开云体育

Hi, Gang

I have a 545 (no suffix) scope, and recently had to do some
trouble-shooting. One hint: when measuring d.c. voltages
along the ceramic terminal strip which has the voltages labeled
on the nearby chassis edge, note that the "225V" label
is offset by one position. The label points to a position
on the strip which has a trimmer capacitor connected,
it should point to the adjacent position which has several
white wires with red stripes connected.

I won't tell you how long I searched for spare tubes
associated with the 225V regulator, before I realized
the error. I have since added an arrow with a magic marker
pointing to the correct spot.

73,
Ed Knobloch

I?purchased mine at Qservice
?
qservice@...
?
Bob

If the surge arrestors get a voltage higher than 230V then they are
going to blow the fuse.

Check to see what voltage the surge arrestors get to before the fuse
blows by ramping up the input voltage to the scope using the variac.
You should also see a spark if they are tripping the fuse.

--- In TekScopes@..., "oldtestgear" <philip.parsons@...>
wrote:

So far I have replaced the main PSU capacitors plus the bridge
rectifier and the DC supply started to come up -- then the mains

fuse

blew. After changing the fuse I tried to power it up using a

variac.

Same result at about 100V, a blown fuse. Below ~100V the

unregulated DC

supply looks stable.
There are no signs of damaged components or singed PCB tracks so

my

guess is something is breaking down suddenly and blowing the

fuse.Has

anyone had experience of the transient protectors tripping early

or any

other suggestions to check.

Thanks in advance.

Phil

Hi everyone

I've looked everywhere for a 442 manual and come up empty.

Any ideas?


Thanks.. Tad WA1FQO

Let me guess, the capacitor was a RIFA cap?

Every Tek scope that I have seen and have checked the X class
suppression capacitors on has at least shown fracture marks in the
epoxy coating if it was of the RIFA type. In the worst case they
have burnt out totally! I have also seen problems with these in
Philips scopes

For what it is worth RIFA still appear to make these caps exactly
the same (don't know if they still come with this nice feature).

Farnell sell a large range of X class caps and if you really wanted
to you could probably replace the cap with the same RIFA cap. I
think I would be going for a different option though given the
issues I have seen. The only problem you may have is manufacturers
have tended to be able to reduce the size of these caps which means
for some values getting the same pitch may be hard although I have
had success in finding suitable replacements for all the caps I have
needed to replace.

Cheers,

Chris

--- In TekScopes@..., "tom jobe" <tomjobe@...> wrote:

Hello Gary,
For what it's worth...
That same capacitor, 285-1222-00, was also used in the military

version of

the 2235, It was used directly across the incoming AC lines just

before the

full wave bridge rectifier as part number C904, and it did not

have a

resistor in series with it..
I have a few partially stripped military 2235 mainboards, and they

are all

missing C904, so I would guess that it must have been a component

that had

problems.
Other 22XX scopes I looked at use a .0022 uF (2200 pF) 250 V

capacitor for

C904.
tom jobe...


----- Original Message -----
From: "Garey Barrell" <k4oah@...>
To: "Tekscopes" <TekScopes@...>
Sent: Thursday, September 18, 2008 7:55 PM
Subject: Re: [TekScopes] 2215 Problem

Stefan -

It's not right across the line. It's in series with a 470 ohm

1/2W CC

resistor (which now measures 19 ohms) and looks like a "snubber"

across

the AC line "after" a series inductor. There's an MOV (250VAC)

and a

.001 cap across the line just after the fuse on the "line" side

of the

inductor. This unit is rated for 220 primary power, although

it's never

been used on anything but 120VAC.

73, Garey - K4OAH
Glen Allen, VA



Stefan Trethan wrote:

I'm assuming this was the x-capacitor (across the power line)?

If so the very same thing happened to me and a fluke 8842a. It

had just

come

from singapure, and worked just fine for a few hours

beforehand.

The cap leaked a nasty brown liquid (and acrid smell). It

stained my

fingers

for days. The cap was actually inside a Schaffner brand mains

filter

module.

Anyway, if it was the x-capacitor, you should replace it with

a rated x1

capacitor for mains filter purposes.

ST

On Thu, Sep 18, 2008 at 11:06 PM, Garey Barrell

<k4oah@...>wrote:

I was using my 2215 for an hour or so the other night, and

moved over

to

the desk to look at something else. About 30 minutes later I

heard a

"sizzle - pop" and smoke comes rolling out the back of the

cabinet!

