Is there a website anywhere that gives a description of the codes found on
surface mount resistors and transistors??
I have just junked two IBM laster printers and they have tons of surface
mount parts on. Ones that i might be able to use.
I also found two nice big steppers ( one of which is bipolar, still gotta
look at the other one.
Is there any use in keeping the laster emitters? What can i do with them.
There is also another motor in the laser unit that has what looks like a
well polished octagonal mirror on it ( very smooth spinning ) and two
sensors ( i presume laser detectors cause theyre at the limits of the
printing area.
John
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John De Villiers wrote:
>
> Is there a website anywhere that gives a description of the codes found on
> surface mount resistors and transistors??
The resistors are usually marked with a 3
digit number that corresponds to the normal
resistor marking, ie brown red red = 122 = 1200.
The transistors get more complicated. :o)
> I have just junked two IBM laster printers and they have tons of surface
> mount parts on. Ones that i might be able to use.
> I also found two nice big steppers ( one of which is bipolar, still gotta
> look at the other one.
>
> Is there any use in keeping the laster emitters? What can i do with them.
> There is also another motor in the laser unit that has what looks like a
> well polished octagonal mirror on it ( very smooth spinning ) and two
> sensors ( i presume laser detectors cause theyre at the limits of the
> printing area.
Maybe you can use it to expose PC boards like someone
wanted to do?
-Roman
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100 is 10 ohm
101 is 100 ohm
102 is 1k ohm
103 is 10k ohm
104 is 100k ohm
105 is 1M ohm
Farnell have some kind of transistor in SMD format and I found interesting info
inside the catalog.
Silvio.
John De Villiers gravada:
> so 101 would be 10 ohm or 100 ohm or 101 ohm???
>
> i have some resistors here that go up to 5 digits ( little blue ones )
>
> The caps have no markings except for their colour. I presume a cap test
> would be the only way out here ?
>
> John
> > {Original Message removed}
> Is there any use in keeping the laster emitters? What can i do with them.
> There is also another motor in the laser unit that has what looks like a
> well polished octagonal mirror on it ( very smooth spinning ) and two
> sensors ( i presume laser detectors cause theyre at the limits of the
> printing area.
If you do try to use the laser diodes, remember that these devices are the
reason for labels identifying the device as a class 2 laser device. As such they
can damage your sight, and you do not know they are on as they are infrared. The
motor you mention is the laser scanning motor which is what makes the typical
"winding up to speed" noise when you start a print job. Even though it feels
very smooth running it may have enough problems that it could not put a straight
vertical line on the page! These have to absolutely perfect to produce an error
free printout, and the slightest problem totally screws up the scanning.
At 05:41 PM 1/8/01 +1100, you wrote:
>John De Villiers wrote:
>>
>> so 101 would be 10 ohm or 100 ohm or 101 ohm???
>
>101 = 100 ohms, like the color codes the third
>digit is the number of trailing zeros.
>Very common surface mount R value.
>
So is 100 = 10 ohms or 100 ohms? Most helpful - if please
explain logic involved in this decision. Thank you.
At 05:29 PM 1/8/01 -0000, you wrote:
>>So is 100 = 10 ohms or 100 ohms? Most helpful - if please
>>explain logic involved in this decision. Thank you.
>
>It is the same as the colour banding. The last digit on the 3 digit series is a
>power of 10, i.e. 100 is 10*10^0 or 10*1
>
>for 101 it is 10*10^1 or 10*10 which is 100
>for 102 it is 10*10^2 or 10*100 which is 1000
>
Regarding my specific question, this means 100 = 10 ohms?
At 12:31 PM 1/8/01 -0500, you wrote:
>>
>>So is 100 = 10 ohms or 100 ohms? Most helpful - if please
>>explain logic involved in this decision. Thank you.
>
>Yes.
>
>The first two are the significant digits, the last is the number of zeroes.
>Just like the color code.
>
>10k is 103 2.7k is 272
>
At 12:54 PM 1/8/01 -0500, Dan Michaels wrote:
>At 12:31 PM 1/8/01 -0500, you wrote:
> >>
> >>So is 100 = 10 ohms or 100 ohms? Most helpful - if please
> >>explain logic involved in this decision. Thank you.
> >
> >Yes.
> >
> >The first two are the significant digits, the last is the number of zeroes.
> >Just like the color code.
> >
> >10k is 103 2.7k is 272
> >
>
>Yes = 10 ohms, or yes = 100 ohms?
At 12:23 PM 1/8/01 -0600, you wrote:
>Dan,
>
>> Regarding my specific question, this means 100 = 10 ohms?
>
>THIS: "100 is 10*10^0 or 10*1" means 100 = 10 ohms
>
>100 = 10 ohm
>101 = 100 ohm
..........
