Date   

Re: A 2465 teaser...

Tom Gardner
 

It would be interesting to know if the "glitch" amplitude depends
on the relative positions of the CH1/2 trace on the screen, with the
inputs grounded and with different DC inputs.

I would identify just about all the analogue switches (e.g. 4053s)
I could find, and see if any of those are being switched too slowly
and/or had too high a resistance and/or whatever was driving their
signals had become too high resistance. Maybe there's a mechanical
failure somewhere in that chain.

I would use another scope to find where the glitch /doesn't/ exist
- trigger on any control signal vaguely associated with the glitch,
potentially even the readout vert/horiz signals diagram 48 and 49
- work back from the Y output deflection voltage, through U600, U400
- then to U100/U200
- then control signals VS1/2/3/4 from U650, checking particularly
if there is any difference between VS1/2 and VS3/4

On 10/11/17 14:19, Chuck Harris cfharris@erols.com [TekScopes] wrote:

Hi Tom,

It looks just like what you would see if you had a fast
marker pulse, and you sped up the timebase. At slow
timebase settings, it is just a spike, at faster settings,
it is a fast rise, with a much, much slower decay.

The "hooks" are about 5us in duration. The risetime is
very fast, but the decay takes most of the 5us.

I believe that I am looking at two things. Probably issues
with the channel switch:

1) a glitch that is leaking through whenever the sweep starts
drawing CH1/CH2 on the screen.
2) a stream of display glitches that leak through whenever the
channel switch switches between CH1/CH2 and the CH5, the
display.

I have zero doubt that the random looking grassy pulses are
the transitions when the display takes over the beam from CH1/CH2.
They disappear when the display is turned off.

Everything is complicated by the display timing logic. The 2465
tries to avoid the "holes" in the traces that happen when the
display has to happen, so it has 4 or 5 different modes that
range from alternating display and trace, to random display
writing, to writing display full time. The display timing logic
makes these decisions based on how long it has been since it has
refreshed the display.

-Chuck Harris

Tom Gardner tggzzz@gmail.com [TekScopes] wrote:
On 10/11/17 06:37, Chuck Harris cfharris@erols.com [TekScopes] wrote:

An additional clue is the leading hook's decay curve changes
slope with sweep speed, but the scope will not trigger on
this signal, nor on any of the random grass that appears on
the trace. That indicates that it is getting injected after
the trigger pickoff.
By that do you mean that when you change the timebase
the decay curve is the same time or the same number
of divisions?

I am pretty certain it has something to do with the display
readout logic.
That was the feeling I got from reading your description.

To see whether it is correlated with the display readout
timing, I would try either of two tests:
1) apply an external signal and adjust its frequency to be
the same as (a harmonic or subharmonic) the display
readout frequency so that any "twinkling" in the traces
is more-or-less stationary. (Start with a timebase of
~200us/div). Then see if the hooks are stationary w.r.t.
the intensity variations. If they are, then the display
readout is involved.
2) without an external signal and a ~2ms/div timebase,
change the holdoff until the twinkling is stationary,
and look for the hooks as above.

If display readout is involved, I would find out what is
happening when the display is switching from trace
to readout. I would observe the Y waveform and blanking
signals after the display sequencer IC and near the
display blanking IC. Trigger on either the blanking
waveform or the Y-waveform.

I would be looking for either the blanking signal to
be mistimed or the Y-waveform to be changing too slowly.
I would suspect the latter, so then it is a case of moving
"away from the output" until you find where it isn't
changing too slowly.

Be careful with probe tips around there; I know they
can short signals and destroy ICs :(


Re: A 2465 teaser...

Chuck Harris <cfharris@...>
 

I should have said: "pulses are "related" to the transitions
when the display takes over the screen... The actual transitions
of the beam are invisible... as they should be.

-Chuck Harris

Chuck Harris cfharris@erols.com [TekScopes] wrote:

Hi Tom,

It looks just like what you would see if you had a fast
marker pulse, and you sped up the timebase. At slow
timebase settings, it is just a spike, at faster settings,
it is a fast rise, with a much, much slower decay.

The "hooks" are about 5us in duration. The risetime is
very fast, but the decay takes most of the 5us.