Both sides! I walked over and turned up the Brightness, and

had a

trace. So I shut it off, took it out of the case and did a

close

inspection. Nothing! I couldn't find my small TORX bits

(don't ever

move.......) but everything looked fine. So I turned it back

on,

measured the supply voltages and all were right on..... Scope

seemed to

be operating normally!?!?!

Today, I found my little TORX bits, and removed the inductor

(the

HUUUMMMMMM) from the back panel and lo and behold, on the

main board

underneath the inductor cover was what remained of C926,

fanned out

like

a Rolodex. P/N 285-1222-00, 0.068 uF @ 250 VDC, 20%. This

is a tiny

rectangular 1/4" x 3/4" by 1/2" high epoxy thing. Of course

none of

the

million and a half capacitors that I have will even come

close to

fitting mechanically.

So. Anyone have a source for these things, or perhaps have

an "extra"

one.

help.....

--
73, Garey - K4OAH
Glen Allen, VA

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

Yahoo! Groups Links

Hi Howard,

mine does not do this, starts up perfectly each time. So something is amiss
here.

Mit freundlichen Grü?en, / Best regards,

Florian Diederichsen

So far I have replaced the main PSU capacitors plus the bridge
rectifier and the DC supply started to come up -- then the mains fuse
blew. After changing the fuse I tried to power it up using a variac.
Same result at about 100V, a blown fuse. Below ~100V the unregulated DC
supply looks stable.
There are no signs of damaged components or singed PCB tracks so my
guess is something is breaking down suddenly and blowing the fuse.Has
anyone had experience of the transient protectors tripping early or any
other suggestions to check.

Thanks in advance.

Phil

The heatgun and cooling spray method is not very pactical in this
instance because it is very difficult to run this unit when it is
disassembled. Some of the boards have machined aluminum heatsinks
that also act as RF shields encasing the whole PC board.

Howard, have you tried calibrating it? I.e. SPCL 099 command. You will
need a 7 or more digit calibrated DMM. To do a proper checkout you
also need a Spectrum Analyzer and a power meter.

--Victor Silva

Very useful info.

There's an error on page 78. An extra digit (4) has been added to
the 4 digit example of the 162k resistor. It should be 1623 not
16234.

--- In TekScopes@..., Jerry Massengale <jmassen418@...>
wrote:

Bravo! Thank You!
?
jerry

--- On Wed, 9/24/08, TekScopes@...

<TekScopes@...> wrote:

From: TekScopes@... <TekScopes@...>
Subject: [TekScopes] New file uploaded to TekScopes
To: TekScopes@...
Date: Wednesday, September 24, 2008, 1:50 PM







Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the TekScopes
group.

File : /SMD_codes.pdf
Uploaded by : udtmang <mwallace9@cfl. rr.com>
Description : smd part code nomenclature

You can access this file at the URL:
. yahoo.com/ group/TekScopes/ files/SMD_ codes.pdf

To learn more about file sharing for your group, please visit:
. yahoo.com/ l/us/yahoo/ groups/original/ members/web/

index.htmlfiles

Regards,

udtmang <mwallace9@cfl. rr.com>

On Thu, 25 Sep 2008, Howard Ashcraft wrote:

I have restored a SG5030 (bad electrolytic smd caps). It works
perfectly if allowed to run for about 5 minutes. If it has been
sitting cold for a few days, however, it will show various errors on
start up (all lock errors) that will disappear if the self-test is run
after a 5 minute warmup. I assume that this is related to the
oscillator being cold. Do others have this behavior or is it
relatively normal. Since it works fine when warm (and should be warm
when used), I'm not terribly concerned, but am interested if others
see this as well.

Having no own experience with this model I can't give you specific advice.
However, this kind of error is usually easy found. You need a hairdryer
and a can of coolant spray. Warm the machine gently with the hairdryer
until it runs good and carefully cool suspect parts with the coolant.
You'll find the temperature sensitive part quickly with this method.

Grü?e aus Hohenlohe,

Martin Jangowski

| Martin Jangowski E-Mail: Martin@...|
| Netzwerke und Multimedia |
| Voice: +49 7946/3723 Fax: +49 7946/940791 |
| Snail Mail: Von-Olnhausen Str. 4 74626 Bretzfeld Germany |

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

I have restored a SG5030 (bad electrolytic smd caps). It works
perfectly if allowed to run for about 5 minutes. If it has been
sitting cold for a few days, however, it will show various errors on
start up (all lock errors) that will disappear if the self-test is run
after a 5 minute warmup. I assume that this is related to the
oscillator being cold. Do others have this behavior or is it
relatively normal. Since it works fine when warm (and should be warm
when used), I'm not terribly concerned, but am interested if others
see this as well.