>Which, naturally, leads to the question: How is 1 ohm represented?
>
Yes. Exactly. How about 100/100 = 10ohms/100 = 1 ohm. [I think
the logic must actually lie in binary, not decimal --> 01+01=10].
And thanks to everyone who answered: 100 = 10 ohms --> Gakkk!
[not that this is a comment on your answers, but that it is
a comment on what passes for supposed "nomenclature"].
>
>And thanks to everyone who answered: 100 = 10 ohms --> Gakkk!
>[not that this is a comment on your answers, but that it is
>a comment on what passes for supposed "nomenclature"].
Resistor color code has worked that way for >50 years.
Alan B. Pearce wrote:
>
> >So is 100 = 10 ohms or 100 ohms? Most helpful - if please
> >explain logic involved in this decision. Thank you.
>
> It is the same as the colour banding. The last digit on the 3 digit series is a
> power of 10, i.e. 100 is 10*10^0 or 10*1
>
> for 101 it is 10*10^1 or 10*10 which is 100
> for 102 it is 10*10^2 or 10*100 which is 1000
Ha ha! That would scare our apprentices half to
death! As we tell the first year guys, "the first
two bands are two numbers, the third band is how
many zeros after it" ;o)
-Roman
>And thanks to everyone who answered: 100 = 10 ohms --> Gakkk!
>[not that this is a comment on your answers, but that it is
>a comment on what passes for supposed "nomenclature"].
Well it is how resistors have been marked ever since colours were used. I am not
sure how you read a resistor with colour band of brown black black, or brown
black brown, but these represent 10 and 100 ohms respectively. It is just that
surface mount components are marked using numbers instead of colours because it
is easier to read, and presumably easier to mark during manufacture.
>At 05:41 PM 1/8/01 +1100, you wrote:
>>John De Villiers wrote:
>>> so 101 would be 10 ohm or 100 ohm or 101 ohm???
>>101 = 100 ohms, like the color codes the third
>>digit is the number of trailing zeros.
>>Very common surface mount R value.
>So is 100 = 10 ohms or 100 ohms? Most helpful - if please
>explain logic involved in this decision. Thank you.
The first and second number are the first and second numbers. Duh. The third number is the number of zeros AFTER the first and second number. So it would be 10 + "zero zeros" = 10 ohms
At 10:14 AM 1/10/01 +0800, you wrote:
>are u people talking about the resistor colour code??
>http://www.elexp.com/t_resist.htm
>it's very self explanatory .....
>
Color code is no problem - translating to #'s is where
they should have called Mr. Spock in as consultant.
>At 10:14 AM 1/10/01 +0800, you wrote:
>>are u people talking about the resistor colour code??
>>http://www.elexp.com/t_resist.htm
>>it's very self explanatory .....
>>
>
>Color code is no problem - translating to #'s is where
>they should have called Mr. Spock in as consultant.
>
>brown-black-gold = 10? or was it ?10
Brown-Black-Gold = 1R0
Brown-Black-Silver = 0R1
>>Color code is no problem - translating to #'s is where
>>they should have called Mr. Spock in as consultant.
>>
>>brown-black-gold = 10? or was it ?10
>Brown-Black-Gold = 1R0
>Brown-Black-Silver = 0R1
>
Good, now that we all have the "nomenclature" straight, here
are a few I found in my box.
>
>Anyone who guesses 15 and 22 pF for the last two, I'll send you
>the caps, and you can measure them.
Build a bridge!
two resistors, two caps (one known, one unknown) and a signal generator.
Ideally, the resistors would be near the impedances of the caps at the test
frequency, but mostly they just need to be equal.
connect an appropriate transformer to the sides, and measure the level of
the signal.
The degree of inequality of the two caps determines the output level, so
tune for minimum "smoke".
There's a lot of fun things you can do with a bridge. :)
>
> Mike Harrison wrote:
>
> >>Color code is no problem - translating to #'s is where
> >>they should have called Mr. Spock in as consultant.
> >>
> >>brown-black-gold = 10? or was it ?10
> >Brown-Black-Gold = 1R0
> >Brown-Black-Silver = 0R1
> >
>
> Good, now that we all have the "nomenclature" straight, here
> are a few I found in my box.
>
> 8-resistor DIP packs:
> R330 = 330 ohms
> R270 = 270 ohms
> -330 = 33 ohms
> -151 = 150 ohms
> [not too confusing, eh]
>
> ceramic caps:
> 471 = 470 pF
> 101 = 100 pF
> 10 = 10 pF
> 2.2 = 2.2 pF
> 150 = ???? [guess]
> 220 = ???? [guess]
Dan-- you cheated us. If the caps have a tolerance on them then they are
in picofarads if not then you use the last digit as a power of 10. (or
maybe the other way around ???).
