Why do triggers always die on o-scopes ?
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Why do triggers always die on o-scopes ?

 
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Tim Kett
Guest
Posted: Wed Feb 09, 2005 8:41 am    Post subject: Why do triggers always die on o-scopes ? Reply with quote
Seems like with every oscilloscope brand i have ever used, the triggers are
always the first thing to quit, not just on me, but on most everyone.

I have never overvoltaged any of the ranges on my Protech, but now it is
worth a cinder-block, and it was the best triggering scope I ever used.

I wonder what takes out triggers for little/no reason ?

Thankfully, the rest of it works, so i just have to find my schematic for
it.

Maybe the diagram will reveal why the triggers always die so fast.

Back to top
N Cook
Guest
Posted: Wed Feb 09, 2005 8:41 am    Post subject: Re: Why do triggers always die on o-scopes ? Reply with quote
"Tim Kett" <timkettring@e-garfield.com> wrote in message
news:01c50e6b$714d2d60$a0fae504@toni...
Quote:

Seems like with every oscilloscope brand i have ever used, the triggers
are
always the first thing to quit, not just on me, but on most everyone.

I have never overvoltaged any of the ranges on my Protech, but now it is
worth a cinder-block, and it was the best triggering scope I ever used.

I wonder what takes out triggers for little/no reason ?

Thankfully, the rest of it works, so i just have to find my schematic for
it.

Maybe the diagram will reveal why the triggers always die so fast.


I have to disagree - HV sections fail more commonly in my experience.
Not surprising as highly stressed area. Trigger problems often due to
failure
of ps caps letting mains 'hum' partially into the system and confusing the
trigger to respond. Or failure of FETs going into parasitic oscillation in
the
trigger area and again falsely triggering. But I would not say I found
trigger probs
a common occurance out of all scope fault conditions.

electronic hints and repair briefs , schematics/manuals list on
http://homepages.tcp.co.uk/~diverse
Back to top
mike
Guest
Posted: Wed Feb 09, 2005 5:41 pm    Post subject: Re: Why do triggers always die on o-scopes ? Reply with quote
Tim Kett wrote:
Quote:
Seems like with every oscilloscope brand i have ever used, the triggers are
always the first thing to quit, not just on me, but on most everyone.

I have never overvoltaged any of the ranges on my Protech, but now it is
worth a cinder-block, and it was the best triggering scope I ever used.

I wonder what takes out triggers for little/no reason ?

Thankfully, the rest of it works, so i just have to find my schematic for
it.

Maybe the diagram will reveal why the triggers always die so fast.


Not been my experience.
But as to why, they're probably the closest tolerance fastest part of
the system. Drift can put them at the wrong operating point. And if
there's a TD in there, that can be the weak link.
mike

--
Return address is VALID.
Wanted, PCMCIA SCSI Card for HP m820 CDRW.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
http://nm7u.tripod.com/homepage/te.html
Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
Bunch of stuff For Sale and Wanted at the link below.
http://www.geocities.com/SiliconValley/Monitor/4710/

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Bob Parker
Guest
Posted: Wed Feb 09, 2005 9:14 pm    Post subject: Re: Why do triggers always die on o-scopes ? Reply with quote
Interesting, because my 1968 vintage BWD521 used to have the best
triggering around, and now it's basically useless. With all the
components drifting in a big way, it's really not worth trying to
restore an instrument that old.
I should point out that the power supply and EHT sections gave a
lot of trouble before the triggering slowly died...

Bob


"Tim Kett" <timkettring@e-garfield.com> wrote:

Quote:

Seems like with every oscilloscope brand i have ever used, the triggers are
always the first thing to quit, not just on me, but on most everyone.

I have never overvoltaged any of the ranges on my Protech, but now it is
worth a cinder-block, and it was the best triggering scope I ever used.

I wonder what takes out triggers for little/no reason ?

Thankfully, the rest of it works, so i just have to find my schematic for
it.

