This is with the main PCB(the top board) just laying on the pins, it was easy to remove, 2 screws and 2 pins.
41 volts in my DVD's AV output jack ground.
- Thread starter tedstruk
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This is with the main PCB(the top board) just laying on the pins, it was easy to remove, 2 screws and 2 pins.
There are these little gears on the DVD, and if you turn them in the right direction it will slowly lower the drive unit, and eject the disk, so you can save your media.
Found something that looks like it is burned, looking through my magnifier, It looked lie it had a little volcano of plastic on it but when I touched it, it disintegrated and crumbled free from the chip leaving what looks like a "crater in a layer".. After a bit of scratching and some higher magnification I can read some of the numbers on the chip.
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No that's just flux residue left from the manufacturing process.
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That's probably your problem.
However we don't know if it was the original problem or not.
In any case, to effect a repair, your have to determine what this IC is and replace it. I can't see any margins on the chip other than the index mark which indicates pin 1. Even if you do manage to find out what it is, could you remove and replace it?
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The correct way to test a fuse is using the ohms range on your multimeter, with the power to the appliance off (and with it unplugged) and without any resistor.
Remember what I asked you to do ages ago?
Yeah...I did it. There wasn't any change in the voltage, but I did experience a strange thing with the unit unplugged... There was about 9v of current still in the power circuits at the fuse to ground, that slowly discharged while I was testing it with the resistor.
Is it OK to power this board without the main PCB hooked up to it? I pulled the main PCB and the AV PCB(the AV has the power circuits on it), I am thinking that I can use my Osc scope to find any faults on the board, but I have to power the board to do that, and I am a chicken to power the AV board without the main PCB connected(the main PCB is attached to the DVD and the AV PCB with ribbon cables. Do I need to use a secondary power system, of less volts or is the 110ac OK?
_NOTE TO MODERATOR_
Please remove this thread as the DVD drive has a broken gear lever, and it cannot be repaired...If anyone is interested in having this in their shop for parts or testing please let me know as I will either be parting it, or tossing it.(probably parting cause I am real sensitive about these electronics gadgets and get attached easily...)
_NOTE TO MODERATOR_
Please remove this thread as the DVD drive has a broken gear lever, and it cannot be repaired...If anyone is interested in having this in their shop for parts or testing please let me know as I will either be parting it, or tossing it.(probably parting cause I am real sensitive about these electronics gadgets and get attached easily...)
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Good progress thus far.
The IC you found looks bad... but it's hard to say that's the culprit.
Electronics have a tendency to show failure on a more sensitive component than to show it on the actual culprit.
Initial tests on the board will be done with the resistance/diode test
When unplugged, this capacitor will hold a charge for a while, that may be what you are measuring.
That being said, you absolutely have to make sure that the black and red probes on your meter are connected properly. Remember that voltage readings are relative...
Putting the black probe on something that is *not* a common connection to the circuit you are measuring will give you odd readings.
When you are prodding a logic board, black is typically connected to the 0V, or 'Common' connection. I know sometimes they call it 'ground', but it's not *really* a ground, because more often then not, it's not connected to the earth pin on a power plug in any way.
As far as safety is concerned, if this is something you want to learn to do, get an isolation transformer. This will make poking around safer. (not safe... but safer)
The IC you found looks bad... but it's hard to say that's the culprit.
Electronics have a tendency to show failure on a more sensitive component than to show it on the actual culprit.
Initial tests on the board will be done with the resistance/diode test
More often then not, the power supply for devices involves a bridge rectifier and a power capacitor.
When unplugged, this capacitor will hold a charge for a while, that may be what you are measuring.
That being said, you absolutely have to make sure that the black and red probes on your meter are connected properly. Remember that voltage readings are relative...
Putting the black probe on something that is *not* a common connection to the circuit you are measuring will give you odd readings.
When you are prodding a logic board, black is typically connected to the 0V, or 'Common' connection. I know sometimes they call it 'ground', but it's not *really* a ground, because more often then not, it's not connected to the earth pin on a power plug in any way.
As far as safety is concerned, if this is something you want to learn to do, get an isolation transformer. This will make poking around safer. (not safe... but safer)
Typically these things are built in stages.
The power board is simply a power board, and will simply put out power all the time, or it will provide a 'standby' voltage that can be fed back to it to tell it to turn completely on. Powering this board by itself is safe, but may be hard to test unless you can identify how to 'turn it on'.
That being said, it's only safe for the components and may not be safe to you.
Thank you for the update on the broken pin. This thread does not need to be deleted though. Sometimes it's nice to have the information present regardless of content.
You can always edit your first post to put a note on the top that the troubleshooting was canceled due to a physical defect with the unit.
Power button OK. Mains Wiring integrity OK. are the little momentary buttons really supposed to read from .005 to .000, when you push them? The controls board is all one piece, so I check them all, and they all read from .005 to .000 when pressed.
Capacitors have a + and a negative side right? so I was thinking, if I test all the caps from the case ground to their + side, I will be able to detect a dead short to ground if one is bad right?
NO!
(not right cause a bad cap is gonna be dead on both sides, so I had to check both sides and I found one that is not doing what the rest did... it is dead on both sides.. should I replace it?)
NO!
(not right cause a bad cap is gonna be dead on both sides, so I had to check both sides and I found one that is not doing what the rest did... it is dead on both sides.. should I replace it?)
none of that even begins to make sense
get a capacitance meter and test them properly
yes
Capacitors will change their 'resistance' value as you measure them. This is normal.
However... there are very few components you can measure resistance of while they are in a circuit!
*Especially if you are unsure of the board layout.
A bad cap may be short-circuit, or open circuit. Changing values like that is a good sign, but hard to tell if it's left in circuit. A bleeder resistor could be present that will skew results / drain the capacitor. To be certain, you need a proper meter to measure the capacitance, and you *must* remove it from the circuit either completely, or by disconnecting one leg.
Additionally, momentary buttons should read as short-circuits or open-circuits, and change from one to the other when you push the button. A very small amount of resistance is fine instead of a short-circuit.
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