Anybody able to ID this SM diode for me?

D

Don Bruder

Guest
Out of a lightning-cooked USR Courier "v.Everything" modem - Nifty flash
of blue light, sound like a .22 rifle going off, modem dead, 3 seconds
later, I heard the thunder from the strike. <sigh> Thunder needs to
preceed the hit to give fair warning, dangit!!!

Anyway, it looks as though the hit came in on the phone line, since
there appears to be an arc-mark from one of the phone input contacts to
a trace that heads for ground through a string of four fried "332"
resistors (they're wired in series, terminating at the main power
ground), and a diode, marked "P5D69", where the "P" looks *ALMOST* as if
it's a subscript label, the "5D" is the main marking, and the "69" is
rotated 90 degrees to the "5D" - sorta like so, as best I can do with
plain text:

5D 6
p 9

Although the "P" isn't *QUITE* that low, and each digit of the "69" is
rotated 90 degrees, forming a two-digit number whose length total length
is the same as the height of the "5D"

Anybody able to tell me anything about this diode? What "flavor" it is,
a possible substitute (SM or thru-hole - I'm more than willing to sub a
thru-hole version if I can find one that's electrically compatible) or
anything else about the beast that would help me with my attempt to
bring this unit back to life?

--
Don Bruder - dakidd@sonic.net <--- Preferred Email - SpamAssassinated.
Hate SPAM? See <http://www.spamassassin.org> for some seriously great info.
I will choose a path that's clear: I will choose Free Will! - N. Peart
Fly trap info pages: <http://www.sonic.net/~dakidd/Horses/FlyTrap/index.html>
 
Don Bruder wrote:
Out of a lightning-cooked USR Courier "v.Everything" modem - Nifty
flash of blue light, sound like a .22 rifle going off, modem dead, 3
seconds later, I heard the thunder from the strike. <sigh> Thunder
needs to preceed the hit to give fair warning, dangit!!!

Anyway, it looks as though the hit came in on the phone line, since
there appears to be an arc-mark from one of the phone input contacts
to a trace that heads for ground through a string of four fried "332"
resistors (they're wired in series, terminating at the main power
ground), and a diode, marked "P5D69", where the "P" looks *ALMOST* as
if it's a subscript label, the "5D" is the main marking, and the "69"
is rotated 90 degrees to the "5D" - sorta like so, as best I can do
with plain text:

5D 6
p 9

Although the "P" isn't *QUITE* that low, and each digit of the "69" is
rotated 90 degrees, forming a two-digit number whose length total
length is the same as the height of the "5D"
Click to expand...
Don, write it off or claim on household contents insurance.

You are looking at the physical damage - there will be far further
electronic damage to sort out including perhaps the serial port
on the computer (assuming this is an external modem).

A recent job I sorted saw the whole computer fried including the
screen from a strike which killed the fax machine as well as the PCI
modem!

A new modem will only cost a few bucks/pounds/pesatas! But check
the rest of the system first.

--
Graham W http://www.gcw.org.uk/ XP1800+ Page added, Graphics Tutorial
WIMBORNE http://www.wessex-astro-society.freeserve.co.uk/ Wessex
Dorset UK Astro Society's Web pages, Info, Meeting Dates, Sites & Maps
Change 'news' to 'sewn' in my Reply address to avoid my spam filter.
 
In article <XRvrb.5$LY5.11751593@news.salzburg-online.at>,
Wolfgang Mahringer <wolfgang.mahringer@sbg.at> wrote:

Hi Don,

Don Bruder wrote:
[ history of fried diode snipped ]

5D 6
p 9


The SMD Code Book says 5D is a 1N914 standard diode.
Click to expand...
ABSOLUTELY WONDERFUL!!!!!!!!!!!! HOORAY!!!! :) I've only got about a
bazillion of those laying around (in thru-hole version, of course...)

Many thanks. It helps greatly!

--
Don Bruder - dakidd@sonic.net <--- Preferred Email - SpamAssassinated.
Hate SPAM? See <http://www.spamassassin.org> for some seriously great info.
I will choose a path that's clear: I will choose Free Will! - N. Peart
Fly trap info pages: <http://www.sonic.net/~dakidd/Horses/FlyTrap/index.html>
 
In article <Mevrb.6305$lm1.42703@wards.force9.net>,
"Graham W" <graham@his.com.puterINVALID> wrote:

Don Bruder wrote:
Out of a lightning-cooked USR Courier "v.Everything" modem - Nifty
flash of blue light, sound like a .22 rifle going off, modem dead, 3
seconds later, I heard the thunder from the strike. <sigh> Thunder
needs to preceed the hit to give fair warning, dangit!!!

