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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

Tektronix 466 Scope Problem



 
 
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  #1  
Old November 10th 03, 02:26 AM
Chris
external usenet poster
 
Posts: n/a
Default Tektronix 466 Scope Problem

Hi guys. I'm hoping that some of the more Electronics oriented
individuals out there may be able to help me. I am pretty much self
taught when it comes to electronics so my knowledge is very limited. I
always try my very best to troubleshoot and fix things when I have a
problem and believe it or not, I'm successful about 90% of the time.
Mainly it's because I can see the "burned" part or "hair line"
fracture in the solder board.

Well my Tektronix scope was something I purchased from e-bay about 2
years ago. It worked perfectly from what I could tell. I was very new
to scopes and didn't have any experience running them. My friend came
over one day and was like "oh yeah I can show you how to run a
scope... bla bla."

To make a long story short during a calibration discussion he
suggested we simply test the AC "house current" for the 60 cycles per
second that it should be. I don't remember exactly how we connected
the probes to the AC but when I made the final connection the circuit
breaker popped and I looked at him with a rather "****ed off"
expression.

I was sure my scope was ruined. I reset the breaker and turned the
scope on. It worked fine ..."See it's ok" my friend said! About 10 or
15 seconds later my scope went into a rather "dead" state. -Needless
to say I was ****ed. I take pride in all of my equipment ...no matter
how old it is. I take good care of it and try to learn as much as I
can with what I have.

We checked the fuses and they were both fine in the scope. He then
said ..."I'll take it to work dude. My buddy Hank at work fixes these
things all day long. He'll have it up and running in under 10 minutes
I bet." Needless to say about 4 months later I got it back ...still
broken. All Hank told my friend was something about the DC power
supply? I assume that means that one of the full wave bridge
rectifiers is bad? -But if that's the case why didn't he find which
one and replace it?

Anyway, from what I can tell, by turning the scope on for several
seconds here is what DOES come on: The lights on the front light up.
The trace dots do come up after a few seconds on the screen, but they
do not move. They get so bright (maybe because they are not moving?)
that I turn the scope off quickly in fear of it burning something
further out.

The fan on the back DOES NOT run anymore and the time portion does not
appear to work since I see only 1 bright or 2 bright dots in the
center (I think it's 2 of them).

I am willing to try or test anything you can suggest to help me fix
this. Please help if you can

Thank You,
-Chris
Ads
  #2  
Old November 10th 03, 03:30 AM
James Sweet
external usenet poster
 
Posts: n/a
Default Tektronix 466 Scope Problem


"Chris" chris1@oupower_dot_com wrote in message
m...
Hi guys. I'm hoping that some of the more Electronics oriented
individuals out there may be able to help me. I am pretty much self
taught when it comes to electronics so my knowledge is very limited. I
always try my very best to troubleshoot and fix things when I have a
problem and believe it or not, I'm successful about 90% of the time.
Mainly it's because I can see the "burned" part or "hair line"
fracture in the solder board.

Well my Tektronix scope was something I purchased from e-bay about 2
years ago. It worked perfectly from what I could tell. I was very new
to scopes and didn't have any experience running them. My friend came
over one day and was like "oh yeah I can show you how to run a
scope... bla bla."

To make a long story short during a calibration discussion he
suggested we simply test the AC "house current" for the 60 cycles per
second that it should be. I don't remember exactly how we connected
the probes to the AC but when I made the final connection the circuit
breaker popped and I looked at him with a rather "****ed off"
expression.

I was sure my scope was ruined. I reset the breaker and turned the
scope on. It worked fine ..."See it's ok" my friend said! About 10 or
15 seconds later my scope went into a rather "dead" state. -Needless
to say I was ****ed. I take pride in all of my equipment ...no matter
how old it is. I take good care of it and try to learn as much as I
can with what I have.

