Date   

Re: Yet another DANGER!

Craig Sawyers <c.sawyers@...>
 

Ouch, well I think I'll add a steel helmet to my workshop kit.
That event was serious stuff, and could have ended much worse. It reminds
me of a Jaguar mailing list that I used to admin. We got a mail from one of
our listers sons, asking for his father to be taken off the list. He's been
working under his classic Jag when the jack collapsed (for whatever reason
he wasn't taking the usual precautions when working under a car) and killed
him outright.

Short of a 'scope falling off a high shelf onto someone's head, I don't
think we have that degree of hazard on this list - but you get the drift...

Craig


Re: Yet another DANGER!

robin.birch@...
 

Ouch, well I think I'll add a steel helmet to my workshop kit.




"Miroslav
Pokorni" To: <TekScopes@yahoogroups.com>, "watchguard.rm"
<mpokorni2000@ya <watchguard@rocketmail.com>
hoo.com> cc:
Subject: Re: [TekScopes] Yet another DANGER!
24/03/2004 00:32
Please respond
to "Miroslav
Pokorni"






As wise Jim Williams says: it happens only when you start feeling your
oats.

Regards

Miroslav Pokorni

----- Original Message -----
From: "watchguard.rm" <watchguard@rocketmail.com>
To: <TekScopes@yahoogroups.com>
Sent: Tuesday, March 23, 2004 1:44 PM
Subject: [TekScopes] Yet another DANGER!


Foolish...no,Freaky...yes. I am very careful around HV CRT's & other
potentially hazardous items, but I have been doing electronic design &
repairs for 35 years. Recently I was repairing a DuMont 274A (~1945)
oscilloscope using tried & true procedures (variac,cap tester,
ammeters,etc) when disaster struck.

I had found all the bad components, replaced some on suspicion and had
a fine display. No components were overheating and all tubes tested
strong so I began a burn-in period.

The burn in was ended early ( 3.5hrs ) with a cloud of smoke, large
bang (possibly a new universe being created), droplets of oil
everywhere and flying glass. It seems one of the HV (.5 1500v oil
filled can)filters went defective, heated up & sent the can soaring
into the CRT shield with such force as to bend the shield 3/4" & smash
the CRT which imploded sending the glass & oil from the cap all over
the bench, test equipment & me.

All is well now! I changed my underwear & the cap, cleaned the bench &
test gear and expained to the family that a call to the National
Security Director wasn't necessary.

I had forgotten about Murphy's 1st law. "if it could happen...it
probally will." Next time I will call a friend & ask him to burn in
the scope for me. Two good things came out of it: 1. I got to see the
insides of a CRT! 2. Nothing on my workbench squeeks.






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CRT rejuvenation

Arthur Shulman <dentist@...>
 

Before you try to clear a short, you should be very sure that it is
indeed the tube that is causing the control failure.

With the CRT out of the socket, or atleast with the filament only
disconnected, measure the difference potential
between the cathode & the control grid. The brightness control should be
able to swing the grid to -50 or maybe
-100 volts with respect to the cathode.
If not, the control circuitry might be defective.
Next, remove the tube and do the test again. If it still fails, the
control circuitry is defective, not the tube.
Having decided which is the culprit, if it's the CRT, inspect the socket
& the base & all the wiring to see if there
might be some external leakage path.
If you decide it HAS to be the CRT, then try the following with due care
for life & limb. You have little to lose
with the CRT at this point.

Never having tried this with a CRT, I can only suggest a method that has
worked for me with standard vacuum
tubes. (Transmitting sizes)

With a variable high voltage power supply, take a suitably rated
electrolytic cap of say, 10 or 20 Mfd & charge it
to say, 100 volts. Disconnect the cap from the supply & discharge it
through the short path while the filament is
energized. Use polarity on the cap so the negative is applied to the
grid. You DONT want to drive the grid 100
volts positive - it'll melt.

Do this once & measure the resistance. See if it changes. If so, repeat
until the short is cleared.
If no change, increase the charging voltage in 25V increments and repeat
step 1.

Let me know how this works.

Arthur VE3ZV

leon545b wrote:

Hello all -

A friend gave me a replacement CR tube for my 545B that has an odd
problem. When I plug it in, the brightness goes to full, and can't
be controlled. Suspecting leakage from the cathode to the 1st grid,


crt rejuvination?

leon545b
 

Hello all -

A friend gave me a replacement CR tube for my 545B that has an odd
problem. When I plug it in, the brightness goes to full, and can't
be controlled. Suspecting leakage from the cathode to the 1st grid,
I pulled the base off of it and cleaned it with distilled water. No
joy. I used a DMM that can read up to 1.2 GOhm and found no
measurable resistance from the cathode to any other element, or in
between another two elements. However, when I run the filament and
get the thing hot, voila! I see about a 5 MOhm resistance between the
1st grid and the cathode. Does anyone know if there's a safe (for me
and the CRT <g>) way to "blow" this short open? Has anyone been
successful in restoring a CR tube in this way?