Anyway, it looks as though the hit came in on the phone line, since
there appears to be an arc-mark from one of the phone input contacts
to a trace that heads for ground through a string of four fried "332"
resistors (they're wired in series, terminating at the main power
ground), and a diode, marked "P5D69", where the "P" looks *ALMOST* as
if it's a subscript label, the "5D" is the main marking, and the "69"
is rotated 90 degrees to the "5D" - sorta like so, as best I can do
with plain text:

5D 6
p 9

Although the "P" isn't *QUITE* that low, and each digit of the "69" is
rotated 90 degrees, forming a two-digit number whose length total
length is the same as the height of the "5D"

Don, write it off or claim on household contents insurance.

You are looking at the physical damage - there will be far further
electronic damage to sort out including perhaps the serial port
on the computer (assuming this is an external modem).
Click to expand...
MAYBE there will be further damage. I'm not as pessimistic as you seem
to be about this thing's chances. Worst case scenario: I spend a buck or
two and a few minutes, and it remains dead. Best case: It returns to
life as good as new. I'm game to try it! :)

I'm quite aware that what I'm looking at is just the *VISIBLE* damage.
But scrapping this rig (which, in its day, was the absolute
top-of-the-line - What am I saying "in its day"? The thing was still the
best modem I've ever met until the hit that killed it. "v.Everything"
meant exactly that...) because it *MIGHT* have more damage is an idea
that's simply repugnant to me.

A recent job I sorted saw the whole computer fried including the
screen from a strike which killed the fax machine as well as the PCI
modem!
Click to expand...
Yeah, I know that lightning can take out a machine from top to bottom
and front to back. In this case, that didn't happen. The modem (which is
an external) died. And it looks like that's all that happened. The diode
exploded, yes, and the 6 resistors are visibly cooked (with one reading
wide open when I put a meter across it, while the rest appear to be just
"cosmetically cooked", without being dead - they all read at their rated
values except for the one) but the rest of the unit seems to be intact.
And in fact, it immediately came up and showed normal status lights when
I power-cycled it. Looks like the MOV did as much as it could do as far
as protection - the arc-mark is before the MOV, unfortunately - right at
the point where the line plugs in, before a torroidal widget. (some kind
of choke, I expect)

Right there where the line comes in, there are two through-hole pads -
one from the phone line, and one running to a jumper-block, and
eventually to the 4 fried resistors, and the cathode of the diode that
literally exploded.
A new modem will only cost a few bucks/pounds/pesatas!
Click to expand...
If the amount of money it will cost to replace it is so insignificant,
I'm sure you'll have no hesitation about sending me however much it
actually takes, will you? Let me know when you're ready, and I'll give
you my address so you can do just that...

But check
the rest of the system first.
Click to expand...
The rest of the system is working fine. Subbed a "backup" USR Sportster
where the blown one was, and it's working just fine. Thing is, the USR
Courier is a *TANK* that I'm not at all willing to just "write off".

Besides... getting this puppy back up and running may be an amusing
project, and god knows I could use one of those right now! :)

--
Don Bruder - dakidd@sonic.net <--- Preferred Email - SpamAssassinated.
Hate SPAM? See <http://www.spamassassin.org> for some seriously great info.
I will choose a path that's clear: I will choose Free Will! - N. Peart
Fly trap info pages: <http://www.sonic.net/~dakidd/Horses/FlyTrap/index.html>
 
Don Bruder wrote:
In article <Mevrb.6305$lm1.42703@wards.force9.net>,
"Graham W" <graham@his.com.puterINVALID> wrote:


MAYBE there will be further damage. I'm not as pessimistic as you seem
to be about this thing's chances. Worst case scenario: I spend a buck
or two and a few minutes, and it remains dead. Best case: It returns
to
life as good as new. I'm game to try it! :)

I'm quite aware that what I'm looking at is just the *VISIBLE* damage.
But scrapping this rig (which, in its day, was the absolute
top-of-the-line - What am I saying "in its day"? The thing was still
the best modem I've ever met until the hit that killed it.
"v.Everything" meant exactly that...) because it *MIGHT* have more
damage is an idea that's simply repugnant to me.
Click to expand...
I wonder, these days, what the old V.Everything actually runs at.
Has it actually done anything that isn't V.90 in the last few years?