I think that capacitor manufacturers are from the dark ages. Remember
the old caps with 6 colored dots or the ones with dots on the body with
no obvious end to read from? They _never_ seem to mark caps in a
consistent way even now.
For instance:
Some small value caps are in picofarads using digits and number of
zeros.
Some small caps are in picofarads only.
Electrolytic caps are marked on the negative side.
Tantalum caps are marked on the positive side.
Surface mount caps are not marked at all.
I am _sure_ there are other cap marking problems that I can't remember
right now.
And you complain about resistors :-)
-- Rich
>
> Anyone who guesses 15 and 22 pF for the last two, I'll send you
> the caps, and you can measure them.
>
> - danM
>
> --
> http://www.piclist.com#nomail Going offline? Don't AutoReply us!
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Rich Ottosen wrote:
....
>> ceramic caps:
>> 471 = 470 pF
>> 101 = 100 pF
>> 10 = 10 pF
>> 2.2 = 2.2 pF
>> 150 = ???? [guess]
>> 220 = ???? [guess]
>
>Dan-- you cheated us. If the caps have a tolerance on them then they are
>in picofarads if not then you use the last digit as a power of 10. (or
>maybe the other way around ???).
>
[What ??? - I sure wouldn't want to cheat "you"].
Ok, the 150 and 220 also say 10%, the 471 and 101 have nothing
else on the caps, except a "bar" under the #'s.
So, now I have to remember all these @#$!!@$^%(^& exceptions !!!
================
>I think that capacitor manufacturers are from the dark ages. Remember
>the old caps with 6 colored dots or the ones with dots on the body with
>no obvious end to read from? They _never_ seem to mark caps in a
>consistent way even now.
No dots on my caps - I'm much too young to have ever encountered
any of those.
===============
>For instance:
> Some small value caps are in picofarads using digits and number of
>zeros.
> Some small caps are in picofarads only.
> Electrolytic caps are marked on the negative side.
> Tantalum caps are marked on the positive side.
> Surface mount caps are not marked at all.
>
> I am _sure_ there are other cap marking problems that I can't remember
>right now.
>
>Mike Harrison wrote:
>
>>>Color code is no problem - translating to #'s is where
>>>they should have called Mr. Spock in as consultant.
>>>
>>>brown-black-gold = 10? or was it ?10
>>Brown-Black-Gold = 1R0
>>Brown-Black-Silver = 0R1
>>
>
>Good, now that we all have the "nomenclature" straight, here
>are a few I found in my box.
>
>8-resistor DIP packs:
>R330 = 330 ohms
>R270 = 270 ohms
>-330 = 33 ohms
>-151 = 150 ohms
>[not too confusing, eh]
R-packs can be somewhat non-standard, but you can usually apply a
'reality check' on the value, as there are only a limited number of
R-pack values in common use.
>ceramic caps:
>471 = 470 pF
>101 = 100 pF
>10 = 10 pF
>2.2 = 2.2 pF
>150 = ???? [guess]
>220 = ???? [guess]
These could be either 15/22 or 150/220 - I've seen both, although the
latter often has a 'p' suffix. If in doubt, measure! At least 151 or
221 is non-ambiguous.
> Rich Ottosen wrote:
> ....
> >> ceramic caps:
> >> 471 = 470 pF
> >> 101 = 100 pF
> >> 10 = 10 pF
> >> 2.2 = 2.2 pF
> >> 150 = ???? [guess]
> >> 220 = ???? [guess]
> >
> >Dan-- you cheated us. If the caps have a tolerance on them then they are
> >in picofarads if not then you use the last digit as a power of 10. (or
> >maybe the other way around ???).
> >
>
> [What ??? - I sure wouldn't want to cheat "you"].
>
> Ok, the 150 and 220 also say 10%, the 471 and 101 have nothing
> else on the caps, except a "bar" under the #'s.
>
> So, now I have to remember all these @#$!!@$^%(^& exceptions !!!
> ================
>
>
> >I think that capacitor manufacturers are from the dark ages. Remember
> >the old caps with 6 colored dots or the ones with dots on the body with
> >no obvious end to read from? They _never_ seem to mark caps in a
> >consistent way even now.
>
> No dots on my caps - I'm much too young to have ever encountered
> any of those.
> ===============
>
>
> >For instance:
> > Some small value caps are in picofarads using digits and number of
> >zeros.
> > Some small caps are in picofarads only.
> > Electrolytic caps are marked on the negative side.
> > Tantalum caps are marked on the positive side.
> > Surface mount caps are not marked at all.
> >
> > I am _sure_ there are other cap marking problems that I can't remember
> >right now.
> >
>
> Spock is turning over in his grave about now.
>
> - danM
>
> --
> http://www.piclist.com#nomail Going offline? Don't AutoReply us!