I searched the archive and didn't find anything... Any help would be
appreciated. This tube is in pristine condition otherwise...


Re: Yet another DANGER!

Miroslav Pokorni
 

As wise Jim Williams says: it happens only when you start feeling your oats.

Regards

Miroslav Pokorni

----- Original Message -----
From: "watchguard.rm" <watchguard@rocketmail.com>
To: <TekScopes@yahoogroups.com>
Sent: Tuesday, March 23, 2004 1:44 PM
Subject: [TekScopes] Yet another DANGER!


Foolish...no,Freaky...yes. I am very careful around HV CRT's & other
potentially hazardous items, but I have been doing electronic design &
repairs for 35 years. Recently I was repairing a DuMont 274A (~1945)
oscilloscope using tried & true procedures (variac,cap tester,
ammeters,etc) when disaster struck.

I had found all the bad components, replaced some on suspicion and had
a fine display. No components were overheating and all tubes tested
strong so I began a burn-in period.

The burn in was ended early ( 3.5hrs ) with a cloud of smoke, large
bang (possibly a new universe being created), droplets of oil
everywhere and flying glass. It seems one of the HV (.5 1500v oil
filled can)filters went defective, heated up & sent the can soaring
into the CRT shield with such force as to bend the shield 3/4" & smash
the CRT which imploded sending the glass & oil from the cap all over
the bench, test equipment & me.

All is well now! I changed my underwear & the cap, cleaned the bench &
test gear and expained to the family that a call to the National
Security Director wasn't necessary.

I had forgotten about Murphy's 1st law. "if it could happen...it
probally will." Next time I will call a friend & ask him to burn in
the scope for me. Two good things came out of it: 1. I got to see the
insides of a CRT! 2. Nothing on my workbench squeeks.



Yet another DANGER!

Watchguard Consulting
 

Foolish...no,Freaky...yes. I am very careful around HV CRT's & other
potentially hazardous items, but I have been doing electronic design &
repairs for 35 years. Recently I was repairing a DuMont 274A (~1945)
oscilloscope using tried & true procedures (variac,cap tester,
ammeters,etc) when disaster struck.

I had found all the bad components, replaced some on suspicion and had
a fine display. No components were overheating and all tubes tested
strong so I began a burn-in period.

The burn in was ended early ( 3.5hrs ) with a cloud of smoke, large
bang (possibly a new universe being created), droplets of oil
everywhere and flying glass. It seems one of the HV (.5 1500v oil
filled can)filters went defective, heated up & sent the can soaring
into the CRT shield with such force as to bend the shield 3/4" & smash
the CRT which imploded sending the glass & oil from the cap all over
the bench, test equipment & me.

All is well now! I changed my underwear & the cap, cleaned the bench &
test gear and expained to the family that a call to the National
Security Director wasn't necessary.

I had forgotten about Murphy's 1st law. "if it could happen...it
probally will." Next time I will call a friend & ask him to burn in
the scope for me. Two good things came out of it: 1. I got to see the
insides of a CRT! 2. Nothing on my workbench squeeks.


Re: 5103N/D13 OPT07 rear signal O/Ps

Stan & Patricia Griffiths <w7ni@...>
 

You are correct that the 5103/D13 is also known as a 5113.

Stan
w7ni@easystreet.com

----- Original Message -----
From: "Tim Phillips" <t.phillips@ucl.ac.uk>
To: <tekscopes@yahoogroups.com>
Sent: Thursday, March 18, 2004 3:52 AM
Subject: [TekScopes] 5103N/D13 OPT07 rear signal O/Ps


Morning all;
I have a 5103N/D13 which *I think* is equiv.to the 5113.
Could someone tell me what the rear-signal-out comprises?
The rear panel of the 'scope is punched for the sockets;
is it just a matter of picking off the signals from the
plug-in connector or is buffering needed? The manual
download from Datasouth doesn't shed any light.
many thanks
Tim





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reference oscillator DSA602

Peter van Daalen <reteb@...>
 

My DSA602 has a reference SAW 500 Mhz oscillator with a 5e5 stability.

Does it make sense to replace this built in reference by a much better one
?

I have a 500 Mhz 1e11 ( tau 1000 sec ) reference.
Sure, this is absurd overkill, but would this one yet improve the 602's
timebase jitter of >20 ps ?