A recent job I sorted saw the whole computer fried including the
screen from a strike which killed the fax machine as well as the PCI
modem!
Click to expand...
I'm glad the rest of the system is OK! I have uploaded a couple of pix:

www.gcw.org.uk/fax241.jpg (33kb)

www.gcw.org.uk/modem247.jpg (36kb)

The fax was a Philips machine, the modem was a noname PCI internal.
You can see the similarities with your description.


--
Graham W http://www.gcw.org.uk/ XP1800+ Page added, Graphics Tutorial
WIMBORNE http://www.wessex-astro-society.freeserve.co.uk/ Wessex
Dorset UK Astro Society's Web pages, Info, Meeting Dates, Sites & Maps
Change 'news' to 'sewn' in my Reply address to avoid my spam filter.
 
In article <S_Mrb.6583$lm1.45274@wards.force9.net>,
"Graham W" <graham@his.com.puterINVALID> wrote:

Don Bruder wrote:
In article <Mevrb.6305$lm1.42703@wards.force9.net>,
"Graham W" <graham@his.com.puterINVALID> wrote:


MAYBE there will be further damage. I'm not as pessimistic as you seem
to be about this thing's chances. Worst case scenario: I spend a buck
or two and a few minutes, and it remains dead. Best case: It returns
to
life as good as new. I'm game to try it! :)

I'm quite aware that what I'm looking at is just the *VISIBLE* damage.
But scrapping this rig (which, in its day, was the absolute
top-of-the-line - What am I saying "in its day"? The thing was still
the best modem I've ever met until the hit that killed it.
"v.Everything" meant exactly that...) because it *MIGHT* have more
damage is an idea that's simply repugnant to me.

I wonder, these days, what the old V.Everything actually runs at.
Has it actually done anything that isn't V.90 in the last few years?
Click to expand...
Actually, it was flashed up to v.92 within the last year or so. Although
I mostly (like 99.99% of the time) use it to hook to my ISP, which, due
to being on the end of a 20+ mile run of mixed copper and glass,
generally means 26400 connects, I like having the ABILITY to "go
anywhere, do anything" that it represents, even if I don't actually
*USE* that ability often.

A recent job I sorted saw the whole computer fried including the
screen from a strike which killed the fax machine as well as the PCI
modem!

I'm glad the rest of the system is OK! I have uploaded a couple of pix:

www.gcw.org.uk/fax241.jpg (33kb)

www.gcw.org.uk/modem247.jpg (36kb)

The fax was a Philips machine, the modem was a noname PCI internal.
You can see the similarities with your description.
Click to expand...
FWIW: There's another reason why I'll *NEVER* own an internal modem -
WAY too much potential to take out the entire machine. With externals, a
hit will take out the modem, and MIGHT (but IMExperience, never has)
take out the serial port. With internals, a hit can easily wipe the
entire machine - there's no "insulation" or "buffer" between the modem
and the computer like a serial port provides - The juice from the strike
is going DIRECTLY to the internals of the computer, with basically
nothing at all standing in its way. Sorta like the difference between
getting tagged by brushing up against 110 (or in your case, 220) with
your hand, vs. grabbing one wire from the mains in each hand - The
former hurts, sure, but it isn't likely to kill. The latter is a real
good way to get an appointment with the coroner.

Looks like that gear you played with took a much "heavier" hit than my
modem did. Aside from having the "two pin" edge of the diode blown off,
the damage in mine is visible mainly as 6 of those little surface-mount
resistors wearing "blisters" (no visible charring or anything like that
- just the paint is blistered up a bit) and a sort of "haze" on the
coating of the board at the point where it looks like the arc jumped
from one of the phone jack pads to a nearby pad that appears to be
associated with a jumper block whose purpose I once knew for sure, but
have now forgotten. (I have a foggy memory of that jumper block having
something to do with "Synchronous" vs "Asynchronous" communication from
modem to phone line.)