Regards,

Howard

Hello Jose,



In the 1986 Tek Catalog, for the 7912AD, Option 13 says the TV Scan is
changed to 625 lines at 50 Hz. I also consulted the 1974 Catalog and it
says Option 13 for the R7912 is TV scan is 625 lines at 50 Hz, too.



Stan



_____

From: TekScopes@... [mailto:TekScopes@...] On Behalf
Of Jose V. Gavila
Sent: Friday, September 19, 2008 10:26 AM
To: TekScopes@...
Subject: [TekScopes] Option 13 in an R7912?



Hello!

Today I have received my last Tek toy, an R7912 mainframe :-). It has a
label in the plug-in compartment base which says 'Option 13'. I wonder if
someone know what does it mean.

Thanks!

JOSE
-------------------------------------------------
73 EB5AGV - JOSE V. GAVILA
IM99sm La Canyada - Valencia (SPAIN)

Hi,

Who sells the matching sockets that fit the P6137 scope probes?
What is the description and part number? I intend to solder these into a pcb at the nodes where I need to make measurements but must cannot use the probe ground lead.

Many thanks, 73, W6MIK, Dave

Bravo! Thank You!
?
jerry

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the TekScopes
group.

File : /SMD_codes.pdf
Uploaded by : udtmang <mwallace9@...>
Description : smd part code nomenclature

You can access this file at the URL:


To learn more about file sharing for your group, please visit:


Regards,

udtmang <mwallace9@...>

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the TekScopes
group.

File : /DiffOscMeasurements.pdf
Uploaded by : udtmang <mwallace9@...>
Description : A Primer on Differential Measurements,

You can access this file at the URL:


To learn more about file sharing for your group, please visit:


Regards,

udtmang <mwallace9@...>

I am not familiar with the 7623 (BAMA is slow downloading today) but my 7633
and 7603 use the same IC part 155-0022-00 for the vertical and horizontal
amp switch so I tested by substitution.



My problem was not in the channel switch IC but in one horizontal amplifier
resistor R563. It gave a similar problem but with a horizontal shift and
dance plus slight right hand sweep compression. I posted last month in
response to someone else working on a 76 series.



I attempted to deduce the internal circuit of 155-0022-00 by a series of DC
measurements but was not satisfied with my efforts as I could not accurately
calculate the output voltages from the current summation. Maybe you will do
better and if so I would like to see your equivalent circuit.



Robert Furniss

RobertFurniss@...



650 504 1468 cel

_____

From: TekScopes@... [mailto:TekScopes@...] On Behalf
Of fuzzbrain01
Sent: Tuesday, September 23, 2008 7:38 PM
To: TekScopes@...
Subject: [TekScopes] 7623A readout problem



I have a 7623A which has developed an unusual problem. Perhaps
someone in the group has dealt with this before?

I have 7A18 and 7A26 vertical plug-ins, and a 7B53A timebase plug-in.
The traces for each vertical channel are visible and operating
normally. When I turn on the readout, I can see the expected
characters; however, the position of each vertical channel's amplitude
readout moves with the vertical centering adjustment for that channel.
The readout for the timebase seems to move with channel 1 of the
selected (right or left) vertical plug-in. When I put a sine wave on
one channel, the readout for that channel has an added vertical offset
that corresponds to the AC component of the sine wave input. It's as
if it were dancing! If I use the variable adjustment on the timebase,
I can "zero-beat" the vertical offset error of the character.

I checked the low and high voltage power supplies, which were all
within tolerances. I cleaned the contacts of the plug-in connectors
on the main interface board, and re-seated the plug-ins in the
mainframe. I swapped the vertical plug-ins, and tried a different
timebase plug-in. Still the same problem.

The symptoms seemed to indicate a problem with vertical channel
switching in the mainframe. I read through the theory of operation
for the readout system, and looked through the schematics. I
concentrated on the A4 Vertical Interface board. Using another
'scope, I checked the waveform at the base of Q2390 (X/Y inhibit). I
found normal voltage levels, and pulses of the correct amplitude that
appeared in small groups, that I took to be the character slots.
Checking the emitter and base of Q2390, I also found correct voltage
levels (per the blue voltages given in the manual's schematic). I
noticed that the X/Y Inhibit line also goes to pin 6 of the Vertical
Channel Switch IC, U2340.

