What diode is used in the r8 locatoin on a charger as the wires were in the wrong position when i brought it and the diode is burnt.

You cannot jump over a failed component. You will have to replace the chip and some other failed components that feed the chip. There is no other solution to repair the charging circuit.

Hello, I was able to fix this charger via replacing several parts in the source part which were either short-circuited (transistors and diodes) or burnt (resistors):
F1 (fuse 2,5A)
R5 0,91R +-1%
V5 (ST)P6NK90Z
V1-V4 1N4007
V6 2N3904
V8 1N4148
R7, R8 300k +-2%
This won't help after 5 years, but maybe it can be helpful for someone else.

reverse polarity diode burnt out

Are you using the correct AC adapter? An aftermarket unit will do this if the power is insufficient, or the polarity is wrong (- / +). If you're using an aftermarket unit, it may not be providing the right amount of Amps and Voltage to the unit; causing the display to blink. You can try this cord to help: http://www.powerpayless.com/ac-power-adapter-for-roland-r-8-r8-drum-machine.html

Wow, smoke right away on the new board? Are you using a AC Adapter and Power Cord that was specifically made for the ACER or are you using one of those one size fits all that some stores sell that comes with a bag or removable tips so that one will fit your laptop? That's exactly what one of the one size fits all will do.

No matter what, you're stuck with buying another motherboard.

just use a ziner diod neg leg of ziner sold to positive of charging connector and positive of ziner to battery connector plus ur problem will be solved

u can find ziner diod in old mobile like 1100 , 3300, 3310, 6600 etc.

Hi Mark,
R8 Should be a 1000 Ohm 1/4Watt resistor
Rgds Ray

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!

The heat sink is not the problem. It was not the voltage but if connected with opposite polarity to a charged battery may lead to this damage.

You should replace the diodes and wires. I hope the other elements are good.

THRE ARE MANY POSIBILITIES.HERE THEY ARE:
1. Check your charger's wire.Most of the wire s are always damage in the root of plug & to the opposite side.
2.Check the fuse.
3.Check the Rectifier Diodes.How many Diodes do your charger has?most of the chargers are only one,sometimes 4(a bridge type,& somtimes only one but 4 legs( it is also called a bridge type)
to test a 2 legs diode is just simply get a multi tester and adjust or set it in X1.,then look for the white band(mark) of diode,if you can see that mark,remember that it is the positive side.what will you do is put the red pin of the tester to the positve side of the diode,& the black pin of the tester to the negative side of the diode.If if the neddle of the diode will move,then you must reverse the pin of the tester,the red pin now will be put in the negative side of the diode and the black pin of the tester now will be put on the positive side( to the side with white mark or band).
now,if the neddle of the tester WILL MOVE after doing this reverse test: im sure that your diode is dead and needs to be replaced

Note:even most of the time you can do testing diodes attached on the board..,it is strongly recomended to detach one leg of the diode to the PCB or circuit befor doing the test.