Maybe the diagram will reveal why the triggers always die so fast.
Back to top
Tim Kett
Guest
Posted: Thu Feb 10, 2005 7:33 am    Post subject: Re: Why do triggers always die on o-scopes ? Reply with quote
mike <spamme0@netscape.net> wrote in article <4209F6EF.705@netscape.net>...
Quote:
Tim Kett wrote:
Seems like with every oscilloscope brand i have ever used, the triggers
are
always the first thing to quit, not just on me, but on most everyone.

I have never overvoltaged any of the ranges on my Protech, but now it
is
worth a cinder-block, and it was the best triggering scope I ever used.

I wonder what takes out triggers for little/no reason ?

Thankfully, the rest of it works, so i just have to find my schematic
for
it.

Maybe the diagram will reveal why the triggers always die so fast.


Not been my experience.
But as to why, they're probably the closest tolerance fastest part of
the system. Drift can put them at the wrong operating point. And if
there's a TD in there, that can be the weak link.
mike


Well, I will consider myself blessed/lucky, because it looks like all the
parts are easily obtainable, or at least substitutable at worst case, and
be glad it in only a trigger problem !

Just curious, What is a TD ??? Toshiba device (IC) ? Thermal Dielectric ?

Glad i have a decent servicable unit, and decent service lit that is
included in Owners Manual !!! - so it is almost sure to be saved, easily,
and reasonably cheaply !!!

Quote:
Return address is VALID.
Wanted, PCMCIA SCSI Card for HP m820 CDRW.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
http://nm7u.tripod.com/homepage/te.html
Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
Bunch of stuff For Sale and Wanted at the link below.
http://www.geocities.com/SiliconValley/Monitor/4710/

Back to top
Tim Kett
Guest
Posted: Thu Feb 10, 2005 7:45 am    Post subject: Re: Why do triggers always die on o-scopes ? Reply with quote
N Cook <diverse2@tcp.co.antyspahm.uk> wrote in article
<6u2dnWzFE_BlWZTfRVn-1w@tcp.co.uk>...
Quote:
"Tim Kett" <timkettring@e-garfield.com> wrote in message
news:01c50e6b$714d2d60$a0fae504@toni...

Seems like with every oscilloscope brand i have ever used, the triggers
are
always the first thing to quit, not just on me, but on most everyone.

I have never overvoltaged any of the ranges on my Protech, but now it
is
worth a cinder-block, and it was the best triggering scope I ever used.

I wonder what takes out triggers for little/no reason ?

Thankfully, the rest of it works, so i just have to find my schematic
for
it.

Maybe the diagram will reveal why the triggers always die so fast.


I have to disagree - HV sections fail more commonly in my experience.

Thank god its not HV trouble !!!

Quote:
Not surprising as highly stressed area. Trigger problems often due to
failure
of ps caps letting mains 'hum' partially into the system and confusing
the
trigger to respond.
Or failure of FETs going into parasitic oscillation in
the
trigger area and again falsely triggering. But I would not say I found
trigger probs
a common occurance out of all scope fault conditions.

OK, Thanks !!! i will fix my $1000 "cinderblock" yet !!! :-)

Quote:
electronic hints and repair briefs , schematics/manuals list on
http://homepages.tcp.co.uk/~diverse




Back to top
budgie
Guest
Posted: Thu Feb 10, 2005 7:53 am    Post subject: Re: Why do triggers always die on o-scopes ? Reply with quote
On 9 Feb 2005 05:46:24 GMT, "Tim Kett" <timkettring@e-garfield.com> wrote:

Quote:

Seems like with every oscilloscope brand i have ever used, the triggers are
always the first thing to quit, not just on me, but on most everyone.

I have never overvoltaged any of the ranges on my Protech, but now it is
worth a cinder-block, and it was the best triggering scope I ever used.

I wonder what takes out triggers for little/no reason ?

I've just finished an exhaustive rebuild of a non-working Telequipment D32
portable (AC/battery) CRO. Triggering circuitry was an issue, but only because
this instrument uses "eyelets" as pcb vias, so there were a zillion dry joints
in every area. But at nearly 30 years of age it is now performing like new,
triggering nicely - although the trigger circuit logic is weird and contorted.

