D33 is soldered to the trace side of the board. Some times you can use a bright light and look at the trace side of the board while the light shines on the other side to locate the part.

Once you have located the points at which the diode is soldered too, do not de-solder it yet. Make note of which side of the diode the white band is on. This is important, putting the diode in with the wrong polarity will make the radio not work.

After you take note of the white band you may now use the de-soldering braid to remove the solder from the trace side of the board. To do this, place the braid over the solder point. put the tip of the soldering iron on the braid and press it down to the solder point. You will see it **** the solder into the braid.

Once the solder is off both solder point, flip the radio and remove the bad diode.

Put the new diode in, making sure the white band is on the same side as the original diode.

Once again flip the radio over to trace side of the board and solder the new diode in. To do this place the tip on the solder point, making sure to touch both the solder point of the board and the wire from the diode. take the solder and touch it to the solder point, not the soldering iron tip. Once enough solder is on the point you can remove the soldering tip. Don't use too much solder.

Once both points have been re-soldered, solder the speaker wires back to the speaker. Red is positive, it connects to the tab marked by the positive symbol "+". The white wire is negative. It goes to the negative symbol, "-". You can just reheat the tab, and put the end of the wire into the melted solder and remove the solder tip while holding the wire in place until it cools enough harden again.

After the speaker is re-soldered, Put the covers back on. Now be very careful hooking up the radio to power. If you hook it up backwards again it will blow the diode again. Once the power wire is connected, turn on the radio, it should work fine at this point.

Good Luck!

You are so right, there is a short.. This is usually a result of hooking the power leads up in reverse-polarity. As a result, the protection diode shorts, preventing the death of the rest of the radio. This diode, a solder-in part, is found on the pc board, next to the red wire that connects from the DC power jack. A 1.5 amp general purpose diode will work. And don't use a 30 amp fuse.

If the adapter is working, the problem could be the jack on the back of the notebook. The nice thing is most of the Vaio notebooks the jack is replaceable without having to solder the jack to the board. I would call SONY regarding the jack for a mode number and a picture. it's easily replaceable but requires the disassembly of the notebook.

If the diode failed by opening, there may be no other damage. If the dioded failed by shorting, the alternating current may have damaged other components. Ohm it out. You can get diodes from digikey.com, mouser.com, or radio shack or any electronics or appliance supply. If the diode is charred and you can't get the part number, the oven rating can be used to select a replacement. Since the fuse was 10 amps, the diode should also handle at least 10 amps. If you can power the unit and read the voltage at the diode input this will give you the power (volts times amps). It's always worth trying as it's cheaper than replacing the unit.

This can be caused by too low of an impedance from the way the speakers are wired, bad speakers, crossed/shorted speaker wires, and sometimes even a poor charging system (if the amp goes into protect when the volume is turned up) and is usually what the problem is 95% of the time. As you said, very possible to be shorted output devices or shorted power supply rectifiers. Beyond that, it could be a shorted filter cap, some sort of short across the power rails, some sort of short across the output, shorts across the primary. And of course loose hardware - any missing screws or nuts? A loose one under a pc board can short out most anything.