A friend of mine, who is paralyzed below the neck and confined to a
wheelchair or bed, has a Doorbell-Phone intercom system with which he
communicates to whoever is ringing his doorbell before activating the
automatic door to let them in. Problem is, it apparently got zapped during
a series of storms some time back, and no longer works as an intercom. I
found a blown cap and replaced that as well as the transistor that was
driving said electrolytic cap, but it still fails to function in intercom
mode and overdrives one power resistor to the point of darkening the PC
board in that spot. Entire board seems to be built around one 18-pin DIP
chip, which I suspect is a PLL. Problem is the surface of the chip has been
planed, removing any trace of whatever identification numbers etc were once
there. Calls to Doorbell-Phone Inc. tell me that this chip is propriatary,
along with any and all knowledge of how the circuit works. Replacement
would run upwards of $200.00. Repair services are not available. So I, in
my innocent ignorance, am trying to help this guy by offering my own
half-vast espertise (weak grin) as an electronics troubleshooter.

Two 18-pin DIP PLLs come to mind: the NTE7108 and the Motorolla MC145155P.
Can anyone offer any suggestions as to how to tell if this thing even *is* a
non-working PLL? The two chips I mention above have distinctive pin-outs,
with one pin being ground in one case, and another pin being clock in the
other case. I am thinking I can check for these conditions on the
appropriate pins, but am wondering what else I can do to determing what it
is I am dealing with and want to replace. Anyone have any ideas on how one
should proceed? I am open to all suggestions/advice. Just trying to help
this friend get his intercom back in working order... If pics would hep, I
can try to get same but it is likely to be a while, with the holidays and
all.

Any help is greatly appreciated.

Dave

On Thu, 18 Dec 2008 10:30:52 -0600, "Dave" put
finger to keyboard and composed:

A friend of mine, who is paralyzed below the neck and confined to a
wheelchair or bed, has a Doorbell-Phone intercom system with which he
communicates to whoever is ringing his doorbell before activating the
automatic door to let them in. Problem is, it apparently got zapped during
a series of storms some time back, and no longer works as an intercom. I
found a blown cap and replaced that as well as the transistor that was
driving said electrolytic cap, but it still fails to function in intercom
mode and overdrives one power resistor to the point of darkening the PC
board in that spot. Entire board seems to be built around one 18-pin DIP
chip, which I suspect is a PLL. Problem is the surface of the chip has been
planed, removing any trace of whatever identification numbers etc were once
there. Calls to Doorbell-Phone Inc. tell me that this chip is propriatary,
along with any and all knowledge of how the circuit works. Replacement
would run upwards of $200.00. Repair services are not available. So I, in
my innocent ignorance, am trying to help this guy by offering my own
half-vast espertise (weak grin) as an electronics troubleshooter.

Two 18-pin DIP PLLs come to mind: the NTE7108 and the Motorolla MC145155P.
Can anyone offer any suggestions as to how to tell if this thing even *is* a
non-working PLL? The two chips I mention above have distinctive pin-outs,
with one pin being ground in one case, and another pin being clock in the
other case. I am thinking I can check for these conditions on the
appropriate pins, but am wondering what else I can do to determing what it
is I am dealing with and want to replace. Anyone have any ideas on how one
should proceed? I am open to all suggestions/advice. Just trying to help
this friend get his intercom back in working order... If pics would hep, I
can try to get same but it is likely to be a while, with the holidays and
all.

Any help is greatly appreciated.

Dave

Does your Doorbell-Phone intercom have an FCC ID?
https://gullfoss2.fcc.gov/oetcf/eas/...ericSearch.cfm

Is there a US patent number?
http://www.google.com/advanced_patent_search

If none of the above, then you will probably need to reverse engineer
the circuit. Otherwise you could try looking for similar devices at
RadioShack:

http://support.radioshack.com/produc...s&ID=002006002

The support documents may include parts lists, owner's manuals, and
exploded views. Notice that most Catalogue numbers begin with "43".

Now go to the FCC site (see above) and search for the relevant
RadioShack device.

RadioShack's Grantee Code is AAO (oh, not zero).

Type "43" or "63" in the "Product Code" box.

Type "200" in the "Show nnn Records at a Time" box.

The search results will include FCC IDs such as "43-nnnn" or "4300nnn"
or "430nnnn". Be aware that RadioShack's numbering system sometimes
converts a catalogue number such as "43-nnn" to "4300nnn".

The search results will often include circuit diagrams, block
diagrams, technical descriptions, internal and external photos, user
manuals, etc. Note that devices registered before the late 1990s may
not have any lodged documents.