> email RemoveMElistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body
>
>
>
Some sub-10R resistors are marked X.Y whch is X.Y ohms. Sub-ohm are
sometimes marked .XX or .X. There are also single-color markings. F.ex.
'zero ohm' resistors are often bottle green. With some imagination they
could pass for 0.05R. There are also zero ohm R's marked with a single 0.
> Some sub-10R resistors are marked X.Y whch is X.Y ohms. Sub-ohm are
> sometimes marked .XX or .X. There are also single-color markings. F.ex.
> 'zero ohm' resistors are often bottle green. With some imagination they
> could pass for 0.05R. There are also zero ohm R's marked with a single 0.
I have also seen zero ohm R's marked with a single black band smack in the
middle.
Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)
AliceC wrote:
>more fun with caps:
>
>how about, 1000k, no other markings
>
>sheesh. im going by weight from now on, teeny tiny are pfs,
>etc.
I'd forget about the 'k'. To be consistent with what most people
have been saying - it must be 100 pF, probably a 1%'er - but
I'd guess more likely 1000pF, +/-30%.
And weight doesn't really cut it - I have many tiny ceramic
disk caps, 1pF up to 0.1uF, and all about the same size.
I suspect after this thread, a lot of cap tester seller companies
are gonna get calls from piclisters - [however, my personal
superstitions are telling me to throw away anything in doubt,
and just order something from Digikey, and you're pretty certain
what it will be - much cheaper than a cap tester].
> I suspect after this thread, a lot of cap tester seller companies
> are gonna get calls from piclisters - [however, my personal
> superstitions are telling me to throw away anything in doubt,
> and just order something from Digikey, and you're pretty certain
> what it will be - much cheaper than a cap tester].
Don't you know it.
I have a cheap radio shack multimeter with a capacitance range. Its not very
accurate, but it lets me get into the correct decade at least.
Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)
>
> Mike Harrison wrote:
>
> >>Color code is no problem - translating to #'s is where
> >>they should have called Mr. Spock in as consultant.
> >>
> >>brown-black-gold = 10? or was it ?10
> >Brown-Black-Gold = 1R0
> >Brown-Black-Silver = 0R1
> >
>
> Good, now that we all have the "nomenclature" straight, here
> are a few I found in my box.
>
> 8-resistor DIP packs:
> R330 = 330 ohms
> R270 = 270 ohms
> -330 = 33 ohms
> -151 = 150 ohms
> [not too confusing, eh]
>
> ceramic caps:
> 471 = 470 pF
> 101 = 100 pF
> 10 = 10 pF
> 2.2 = 2.2 pF
> 150 = ???? [guess]
> 220 = ???? [guess]
>
> Anyone who guesses 15 and 22 pF for the last two, I'll send you
> the caps, and you can measure them.
>
> - danM
I guess 150pf and 220pf for the last two, it is common
in very small caps (<999pf) just to label the pf value,
hence the 10=10pf etc you show above. Did I mention
our workshop has 3 capacitance meters, and two ESR
capacitor testers? Who trusts the written label? ;o)
-Roman
>
> more fun with caps:
>
> how about, 1000k, no other markings
>
> sheesh. im going by weight from now on, teeny tiny are pfs,
> etc.
>
> alice
>
> > Rich Ottosen wrote:
> > ....
> > >> ceramic caps:
> > >> 471 = 470 pF
> > >> 101 = 100 pF
> > >> 10 = 10 pF
> > >> 2.2 = 2.2 pF
> > >> 150 = ???? [guess]
> > >> 220 = ???? [guess]
> > >
> > >Dan-- you cheated us. If the caps have a tolerance on them then they are
> > >in picofarads if not then you use the last digit as a power of 10. (or
> > >maybe the other way around ???).
> > >
> >
> > [What ??? - I sure wouldn't want to cheat "you"].
> >
> > Ok, the 150 and 220 also say 10%, the 471 and 101 have nothing
> > else on the caps, except a "bar" under the #'s.
> >
> > So, now I have to remember all these @#$!!@$^%(^& exceptions !!!
> > ================
> >
> >
> > >I think that capacitor manufacturers are from the dark ages. Remember
> > >the old caps with 6 colored dots or the ones with dots on the body with
> > >no obvious end to read from? They _never_ seem to mark caps in a
> > >consistent way even now.
> >
> > No dots on my caps - I'm much too young to have ever encountered
> > any of those.
> > ===============
> >
> >
> > >For instance:
> > > Some small value caps are in picofarads using digits and number of
> > >zeros.
> > > Some small caps are in picofarads only.
> > > Electrolytic caps are marked on the negative side.
> > > Tantalum caps are marked on the positive side.
> > > Surface mount caps are not marked at all.
> > >
> > > I am _sure_ there are other cap marking problems that I can't remember
> > >right now.