Does anyone have a cross-reference or data sheet for 155-0022-00,
U2340? Without knowing what's inside, it's difficult to know what to
expect on the output pins.

Or perhaps I'm on the wrong track. Has anyone seen this before? What
should I look for?

Thanks for your help.

I have a 7623A which has developed an unusual problem. Perhaps
someone in the group has dealt with this before?

When you say "developed", do you mean that this is a problem that has not
occurred before with this particular mainframe?

Craig

I have a 496 SA s/n b010424 that was converted into a hangar queen
at some point in its life.

It has a mix of modules pulled from five different units. Very
organized module changers worked on this unit, and left notes
on color coded tags...

I have worked my way through the unit to the point that I have
occasional error 58's (I need to go through the cal sequence).

If the phase lock control module is installed the digital storage
option fails to operate. If the phase lock module is activated
it hangs the data bus and the unit displays garbage on the display
and ceases to respond to the controls.

I do have a set of card extenders and a 1230 logic analyzer and
enjoy a good mystery, however I am not sure that I wish to spend
a couple of weeks chasing this problem.

Any suggestions on common failures on this unit?

Does anyone have have a reasonably priced spare available?

Jim, n8qoh

Many thanks to the Tektronix forum and for all of the terrific help
received from the members.

The 465 scope is now fixed. Capacitor C1419 was shorted to ground.
Once the capacitor and fuse were replaced, the scope was back to normal.

A series of pictures are posted in photo album 465 - HV Bad Cap C1419,
linked below:


Some confusion occurred due to different schematic versions of the HV
section. Newer 465 scopes (S/N B289565 and above ) use two 22 uFd
caps in parallel (C1419 and 1418):


Older 465 scopes (S/N B289564 and below) have a single 47 uFd
capacitor (C1419). Older models do not have a capacitor named C1418.


The voltage to fuse F1419 is around 24.4 to 24.9 volts. The schematic
is labeled +15 unregulated. While technically correct, that's a bit
misleading because the normal voltage is listed as 24.4 volts. Since
C1419 is rated at 25 volts, capacitor C1419 operates at the brink of
destruction.


Kemet's Tantalum Dipped / Radial - Polar capacitor specifications were
researched. This document is posted in the links section as Tantalum
Replacement Caps and also listed here:


On page 61 (the first page of this document), a table lists all of the
capacitors available with various voltage ratings.

This document shows that the highest voltage rating available for a 47
uFd capacitor is 35 volts. But, 22 uFd capacitors are rated as high
as 50 volts (and are less expensive).

It is speculated that newer 465 scopes use two 22 uFd capacitors in
parallel with a higher voltage rating to overcome frequent failures of
the 25 volt, 47 uFd capacitors.


The shorted C1419 capacitor in my scope was replaced with a Kemet 47
uFd tantulum capacitor rated for 35 volts. It seems to work fine and
cost $5.76 from Mouser Electronics. The fuse cost $0.28, so six were
purchased (just in case).

Of particular interest, notice the steep voltage derating curve of
tantalum capacitors based on temperature. A tantalum capacitor rated
for 25 volts at 85 degrees C is only rated for 16.5 volts at 125
degrees C! With an input voltage approaching 25 volts, C1419 is at
high risk of failure, especially if the fan is not doing a good job.
Since the old Tektronix scopes are full of Tantalum capacitors, a high
temperature excursion could be quite costly, if not catastrophic. So,
careful consideration is highly recommended when choosing a fan
replacement.

A great trouble-shooting tip is to disconnect Q1418 by unplugging
connector P1400. This enables Q1418 (under the A9 board) to be tested
without removal and also allows continuity checks from fuse F1419 down
through the transformer primary winding. If the demand side of F1419
is shorted to ground with P1400 disconnected, you can bet C1419 is bad.

Capacitor C1419 is located at the corner of the A9 board under the
high voltage shield.


Once the shield is removed, be careful poking around those high
voltage caps! The good news is that board A9 does not have to be
removed. C1419 is easily removed and replaced from the top side of
the circuit board using a low wattage soldering iron and a bit of care.

I am very pleased to have my old 465 scope going again. Again many
thanks to the Tektronix forum. Having the guidance of such
experienced members was a big help and made this project a lot of fun!

Ron