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

"Dave" wrote in message
netamerica...
A friend of mine, who is paralyzed below the neck and confined to a
wheelchair or bed, has a Doorbell-Phone intercom system with which he
communicates to whoever is ringing his doorbell before activating the
automatic door to let them in. Problem is, it apparently got zapped during
a series of storms some time back, and no longer works as an intercom. I
found a blown cap and replaced that as well as the transistor that was
driving said electrolytic cap, but it still fails to function in intercom
mode and overdrives one power resistor to the point of darkening the PC
board in that spot. Entire board seems to be built around one 18-pin DIP
chip, which I suspect is a PLL. Problem is the surface of the chip has
been planed, removing any trace of whatever identification numbers etc were
once there. Calls to Doorbell-Phone Inc. tell me that this chip is
propriatary, along with any and all knowledge of how the circuit works.
Replacement would run upwards of $200.00. Repair services are not
available. So I, in my innocent ignorance, am trying to help this guy by
offering my own half-vast espertise (weak grin) as an electronics
troubleshooter.

Two 18-pin DIP PLLs come to mind: the NTE7108 and the Motorolla MC145155P.
Can anyone offer any suggestions as to how to tell if this thing even *is*
a non-working PLL? The two chips I mention above have distinctive
pin-outs, with one pin being ground in one case, and another pin being
clock in the other case. I am thinking I can check for these conditions
on the appropriate pins, but am wondering what else I can do to determing
what it is I am dealing with and want to replace. Anyone have any ideas
on how one should proceed? I am open to all suggestions/advice. Just
trying to help this friend get his intercom back in working order... If
pics would hep, I can try to get same but it is likely to be a while, with
the holidays and all.

Any help is greatly appreciated.

Dave



I think that it is highly unlikely that the IC would be a PLL in an intercom
circuit. What is it about it that led you to this dubious conclusion ? Have
you tried wiping a light film of oil across the top of the chip, and then
looking very carefully under a strong light and magnifying glass ? Often, if
they haven't gone mad with the grinder on the top of the chip, the lettering
can still be read after this 'treatment'.

Arfa

"Franc Zabkar" wrote in message
...
On Thu, 18 Dec 2008 10:30:52 -0600, "Dave" put
finger to keyboard and composed:

A friend of mine, who is paralyzed below the neck and confined to a
wheelchair or bed, has a Doorbell-Phone intercom system with which he
communicates to whoever is ringing his doorbell before activating the
automatic door to let them in. Problem is, it apparently got zapped
during
a series of storms some time back, and no longer works as an intercom. I
found a blown cap and replaced that as well as the transistor that was
driving said electrolytic cap, but it still fails to function in intercom
mode and overdrives one power resistor to the point of darkening the PC
board in that spot. Entire board seems to be built around one 18-pin DIP
chip, which I suspect is a PLL. Problem is the surface of the chip has
been
planed, removing any trace of whatever identification numbers etc were
once
there. Calls to Doorbell-Phone Inc. tell me that this chip is
propriatary,
along with any and all knowledge of how the circuit works. Replacement
would run upwards of $200.00. Repair services are not available. So I,
in
my innocent ignorance, am trying to help this guy by offering my own
half-vast espertise (weak grin) as an electronics troubleshooter.

Two 18-pin DIP PLLs come to mind: the NTE7108 and the Motorolla MC145155P.
Can anyone offer any suggestions as to how to tell if this thing even *is*
a
non-working PLL? The two chips I mention above have distinctive pin-outs,
with one pin being ground in one case, and another pin being clock in the
other case. I am thinking I can check for these conditions on the
appropriate pins, but am wondering what else I can do to determing what it
is I am dealing with and want to replace. Anyone have any ideas on how
one
should proceed? I am open to all suggestions/advice. Just trying to help
this friend get his intercom back in working order... If pics would hep,
I
can try to get same but it is likely to be a while, with the holidays and
all.

Any help is greatly appreciated.

Dave

Does your Doorbell-Phone intercom have an FCC ID?
https://gullfoss2.fcc.gov/oetcf/eas/...ericSearch.cfm

Is there a US patent number?
http://www.google.com/advanced_patent_search

If none of the above, then you will probably need to reverse engineer
the circuit. Otherwise you could try looking for similar devices at
RadioShack:

http://support.radioshack.com/produc...s&ID=002006002

The support documents may include parts lists, owner's manuals, and
exploded views. Notice that most Catalogue numbers begin with "43".

Now go to the FCC site (see above) and search for the relevant
RadioShack device.

RadioShack's Grantee Code is AAO (oh, not zero).

Type "43" or "63" in the "Product Code" box.

Type "200" in the "Show nnn Records at a Time" box.

The search results will include FCC IDs such as "43-nnnn" or "4300nnn"
or "430nnnn". Be aware that RadioShack's numbering system sometimes
converts a catalogue number such as "43-nnn" to "4300nnn".

The search results will often include circuit diagrams, block
diagrams, technical descriptions, internal and external photos, user
manuals, etc. Note that devices registered before the late 1990s may
not have any lodged documents.