Anyway, those jumpers were all "open", but the trace that got jumped to
is hooked into a series of 4 resistors (marked "332" - I'm weak with
surface-mount devices - should I, as I expect, be reading those as "3300
ohms"?) that are wired back-to-back-to-back-to-back, then into the
cathode side of the exploded diode, which connects the resistors and
jumper block directly from the negative side of the bridge rectifier
that turns the juice from the wall-wart (nameplated as putting out 20
VAC @ 500 mA, measured as 21.6 VAC) into 27-ish volts of DC. (The "-ish"
is because I never got it to "settle" - it bounces around from 26.8 to
27.5 VDC according to my DMM - since there's an LT1271 regulator a bit
further downstream, I have *SERIOUS* doubts about a 0.7V variance on the
rectifier pins being significant to a switch-mode regulator that's rated
for an input voltage of +5 to +30 VDC)

On the "update" side of things, I managed to locate a "5D" diode
(actually, several dozen of them) on one of the bazillion
broken/obsolete/partially stripped boards that we've got laying around
here, and after replacing the blown one, found that there's
(Surprise...) nothing getting from the phone line into the "guts" of the
modem. I say "Surprise..." because two of the cooked resistors (both
marked "501") are connected almost directly (through a toroidal coil I
expect is a noise choke, and then through a MOV that bridges the outputs
from the coil) to the input pins from the phone line - One on each trace
that the MOV is on. So, I got out the magnifying glass and started
hunting for "501" (500 ohms, right?) SMD resistors. Of course, Murphy's
law kicked in, and I was unable to find a pair of them. So, going with
the hunch that a 30 ohm difference wouldn't be enough to mean anything,
I grabbed a couple of similar-sized resistors marked "471" (470 ohms,
right?) and replaced the two on the board (After removing them from the
circuit, both of them read as wide open on my DMM. In-circuit, I
couldn't get a reading that I'd call reliable) and tried again.

This time, what came out of the speaker sounded like crap, but at least
it was *SOMETHING* - I couldn't pick dial-tone out of the static, but
hey... I'm now better off than I was before... At least *SOME* kind of
noise is coming out of the speaker, which tells me that I've fixed one
(of who-knows-how-many-yet-to-come...) problems!

I'm suspecting that the 30 ohms I wrote off as "no big deal" might be
more important than I realized, since the "static" coming out of the
speaker now is strongly suggestive of the kind of distortion and noise
you'd get from *MASSIVELY* over-driving a speaker. Obviously, it's not
yet working...

--
Don Bruder - dakidd@sonic.net <--- Preferred Email - SpamAssassinated.
Hate SPAM? See <http://www.spamassassin.org> for some seriously great info.
I will choose a path that's clear: I will choose Free Will! - N. Peart
Fly trap info pages: <http://www.sonic.net/~dakidd/Horses/FlyTrap/index.html>
 
I have seen a lot of sterios trashed by lightning . Few were reasonably
fixable .

tim

--
.....( remove the " 6 " to e-mail reply )

"Don Bruder" <dakidd@sonic.net> wrote in message
news:k1Orb.5709$Wy2.69285@typhoon.sonic.net...
In article <S_Mrb.6583$lm1.45274@wards.force9.net>,
"Graham W" <graham@his.com.puterINVALID> wrote:

Don Bruder wrote:
In article <Mevrb.6305$lm1.42703@wards.force9.net>,
"Graham W" <graham@his.com.puterINVALID> wrote:


MAYBE there will be further damage. I'm not as pessimistic as you seem
to be about this thing's chances. Worst case scenario: I spend a buck
or two and a few minutes, and it remains dead. Best case: It returns
to
life as good as new. I'm game to try it! :)

I'm quite aware that what I'm looking at is just the *VISIBLE* damage.
But scrapping this rig (which, in its day, was the absolute
top-of-the-line - What am I saying "in its day"? The thing was still
the best modem I've ever met until the hit that killed it.
"v.Everything" meant exactly that...) because it *MIGHT* have more
damage is an idea that's simply repugnant to me.

I wonder, these days, what the old V.Everything actually runs at.
Has it actually done anything that isn't V.90 in the last few years?

Actually, it was flashed up to v.92 within the last year or so. Although
I mostly (like 99.99% of the time) use it to hook to my ISP, which, due
to being on the end of a 20+ mile run of mixed copper and glass,
generally means 26400 connects, I like having the ABILITY to "go
anywhere, do anything" that it represents, even if I don't actually
*USE* that ability often.


A recent job I sorted saw the whole computer fried including the
screen from a strike which killed the fax machine as well as the PCI
modem!

I'm glad the rest of the system is OK! I have uploaded a couple of pix:

www.gcw.org.uk/fax241.jpg (33kb)

www.gcw.org.uk/modem247.jpg (36kb)

The fax was a Philips machine, the modem was a noname PCI internal.
You can see the similarities with your description.

