Identify Part - Help Needed

[Bob Kos]

Hi All:

I'm trying to repair a CDRW drive that is part of a Sony Laptop Computer.
The drive is a Panasonic / Matsushita model UJDA730. It is a combo CD /
CDRW / DVDROM. The drive is totally dead. I have substituted a drive into
the computer and it works fine. I have isolated the problem to the drive
itself. I took this drive apart and ran some voltage tests. Panasonic was
nice enough to silkscreen voltages on the board in various places and those
voltages are in place except for one. The component pointed out in the
photo linked below has 5v on one end but 0v on the other end. The sister
part to it has voltage at both ends. Resistance testing shows my mystery
part having 420K ohms or therebouts, the sister part has .4 ohms resistance.

http://bkos.home.infionline.net/MysPart.jpg

My guess is that this part has an open or high resistance. My problem is
that I haven't a clue what it is. It looks like a very tiny coil. But I
could be wrong about that.

Does anybody know what this part is? Any thoughts on the markings - '270
M23' ? Any idea where to get one? Are they difficult to change? It
appears as if the entire component is soldered to the board, not just the
corners.

I'd hate to trash this drive if it is repairable. Even used they cost over
$30 and what will I get for that money? New is out of the question - $150
or therebouts.

Any help or advice would be appreciated.

 

[gb]

Hi All:

I'm trying to repair a CDRW drive that is part of a Sony Laptop Computer.
The drive is a Panasonic / Matsushita model UJDA730. It is a combo CD /
CDRW / DVDROM. The drive is totally dead. I have substituted a drive
into
the computer and it works fine. I have isolated the problem to the drive
itself. I took this drive apart and ran some voltage tests. Panasonic
was
nice enough to silkscreen voltages on the board in various places and
those
voltages are in place except for one. The component pointed out in the
photo linked below has 5v on one end but 0v on the other end. The sister
part to it has voltage at both ends. Resistance testing shows my mystery
part having 420K ohms or therebouts, the sister part has .4 ohms
resistance.

http://bkos.home.infionline.net/MysPart.jpg

My guess is that this part has an open or high resistance. My problem is
that I haven't a clue what it is. It looks like a very tiny coil. But I
could be wrong about that.

Does anybody know what this part is? Any thoughts on the markings - '270
M23' ? Any idea where to get one? Are they difficult to change? It
appears as if the entire component is soldered to the board, not just the
corners.

Surface mounted components. Google on that -- and you will find proper
methods for applying and removing the parts (you need a temperature
controlled soldering station with a fine tip ~ 1/32 inch) - forget using the
cheap stick irons -- you'll ruin more than you will fix.

Got a capacitance meter?

 

[Ross Herbert]

Hi All:

I'm trying to repair a CDRW drive that is part of a Sony Laptop Computer.
The drive is a Panasonic / Matsushita model UJDA730. It is a combo CD /
CDRW / DVDROM. The drive is totally dead. I have substituted a drive into
the computer and it works fine. I have isolated the problem to the drive
itself. I took this drive apart and ran some voltage tests. Panasonic was
nice enough to silkscreen voltages on the board in various places and those
voltages are in place except for one. The component pointed out in the
photo linked below has 5v on one end but 0v on the other end. The sister
part to it has voltage at both ends. Resistance testing shows my mystery
part having 420K ohms or therebouts, the sister part has .4 ohms resistance.

http://bkos.home.infionline.net/MysPart.jpg

My guess is that this part has an open or high resistance. My problem is
that I haven't a clue what it is. It looks like a very tiny coil. But I
could be wrong about that.

Does anybody know what this part is? Any thoughts on the markings - '270
M23' ? Any idea where to get one? Are they difficult to change? It
appears as if the entire component is soldered to the board, not just the
corners.

I'd hate to trash this drive if it is repairable. Even used they cost over
$30 and what will I get for that money? New is out of the question - $150
or therebouts.

Any help or advice would be appreciated.

It definitely is an inductor (coil). Could be associated with the
power supply part going by the type and size of adjacent components.

These items are relatively easy to remove even without specialised smd
tools. Use a fine conical tip soldering iron and remove as much solder
as possible using solder wick or a vacuum pump taking care not to
apply heat for too long. Even though the inductor is less sensitive to
heat applying the tip for too long may damage the pcb tracks. Now
apply heat to one corner at a time and while the solder is molten
carefully prise up that corner with a small flat bladed screwdriver or
knife. Do the same to the other corner. It may take a couple of goes
if you are to avoid ripping the copper tracks off the pcb.

Since the item is a coil you may find that one end has simply become
disconnected where it terminates on the solder pad and you can repair
it. If not then a new inductor will be required. Looks like it could
be a 270uH to me.

 

[Ross Herbert]

PS. Usually smd devices are glued to the pcb in addition to the solder
so that might present a bit of difficulty. Still, I have successfully
removed smd devices using the technique I described.

 

[Bob Kos]

It definitely is an inductor (coil). Could be associated with the
power supply part going by the type and size of adjacent components.