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

Wow. FCC ID. Patent number. Of course. Shaking my head. Why didn't I
think of these things?

And similar devices at Radioshack. Damn! Thank you, so much! I now have a
whole slew of new possibilities to track down. Very much appreciated.

Dave

"Arfa Daily" wrote in message
...

"Dave" wrote in message
netamerica...
A friend of mine, who is paralyzed below the neck and confined to a
wheelchair or bed, has a Doorbell-Phone intercom system with which he
communicates to whoever is ringing his doorbell before activating the
automatic door to let them in. Problem is, it apparently got zapped
during a series of storms some time back, and no longer works as an
intercom. I found a blown cap and replaced that as well as the transistor
that was driving said electrolytic cap, but it still fails to function in
intercom mode and overdrives one power resistor to the point of darkening
the PC board in that spot. Entire board seems to be built around one
18-pin DIP chip, which I suspect is a PLL. Problem is the surface of the
chip has been planed, removing any trace of whatever identification
numbers etc were once there. Calls to Doorbell-Phone Inc. tell me that
this chip is propriatary, along with any and all knowledge of how the
circuit works. Replacement would run upwards of $200.00. Repair services
are not available. So I, in my innocent ignorance, am trying to help this
guy by offering my own half-vast espertise (weak grin) as an electronics
troubleshooter.

Two 18-pin DIP PLLs come to mind: the NTE7108 and the Motorolla
MC145155P. Can anyone offer any suggestions as to how to tell if this
thing even *is* a non-working PLL? The two chips I mention above have
distinctive pin-outs, with one pin being ground in one case, and another
pin being clock in the other case. I am thinking I can check for these
conditions on the appropriate pins, but am wondering what else I can do
to determing what it is I am dealing with and want to replace. Anyone
have any ideas on how one should proceed? I am open to all
suggestions/advice. Just trying to help this friend get his intercom
back in working order... If pics would hep, I can try to get same but it
is likely to be a while, with the holidays and all.

Any help is greatly appreciated.

Dave



I think that it is highly unlikely that the IC would be a PLL in an
intercom circuit. What is it about it that led you to this dubious
conclusion ? Have you tried wiping a light film of oil across the top of
the chip, and then looking very carefully under a strong light and
magnifying glass ? Often, if they haven't gone mad with the grinder on the
top of the chip, the lettering can still be read after this 'treatment'.

Arfa


Hey Arfa,

Bottom line, it's a piece of communications equipment interfacing several
different protocols, and a PLL is just what came to mind when asking myself
"What could this chip be?" It appears to be at the heart of the circuit,
and seems to be the center of activity. Do you have any other ideas as to
what this 18-pin DIP IC might be? I am seriously asking here, as I am
flying by the seat of my pants.

BTW, the top 1 or 2 thousandths of an inch of the DIP IC were literrally
planed off, and there does not appear to be any remnents of it's identifying
marks. I'll try the light coat of oil idea along with a bright light and
magnifying glass, but recent attempts with something similar turned up a
completely smooth surface.

Thanks,

Dave

Arfa Daily wrote in message
...

"Dave" wrote in message
netamerica...
A friend of mine, who is paralyzed below the neck and confined to a
wheelchair or bed, has a Doorbell-Phone intercom system with which he
communicates to whoever is ringing his doorbell before activating the
automatic door to let them in. Problem is, it apparently got zapped
during
a series of storms some time back, and no longer works as an intercom. I
found a blown cap and replaced that as well as the transistor that was
driving said electrolytic cap, but it still fails to function in intercom
mode and overdrives one power resistor to the point of darkening the PC
board in that spot. Entire board seems to be built around one 18-pin DIP
chip, which I suspect is a PLL. Problem is the surface of the chip has
been planed, removing any trace of whatever identification numbers etc
were
once there. Calls to Doorbell-Phone Inc. tell me that this chip is
propriatary, along with any and all knowledge of how the circuit works.
Replacement would run upwards of $200.00. Repair services are not
available. So I, in my innocent ignorance, am trying to help this guy by
offering my own half-vast espertise (weak grin) as an electronics
troubleshooter.

Two 18-pin DIP PLLs come to mind: the NTE7108 and the Motorolla
MC145155P.
Can anyone offer any suggestions as to how to tell if this thing even
*is*
a non-working PLL? The two chips I mention above have distinctive
pin-outs, with one pin being ground in one case, and another pin being
clock in the other case. I am thinking I can check for these conditions
on the appropriate pins, but am wondering what else I can do to
determing
what it is I am dealing with and want to replace. Anyone have any ideas
on how one should proceed? I am open to all suggestions/advice. Just
trying to help this friend get his intercom back in working order... If
pics would hep, I can try to get same but it is likely to be a while,
with
the holidays and all.

Any help is greatly appreciated.