I believe that I am looking at two things. Probably issues
with the channel switch:

1) a glitch that is leaking through whenever the sweep starts
drawing CH1/CH2 on the screen.
2) a stream of display glitches that leak through whenever the
channel switch switches between CH1/CH2 and the CH5, the
display.

I have zero doubt that the random looking grassy pulses are
the transitions when the display takes over the beam from CH1/CH2.
They disappear when the display is turned off.

Everything is complicated by the display timing logic. The 2465
tries to avoid the "holes" in the traces that happen when the
display has to happen, so it has 4 or 5 different modes that
range from alternating display and trace, to random display
writing, to writing display full time. The display timing logic
makes these decisions based on how long it has been since it has
refreshed the display.

-Chuck Harris


Re: 2465B error code

Chris
 

Hello Raymond and Jon, I did as you suggested and downloaded manual copies although digital downloads. Just going over them quickly,I was looking for the board for the CTT (counter timer) and I think it is A26 and its location is vertically installed next to the CRT. Correct me if I am wrong but It looks like this board has part of the TV board included?At least that is indicated in the CTT section of the manual. I read a little about the error messages and this one gave me the option of pressing the A/B trigger which makes it operational. Although with a note to get it repaired. I did this and it worked but would rather have no error codes at all. It seems to me that these are factory installed options. If they are not,please advise if you know. If there is a way to disconnect the option and bypass so no error is recieved, I am ok with that. I have a dedicated counter. Having the option installation instructions would go far if they exist. I am greatful for any assistance of those that can help. I have been a member for quite a few years but more of a lurker who read(s) and follows many of the repairs accomplished here. I am not a trained electronics tech in any way shape or form and have used the 475B that was repaired years ago with help from this group to make several repairs to my ham gear. My goal here is to insure the scope is functional. I am ok with troubleshooting the CTT board as long as I have guidance and the equipment to do so but it is not needed imperative to keep the function. I will be getting the scope off the rack and on the bench. Thank you , Chris


Re: 7854 fixed, now for some newb questions

Chuck Harris <cfharris@...>
 

The USA market for USA made test equipment back then was essentially
unlimited. The European market was just a little extra greed. So,
the bean counters wanted it, but the engineers doing the designs didn't
spend much time thinking about it.

As a result, things like using 120V safety caps that though rated to
handle 240V were used... even though the safety margin was much reduced
of what you would like to see in 240V land. And the biggest offense
was treating 50Hz as if it the 16% reduction if frequency wouldn't matter
to 60Hz power transformers and fan motors.

Not a conspiracy, just greed and indifference of USA engineers.

Solid state scopes from the discrete component era usually have a
some method to affect a slow increase in intensity on power up. My
7854 doesn't start bright, but rather the intensity ramps up to just
about right.

As far as I know, all 7854 keyboard units have sticky switches. It is a
simple clearance issue. Tektronix made the holes in the aluminum front
panel too close tolerance to the plastic buttons. Further, the buttons
are tapered so that they are narrow at the front, and wide behind the
panel... Only, the holes in the panel are punched square.. not tapered.

If you file the squareness into a taper by relieving the hole on the back
of the aluminum panel, you can improve the situation without making a
noticeable change to the panel. It must be disassembled, which isn't
hard at all.

Lubrication won't do the job.

There is a lot of very fast digital circuitry, packed very tightly, into
the 7854. It needs the air. Do not put a reduced capacity fan in this
scope.

Also, it is easy to have the fan rotating the wrong way. It has a plug
with no key, and it is a DC fan. The fan should suck the air out of the
case, not blow air into the case.

The RAM in the 7854 is not low power stuff. It will suck a big battery
down pretty quickly, which is why the older scopes had the ability to use
a large external battery. The last version of the scope had more modern
memory, and tektronix decided to use an internal battery... but I would
bet that it would be shot lived too, as they put a switch to disable the
battery on the back of the scope.

One of the nicest features of the scope is the standard GPIB interface
on the back. It works very well. But, by now, the address selection
DIP switch will be dirty, and the address might not be what the switch
says it is. You should replace it, or clean it, and verify its function.