> > >
> >
> > Spock is turning over in his grave about now.
> >
> > - danM
> >
> > --
> > http://www.piclist.com#nomail Going offline? Don't AutoReply us!
> > email KILLspamlistservspamBeGonemitvma.mit.edu with SET PICList DIGEST in the body
> >
> >
> >
>
> --
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Peter L. Peres wrote:
>
> Some sub-10R resistors are marked X.Y whch is X.Y ohms. Sub-ohm are
> sometimes marked .XX or .X. There are also single-color markings. F.ex.
> 'zero ohm' resistors are often bottle green. With some imagination they
> could pass for 0.05R. There are also zero ohm R's marked with a single 0.
You guys are softies! Try being a TV repairer doing
10 or 15 repairs a day. Each one with a number of parts
need replacing. Most commonly my resistors are grey,
totally ash grey, with maybe some charcoal coloured
patches or silvery wire stuff visible. And you complain
about color codes?? ;o)
So what do you do with a resistor with NO colors left?
One in 3 jobs we have a circuit diagram, about 20% of
whats left we can ring the service agent and ask them,
and the rest we make an educated guess as to its
value based on where it is in the circuit board
and what it probably does. We put in a "probable"
value and then run test and measure for expected
too-high or too-low symptoms. I can usually get it
right by the second resistor.
:o)
-Roman
PS. Buy a cap meter!!! You can't work without an
ohmmeter can you?
Bob Ammerman wrote:
>
> ----- Original Message -----
> From: Peter L. Peres <.....plpspam_OUTACTCOM.CO.IL>
> To: <TakeThisOuTPICLIST.....TakeThisOuTMITVMA.MIT.EDU>
> Sent: Tuesday, January 09, 2001 6:43 PM
> Subject: Re: [EE]: Surface mount components
>
> > Some sub-10R resistors are marked X.Y whch is X.Y ohms. Sub-ohm are
> > sometimes marked .XX or .X. There are also single-color markings. F.ex.
> > 'zero ohm' resistors are often bottle green. With some imagination they
> > could pass for 0.05R. There are also zero ohm R's marked with a single 0.
>
> I have also seen zero ohm R's marked with a single black band smack in the
> middle.
There are lots of these, some marked, some just
plain coloured. In reality they are "wire links"
but machine insertable. Which dates the start of
their use to the mid '80s generally. I remember
scratching my head when I started to see a lot
of them! :o)
-Roman
>more fun with caps:
>
>how about, 1000k, no other markings
>
>sheesh. im going by weight from now on, teeny tiny are pfs,
>etc.
1000pF - K is tolerance I think - there are some 'standard-ish'
letter codes for this
Roman wrote:
.......
>> 150 = ???? [guess]
>> 220 = ???? [guess]
>>
>> Anyone who guesses 15 and 22 pF for the last two, I'll send you
>> the caps, and you can measure them.
>>
>> - danM
>
>
>I guess 150pf and 220pf for the last two, it is common
>in very small caps (<999pf) just to label the pf value,
>hence the 10=10pf etc you show above. Did I mention
>our workshop has 3 capacitance meters, and two ESR
>capacitor testers? Who trusts the written label? ;o)
Yeah, who/what can be trusted at all anymore? I put my sine
generator to the cap marked 220 thru a 10K [5%] resistor, and
adjusted freq until the voltage across the cap dropped to 50%
on the scope. Using Xc = 1/(2*pi*F*C) gave me a value of 130 pf
--> :). I was hoping for something ~250 = 220+scopeprobe_cap.
I then took another cap marked 270+/-10% and did the same. This
time I got a value of 160pF --> :):).
Roman:
I have a cap meter and an ESR tester. I shouldn't need either one for
parts that have markings on them. But I, in fact, _do_ have to use the
cap meter because of the capacitor industries' refusal to mark their
parts in a consistant way.
>
> Peter L. Peres wrote:
> >
> > Some sub-10R resistors are marked X.Y whch is X.Y ohms. Sub-ohm are
> > sometimes marked .XX or .X. There are also single-color markings. F.ex.
> > 'zero ohm' resistors are often bottle green. With some imagination they
> > could pass for 0.05R. There are also zero ohm R's marked with a single 0.
>
> You guys are softies! Try being a TV repairer doing
> 10 or 15 repairs a day. Each one with a number of parts
> need replacing. Most commonly my resistors are grey,
> totally ash grey, with maybe some charcoal coloured
> patches or silvery wire stuff visible. And you complain
> about color codes?? ;o)
>
> So what do you do with a resistor with NO colors left?
> One in 3 jobs we have a circuit diagram, about 20% of
> whats left we can ring the service agent and ask them,
> and the rest we make an educated guess as to its
> value based on where it is in the circuit board
> and what it probably does. We put in a "probable"
> value and then run test and measure for expected
> too-high or too-low symptoms. I can usually get it
> right by the second resistor.