Dave



I think that it is highly unlikely that the IC would be a PLL in an
intercom
circuit. What is it about it that led you to this dubious conclusion ?
Have
you tried wiping a light film of oil across the top of the chip, and then
looking very carefully under a strong light and magnifying glass ? Often,
if
they haven't gone mad with the grinder on the top of the chip, the
lettering
can still be read after this 'treatment'.

Arfa



In similar vein
This tip of mine may be worth a try

How to read unreadable IC/transistor lettering
Yes, just like magic.
I could not read 3 of the 5 characters on a heat damaged TOP66 power
transistor.
I wondered if a sort of "brass rubbing" would work.
I just happened to have some plumber's PTFE tape to hand ( nominal 0.05 to
0.08 mm thick).
Laid a piece over the power tranny, rubbed with a finger nail, and the
missing characters
came up like magic.
As the characters remained on the PTFE, as an image , I realised you could
use this technique to read IC lettering where it is imppossible to read,
because of constrictions and inability to introduce an inspection mirror or
even just
where you cannot get the illumination at just the right angle to read.
You need access space enough to introduce a piece of PTFE and then rub it
with the wooden end of a small artist's brush, or similar, wrapped in some
of the PTFE, so it rubs easily without dragging.
Don't rub too firmly because you want the relief print to show as clear and
the rest of the PTFE becoming translucent rather than the original white.
Remove and read with a backlight or against something matt black. Maybe a
couple of attempts to get a clear image in all parts of the label.
May even be worth trying on reverse-engineering-proofed, rubbed off, IC
lettering. Useful for indistinct moulding logos /
lettering etc on small plastic parts, gives some contrast.
Confirmed - this time a SIL IC with
the lettering side of the IC 2 mm from a large block cap. Would have
required 3 hours taking boards apart and back together to desolder just
to read.
Used a 1mm steel rod covered with some PTFE tape for the "rubbing" and
pulling
a length of PTFE tight around the IC through the gap,
and held tight while rubbing. I urge everyone to give it
a try, so it is impressed on memory fo rwhen required in earnest, its just
like magic



--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Dave wrote in message
netamerica...
A friend of mine, who is paralyzed below the neck and confined to a
wheelchair or bed, has a Doorbell-Phone intercom system with which he
communicates to whoever is ringing his doorbell before activating the
automatic door to let them in. Problem is, it apparently got zapped
during
a series of storms some time back, and no longer works as an intercom. I
found a blown cap and replaced that as well as the transistor that was
driving said electrolytic cap, but it still fails to function in intercom
mode and overdrives one power resistor to the point of darkening the PC
board in that spot. Entire board seems to be built around one 18-pin DIP
chip, which I suspect is a PLL. Problem is the surface of the chip has
been
planed, removing any trace of whatever identification numbers etc were
once
there. Calls to Doorbell-Phone Inc. tell me that this chip is
propriatary,
along with any and all knowledge of how the circuit works. Replacement
would run upwards of $200.00. Repair services are not available. So I,
in
my innocent ignorance, am trying to help this guy by offering my own
half-vast espertise (weak grin) as an electronics troubleshooter.

Two 18-pin DIP PLLs come to mind: the NTE7108 and the Motorolla MC145155P.
Can anyone offer any suggestions as to how to tell if this thing even *is*
a
non-working PLL? The two chips I mention above have distinctive pin-outs,
with one pin being ground in one case, and another pin being clock in the
other case. I am thinking I can check for these conditions on the
appropriate pins, but am wondering what else I can do to determing what it
is I am dealing with and want to replace. Anyone have any ideas on how
one
should proceed? I am open to all suggestions/advice. Just trying to help
this friend get his intercom back in working order... If pics would hep,
I
can try to get same but it is likely to be a while, with the holidays and
all.

Any help is greatly appreciated.

Dave




Of course , if it was proprietary then there is little point in removing the
lettering.
Start by identifying rail pins, oscillator or clock pin .
Why a PLL , is it mains bourne carrier ?


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

"N_Cook" wrote in message
...
Arfa Daily wrote in message
...

"Dave" wrote in message
netamerica...
A friend of mine, who is paralyzed below the neck and confined to a
wheelchair or bed, has a Doorbell-Phone intercom system with which he
communicates to whoever is ringing his doorbell before activating the
automatic door to let them in. Problem is, it apparently got zapped
during
a series of storms some time back, and no longer works as an intercom.
I
found a blown cap and replaced that as well as the transistor that was
driving said electrolytic cap, but it still fails to function in
intercom
mode and overdrives one power resistor to the point of darkening the PC
board in that spot. Entire board seems to be built around one 18-pin
DIP
chip, which I suspect is a PLL. Problem is the surface of the chip has
been planed, removing any trace of whatever identification numbers etc
were
once there. Calls to Doorbell-Phone Inc. tell me that this chip is
propriatary, along with any and all knowledge of how the circuit works.
Replacement would run upwards of $200.00. Repair services are not
available. So I, in my innocent ignorance, am trying to help this guy
by
offering my own half-vast espertise (weak grin) as an electronics
troubleshooter.