The 7B87 has an ability to trigger the scope's waveform memory at any
point in time after the 7B87 is triggered. That way you can record
with great fineness an event that occurs later. You don't really need
it, but it is nice to have.

Single shot events are not the 7854's forte. It is only capable of
50K samples per second in that mode. The 7854 is really a sampling
scope with storage, that doubles as a 400MHz 7000 mainframe.

-Chuck Harris



Nenad Filipovic ilmuerte@gmail.com [TekScopes] wrote:

Dear All,

A few days ago I've become a proud owner of a mint condition 7854 with the
calculator keyboard (still in its original plastic wrap). What was wrong
with it - exploded capacitor in the integral EMI filter of the power
connector. It splattered a load of brown goo on the outside, the filter
itself bulged so hard that I couldn't pull it out at first. I was already
thinking about a conspiracy of fancy US gear against European line voltage,
but then noticed that the filter itself is "Made in Switzerland", splendid.

Cute mainframe, especially the programming mode that constantly reminds me
of the T-800's red first person view from Terminator 2. And that postfix
notation gets me talking like Yoda after a long programming session. It's
my first 4-bay mainframe from the 7000 series, so I have a lot of questions:

1. Excessive brightness on power up. My 465 does this as well, when powered
up from cold state the image comes up quite bright, somewhat defocused, and
then settles to normal after ~10min. Not a major showstopper but it's
annoying to have to turn it down on every power up, and then back up once
it warms up. On the 7854 it seems more pronounced on scope trace
brightness, and less pronounced on readout brightness. Any suggestions?

2. My unit is a late model, it does not have the usual memory backup power
connectors at the back, but instead a memory backup switch. What is the
life of that backup battery inside, should I replace it? I read that long
thread about 7854 RAM/ROM board upgrade, ROM rot was reported as a common
issue on 7854s, are the late models free from this problem?

3. Sticky buttons. I remember there was a thread discussing this, but could
not find it in the group archive. There were talks about plastic swelling
over time and getting stuck in those tight tolerance holes, so filing away
hole edges was proposed as a solution. I wonder if this issue could be
fixed without taking everything apart? Keywords to find the original sticky
buttons thread would also help (I've read "7854 build in keyboard sticky"
but it's not that one).

4. Noisy fan. It's not worn out, it's the sheer speed that creates the
noise. I'm not sure if it's original, so I was wondering if it's normal to
be so noisy? Of course it keeps the scope quite cool (even with the
monstrous 7L18), but November in Europe is chilly so most tech stuff like
it. I'm wondering if it would be safe to turn the RPM of that fan down?

5. I don't have the 7B87, so am I missing much? To be honest, at the moment
I do not have any proper time bases to experiment with (while waiting for
7B10 and 7B15 to arrive I'm temporarily using the 7L18's sweep to mock time
base functionality). I would like to use my 7854 to record single shot
events, I hope a delaying time base + it's internal trigger would be
enough. Not sure what I'd really gain with the external sampling clock
input of the 7B87?

Best regards and thanks,
Nenad Filipovic






------------------------------------
Posted by: Nenad Filipovic <ilmuerte@gmail.com>
------------------------------------


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

Yahoo Groups Links




Re: are the 500 series scopes still usefull

Nenad Filipovic
 

Hi Mike,

Yes they are, if maintained correctly they can serve very well, and you can
use their stabilized power supply as a neat power source if you like
experimenting with tubes.
Which models do you have? 555 is especially useful in cold winters.

Best Regards,
Nenad Filipovic


On Fri, Nov 10, 2017 at 3:35 PM, mike53558@yahoo.com [TekScopes] <
TekScopes@yahoogroups.com> wrote:



have three different models of this series of scope . just do basic stuff
with a scope still learning picked these up for free . and any info on this
series as far as what problems to look for.




Mike Jaeger







are the 500 series scopes still usefull

mike53558@...
 

have three different models of this series of scope . just do basic stuff with a scope still learning picked these up for free . and any info on this series as far as what problems to look for.




Mike Jaeger


Re: A 2465 teaser...

Chuck Harris <cfharris@...>
 

That sort of failure would affect all channels equally.
This is only a problem with CH1 and CH2.