These items are relatively easy to remove even without specialised smd
tools. Use a fine conical tip soldering iron and remove as much solder
as possible using solder wick or a vacuum pump taking care not to
apply heat for too long. Even though the inductor is less sensitive to
heat applying the tip for too long may damage the pcb tracks. Now
apply heat to one corner at a time and while the solder is molten
carefully prise up that corner with a small flat bladed screwdriver or
knife. Do the same to the other corner. It may take a couple of goes
if you are to avoid ripping the copper tracks off the pcb.

Since the item is a coil you may find that one end has simply become
disconnected where it terminates on the solder pad and you can repair
it. If not then a new inductor will be required. Looks like it could
be a 270uH to me.

Thanks for your reply. Your information is good. Unfortunately for me, I
was not able to save the inductor. It had some kind of corrosion or
reaction that weakened the wire and allowed it to open. The part is
destroyed. Now I must try to locate a replacement. Any recommendations on
where to go? Any ideas on a substitute item that will work? I cannot find
anything even closely resembling what I have at any source close to me (
parts chassis, catalogs, etc.). FWIW, this inductor has a solid ferrite
bobbin. Again, any help would be appreciated.

 

[Sam Goldwasser]

Thanks for your reply. Your information is good. Unfortunately for me, I
was not able to save the inductor. It had some kind of corrosion or
reaction that weakened the wire and allowed it to open. The part is
destroyed. Now I must try to locate a replacement. Any recommendations on
where to go? Any ideas on a substitute item that will work? I cannot find
anything even closely resembling what I have at any source close to me (
parts chassis, catalogs, etc.). FWIW, this inductor has a solid ferrite
bobbin. Again, any help would be appreciated.

Can you tell where in the circuit it is?

For example, if it's directly in one of the input voltage lines, then
it is only serving as filtering/RFI suppression and the drive will run
without it for testing at least. Anything reasonably similar can then
be installed.

Of course, if it is part of a DC-DC convertor, you'll need a close replacement.

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Important: Anything sent to the email address in the message header above is
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[JW]

Thanks for your reply. Your information is good. Unfortunately for me, I
was not able to save the inductor. It had some kind of corrosion or
reaction that weakened the wire and allowed it to open. The part is
destroyed. Now I must try to locate a replacement. Any recommendations on
where to go? Any ideas on a substitute item that will work? I cannot find
anything even closely resembling what I have at any source close to me (
parts chassis, catalogs, etc.). FWIW, this inductor has a solid ferrite
bobbin. Again, any help would be appreciated.

Possible to unwind the bobbin and count the windings while doing so? If
you can do that, you could re-wind the bobbin with new magnet wire.

 

[Franc Zabkar]

Thanks for your reply. Your information is good. Unfortunately for me, I
was not able to save the inductor. It had some kind of corrosion or
reaction that weakened the wire and allowed it to open. The part is
destroyed. Now I must try to locate a replacement. Any recommendations on
where to go? Any ideas on a substitute item that will work? I cannot find
anything even closely resembling what I have at any source close to me (
parts chassis, catalogs, etc.). FWIW, this inductor has a solid ferrite
bobbin. Again, any help would be appreciated.

The inductor is near a test point marked D25V. Does this make it part
of a 5V-25V DC-DC converter? Can you trace the circuit between the
"0V" end of the coil and the D25V test point? Can you see the part
number on the IC with the 6 pins?

-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

 

[Ross Herbert]

Thanks for your reply. Your information is good. Unfortunately for me, I
was not able to save the inductor. It had some kind of corrosion or
reaction that weakened the wire and allowed it to open. The part is
destroyed. Now I must try to locate a replacement. Any recommendations on
where to go? Any ideas on a substitute item that will work? I cannot find
anything even closely resembling what I have at any source close to me (
parts chassis, catalogs, etc.). FWIW, this inductor has a solid ferrite
bobbin. Again, any help would be appreciated.

Bob,

It is difficult to be specific about where you might obtain a
replacement since there is no manufacturer info on the inductor photo.
The physical size is also difficult to guess but I am thinking it
would be something like 8mm x 8mm and about 4mm high and it is
unshielded. The wire gauge doesn't appear to be that large so it is
most likely not a high current inductor (possibly around 1A). Also, on
second thought, the value is more likely to be 27uH and not 270uH.

In looking at what is around on the www it would most likely be
similar to the Delevan 3483R-270M listed on this page
http://www.delevan.com/product/src/standard/3483_S3483.pdf

If further info is available then I could probably be a bit more
helpful.

 

[Bob Kos]

It is difficult to be specific about where you might obtain a
replacement since there is no manufacturer info on the inductor photo.
The physical size is also difficult to guess but I am thinking it
would be something like 8mm x 8mm and about 4mm high and it is
unshielded. The wire gauge doesn't appear to be that large so it is
most likely not a high current inductor (possibly around 1A). Also, on
second thought, the value is more likely to be 27uH and not 270uH.