Two 18-pin DIP PLLs come to mind: the NTE7108 and the Motorolla
MC145155P.
Can anyone offer any suggestions as to how to tell if this thing even
*is*
a non-working PLL? The two chips I mention above have distinctive
pin-outs, with one pin being ground in one case, and another pin being
clock in the other case. I am thinking I can check for these
conditions
on the appropriate pins, but am wondering what else I can do to
determing
what it is I am dealing with and want to replace. Anyone have any
ideas
on how one should proceed? I am open to all suggestions/advice. Just
trying to help this friend get his intercom back in working order...
If
pics would hep, I can try to get same but it is likely to be a while,
with
the holidays and all.

Any help is greatly appreciated.

Dave



I think that it is highly unlikely that the IC would be a PLL in an
intercom
circuit. What is it about it that led you to this dubious conclusion ?
Have
you tried wiping a light film of oil across the top of the chip, and then
looking very carefully under a strong light and magnifying glass ? Often,
if
they haven't gone mad with the grinder on the top of the chip, the
lettering
can still be read after this 'treatment'.

Arfa



In similar vein
This tip of mine may be worth a try

How to read unreadable IC/transistor lettering
Yes, just like magic.
I could not read 3 of the 5 characters on a heat damaged TOP66 power
transistor.
I wondered if a sort of "brass rubbing" would work.
I just happened to have some plumber's PTFE tape to hand ( nominal 0.05 to
0.08 mm thick).
Laid a piece over the power tranny, rubbed with a finger nail, and the
missing characters
came up like magic.
As the characters remained on the PTFE, as an image , I realised you could
use this technique to read IC lettering where it is imppossible to read,
because of constrictions and inability to introduce an inspection mirror
or
even just
where you cannot get the illumination at just the right angle to read.
You need access space enough to introduce a piece of PTFE and then rub it
with the wooden end of a small artist's brush, or similar, wrapped in some
of the PTFE, so it rubs easily without dragging.
Don't rub too firmly because you want the relief print to show as clear
and
the rest of the PTFE becoming translucent rather than the original white.
Remove and read with a backlight or against something matt black. Maybe a
couple of attempts to get a clear image in all parts of the label.
May even be worth trying on reverse-engineering-proofed, rubbed off, IC
lettering. Useful for indistinct moulding logos /
lettering etc on small plastic parts, gives some contrast.
Confirmed - this time a SIL IC with
the lettering side of the IC 2 mm from a large block cap. Would have
required 3 hours taking boards apart and back together to desolder just
to read.
Used a 1mm steel rod covered with some PTFE tape for the "rubbing" and
pulling
a length of PTFE tight around the IC through the gap,
and held tight while rubbing. I urge everyone to give it
a try, so it is impressed on memory fo rwhen required in earnest, its just
like magic



--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/



YES! YES! This reallly does work like magic. And this is what I tried, but
the surface was totally and completely smooth. No marks of any kind... But
thanks for the posting. Was trying to figure out how to tell what I tried.
This was it. And thanks for the idea/tip in the first place. Have used it
many times.

Dave

"N_Cook" wrote in message
...
Dave wrote in message
netamerica...
A friend of mine, who is paralyzed below the neck and confined to a
wheelchair or bed, has a Doorbell-Phone intercom system with which he
communicates to whoever is ringing his doorbell before activating the
automatic door to let them in. Problem is, it apparently got zapped
during
a series of storms some time back, and no longer works as an intercom. I
found a blown cap and replaced that as well as the transistor that was
driving said electrolytic cap, but it still fails to function in intercom
mode and overdrives one power resistor to the point of darkening the PC
board in that spot. Entire board seems to be built around one 18-pin DIP
chip, which I suspect is a PLL. Problem is the surface of the chip has
been
planed, removing any trace of whatever identification numbers etc were
once
there. Calls to Doorbell-Phone Inc. tell me that this chip is
propriatary,
along with any and all knowledge of how the circuit works. Replacement
would run upwards of $200.00. Repair services are not available. So I,
in
my innocent ignorance, am trying to help this guy by offering my own
half-vast espertise (weak grin) as an electronics troubleshooter.

Two 18-pin DIP PLLs come to mind: the NTE7108 and the Motorolla
MC145155P.
Can anyone offer any suggestions as to how to tell if this thing even
*is*
a
non-working PLL? The two chips I mention above have distinctive
pin-outs,
with one pin being ground in one case, and another pin being clock in the
other case. I am thinking I can check for these conditions on the
appropriate pins, but am wondering what else I can do to determing what
it
is I am dealing with and want to replace. Anyone have any ideas on how
one
should proceed? I am open to all suggestions/advice. Just trying to
help
this friend get his intercom back in working order... If pics would hep,
I
can try to get same but it is likely to be a while, with the holidays and
all.