The panel works fully.

-Chuck Harris

davidazzz8@gmail.com [TekScopes] wrote:

Have you checked the A6 board
Of the front panel
From experience I when i fix my 2465
Failure in one of the diodes can cause such a problem
You can also do a pot test



Exercise 1



And check that all buttons work correctly.



also check the continuity
from J652 on A6 to

( a sec dev /b sec dev)

col 0
col 1
col 2
col 3
col 4
( volts dev ch1 ch2 )

row 0
row 1
row 2
row 3
row 4















------------------------------------
Posted by: davidazzz8@gmail.com
------------------------------------


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

Yahoo Groups Links




Re: A 2465 teaser...

Chuck Harris <cfharris@...>
 

Hi Tom,

It looks just like what you would see if you had a fast
marker pulse, and you sped up the timebase. At slow
timebase settings, it is just a spike, at faster settings,
it is a fast rise, with a much, much slower decay.

The "hooks" are about 5us in duration. The risetime is
very fast, but the decay takes most of the 5us.

I believe that I am looking at two things. Probably issues
with the channel switch:

1) a glitch that is leaking through whenever the sweep starts
drawing CH1/CH2 on the screen.
2) a stream of display glitches that leak through whenever the
channel switch switches between CH1/CH2 and the CH5, the
display.

I have zero doubt that the random looking grassy pulses are
the transitions when the display takes over the beam from CH1/CH2.
They disappear when the display is turned off.

Everything is complicated by the display timing logic. The 2465
tries to avoid the "holes" in the traces that happen when the
display has to happen, so it has 4 or 5 different modes that
range from alternating display and trace, to random display
writing, to writing display full time. The display timing logic
makes these decisions based on how long it has been since it has
refreshed the display.

-Chuck Harris

Tom Gardner tggzzz@gmail.com [TekScopes] wrote:

On 10/11/17 06:37, Chuck Harris cfharris@erols.com [TekScopes] wrote:

An additional clue is the leading hook's decay curve changes
slope with sweep speed, but the scope will not trigger on
this signal, nor on any of the random grass that appears on
the trace. That indicates that it is getting injected after
the trigger pickoff.
By that do you mean that when you change the timebase
the decay curve is the same time or the same number
of divisions?

I am pretty certain it has something to do with the display
readout logic.
That was the feeling I got from reading your description.

To see whether it is correlated with the display readout
timing, I would try either of two tests:
1) apply an external signal and adjust its frequency to be
the same as (a harmonic or subharmonic) the display
readout frequency so that any "twinkling" in the traces
is more-or-less stationary. (Start with a timebase of
~200us/div). Then see if the hooks are stationary w.r.t.
the intensity variations. If they are, then the display
readout is involved.
2) without an external signal and a ~2ms/div timebase,
change the holdoff until the twinkling is stationary,
and look for the hooks as above.

If display readout is involved, I would find out what is
happening when the display is switching from trace
to readout. I would observe the Y waveform and blanking
signals after the display sequencer IC and near the
display blanking IC. Trigger on either the blanking
waveform or the Y-waveform.

I would be looking for either the blanking signal to
be mistimed or the Y-waveform to be changing too slowly.
I would suspect the latter, so then it is a case of moving
"away from the output" until you find where it isn't
changing too slowly.

Be careful with probe tips around there; I know they
can short signals and destroy ICs :(


Re: A 2465 teaser...

Chuck Harris <cfharris@...>
 

U400 was high on my list. Its pins have all been given a drop
of deOxit, a second U400 was tried, and the suspect U400 was
tried in the working scope.

I checked the bias resistor, when the hybrid was out, and it measured
correctly, it had continuity to its supply. I checked the HF response
5K pot, it is good, and was adjusted to near full value... which means
the scope would have been a good candidate for the 1K -> 4.3K series
resistor change that happened at later serial numbers.

But, I agree, it would be worth looking at supply and bias connections
a little more carefully.. probably doing something like drawing current
from them to smoke out bad solder joints, etc... that might not be seen
with a low current ohmmeter.