We checked the fuses and they were both fine in the scope. He then
said ..."I'll take it to work dude. My buddy Hank at work fixes these
things all day long. He'll have it up and running in under 10 minutes
I bet." Needless to say about 4 months later I got it back ...still
broken. All Hank told my friend was something about the DC power
supply? I assume that means that one of the full wave bridge
rectifiers is bad? -But if that's the case why didn't he find which
one and replace it?

Anyway, from what I can tell, by turning the scope on for several
seconds here is what DOES come on: The lights on the front light up.
The trace dots do come up after a few seconds on the screen, but they
do not move. They get so bright (maybe because they are not moving?)
that I turn the scope off quickly in fear of it burning something
further out.

The fan on the back DOES NOT run anymore and the time portion does not
appear to work since I see only 1 bright or 2 bright dots in the
center (I think it's 2 of them).

I am willing to try or test anything you can suggest to help me fix
this. Please help if you can

Thank You,
-Chris


Sounds like one output of the power supply is dead, you'll need to do some
testing, do you have a multimeter? Turn the brightness way down, the static
dot will burn into the tube quickly.


  #3  
Old November 10th 03, 03:21 PM
Chris
external usenet poster
 
Posts: n/a
Default Tektronix 466 Scope Problem

On Mon, 10 Nov 2003 02:30:08 GMT, "James Sweet"
wrote:

"Chris" chris1@oupower_dot_com wrote in message
om...
Hi guys. I'm hoping that some of the more Electronics oriented
individuals out there may be able to help me. I am pretty much self
taught when it comes to electronics so my knowledge is very limited. I
always try my very best to troubleshoot and fix things when I have a
problem and believe it or not, I'm successful about 90% of the time.
Mainly it's because I can see the "burned" part or "hair line"
fracture in the solder board.

Well my Tektronix scope was something I purchased from e-bay about 2
years ago. It worked perfectly from what I could tell. I was very new
to scopes and didn't have any experience running them. My friend came
over one day and was like "oh yeah I can show you how to run a
scope... bla bla."

To make a long story short during a calibration discussion he
suggested we simply test the AC "house current" for the 60 cycles per
second that it should be. I don't remember exactly how we connected
the probes to the AC but when I made the final connection the circuit
breaker popped and I looked at him with a rather "****ed off"
expression.

I was sure my scope was ruined. I reset the breaker and turned the
scope on. It worked fine ..."See it's ok" my friend said! About 10 or
15 seconds later my scope went into a rather "dead" state. -Needless
to say I was ****ed. I take pride in all of my equipment ...no matter
how old it is. I take good care of it and try to learn as much as I
can with what I have.

We checked the fuses and they were both fine in the scope. He then
said ..."I'll take it to work dude. My buddy Hank at work fixes these
things all day long. He'll have it up and running in under 10 minutes
I bet." Needless to say about 4 months later I got it back ...still
broken. All Hank told my friend was something about the DC power
supply? I assume that means that one of the full wave bridge
rectifiers is bad? -But if that's the case why didn't he find which
one and replace it?

Anyway, from what I can tell, by turning the scope on for several
seconds here is what DOES come on: The lights on the front light up.
The trace dots do come up after a few seconds on the screen, but they
do not move. They get so bright (maybe because they are not moving?)
that I turn the scope off quickly in fear of it burning something
further out.

The fan on the back DOES NOT run anymore and the time portion does not
appear to work since I see only 1 bright or 2 bright dots in the
center (I think it's 2 of them).

I am willing to try or test anything you can suggest to help me fix
this. Please help if you can

Thank You,
-Chris


Sounds like one output of the power supply is dead, you'll need to do some
testing, do you have a multimeter? Turn the brightness way down, the static
dot will burn into the tube quickly.



James,

I have started to test the transformer and it appears to be good. I
have 5 labeled pins on the transformer (10 - 14) and they all measure
resistance so I assume the windings are all intact. I started
measuring with my multi-meter by connecting my negative probe to the
ground and then testing various points with the positive probe, while
the power was on to my scope. Everything appears normal from the few
things I have tested, except for the 1 full wave bridge rectifier. It
is getting some strange readings. Maybe this is the problem or maybe
the capacitor that it's connected to is the problem? I would love to
check some values against anyone with another 466 scope. Can I ask for
some assistance in that area please guys?