Any help is greatly appreciated.

Dave




Of course , if it was proprietary then there is little point in removing
the
lettering.
Start by identifying rail pins, oscillator or clock pin .
Why a PLL , is it mains bourne carrier ?


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/





Hello again,

I'm not sure what you are asking, here. What is "mains bourne carrier"? Is
that a manufacturer? I thought it might be a PLL because of the application
it is used in, which is a piece of communications equipment interfacing
several protocols (it links in with the other controlls he activates by
voice command from his bed or wheelchair. A very complex setup.)

Dave

Dave wrote:

"N_Cook" wrote:

Of course , if it was proprietary then there is little point in removing
the lettering.


The markings are ground off to prevent someone from directly stealing
a design, or from stealing reels of parts and reselling them.


Start by identifying rail pins, oscillator or clock pin .




Why a PLL , is it mains bourne carrier ?


PLLs are common in any multi channel communications device these
days. They are a lot cheaper than a handful of separate crystals, and
only one or two oscillators have to be tweaked during final testing.


Hello again,

I'm not sure what you are asking, here. What is "mains bourne carrier"?

Over the power line, AKA as 'Carrier Current'.

Is
that a manufacturer? I thought it might be a PLL because of the application
it is used in, which is a piece of communications equipment interfacing
several protocols (it links in with the other controlls he activates by
voice command from his bed or wheelchair. A very complex setup.)

Dave


--
http://improve-usenet.org/index.html

aioe.org, Goggle Groups, and Web TV users must request to be white
listed, or I will not see your messages.

If you have broadband, your ISP may have a NNTP news server included in
your account: http://www.usenettools.net/ISP.htm


There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.

Dave wrote:
I'm not sure what you are asking, here. What is "mains bourne carrier"? Is
that a manufacturer? I thought it might be a PLL because of the application
it is used in, which is a piece of communications equipment interfacing
several protocols (it links in with the other controlls he activates by
voice command from his bed or wheelchair. A very complex setup.)

Don't think you mean PLL - "phase locked loop" somehow. What do you
think PLL is an acronym of?

Perhaps your previous experience of ripping radio equipment apart has
been to stop at the spider thing and call it a "PLL", as the radio
jobbie is lacking several crystals so that's what it must be (among
other things) - but there are many things with multiple legs doing
multiple things in most bits of kit now.

The chip is probably an ASIC "application specific integrated circuit"
or possibly some variant of microcontroller.

--
Adrian C

"Adrian C" wrote in message
...
Dave wrote:
I'm not sure what you are asking, here. What is "mains bourne carrier"?
Is that a manufacturer? I thought it might be a PLL because of the
application it is used in, which is a piece of communications equipment
interfacing several protocols (it links in with the other controlls he
activates by voice command from his bed or wheelchair. A very complex
setup.)

Don't think you mean PLL - "phase locked loop" somehow. What do you think
PLL is an acronym of?

Um, I am indeed thinking "Phase Locked Loop."


Perhaps your previous experience of ripping radio equipment apart has been
to stop at the spider thing and call it a "PLL", as the radio jobbie is
lacking several crystals so that's what it must be (among other things) -
but there are many things with multiple legs doing multiple things in most
bits of kit now.

The chip is probably an ASIC "application specific integrated circuit" or
possibly some variant of microcontroller.

I was thinking that they used a more or less commonly availale part and
planed the numbers off to frustrate people like me, trying to fix the stupid
thing. They don't offer service/repair, only sales of new units.

Thanks,

Dave


--
Adrian C

"Dave" wrote in message
netamerica...

"Adrian C" wrote in message
...
Dave wrote:
I'm not sure what you are asking, here. What is "mains bourne carrier"?
Is that a manufacturer? I thought it might be a PLL because of the
application it is used in, which is a piece of communications equipment
interfacing several protocols (it links in with the other controlls he
activates by voice command from his bed or wheelchair. A very complex
setup.)

Don't think you mean PLL - "phase locked loop" somehow. What do you think
PLL is an acronym of?

Um, I am indeed thinking "Phase Locked Loop."


Perhaps your previous experience of ripping radio equipment apart has
been to stop at the spider thing and call it a "PLL", as the radio jobbie
is lacking several crystals so that's what it must be (among other
things) - but there are many things with multiple legs doing multiple
things in most bits of kit now.

The chip is probably an ASIC "application specific integrated circuit" or
possibly some variant of microcontroller.

I was thinking that they used a more or less commonly availale part and
planed the numbers off to frustrate people like me, trying to fix the
stupid thing. They don't offer service/repair, only sales of new units.