Like Bob, I have a(nother) CRO which is 30 years old this year - Trio/Kenwood.
Touch wood, it has run fault free since new and triggers very nicely.

I guess these don't help your stats - 0 faults in triggering circuits out of 0
total (discounting dry joints as faults).
Back to top
Tim Kett
Guest
Posted: Thu Feb 10, 2005 8:41 am    Post subject: Re: Why do triggers always die on o-scopes ? Reply with quote
budgie <me@privacy.net> wrote in article
<c9fl01lribl747hmc7nn6ktbmdnprrc9d7@4ax.com>...
Quote:
On 9 Feb 2005 05:46:24 GMT, "Tim Kett" <timkettring@e-garfield.com
wrote:


Seems like with every oscilloscope brand i have ever used, the triggers
are
always the first thing to quit, not just on me, but on most everyone.

I have never overvoltaged any of the ranges on my Protech, but now it is
worth a cinder-block, and it was the best triggering scope I ever used.

I wonder what takes out triggers for little/no reason ?

I've just finished an exhaustive rebuild of a non-working Telequipment
D32
portable (AC/battery) CRO. Triggering circuitry was an issue, but only
because
this instrument uses "eyelets" as pcb vias, so there were a zillion dry
joints
in every area. But at nearly 30 years of age it is now performing like
new,
triggering nicely - although the trigger circuit logic is weird and
contorted.


A friend ( avionics repair shop boss ) soldered "bellwire" through those on
a TV ( in spare time at home ), and it took all day, but he fixed it. Not
really worth it for just a 13 inch, but he just wanted to see if it would
repair it.

Quote:
Like Bob, I have a(nother) CRO which is 30 years old this year -
Trio/Kenwood.
Touch wood, it has run fault free since new and triggers very nicely.

I guess these don't help your stats - 0 faults in triggering circuits out
of 0
total (discounting dry joints as faults).


Maybe half the calibration people didnt check the triggers on the
Tectronics o-scope plugins where i worked ?

In any event, I will fix this Protek p-2560, and consider myself lucky !!!
:-)

Even though i never worked on any o-scope. Sure beats the heck out of
modern consumer CD players and Most modern sterios for simplicity, and
obtainable parts !!!

tim
Back to top
N Cook
Guest
Posted: Fri Feb 11, 2005 12:44 am    Post subject: Re: Why do triggers always die on o-scopes ? Reply with quote
TD = Time Delay used to be those mysterous coils of wire (delay line ) to
delay the signal so leading edges can be observed.

electronic hints and repair briefs , schematics/manuals list on
http://homepages.tcp.co.uk/~diverse


"Tim Kett" <timkettring@e-garfield.com> wrote in message
news:01c50f11$445e0440$fef9e504@toni...
Quote:
mike <spamme0@netscape.net> wrote in article
4209F6EF.705@netscape.net>...
Tim Kett wrote:
Seems like with every oscilloscope brand i have ever used, the
triggers
are
always the first thing to quit, not just on me, but on most everyone.

I have never overvoltaged any of the ranges on my Protech, but now it
is
worth a cinder-block, and it was the best triggering scope I ever
used.

I wonder what takes out triggers for little/no reason ?

Thankfully, the rest of it works, so i just have to find my schematic
for
it.

Maybe the diagram will reveal why the triggers always die so fast.


Not been my experience.
But as to why, they're probably the closest tolerance fastest part of
the system. Drift can put them at the wrong operating point. And if
there's a TD in there, that can be the weak link.
mike


Well, I will consider myself blessed/lucky, because it looks like all the
parts are easily obtainable, or at least substitutable at worst case, and
be glad it in only a trigger problem !

Just curious, What is a TD ??? Toshiba device (IC) ? Thermal Dielectric ?

Glad i have a decent servicable unit, and decent service lit that is
included in Owners Manual !!! - so it is almost sure to be saved, easily,
and reasonably cheaply !!!