If you have a TEK 466 storage scope, please let me know and I'll tell
you which rectifier measured oddly and how I got the measurement.

Are there any repair manuals with these that I can download or order?
I would like to know if there is some simple standard tests to try to
pinpoint my problem. I am very new to troubleshooting electronics like
this but I'm willing to learn

The DOT is off to the side far enough that it is not visible. I have
tried to center it to see the dot but can not, I played with the "Find
Beam" and that does center it, but I only dare to hit the button for a
moment, as I don't want to burn my screen. I have turned it down as
far as I can so I just don't keep the scope turned on very long while
I'm testing. I hope I am not hurting it during my short tests.

I'm looking for any help you guys can offer. I can not afford to send
it in for repairs so I have to do this with your help if you can help
I am grateful!

-Chris
  #4  
Old November 10th 03, 03:22 PM
Chris
external usenet poster
 
Posts: n/a
Default Tektronix 466 Scope Problem

Jack, do you have a repair manual for the 466 scopes that I can
obtain? If not, perhaps you have some testing procedures or
instructions I can get?

Thank You,
-Chris

On Tue, 9 Dec 2003 21:49:39 -0600, "Jack" wrote:
http://www.tyrosys.com/cal.html



"Chris" chris1@oupower_dot_com wrote in message
om...
Hi guys. I'm hoping that some of the more Electronics oriented
individuals out there may be able to help me. I am pretty much self
taught when it comes to electronics so my knowledge is very limited. I
always try my very best to troubleshoot and fix things when I have a
problem and believe it or not, I'm successful about 90% of the time.
Mainly it's because I can see the "burned" part or "hair line"
fracture in the solder board.

Well my Tektronix scope was something I purchased from e-bay about 2
years ago. It worked perfectly from what I could tell. I was very new
to scopes and didn't have any experience running them. My friend came
over one day and was like "oh yeah I can show you how to run a
scope... bla bla."

To make a long story short during a calibration discussion he
suggested we simply test the AC "house current" for the 60 cycles per
second that it should be. I don't remember exactly how we connected
the probes to the AC but when I made the final connection the circuit
breaker popped and I looked at him with a rather "****ed off"
expression.

I was sure my scope was ruined. I reset the breaker and turned the
scope on. It worked fine ..."See it's ok" my friend said! About 10 or
15 seconds later my scope went into a rather "dead" state. -Needless
to say I was ****ed. I take pride in all of my equipment ...no matter
how old it is. I take good care of it and try to learn as much as I
can with what I have.

We checked the fuses and they were both fine in the scope. He then
said ..."I'll take it to work dude. My buddy Hank at work fixes these
things all day long. He'll have it up and running in under 10 minutes
I bet." Needless to say about 4 months later I got it back ...still
broken. All Hank told my friend was something about the DC power
supply? I assume that means that one of the full wave bridge
rectifiers is bad? -But if that's the case why didn't he find which
one and replace it?

Anyway, from what I can tell, by turning the scope on for several
seconds here is what DOES come on: The lights on the front light up.
The trace dots do come up after a few seconds on the screen, but they
do not move. They get so bright (maybe because they are not moving?)
that I turn the scope off quickly in fear of it burning something
further out.

The fan on the back DOES NOT run anymore and the time portion does not
appear to work since I see only 1 bright or 2 bright dots in the
center (I think it's 2 of them).

I am willing to try or test anything you can suggest to help me fix
this. Please help if you can

Thank You,
-Chris




  #5  
Old November 10th 03, 05:21 PM
Jim Yanik
external usenet poster
 
Posts: n/a
Default Tektronix 466 Scope Problem



My first suggestion is to get a 466 SERVICE manual,with the parts
lists,schematics,and VERY important;the CIRCUIT DESCRIPTIONS,which are very
detailed,and tell how each section of your scope work.

Try Ebay or www.big-list.com,TEK no longer supports this model.