Thanks,

Dave


--
Adrian C



Like the others, I'm still struggling to associate a PLL with the
application. The chip could be almost anything from an ASIC as Adrian
suggests, through microcontrollers like PICs and similar, to an audio preamp
or even a logic IC. PLLs are used typically where a frequency needs to be
kept stable by being locked to some other frequency source, or where a
number of frequencies need to be generated with the change between them
being quick and easy, or under uP control, such as in a multi-channel radio
transceiver, or sometimes for the purposes of demodulating an FM signal.

The reason that you were asked if it is a mains-borne system, is that
sometimes, household mains (U.S. line power) wiring is used to communicate
between several units which are remotely located from one another. To do
this, a high frequency carrier is generated. This is then modulated by the
comms data, and then injected into the household power wiring by the master
control unit. 'Slave' units are then plugged in at wherever they are needed,
and these are able to pick off the HF carrier, demodulate the code stream,
and determine if the data being sent is for them.

The HF carrier is quite likely to be generated using a PLL, and the code
demodulator at the slave may well also use one.

As for your contention that a power resistor is being overdriven by the
problem to the point that it is scorching the board, this is probably a red
herring. Power resistors often scorch boards when operating completely
within their specs, particularly if the board substrate is an SRBP type.

What was actually wrong with the cap which you replaced ? It is rare for
electrolytic caps to 'blow' as a result of any external influence like
storms. Is this board too complicated to rev-eng so that you can get a
better idea of what the circuitry on it is ? If it's not too big /
complicated, it's sometimes possible to use a flatbed scanner to take a
picture of the print side, and then to draw in the components by hand as
circuit symbols. It's then not especially difficult, if a little tedious, to
derive a basic schematic. If you could take a photo of the board and post it
somewhere, it might give us all a bit more of a clue about the support
components around the chip, which may help to at least identify its basic
function.

Arfa

On Fri, 19 Dec 2008 16:25:59 -0000, "Arfa Daily"
put finger to keyboard and composed:

Like the others, I'm still struggling to associate a PLL with the
application. The chip could be almost anything from an ASIC as Adrian
suggests, through microcontrollers like PICs and similar, to an audio preamp
or even a logic IC. PLLs are used typically where a frequency needs to be
kept stable by being locked to some other frequency source, or where a
number of frequencies need to be generated with the change between them
being quick and easy, or under uP control, such as in a multi-channel radio
transceiver, or sometimes for the purposes of demodulating an FM signal.

The reason that you were asked if it is a mains-borne system, is that
sometimes, household mains (U.S. line power) wiring is used to communicate
between several units which are remotely located from one another. To do
this, a high frequency carrier is generated. This is then modulated by the
comms data, and then injected into the household power wiring by the master
control unit. 'Slave' units are then plugged in at wherever they are needed,
and these are able to pick off the HF carrier, demodulate the code stream,
and determine if the data being sent is for them.

The HF carrier is quite likely to be generated using a PLL, and the code
demodulator at the slave may well also use one.

I've had a look at the parts lists for various Radioshack intercoms.
Many of the "mains-borne" designs appear to use an LM567 and an
MC14069. Some also have an LM386 amp to drive the speaker. The carrier
frequency appears to be 200kHz. One could expect that these intercoms
would require additional ICs which are not included in the parts
lists. For example, there may be surface mounted types which cannot be
supplied as spares. However, ISTR taking apart one of these intercoms
a few years ago and I don't recall seeing anything particularly
complicated. In fact the datasheet for the LM567/NE567 suggests that
this IC can function as a "carrier-current remote control or
intercom":

http://www.datasheetarchive.com/pdf-...Book-35220.pdf

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

"Arfa Daily" wrote in message
...

"Dave" wrote in message
netamerica...

"Adrian C" wrote in message
...
Dave wrote:
I'm not sure what you are asking, here. What is "mains bourne
carrier"? Is that a manufacturer? I thought it might be a PLL because
of the application it is used in, which is a piece of communications
equipment interfacing several protocols (it links in with the other
controlls he activates by voice command from his bed or wheelchair. A
very complex setup.)

Don't think you mean PLL - "phase locked loop" somehow. What do you
think PLL is an acronym of?

Um, I am indeed thinking "Phase Locked Loop."


Perhaps your previous experience of ripping radio equipment apart has
been to stop at the spider thing and call it a "PLL", as the radio
jobbie is lacking several crystals so that's what it must be (among
other things) - but there are many things with multiple legs doing
multiple things in most bits of kit now.

The chip is probably an ASIC "application specific integrated circuit"
or possibly some variant of microcontroller.

I was thinking that they used a more or less commonly availale part and
planed the numbers off to frustrate people like me, trying to fix the
stupid thing. They don't offer service/repair, only sales of new units.

Thanks,

Dave


--
Adrian C



Like the others, I'm still struggling to associate a PLL with the
application. The chip could be almost anything from an ASIC as Adrian
suggests, through microcontrollers like PICs and similar, to an audio
preamp or even a logic IC. PLLs are used typically where a frequency needs
to be kept stable by being locked to some other frequency source, or where
a number of frequencies need to be generated with the change between them
being quick and easy, or under uP control, such as in a multi-channel
radio transceiver, or sometimes for the purposes of demodulating an FM
signal.