> :o)
> -Roman
>
> PS. Buy a cap meter!!! You can't work without an
> ohmmeter can you?
>
> --
> http://www.piclist.com hint: To leave the PICList
> spamBeGonepiclist-unsubscribe-request@spam@spam_OUTmitvma.mit.edu
>
> Roman wrote:
> .......
> >> 150 = ???? [guess]
> >> 220 = ???? [guess]
> >>
> >> Anyone who guesses 15 and 22 pF for the last two, I'll send you
> >> the caps, and you can measure them.
> >>
> >> - danM
> >
> >
> >I guess 150pf and 220pf for the last two, it is common
> >in very small caps (<999pf) just to label the pf value,
> >hence the 10=10pf etc you show above. Did I mention
> >our workshop has 3 capacitance meters, and two ESR
> >capacitor testers? Who trusts the written label? ;o)
>
> Yeah, who/what can be trusted at all anymore? I put my sine
> generator to the cap marked 220 thru a 10K [5%] resistor, and
> adjusted freq until the voltage across the cap dropped to 50%
> on the scope. Using Xc = 1/(2*pi*F*C) gave me a value of 130 pf
> --> :). I was hoping for something ~250 = 220+scopeprobe_cap.
>
> I then took another cap marked 270+/-10% and did the same. This
> time I got a value of 160pF --> :):).
>
> - danM
>
Oops. I think that you meant to go to 70.7% not 50% of the input
voltage.
> Yeah, who/what can be trusted at all anymore? I put my sine
> generator to the cap marked 220 thru a 10K [5%] resistor, and
> adjusted freq until the voltage across the cap dropped to 50%
> on the scope. Using Xc = 1/(2*pi*F*C)
That's the magnitude of the impedance, but is not valid the way you used it
due to being 90 degrees out of phase with the resistor.
Olin wrote:
>> Yeah, who/what can be trusted at all anymore? I put my sine
>> generator to the cap marked 220 thru a 10K [5%] resistor, and
>> adjusted freq until the voltage across the cap dropped to 50%
>> on the scope. Using Xc = 1/(2*pi*F*C)
>
>That's the magnitude of the impedance, but is not valid the way you used it
>due to being 90 degrees out of phase with the resistor.
>
Thank you - as was also brought to my attention by RichO.
[I am now limping off into the sunset on my single living brain
cell].
John De Villiers wrote:
> I have just junked two IBM laser printers and they have tons of surface
> mount parts on. Ones that I might be able to use.
Yes, junk printers, motherboards, hard drives and floppy drives have tons of
surface mount components.
Recently, when I needed a 4.7K resistor urgently, it was convenient for me
to desolder a resistor from one junk hard disk board instead of going out to
purchase it. But the big problem is the difficulty involved in removing the
surface mount components like resistors and capacitors. Removing ICs is a
lot more difficult without proper tools.
I have a desoldering pump. But I found the following method easier to remove
a surface mount resistor: Use the soldering iron and a thin stainless steel
blade (solder doesn't stick to the SS blade) to separate one end of the
resistor from the board and do the same thing to the other end.
Considering the cost of the resistor, it's of course pointless to waste time
and energy to salvage it from a junk board. But when you need it urgently,
this may be a better option.
Now, my questions:
- Are there other (better) methods of removing surface mount parts from a
board when you only have the soldering iron and the desoldering pump?
- What are the tools used by professionals for removal of surface mount
parts? How expensive are they?
Thanks.
Regards,
Bala
Bombay, India
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I prefer using a heat gun on surface mount stuff... heat whatever size area
you want and with a quick flick of the board, you will have teeny tiny parts
all over your bench.
Have fun... it fairly easy stripping boards this way but sorting out the
parts is a pain.
=======================================================
Lawrence Glaister VE7IT email: lgspamBeGonejfm.bc.ca
1462 Madrona Drive http://jfm.bc.ca
Nanoose Bay BC Canada
V9P 9C9 http://members.home.net/cncstuff/
=======================================================
{Original Message removed}
> -----Original Message-----
> From: Bala Chandar [SMTP:RemoveMEBala.Chandar@spam@spamBeGoneAVENTIS.COM]
> Sent: Friday, January 12, 2001 5:03 AM
> To: .....PICLIST@spam@EraseMEMITVMA.MIT.EDU
> Subject: [EE]: Surface mount components
>
> Now, my questions:
> - Are there other (better) methods of removing surface mount parts from a
> board when you only have the soldering iron and the desoldering pump?
> - What are the tools used by professionals for removal of surface mount
> parts? How expensive are they?