In looking at what is around on the www it would most likely be
similar to the Delevan 3483R-270M listed on this page
http://www.delevan.com/product/src/standard/3483_S3483.pdf

If further info is available then I could probably be a bit more
helpful.

Hi:

I hunted around Mouser's site till I found the smallest 270 uh inductor that
I could find that looked similar to mine. Although it was close, it was
still too large for the PCB inside the drive. I simply relocated it to a
place where it's larger size could be accomodated and ran short jumper wires
to connect it to the PCB pads. The drive is up and running just fine. I
admit that I may have the wrong value for this part. But I'll use it and
see how it holds up.

Thanks much to all who responded to my query. I couldn't have fixed it
without your help.

Bob

 

[Ross Herbert]

Hi:

I hunted around Mouser's site till I found the smallest 270 uh inductor that
I could find that looked similar to mine. Although it was close, it was
still too large for the PCB inside the drive. I simply relocated it to a
place where it's larger size could be accomodated and ran short jumper wires
to connect it to the PCB pads. The drive is up and running just fine. I
admit that I may have the wrong value for this part. But I'll use it and
see how it holds up.

Thanks much to all who responded to my query. I couldn't have fixed it
without your help.

Bob

Did you notice that I had revised my thinking on the inductance value?
It is more likely a 27uH than 270uH.

 

[Bob Kos]

Did you notice that I had revised my thinking on the inductance value?
It is more likely a 27uH than 270uH.

Hi Ross:

I did notice that you changed your suggestion on the value of the inductor.
I had already ordered the 270 uh part and received it before I saw your
later post. I'm wondering what the ramifications of using the 270 uh vs the
27 uh part? The part appears to be in a DC / DC converter. What are your
thoughts on the substitution? If it will destroy the drive, I'll order
another per your post. Otherwise I'll leave it run & see if it reads /
writes reliably. It does do those things now.

 

[Ross Herbert]

Hi Ross:

I did notice that you changed your suggestion on the value of the inductor.
I had already ordered the 270 uh part and received it before I saw your
later post. I'm wondering what the ramifications of using the 270 uh vs the
27 uh part? The part appears to be in a DC / DC converter. What are your
thoughts on the substitution? If it will destroy the drive, I'll order
another per your post. Otherwise I'll leave it run & see if it reads /
writes reliably. It does do those things now.

It is not possible for me to say exactly what the inductance value is
without the original manufacturer's specs. I have seen some
manufacturers mark an inductor with 270 to signify 270uH but in other
cases a 270 marking will mean 27uH. Unless you can actually measure
the value of the original inductor then one can only guess.

Not having actually tried using an inductor 10x higher than the design
value I can't say exactly. If it is the output inductor of the
switcher I would guess that it might drastically affect the output
voltage at best. It may cause the IC to run hotter than intended and I
wouldn't want to try it if it meant I had to replace the IC
afterwards. Better to stick to the design value.

 

[Bob Kos]

It is not possible for me to say exactly what the inductance value is
without the original manufacturer's specs. I have seen some
manufacturers mark an inductor with 270 to signify 270uH but in other
cases a 270 marking will mean 27uH. Unless you can actually measure
the value of the original inductor then one can only guess.

Not having actually tried using an inductor 10x higher than the design
value I can't say exactly. If it is the output inductor of the
switcher I would guess that it might drastically affect the output
voltage at best. It may cause the IC to run hotter than intended and I
wouldn't want to try it if it meant I had to replace the IC
afterwards. Better to stick to the design value.

I have another identical inductor on this board. Is it feasible to
calculate the value of it while it is in circuit? If so, can you offer me
help on how to determine the value? Is it a resistance type of measurement?
I'm a bit out of my league in trying to determine how to measure this
inductor. Again, your help is greatly appreciated.

 

[Ross Herbert]

SNIP

I have another identical inductor on this board. Is it feasible to
calculate the value of it while it is in circuit? If so, can you offer me
help on how to determine the value? Is it a resistance type of measurement?
I'm a bit out of my league in trying to determine how to measure this
inductor. Again, your help is greatly appreciated.

The best way to measure inductance is to use an inductance meter, and
unless you do some design work you are not likely to have such an
instrument. It is possible to determine inductance using an
oscillator, a digital multimeter and some math as shown here
http://et.nmsu.edu/~etti/fall96/electronics/induct/induct.html

The inductor being measured must be removed from the pcb.

If I were doing the job I would be tempted to count the number of
turns on the good inductor and using the same gauge wire rewind the
old inductor core with the same number of turns. You may have to break
the plastic carrier for the old core but it wouldn't really matter
since the core is what you need. After winding the core I would coat
it in nail varnish or epoxy and after that sets I would simply solder
the ends of the stripped wires (as short as possible) to the solder
pads on the board. Finally I would place a thin piece of insulation
(insulation tape would do) under the core and fix the core to the pcb
with hot melt glue or even a small dab of epoxy. Of course this
procedure should only be contemplated if you have a steady hand , a
magnifying loupe and you are good at soldering.

Ross