The reason that you were asked if it is a mains-borne system, is that
sometimes, household mains (U.S. line power) wiring is used to communicate
between several units which are remotely located from one another. To do
this, a high frequency carrier is generated. This is then modulated by the
comms data, and then injected into the household power wiring by the
master control unit. 'Slave' units are then plugged in at wherever they
are needed, and these are able to pick off the HF carrier, demodulate the
code stream, and determine if the data being sent is for them.

The HF carrier is quite likely to be generated using a PLL, and the code
demodulator at the slave may well also use one.

As for your contention that a power resistor is being overdriven by the
problem to the point that it is scorching the board, this is probably a
red herring. Power resistors often scorch boards when operating completely
within their specs, particularly if the board substrate is an SRBP type.

What was actually wrong with the cap which you replaced ? It is rare for
electrolytic caps to 'blow' as a result of any external influence like
storms. Is this board too complicated to rev-eng so that you can get a
better idea of what the circuitry on it is ? If it's not too big /
complicated, it's sometimes possible to use a flatbed scanner to take a
picture of the print side, and then to draw in the components by hand as
circuit symbols. It's then not especially difficult, if a little tedious,
to derive a basic schematic. If you could take a photo of the board and
post it somewhere, it might give us all a bit more of a clue about the
support components around the chip, which may help to at least identify
its basic function.

Arfa



Hey again,

Hard to know where to start, but I suppose I should begin here by mentioning
that this intercom unit interfaces with the microprocessor controlled device
over his bed (called a Quartet) which gives him control over the opening of
the door, the operation of his telephone (to answer or make calls) and a
host of other tasks, all by voice operated control. It is more than a
simple intercom, even if that's what I call it. Doorbell-Phone is the name
of the company that manufactures/sells this device. I forget the model
number. I will see if I can get a picure of the board to upload to A.B.S.E.
As for the power resistor, it appears to be a five-watt or so, but seems to
be dissipating something like 25 to 30 watts of power. The cap, if I recall
correctly, appeared to have overheated. Originally thought it was probably
shorted and that replacement would correct the failure. Replacement only
put a new (also high-temp) cap in it's place. Also replaced the
audio-amplifier transistor associated with that cap, and observed that the
overheating resistor was still far, far too hot to touch. The two resistors
next to that one, of similar type, were barely warm. Following the circuit
back from the resistor/cap/transistor led me to the 18-pin IC in question.
And I could easily be wrong about it being a PLL. I honestly forget now
what led me to that conclusion, as it has been several weeks since I last
worked on the device. I am hoping to get my scope down there and check the
one pin for a clock pulse and the other for continuity with ground to see if
it *could* be either of the two PLLs I have identified as possible
replacements for that chip. If that doesn't pan out, I'm out of ideas. As
you point out, it *could* be nearly anything.

Thanks,

Dave

Dave wrote in message
news

"Arfa Daily" wrote in message
...

"Dave" wrote in message
netamerica...

"Adrian C" wrote in message
...
Dave wrote:

Hey again,

Hard to know where to start, but I suppose I should begin here by
mentioning
that this intercom unit interfaces with the microprocessor controlled
device
over his bed (called a Quartet) which gives him control over the opening
of
the door, the operation of his telephone (to answer or make calls) and a
host of other tasks, all by voice operated control. It is more than a
simple intercom, even if that's what I call it. Doorbell-Phone is the
name
of the company that manufactures/sells this device. I forget the model
number. I will see if I can get a picure of the board to upload to
A.B.S.E.
As for the power resistor, it appears to be a five-watt or so, but seems
to
be dissipating something like 25 to 30 watts of power. The cap, if I
recall
correctly, appeared to have overheated. Originally thought it was
probably
shorted and that replacement would correct the failure. Replacement only
put a new (also high-temp) cap in it's place. Also replaced the
audio-amplifier transistor associated with that cap, and observed that the
overheating resistor was still far, far too hot to touch. The two
resistors
next to that one, of similar type, were barely warm. Following the
circuit
back from the resistor/cap/transistor led me to the 18-pin IC in question.
And I could easily be wrong about it being a PLL. I honestly forget now
what led me to that conclusion, as it has been several weeks since I last
worked on the device. I am hoping to get my scope down there and check
the
one pin for a clock pulse and the other for continuity with ground to see
if
it *could* be either of the two PLLs I have identified as possible
replacements for that chip. If that doesn't pan out, I'm out of ideas.
As
you point out, it *could* be nearly anything.

Thanks,

Dave




If zapped by electrical storm , why is most of the system still working?
Please put any pics on a proper website,eg the the one I use below is quick
and easy to set up, at no cost.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/