>
>
For resistors and caps, it's hard to beat using two soldering irons. For
multi-legged parts, we use a hot air blower with special replaceable tips
that direct the hot air around the component. It still gets the pcb pretty
warm though, and you allways have a risk of desoldering nearby components.
For rework, if we need to replace something like a TSOP package, we just cut
the legs off the old one with a scalpel and then remove the remaining legs
with a quick wipe of the iron.
Mike
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>
>Now, my questions:
> - Are there other (better) methods of removing surface mount parts from a
>board when you only have the soldering iron and the desoldering pump?
for resistor/caps dab one end with the iron until hot, then quickly move the
iron to the other end...it'll come off on your tip, flick it on the table..
takes 2 seconds...if it doesn't then jump from end to end quickly with the iron.
> -----Original Message-----
> From: Graham [SMTP:.....Graham.DRemoveMEWANADOO.FR]
> Sent: Friday, January 12, 2001 9:38 AM
> To: .....PICLISTSTOPspam@spam@MITVMA.MIT.EDU
> Subject: Re: [EE]: Surface mount components
>
> >
> >Now, my questions:
> > - Are there other (better) methods of removing surface mount parts from
> a
> >board when you only have the soldering iron and the desoldering pump?
>
> for resistor/caps dab one end with the iron until hot, then quickly move
> the
> iron to the other end...it'll come off on your tip, flick it on the
> table..
>
> takes 2 seconds...if it doesn't then jump from end to end quickly with the
> iron.
>
> Graham
>
If I'm stuck with one soldering iron, then I find laying the tip accross the
length of the cap or resistor is usualy enough to melt the solder at both
ends at once. Takes a bit of practice though.
Mike
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>
> Roman wrote:
> .......
> >> 150 = ???? [guess]
> >> 220 = ???? [guess]
> >>
> >> Anyone who guesses 15 and 22 pF for the last two, I'll send you
> >> the caps, and you can measure them.
> >>
> >> - danM
> >
> >
> >I guess 150pf and 220pf for the last two, it is common
> >in very small caps (<999pf) just to label the pf value,
> >hence the 10=10pf etc you show above. Did I mention
> >our workshop has 3 capacitance meters, and two ESR
> >capacitor testers? Who trusts the written label? ;o)
>
> Yeah, who/what can be trusted at all anymore? I put my sine
> generator to the cap marked 220 thru a 10K [5%] resistor, and
> adjusted freq until the voltage across the cap dropped to 50%
> on the scope. Using Xc = 1/(2*pi*F*C) gave me a value of 130 pf
> --> :). I was hoping for something ~250 = 220+scopeprobe_cap.
>
> I then took another cap marked 270+/-10% and did the same. This
> time I got a value of 160pF --> :):).
Hi Dan, do you have a frequency meter, you know,
usually about 7 digits and can switch for
freq/period?
My favorite cap tester is home made, its more
accurate for very small caps, I just used a
hex inverter oscillator (very simple!) and run
the freq meter on "period" and adjusted the
resistor so that it reads correct. I made it
when I was about 15 and it has worked well
for 20 years. It's inside the freq meter box,
(which was a kit one), with it's own switch and
two short leads to keep lead capacitance down.
Since then I have purchased dedicated units,
but nothing measure sub 100pf parts like mine,
and with 7 digit accuracy, good for "seeing"
caps drift off value with heat, time, etc. :o)
The commercial ones have leads too long and
are never good for very small caps. I let the
apprentices use them.
-Roman
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> I have a desoldering pump. But I found the following method easier to remove
> a surface mount resistor: Use the soldering iron and a thin stainless steel
> blade (solder doesn't stick to the SS blade) to separate one end of the
> resistor from the board and do the same thing to the other end.
>
> Considering the cost of the resistor, it's of course pointless to waste time
> and energy to salvage it from a junk board. But when you need it urgently,
> this may be a better option.
>
> Now, my questions:
> - Are there other (better) methods of removing surface mount parts from a
> board when you only have the soldering iron and the desoldering pump?
> - What are the tools used by professionals for removal of surface mount
> parts? How expensive are they?
I do it "professionally" (or for a living anyway!!
ha ha!) using a standard soldering iron. SM parts are
rugged, and by far the best way to work them is
QUICKLY.
I put a blob of solder on the tip of the iron,
stick it beside the resistor so it engulfs both
the connections, the resistor comes off instantly,
and gets stuck in the surface tension of the blob
on the end of the iron. One "flick" of the wrist
and the part flings off onto the workbench and
the right velocity removes all the solder from
it. You now have a clean part ready for microscope
inspection with one of those radio shack $15
30x units. Note sometimes the parts have a heat
proof glue as well, they take a little bit of
prying with a tiny jewellers screwdriver, but
again heat both pins at once. Forget solder
removal, think part removal. It's quicker to do
it and clean the mess up later than try to work
on a microscopic level.