-Chuck Harris

very_fuzzy_logic@yahoo.com [TekScopes] wrote:

A fault on Ch1, Ch2 but not Ch3, Ch4 or vice versa makes U400 the obvious culprit but you have checked most possibilities. It might be a long shot but incorrect bias current into U400 would probably change its switching speeds and it's worth checking the bias resistor. Also clean the contacts in U400's socket?

Roger


Re: tek 2712 freezes during startup

Chuck Harris <cfharris@...>
 

It is a normal part of the startup sequence, if the
CMOS RAM's contents is corrupted, which usually means
the lithium cell is bad.

For whatever reason, the 2710. 2711, and 2712, do not
flush the RAM and automatically start over if the RAM
is corrupted. Instead, they give a warning message,
quit start up, and expect you to do the deed.

-Chuck Harris

rodd@globo.com [TekScopes] wrote:

Hi, Does anyone have an idea if the "file system cleanup" is part of the normal startup sequence?
If not, what may be causing this behaviour.
Thanks






------------------------------------
Posted by: rodd@globo.com
------------------------------------


Re: 7854 fixed, now for some newb questions

Craig Sawyers <c.sawyers@...>
 

Well done!

A few days ago I've become a proud owner of a mint condition 7854 with the calculator keyboard
(still
in its original plastic wrap). What was wrong with it - exploded capacitor in the integral EMI
filter of the
power connector. It splattered a load of brown goo on the outside, the filter itself bulged so
hard that
I couldn't pull it out at first. I was already thinking about a conspiracy of fancy US gear
against European
line voltage, but then noticed that the filter itself is "Made in Switzerland", splendid.
That is alas well known - Schaffner, the filter maker, used epoxy-potted RIFA paper filter
capacitors. After a decade or three they basically explode
https://www.vintage-radio.net/forum/showthread.php?t=88137 . They were used in vast quantities; it
they are soldered to a circuit board they just generate a lot of white smoke and a smell of hot
epoxy from the burst case. If they are a filter, all that energy has nowhere to go, with the effect
that you saw.

Chapter and verse here http://www.vintage-radio.net/forum/showthread.php?t=69128&highlight=rifa

Craig


Re: A 2465 teaser...

Roger Evans
 

A fault on Ch1, Ch2 but not Ch3, Ch4 or vice versa makes U400 the obvious culprit but you have checked most possibilities. It might be a long shot but incorrect bias current into U400 would probably change its switching speeds and it's worth checking the bias resistor. Also clean the contacts in U400's socket?

Roger


7854 fixed, now for some newb questions

Nenad Filipovic
 

Dear All,

A few days ago I've become a proud owner of a mint condition 7854 with the
calculator keyboard (still in its original plastic wrap). What was wrong
with it - exploded capacitor in the integral EMI filter of the power
connector. It splattered a load of brown goo on the outside, the filter
itself bulged so hard that I couldn't pull it out at first. I was already
thinking about a conspiracy of fancy US gear against European line voltage,
but then noticed that the filter itself is "Made in Switzerland", splendid.

Cute mainframe, especially the programming mode that constantly reminds me
of the T-800's red first person view from Terminator 2. And that postfix
notation gets me talking like Yoda after a long programming session. It's
my first 4-bay mainframe from the 7000 series, so I have a lot of questions:

1. Excessive brightness on power up. My 465 does this as well, when powered
up from cold state the image comes up quite bright, somewhat defocused, and
then settles to normal after ~10min. Not a major showstopper but it's
annoying to have to turn it down on every power up, and then back up once
it warms up. On the 7854 it seems more pronounced on scope trace
brightness, and less pronounced on readout brightness. Any suggestions?

2. My unit is a late model, it does not have the usual memory backup power
connectors at the back, but instead a memory backup switch. What is the
life of that backup battery inside, should I replace it? I read that long
thread about 7854 RAM/ROM board upgrade, ROM rot was reported as a common
issue on 7854s, are the late models free from this problem?

3. Sticky buttons. I remember there was a thread discussing this, but could
not find it in the group archive. There were talks about plastic swelling
over time and getting stuck in those tight tolerance holes, so filing away
hole edges was proposed as a solution. I wonder if this issue could be
fixed without taking everything apart? Keywords to find the original sticky
buttons thread would also help (I've read "7854 build in keyboard sticky"
but it's not that one).