In connecting to the AC mains,it's very likely that you burned up some
ground runs on circuit boards.

IIRC,TEK has some literature on why one should not make un-isolated
measurements with grounded scopes. www.tek.com.
--
Jim Yanik,NRA member
jyanik-at-kua.net
  #6  
Old November 10th 03, 08:59 PM
Chris
external usenet poster
 
Posts: n/a
Default Tektronix 466 Scope Problem

Does anyone have an online version of the TEK 466 Service manual with
the Circuit Descriptions that Jim recommends? I would bet these things
are available in Adobe format.

I would be grateful to anyone who has an online manual, if they would
be kind enough to e-mail it to me.

Thank You,
-Chris

On Mon, 10 Nov 2003 16:21:00 +0000 (UTC), Jim Yanik
wrote:


My first suggestion is to get a 466 SERVICE manual,with the parts
lists,schematics,and VERY important;the CIRCUIT DESCRIPTIONS,which are very
detailed,and tell how each section of your scope work.

Try Ebay or www.big-list.com,TEK no longer supports this model.

In connecting to the AC mains,it's very likely that you burned up some
ground runs on circuit boards.

IIRC,TEK has some literature on why one should not make un-isolated
measurements with grounded scopes. www.tek.com.
--
Jim Yanik,NRA member
jyanik-at-kua.net


  #7  
Old November 10th 03, 11:04 PM
James Sweet
external usenet poster
 
Posts: n/a
Default Tektronix 466 Scope Problem


"Chris" chris1@oupower_dot_com wrote in message
om...
Does anyone have an online version of the TEK 466 Service manual with
the Circuit Descriptions that Jim recommends? I would bet these things
are available in Adobe format.

I would be grateful to anyone who has an online manual, if they would
be kind enough to e-mail it to me.



These scopes became "obsolete" long before Adobe Acrobat appeared, and
before there was a practical way of moving computer files around if it had
existed. They're still great scopes, but you won't find the documentation
online, you'll have to buy the real manual or find someone who can photocopy
the relevant section for you.


  #8  
Old November 12th 03, 01:51 PM
TekMan
external usenet poster
 
Posts: n/a
Default Tektronix 466 Scope Problem

chris1@oupower_dot_com (Chris) wrote in message om...
...SNIPPED..

Thank You,
-Chris




Hi Cris,

as Jim pointed to: You need a schematic.

for a guideline: Looks like the +15V pwr supply has dies during your
"house AC test".
Go to logsa.army.mil, do a search for tektronix and download the 475
scope manual (jep, 475, not 466 - since there is no 466 in logsa).

The pwr supply in the LV section is pretty much the same to the 466.

And then download from from http://www.teknetelectronics.com the
Tektronix 466 operating manual -- this will help your friend teach how
to use the scope.

Both sites are free download, just follow the instructions (or google
in the web).


good luck for the repair.

scnr,
Andreas
  #9  
Old November 13th 03, 02:15 PM
Thomas P. Gootee
external usenet poster
 
Posts: n/a
Default Tektronix 466 Scope Problem

------------------------------------

[Flamers, note: This reply is "top-posted" so people using the Google
Groups website don't have to click on "See the rest of this message".
(Get over it.)]

Chris,

The power supply's test points' voltages (relative to chassis ground)
should be labeled, right on the circuit board. If those voltages
aren't all within a few percent of nominal, fix them before looking
for anything else. You can also check the AC ripple on them. Most of
them should probably have less than about 20 mv of AC.

For Tektronix service manuals, there are many places to buy. At
http://www.w7fg.com, they have truly-excellent-quality photocopies,
with proper foldout schematics, nicely bound, etc., that are usually
significantly cheaper than original manuals. I am not aware of *any*
PDF version of the 466 service manual, although the sites mentioned by
others do have the 466 *ops* manual. I have more sources for Tek
manuals and info, listed at:

http://www.fullnet.com/u/tomg/links.htm

I will also email you my list of the "best" sources for Tek manuals
and parts.