FWIW: There's another reason why I'll *NEVER* own an internal modem -
WAY too much potential to take out the entire machine. With externals, a
hit will take out the modem, and MIGHT (but IMExperience, never has)
take out the serial port. With internals, a hit can easily wipe the
entire machine - there's no "insulation" or "buffer" between the modem
and the computer like a serial port provides - The juice from the strike
is going DIRECTLY to the internals of the computer, with basically
nothing at all standing in its way. Sorta like the difference between
getting tagged by brushing up against 110 (or in your case, 220) with
your hand, vs. grabbing one wire from the mains in each hand - The
former hurts, sure, but it isn't likely to kill. The latter is a real
good way to get an appointment with the coroner.

Looks like that gear you played with took a much "heavier" hit than my
modem did. Aside from having the "two pin" edge of the diode blown off,
the damage in mine is visible mainly as 6 of those little surface-mount
resistors wearing "blisters" (no visible charring or anything like that
- just the paint is blistered up a bit) and a sort of "haze" on the
coating of the board at the point where it looks like the arc jumped
from one of the phone jack pads to a nearby pad that appears to be
associated with a jumper block whose purpose I once knew for sure, but
have now forgotten. (I have a foggy memory of that jumper block having
something to do with "Synchronous" vs "Asynchronous" communication from
modem to phone line.)

Anyway, those jumpers were all "open", but the trace that got jumped to
is hooked into a series of 4 resistors (marked "332" - I'm weak with
surface-mount devices - should I, as I expect, be reading those as "3300
ohms"?) that are wired back-to-back-to-back-to-back, then into the
cathode side of the exploded diode, which connects the resistors and
jumper block directly from the negative side of the bridge rectifier
that turns the juice from the wall-wart (nameplated as putting out 20
VAC @ 500 mA, measured as 21.6 VAC) into 27-ish volts of DC. (The "-ish"
is because I never got it to "settle" - it bounces around from 26.8 to
27.5 VDC according to my DMM - since there's an LT1271 regulator a bit
further downstream, I have *SERIOUS* doubts about a 0.7V variance on the
rectifier pins being significant to a switch-mode regulator that's rated
for an input voltage of +5 to +30 VDC)

On the "update" side of things, I managed to locate a "5D" diode
(actually, several dozen of them) on one of the bazillion
broken/obsolete/partially stripped boards that we've got laying around
here, and after replacing the blown one, found that there's
(Surprise...) nothing getting from the phone line into the "guts" of the
modem. I say "Surprise..." because two of the cooked resistors (both
marked "501") are connected almost directly (through a toroidal coil I
expect is a noise choke, and then through a MOV that bridges the outputs
from the coil) to the input pins from the phone line - One on each trace
that the MOV is on. So, I got out the magnifying glass and started
hunting for "501" (500 ohms, right?) SMD resistors. Of course, Murphy's
law kicked in, and I was unable to find a pair of them. So, going with
the hunch that a 30 ohm difference wouldn't be enough to mean anything,
I grabbed a couple of similar-sized resistors marked "471" (470 ohms,
right?) and replaced the two on the board (After removing them from the
circuit, both of them read as wide open on my DMM. In-circuit, I
couldn't get a reading that I'd call reliable) and tried again.

This time, what came out of the speaker sounded like crap, but at least
it was *SOMETHING* - I couldn't pick dial-tone out of the static, but
hey... I'm now better off than I was before... At least *SOME* kind of
noise is coming out of the speaker, which tells me that I've fixed one
(of who-knows-how-many-yet-to-come...) problems!

I'm suspecting that the 30 ohms I wrote off as "no big deal" might be
more important than I realized, since the "static" coming out of the
speaker now is strongly suggestive of the kind of distortion and noise
you'd get from *MASSIVELY* over-driving a speaker. Obviously, it's not
yet working...

--
Don Bruder - dakidd@sonic.net <--- Preferred Email - SpamAssassinated.
Hate SPAM? See <http://www.spamassassin.org> for some seriously great
info.
I will choose a path that's clear: I will choose Free Will! - N. Peart
Fly trap info pages:
http://www.sonic.net/~dakidd/Horses/FlyTrap/index.html
Click to expand...
 
In article <booqk0$1ha9k5$1@ID-212626.news.uni-berlin.de>,
"Tim Kettring" <tim6kettring@e-garfield.com> wrote:

I have seen a lot of sterios trashed by lightning . Few were reasonably
fixable .
Click to expand...