I can remove resistors, etc in about one second
each, examine them all and put each one back in
a few seconds with tweezers. And I still hate
them! ;o)
-Roman
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Salvaging components from a surface mount board can be much different than
"rework" of such a board (where you want it to continue to work.) For
instance, I usually use a blowtorch or oven to heat the backside of a board
(aimed at extracting significant through-hole components) - once the board
is hot and smoking and you've pulled out your throughhole components, a
quick whack on the ground (you didn't take a blowtorch to your board inside,
did you?!) will result in a sprinkling of surface mount components. An oven
is a more controlled heatsouce, and works fine too, but unless you can
dedicate an oven to electronics work (not too hard if boards are toaster oven
sized), I'd start to worry about lead contamination from solder...
People who do "real rework" have solding irons with a wide assortment of
special tips to span the width of different sized SM components, plus
hot air guns with a similar set of nozzles, plus IR, plus some special
purpose gear (go to an electronics show like WESCON, and you'll see some
neat gadgets involving very-low-temperature solders designed to melt and
lower the temperature of any existing "normal" solder as well, for instance.)
Such equipment runs $$$$$$, though...
BillW
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>John De Villiers wrote:
>> I have just junked two IBM laser printers and they have tons of surface
>> mount parts on. Ones that I might be able to use.
>
>Yes, junk printers, motherboards, hard drives and floppy drives have tons of
>surface mount components.
>
>Recently, when I needed a 4.7K resistor urgently, it was convenient for me
>to desolder a resistor from one junk hard disk board instead of going out to
>purchase it. But the big problem is the difficulty involved in removing the
>surface mount components like resistors and capacitors. Removing ICs is a
>lot more difficult without proper tools.
>
>I have a desoldering pump. But I found the following method easier to remove
>a surface mount resistor: Use the soldering iron and a thin stainless steel
>blade (solder doesn't stick to the SS blade) to separate one end of the
>resistor from the board and do the same thing to the other end.
You can pic resistors off easily by alternately heating each end
quickly.
>Considering the cost of the resistor, it's of course pointless to waste time
>and energy to salvage it from a junk board. But when you need it urgently,
>this may be a better option.
>
>Now, my questions:
> - Are there other (better) methods of removing surface mount parts from a
>board when you only have the soldering iron and the desoldering pump?
> - What are the tools used by professionals for removal of surface mount
>parts? How expensive are they?
Forget puimps. Use a good quality desolder braid - Soder-Wick by
Chemtronics is by far the best I've found. For SO chips, this will
usually clean off enough of the solder that you can then just lever
the chip off the PCB without damaging either - the remaining solder is
so thin it just snaps cleanly. A wipe with a flux pen first also
helps. A large, half-inch long blade bit on your iron is also a very quick
way of remofing small SO chips.
For bulk removal of parts from scrap boards, a hot-air paintstripping
gun is highly effective and very cheap. Again, spraying the board with
rework flux first seems to help.
A Weller PyroPen gas soldering iron with the hot-air tip is also very
handy.
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Peter Peres wrote:
>Dan,
>
>try again, but this time select 1:10 probe attenuation and try to find out
>if you are resonating by any chance ;) (vary the sine frequency).
>
Problem is fixed. Turn up frequency only to point where
Vcap is down to .707*Vmax. [please help me preserve my single
still-functioning brain-cell - misspent youth, wild nites,
bad choices, living at high elevations - shrivel the brain].
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>>
- What are the tools used by professionals for removal of surface mount
parts? How expensive are they?
<<
We have two Metcal solder stations around here for the guys that do the
solder work. These are high frequency, "instant on" devices. In
addition to a soldering tip, they have an attachment that could best
be described as a soldering tweezer, which allows both sides of a
SM component to be heated and also grasped for removal. Very quick
and easy - even I can do it. The inserts for the tweezers range in
size from a tip for doing resistors and such, to large "paddles" that
allow a SM pic to be removed just as quickly. They cost approx US
$2000.
by the way - different subject: I use Lotus Notes and don't ever see
an "att1.eml" file at the end of the stuff echoed back to me. Does the
list see this file and I don't because I'm also reading in Notes??
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>There's a lot of fun things you can do with a bridge. :)
Just check with the guys who designed the millennium bridge across the Thames
river in London. The tolerance on the sway does not seem quite right though
> I am _sure_ there are other cap marking problems that I can't remember
>right now.
One of the problem ones are silvered mica capacitors which come in a "teardrop
epoxy" coating. These always seemed to be marked in actual pF rather than using
a multiplier digit. Typically only come across these when dealing with very high
stability issues or high voltage items though, as they seem to be relatively
expensive.
JGED.COM> on 01/08/2001 01:23:59 PM