4. Noisy fan. It's not worn out, it's the sheer speed that creates the
noise. I'm not sure if it's original, so I was wondering if it's normal to
be so noisy? Of course it keeps the scope quite cool (even with the
monstrous 7L18), but November in Europe is chilly so most tech stuff like
it. I'm wondering if it would be safe to turn the RPM of that fan down?

5. I don't have the 7B87, so am I missing much? To be honest, at the moment
I do not have any proper time bases to experiment with (while waiting for
7B10 and 7B15 to arrive I'm temporarily using the 7L18's sweep to mock time
base functionality). I would like to use my 7854 to record single shot
events, I hope a delaying time base + it's internal trigger would be
enough. Not sure what I'd really gain with the external sampling clock
input of the 7B87?

Best regards and thanks,
Nenad Filipovic


Re: tek 2712 freezes during startup

 

Hi, Does anyone have an idea if the "file system cleanup" is part of the normal startup sequence?
If not, what may be causing this behaviour.
Thanks


Re: A 2465 teaser...

Tom Gardner
 

On 10/11/17 06:37, Chuck Harris cfharris@erols.com [TekScopes] wrote:

An additional clue is the leading hook's decay curve changes
slope with sweep speed, but the scope will not trigger on
this signal, nor on any of the random grass that appears on
the trace. That indicates that it is getting injected after
the trigger pickoff.
By that do you mean that when you change the timebase
the decay curve is the same time or the same number
of divisions?

I am pretty certain it has something to do with the display
readout logic.
That was the feeling I got from reading your description.

To see whether it is correlated with the display readout
timing, I would try either of two tests:
1) apply an external signal and adjust its frequency to be
the same as (a harmonic or subharmonic) the display
readout frequency so that any "twinkling" in the traces
is more-or-less stationary. (Start with a timebase of
~200us/div). Then see if the hooks are stationary w.r.t.
the intensity variations. If they are, then the display
readout is involved.
2) without an external signal and a ~2ms/div timebase,
change the holdoff until the twinkling is stationary,
and look for the hooks as above.

If display readout is involved, I would find out what is
happening when the display is switching from trace
to readout. I would observe the Y waveform and blanking
signals after the display sequencer IC and near the
display blanking IC. Trigger on either the blanking
waveform or the Y-waveform.

I would be looking for either the blanking signal to
be mistimed or the Y-waveform to be changing too slowly.
I would suspect the latter, so then it is a case of moving
"away from the output" until you find where it isn't
changing too slowly.

Be careful with probe tips around there; I know they
can short signals and destroy ICs :(


-Chuck Harris

edbreya@yahoo.com [TekScopes] wrote:
You may want to check all readily accessible hardware mounting and
grounding, particularly around the delay line. If the hooks are constant, then
they must be leaking into the circuit past the front-end, and somehow
localized so some parts are not affected. The one thing that is commonest to
all sections and operations is the grounding. Check that all screws are
tightened up snug (and that none are missing), and jiggle things around to see
if the symptoms can be aggravated.

To see if you've got some kind of ground loops at the front, jump the
apparently unaffected CH3 and CH4 inputs to the CH1 and CH2 - it's easy to
just use BNC cables for this.


Re: A 2465 teaser...

David Az
 

Have you checked the A6 board
Of the front panel
From experience I when i fix my 2465
Failure in one of the diodes can cause such a problem
You can also do a pot test



Exercise 1



And check that all buttons work correctly.



also check the continuity
from J652 on A6 to

( a sec dev /b sec dev)

col 0
col 1
col 2
col 3
col 4
( volts dev ch1 ch2 )

row 0
row 1
row 2
row 3
row 4


Re: A 2465 teaser...

Chuck Harris <cfharris@...>
 

When I first got the scope, it was good, but as I recall,
the fuzz just slowly progressed until it was there always.

That seemed like a capacitor problem, so I started there.

I removed the A1 board to do the capacitor replacement,
and I put all of the screws back myself. They are properly
tightened. That act alone should have refreshed all of the
ground contacts.