Gee Whiz! Ain't the internet great? Thanks for such an incredibly useful
and informative answer, Tim! What would I have ever done without your
input?

Look, seriously, I know the thing is likely dead. That doesn't mean I'm
going to shitcan it automatically. For all anybody knows at this point,
I may be able to fix it completely by finding the one critical
three-cent piece that got burnt and replacing it. Or, alternatively, I
may never get it to anything approaching functional. Either way, I'm
quite aware that lightning makes a mess of electronics, and replacing
hit items is usually easier than fixing them. That doesn't stop the
cheap bastard in me from trying.

Now, if you've got something helpful to say on the topic of
diagnosing/repairing a lightning-hit modem, I'd love to hear it. But
your top-posted one-line response that even an idiot already knows,
complete with nearly 150 lines of original text retained, isn't doing
any good whatsoever.

--
Don Bruder - dakidd@sonic.net <--- Preferred Email - SpamAssassinated.
Hate SPAM? See <http://www.spamassassin.org> for some seriously great info.
I will choose a path that's clear: I will choose Free Will! - N. Peart
Fly trap info pages: <http://www.sonic.net/~dakidd/Horses/FlyTrap/index.html>
 
Don Bruder wrote:

The SMD Code Book says 5D is a 1N914 standard diode.

ABSOLUTELY WONDERFUL!!!!!!!!!!!! HOORAY!!!! :) I've only got about a
bazillion of those laying around (in thru-hole version, of course...)
Click to expand...
But you ought to have enough room to tack on a through hole
version to at least test the thing out!

By the way - I'm with you on trying to fix the thing,
even if you fully intend to throw it in the trash can
after fixing it. You never can tell what you might
learn in the effort.


Many thanks. It helps greatly!

--
Don Bruder - dakidd@sonic.net <--- Preferred Email - SpamAssassinated.
Hate SPAM? See <http://www.spamassassin.org> for some seriously great info.
I will choose a path that's clear: I will choose Free Will! - N. Peart
Fly trap info pages: <http://www.sonic.net/~dakidd/Horses/FlyTrap/index.html
Click to expand...
 
Don Bruder wrote:
In article <S_Mrb.6583$lm1.45274@wards.force9.net>,
"Graham W" <graham@his.com.puterINVALID> wrote:

Don Bruder wrote:
In article <Mevrb.6305$lm1.42703@wards.force9.net>,
"Graham W" <graham@his.com.puterINVALID> wrote:


I'm glad the rest of the system is OK! I have uploaded a couple of
pix:

www.gcw.org.uk/fax241.jpg (33kb)

www.gcw.org.uk/modem247.jpg (36kb)

The fax was a Philips machine, the modem was a noname PCI internal.
You can see the similarities with your description.
Click to expand...
I forgot to say that in both pix, the phoneline sockets are at the top
of the picture.

FWIW: There's another reason why I'll *NEVER* own an internal modem -
WAY too much potential to take out the entire machine.
Click to expand...
Yep, I like externals, too. So much so that I put one *inside* my
computer! One of the pages in the Miscellanea->XP1800+ article
shows how I did it!
<...>
Anyway, those jumpers were all "open", but the trace that got jumped
to is hooked into a series of 4 resistors (marked "332" - I'm weak
with surface-mount devices - should I, as I expect, be reading those
as "3300 ohms"?)
Click to expand...
Yes, me too! But 332 does tie in nicely with 3,300 ohms.

<...>
On the "update" side of things, I managed to locate a "5D" diode
...
So, I got out the magnifying
glass and started hunting for "501" (500 ohms, right?) SMD resistors.
Click to expand...
I wonder if these really are resistors? Although I don't know what else
they could be - anyone?

Of course, Murphy's law kicked in, and I was unable to find a pair of
them. So, going with the hunch that a 30 ohm difference wouldn't be
enough to mean anything,
I grabbed a couple of similar-sized resistors marked "471" (470 ohms,
right?)
Click to expand...
Agreed.

and replaced the two on the board (After removing them from
the circuit, both of them read as wide open on my DMM. In-circuit, I
couldn't get a reading that I'd call reliable) and tried again.