If you had another scope to use to troubleshoot your 466, it might be
very helpful. The service manual has sample waveforms, etc, for you to
check, in many places in your scope.

You could also use another scope to build (in minutes) a "quick and
dirty curve tracer", to test components (in-circuit, if you use a
low-enough voltage; power OFF of course), such as the one described
at:

http://www.repairfaq.org/REPAIR/F_semitest.html#stqdc

You could also use a second scope to test the ESR (Equivalent Series
Resistance) of the electrolytic capacitors, which is a very good way
to check for their common failure mode, using the technique outlined
at:

http://www.fullnet.com/u/tomg/esrscope.htm

Another alternative: You should be able to find a 466 that's "almost
working" at http://www.ebay.com, probably for less than $100. Then you
could compare measurments between that 466 and your 466. Maybe you
could even fix that one instead. Either way, having two of them
side-by-side can be a great aid in tracking down a problem.

Good luck!

Regards,

Tom Gootee

------------------------------------

chris1@oupower_dot_com (Chris) wrote in message om...
Hi guys. I'm hoping that some of the more Electronics oriented
individuals out there may be able to help me. I am pretty much self
taught when it comes to electronics so my knowledge is very limited. I
always try my very best to troubleshoot and fix things when I have a
problem and believe it or not, I'm successful about 90% of the time.
Mainly it's because I can see the "burned" part or "hair line"
fracture in the solder board.

Well my Tektronix scope was something I purchased from e-bay about 2
years ago. It worked perfectly from what I could tell. I was very new
to scopes and didn't have any experience running them. My friend came
over one day and was like "oh yeah I can show you how to run a
scope... bla bla."

To make a long story short during a calibration discussion he
suggested we simply test the AC "house current" for the 60 cycles per
second that it should be. I don't remember exactly how we connected
the probes to the AC but when I made the final connection the circuit
breaker popped and I looked at him with a rather "****ed off"
expression.

I was sure my scope was ruined. I reset the breaker and turned the
scope on. It worked fine ..."See it's ok" my friend said! About 10 or
15 seconds later my scope went into a rather "dead" state. -Needless
to say I was ****ed. I take pride in all of my equipment ...no matter
how old it is. I take good care of it and try to learn as much as I
can with what I have.

We checked the fuses and they were both fine in the scope. He then
said ..."I'll take it to work dude. My buddy Hank at work fixes these
things all day long. He'll have it up and running in under 10 minutes
I bet." Needless to say about 4 months later I got it back ...still
broken. All Hank told my friend was something about the DC power
supply? I assume that means that one of the full wave bridge
rectifiers is bad? -But if that's the case why didn't he find which
one and replace it?

Anyway, from what I can tell, by turning the scope on for several
seconds here is what DOES come on: The lights on the front light up.
The trace dots do come up after a few seconds on the screen, but they
do not move. They get so bright (maybe because they are not moving?)
that I turn the scope off quickly in fear of it burning something
further out.

The fan on the back DOES NOT run anymore and the time portion does not
appear to work since I see only 1 bright or 2 bright dots in the
center (I think it's 2 of them).

I am willing to try or test anything you can suggest to help me fix
this. Please help if you can

Thank You,
-Chris

  #10  
Old November 14th 03, 12:10 AM
Scott
external usenet poster
 
Posts: n/a
Default Tektronix 466 Scope Problem


"James Sweet" wrote in message
news:PXTrb.120249$9E1.592552@attbi_s52...

"Chris" chris1@oupower_dot_com wrote in message
om...
Does anyone have an online version of the TEK 466 Service manual with
the Circuit Descriptions that Jim recommends? I would bet these things
are available in Adobe format.

I would be grateful to anyone who has an online manual, if they would
be kind enough to e-mail it to me.



These scopes became "obsolete" long before Adobe Acrobat appeared, and
before there was a practical way of moving computer files around if it had
existed. They're still great scopes, but you won't find the documentation
online, you'll have to buy the real manual or find someone who can

photocopy
the relevant section for you.

Try http://www.fullnet.com/u/tomg/manuals.htm


 




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