Return address is VALID.
Wanted, PCMCIA SCSI Card for HP m820 CDRW.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
http://nm7u.tripod.com/homepage/te.html
Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
Bunch of stuff For Sale and Wanted at the link below.
http://www.geocities.com/SiliconValley/Monitor/4710/

Back to top
Franc Zabkar
Guest
Posted: Fri Feb 11, 2005 2:52 am    Post subject: Re: Why do triggers always die on o-scopes ? Reply with quote
On Thu, 10 Feb 2005 09:53:53 +0800, budgie <me@privacy.net> put finger
to keyboard and composed:

Quote:
On 9 Feb 2005 05:46:24 GMT, "Tim Kett" <timkettring@e-garfield.com> wrote:


Seems like with every oscilloscope brand i have ever used, the triggers are
always the first thing to quit, not just on me, but on most everyone.

I have never overvoltaged any of the ranges on my Protech, but now it is
worth a cinder-block, and it was the best triggering scope I ever used.

I wonder what takes out triggers for little/no reason ?

I've just finished an exhaustive rebuild of a non-working Telequipment D32
portable (AC/battery) CRO. Triggering circuitry was an issue, but only because
this instrument uses "eyelets" as pcb vias, so there were a zillion dry joints
in every area.

I've had to do the same thing for the same reason for my Leader
LBO-514 scope.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
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Jim Yanik
Guest
Posted: Fri Feb 11, 2005 6:11 am    Post subject: Re: Why do triggers always die on o-scopes ? Reply with quote
"Tim Kett" <timkettring@e-garfield.com> wrote in
news:01c50f33$eab36020$fef9e504@toni:



Quote:

Maybe half the calibration people didnt check the triggers on the
Tectronics o-scope plugins where i worked ?

If they were calibrated at all.

Are you referrring to 500 series scopes,or 5000 or 7000 series plug-ins?
(BTW,the triggering is in the mainframes,not the PIs)

--
Jim Yanik
jyanik
at
kua.net
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Jim Yanik
Guest
Posted: Fri Feb 11, 2005 6:11 am    Post subject: Re: Why do triggers always die on o-scopes ? Reply with quote
"N Cook" <diverse2@tcp.co.antyspahm.uk> wrote in
news:odadnRCPkI9zNpbfRVn-sw@tcp.co.uk:

Quote:
TD = Time Delay used to be those mysterous coils of wire (delay line )
to delay the signal so leading edges can be observed.

electronic hints and repair briefs , schematics/manuals list on
http://homepages.tcp.co.uk/~diverse



Quote:
mike <spamme0@netscape.net> wrote in article


Quote:
Not been my experience.
But as to why, they're probably the closest tolerance fastest part
of the system. Drift can put them at the wrong operating point.
And if there's a TD in there, that can be the weak link.
mike


Well, I will consider myself blessed/lucky, because it looks like all
the parts are easily obtainable, or at least substitutable at worst
case, and be glad it in only a trigger problem !

Just curious, What is a TD ??? Toshiba device (IC) ? Thermal
Dielectric ?

tunnel diode. Used for fast switching and short rise times.
TEK used them in their trigger circuits.


--
Jim Yanik
jyanik
at
kua.net
Back to top
Jim Yanik
Guest
Posted: Fri Feb 11, 2005 6:20 pm    Post subject: Re: Why do triggers always die on o-scopes ? Reply with quote
Jim Yanik <jyanik@abuse.gov.> wrote in
news:Xns95F9C99017613jyanikkuanet@129.250.170.85:

Quote:
"Tim Kett" <timkettring@e-garfield.com> wrote in
news:01c50f33$eab36020$fef9e504@toni:




Maybe half the calibration people didnt check the triggers on the
Tectronics o-scope plugins where i worked ?

If they were calibrated at all.

Are you referrring to 500 series scopes,or 5000 or 7000 series plug-ins?
(BTW,the triggering is in the mainframes,not the PIs)


(of the 500 series,not the 5K and 7K)

--
Jim Yanik
jyanik
at
kua.net
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