This time, what came out of the speaker sounded like crap, but at
least it was *SOMETHING* - I couldn't pick dial-tone out of the
static, but hey... I'm now better off than I was before... At least
*SOME* kind of noise is coming out of the speaker, which tells me
that I've fixed one (of who-knows-how-many-yet-to-come...) problems!

I'm suspecting that the 30 ohms I wrote off as "no big deal" might be
more important than I realized, since the "static" coming out of the
speaker now is strongly suggestive of the kind of distortion and noise
you'd get from *MASSIVELY* over-driving a speaker. Obviously, it's not
yet working...
Click to expand...
It may also be due to those 501s not being resistors, or there being
a bad resistor that is now falling apart and injecting noise.


--
Graham W http://www.gcw.org.uk/ XP1800+ Page added, Graphics Tutorial
WIMBORNE http://www.wessex-astro-society.freeserve.co.uk/ Wessex
Dorset UK Astro Society's Web pages, Info, Meeting Dates, Sites & Maps
Change 'news' to 'sewn' in my Reply address to avoid my spam filter.
 
In article <3FB03098.45D19F4D@bellatlantic.net>, ehsjr@bellatlantic.net
wrote:

Don Bruder wrote:


The SMD Code Book says 5D is a 1N914 standard diode.

ABSOLUTELY WONDERFUL!!!!!!!!!!!! HOORAY!!!! :) I've only got about a
bazillion of those laying around (in thru-hole version, of course...)

But you ought to have enough room to tack on a through hole
version to at least test the thing out!
Click to expand...
No need... not when I found a board that has AT LEAST a dozen of the
"proper" surface-mount version on it :)

I was prepared, if neccesary, to "convert" a thru-hole package into a SM
version (with judicious lead-bending, pre-tinning, and re-flowing) to
sdo exactly what you're saying, but then I found that board (I think it
was out of a fax machine) and that plan got pitched.
By the way - I'm with you on trying to fix the thing,
even if you fully intend to throw it in the trash can
after fixing it. You never can tell what you might
learn in the effort.
Click to expand...
A big part of my reasoning - Learn what you can, when you can, however
you can. Failure is part of learning. If this little project fails...
<shrug> No biggie. It's dead already, I can't kill it any worse. BUT!!!!
If I manage to pin down the problem, a mighty fine modem is saved from
the trash-heap.

--
Don Bruder - dakidd@sonic.net <--- Preferred Email - SpamAssassinated.
Hate SPAM? See <http://www.spamassassin.org> for some seriously great info.
I will choose a path that's clear: I will choose Free Will! - N. Peart
Fly trap info pages: <http://www.sonic.net/~dakidd/Horses/FlyTrap/index.html>
 
So, I got out the magnifying
glass and started hunting for "501" (500 ohms, right?) SMD resistors.

I wonder if these really are resistors? Although I don't know what else
they could be - anyone?
Click to expand...
If it is a 2-terminal device marked with nothing more than a 3- or
4-digit code like this, then it is almost certainly a resistor.
 
In article <608b6569.0311110932.205d4b90@posting.google.com>,
larwe@larwe.com (Lewin A.R.W. Edwards) wrote:

So, I got out the magnifying
glass and started hunting for "501" (500 ohms, right?) SMD resistors.

I wonder if these really are resistors? Although I don't know what else
they could be - anyone?

If it is a 2-terminal device marked with nothing more than a 3- or
4-digit code like this, then it is almost certainly a resistor.
Click to expand...
That's what I thought... The parts in question are have black (although
they do seem to have a tiny bit of greenish tint to them) bodies, a
narrow, obviously solder-colored band at each end, and three clearly
visible digits - "501" - which I interpret, using the standard practice
that goes with decoding conventional color-banded resistors, to be "5"
followed by "0" followed by "a single 0", or 500 ohms. There is zero
possibility that the "5" is actually an upside-down "2", and I'm reading
it backwards - It's quite clearly a "5", and the "1" is most definitely
a "1" (it has a serif, albeit a small one) but only when oriented so
that the "5" is really a "5". Any other way of trying to read this thing
gives gibberish. (unless, perhaps, "20L" is supposed to be read as
something like "20 followed by 12 zeroes ohms"...)

--
Don Bruder - dakidd@sonic.net <--- Preferred Email - SpamAssassinated.
Hate SPAM? See <http://www.spamassassin.org> for some seriously great info.
I will choose a path that's clear: I will choose Free Will! - N. Peart
Fly trap info pages: <http://www.sonic.net/~dakidd/Horses/FlyTrap/index.html>
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top