The delay line on the 2465 is soldered onto the back of
the A1 board. It doesn't use the little socket pins like
the 465/475 family does.

There is no sensitivity to prodding or smacking the scope
around.

Putting a jumper between CH3/4 and CH1/2 had no effect.

An additional clue is the leading hook's decay curve changes
slope with sweep speed, but the scope will not trigger on
this signal, nor on any of the random grass that appears on
the trace. That indicates that it is getting injected after
the trigger pickoff.

I am pretty certain it has something to do with the display
readout logic.

-Chuck Harris

edbreya@yahoo.com [TekScopes] wrote:

You may want to check all readily accessible hardware mounting and grounding, particularly around the delay line. If the hooks are constant, then they must be leaking into the circuit past the front-end, and somehow localized so some parts are not affected. The one thing that is commonest to all sections and operations is the grounding. Check that all screws are tightened up snug (and that none are missing), and jiggle things around to see if the symptoms can be aggravated.

To see if you've got some kind of ground loops at the front, jump the apparently unaffected CH3 and CH4 inputs to the CH1 and CH2 - it's easy to just use BNC cables for this.

Ed


Re: tek 2712 freezes during startup

Chuck Harris <cfharris@...>
 

Have each of you looked into the condition of the SMD electrolytic
capacitors on your spectrum analyzers?

In the few examples of these spectrum analyzers that I have worked
on, I have found a number of problems:

1) focus string SMD 1M and 2M resistors that weren't properly
soldered due to a plating failure on the board.
2) a whole slew of SMD electrolytic capacitors that were leaking
electrolyte.
3) dead lithium cells used for memory functions...
4) switching power supply capacitors that are high ESR.

If any of the solder joints around the SMD electrolytic capacitors
are milky white in color, rather than shiny and metallic, the
capacitors are leaking electrolyte.

-Chuck Harris

Joachim Lange ti8jlh@gmail.com [TekScopes] wrote:

El 08/11/2017 a las 05:50 p.m., rodd@globo.com [TekScopes] escribi�:

Hi, I have replaced the batteries but the SA freezes at the same point.
I was hoping that I would find a loose connection or similar issue
since it is a long way from US to Brazil, and it was "in working
condition" when I bought it (with photos).
Unfortunately that was not the case.
I wonder if the problem is related to the front panel since the last
line of the error screen says "press W to cont; Z to abort" but I have
tried every key and nothing happens.
Is it possible to know if the problem is really a freeze during boot
or a defective front panel?
Any other ideas?
The link to the error screen and the lighted leds of the front panel
is attached below.
https://groups.yahoo.com/neo/groups/TekScopes/photos/photostream/lightbox/191654049?orderBy=mtime&sortOrder=desc&photoFilter=ALL#zax/2075059146
https://groups.yahoo.com/neo/groups/TekScopes/photos/photostream/lightbox/191654049?orderBy=mtime&sortOrder=desc&photoFilter=ALL#zax/2075059146





Hello Roger, I forgot to ask you if you looked at the 100 Mhz TXCO as
Jochen wrote?
I will try to do that tomorrow.
Joachim






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Yahoo Groups Links




Re: A 2465 teaser...

Ed Breya
 

You may want to check all readily accessible hardware mounting and grounding, particularly around the delay line. If the hooks are constant, then they must be leaking into the circuit past the front-end, and somehow localized so some parts are not affected. The one thing that is commonest to all sections and operations is the grounding. Check that all screws are tightened up snug (and that none are missing), and jiggle things around to see if the symptoms can be aggravated.

To see if you've got some kind of ground loops at the front, jump the apparently unaffected CH3 and CH4 inputs to the CH1 and CH2 - it's easy to just use BNC cables for this.

Ed


Re: 2465B error code

 

The error indicates a problem with the CT (Counter-Timer) option.
My 2465B, 2445B, 2467B Options Service Manual (070-6864-01), available as a PDF scan from Artek Manuals (no affiliation) describes your error in table 5.4 (Maintenance Chapter), last item on page 5.4
The message indicates an error with the trigger path tests and tells you to check the associated circuits.

You'll need to get a service manual if only to find your way around the circuits.

Raymond

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