Date   

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






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Posted by: rodd@globo.com
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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


Re: 2465B error code

Jon Batters
 

Hi Chris,

You must be more informative.

1) What do the User & Service Manuals say about this ?

2) What does CT & OC stand for ?

3) Is this just a status alert or does the scope halt?

4) Any other faults ?

5) Maybe you’re just hoping a 2456B owner will jump-in and say : Go to PCB A4 and change IC #3 ; w/o having to do any work. (Do NOT take the cover off and do wild-probing ! )

6) 95% of us cannot help, with such a vague report. We do want to help ; when we help you, we help all of us learn…………

Jon Batters, Grants Pass, Or.


Re: Tek 465B Magic Soot

 

What is the resistance from the cap side of the fuse to ground? Ohmmeter lead + to the fuse.

----- Original Message -----
From: cmguitar50@gmail.com [TekScopes]
To: TekScopes@yahoogroups.com
Sent: Thursday, November 09, 2017 9:02 PM
Subject: [TekScopes] Re: Tek 465B Magic Soot



The cap measures 48.55 uF and ESR is .26.

I'll put this aside and think about digging deeper. I picked up a BK PR-28A in case I go further. I also have a variac and thought of bringing it up to around 70v as I saw in a tech training service manual


http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf



There seems to be a lot for me to learn on this , as I only dabble with tube amps for guitars, etc. This makes 500 VDC look like candy!


Re: Tek 465B Magic Soot

CARL MESROBIAN
 

The cap measures 48.55 uF and ESR is .26.

I'll put this aside and think about digging deeper. I picked up a BK PR-28A in case I go further. I also have a variac and thought of bringing it up to around 70v as I saw in a tech training service manual


http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf



There seems to be a lot for me to learn on this , as I only dabble with tube amps for guitars, etc. This makes 500 VDC look like candy!


scanned: 5B25N manual

Kurt Rosenfeld
 


2465B error code

Chris
 

Hello members,I have not been on in quit awhile and have recently run across an error in a 2456B scope. It pops up after the start up cyle and curious what it means? What shows up is CT test 84 fail OC . I have not used this scope at all but got it to play with awhile ago and it has been sitting. I am only a hobbiest so please bear with me. Thanks ahead, Chris


Re: Tek 465B Magic Soot

CARL MESROBIAN
 

I have the Artek manual - it's searchable, too :)

I will check c4006 at some point - thanks!


Re: Tek 465B Magic Soot

 

The 465B is a fine analog scope.

Ok, first, the black soot is just that. It is attracted by the high voltage field around the red cable. It is just mostly carbon exhaust.

The fuse is in the unregulated +15 supply and _IF_ you are very lucky, it is just a shorted tantalum capacitor C4006. The capacitor is under the HV shield in the corner of the board and is a 47uF-35 volt dipped tant. You can just use a good quality 105°C aluminum electrolytic

The second most likely thing that blows that fuse is the HV multiplier module. They run around $50+ and it is a task to replace. The procedure is covered in the service manual.

Do you have the service manual?


Retards,
Tom

----- Original Message -----
From: cmguitar50@gmail.com [TekScopes]
To: TekScopes@yahoogroups.com
Sent: Thursday, November 09, 2017 6:43 PM
Subject: [TekScopes] Tek 465B Magic Soot



I bought a 465B as-is, etc. and thought I could get it up and running and discovered fuse 4508 was blown. I put a 1A in it's place and that blew also.



I decided to move this beast off my bench and while doing so discovered some magic soot on the inside of the case and on a CRT connection ? (red wire). also. Is this thing worth fixing? I have another scope that works, so theres no urgency to it.




https://groups.yahoo.com/neo/groups/TekScopes/photos/albums/1633260205 https://groups.yahoo.com/neo/groups/TekScopes/photos/albums/1633260205


Re: tek 2712 freezes during startup

ti8jlh
 

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



[Non-text portions of this message have been removed]

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


[Non-text portions of this message have been removed]


Tek 2711 freezes

ti8jlh
 

Hello RogerAs you can see my SA shows a similar or the same problem.I will look at the 100 Mhz TCXO as Jochen posted.I hope this will be the solution.I tried many times to repair it without success. RegardsJoachim  TI8JLH

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