What else better measuring results ( if any at all ) could be expected by
replacing the reference oscillator ?

I have a few more questions on the DSA602.
In particular on the enhanced accury.

Some more DSA602 users on this list ?

Thanks.
Peter PE1ECM


7904 readout board

Craig Sawyers <c.sawyers@...>
 

Hi folks

I recently bought a 7904, cleaned it up and calibrated it and it is a source
of joy. One problem is that it is Option 1, which deletes the readout board
(there is a so-called dummy board in its place).

Question: Does anyone have a parts 7904 from which I could (for some cash!)
get a readout board?

Cheers

Craig


Tek Model 932A

j.foster <j.foster@...>
 

Hello Folks:

Does anybody have any general information on this model; dates of manufacture,
common problems, unobtanium parts etc?

TIA John Foster.


Tek 536 For Sale

dean_metzler <dametz@...>
 

Hi, I'm new to the group. A friend of mine recommended this site to
get in contact with those who might be interested in old Tek scopes.
Well I have a Tektronix 536 with Type T timebase and Type CA dual
channel plugins for sale. The condition of this scope is fair. The
CRT is very bright (blindingly) and it appears to be in good cosmetic
condition inside and out considering its age. It powers up and both
channels display a waveform. The main problem with it is that it
doesn't trigger properly and therefore doesn't "lock on" to the
waveform. Maybe I have a switch in the wrong setting or maybe
something went south, but I just don't want to fiddle with it
any more. I do have a wire connected from the vertical trigger output
to the external trigger input. It used to work in this mode, but
haven't had luck recently. A couple of the red calibration knobs are
freewheeling. The scope will also come with a Model B Scope-Mobile
cart with a shallow drawer. I don't know how much this piece is
worth, but I owned it since 1986 when I was in college and have
rarely used it since. No probes or manual included. It does have a
plastic camera mount bezel. I would be happy to send some low
resolution pics to those who are interested. I live near Lancaster,
PA and certainly anyone within driving distance to pick it up would
be an advantage. Can anyone advise me on how much this package is
worth and/or give me an offer? I will consider any reasonable offer.
I recently picked up a newer, much smaller scope for my hobby needs
and the big, old one has to go...I will miss it. Thanks.

Dean

P.S. - I also have a large box of vacuum tubes for sale, mostly taken
from old TV's and radios. Just not enough space to keep them!


Tek 536 For Sale

dean_metzler <dametz@...>
 

Hi, I'm new to the group. A friend of mine recommended this site to
get in contact with those who might be interested in old Tek scopes.
Well I have a Tektronix 536 with Type T timebase and Type CA dual
channel plugins for sale. The condition of this scope is fair. The
CRT is very bright (blindingly) and it appears to be in good cosmetic
condition inside and out considering its age. It powers up and both
channels display a waveform. The main problem with it is that it
doesn't trigger properly and therefore doesn't "lock on" to the
waveform. Maybe I have a switch in the wrong setting or maybe
something went south, but I just don't want to fiddle with it
any more. I do have a wire connected from the vertical trigger output
to the external trigger input. It used to work in this mode, but
haven't had luck recently. A couple of the red calibration knobs are
freewheeling. The scope will also come with a Model B Scope-Mobile
cart with a shallow drawer. I don't know how much this piece is
worth, but I owned it since 1986 when I was in college and have
rarely used it since. No probes or manual included. It does have a
plastic camera mount bezel. I would be happy to send some low
resolution pics to those who are interested. I live near Lancaster,
PA and certainly anyone within driving distance to pick it up would
be an advantage. Can anyone advise me on how much this package is
worth and/or give me an offer? I will consider any reasonable offer.
I recently picked up a newer, much smaller scope for my hobby needs
and the big, old one has to go...I will miss it. Thanks.

Dean

P.S. - I also have a large box of vacuum tubes for sale, mostly taken
from old TV's and radios. Just not enough space to keep them!


Manuals for S-51 and S-53

Miroslav Pokorni
 

Does anyone have scanned manuals or schematics for S-51 (Count Down Trigger
Synchronizer Head) and S-53 (Trigger Recognizer Head) that could be e
mailed?

Thank you,

Miroslav Pokorni


Re: 7704A - Vertical non-linear depending on vertical position

pe1fbo <sh331182@...>
 

--- In TekScopes@yahoogroups.com, "Heather" <smithd.mn@c...> wrote:
Hello all - I'm trying to bring a 7704A back into service after
several years of downtime. Everything seems to be working with
the
exception of the vertical non-linearity I'm seeing. For example -
if
I input a signal and set up for 1 division of deflection near the
top
of the screen and move the position knob on the vertical amp
(7A26)
to move the trace to the bottom of the screen the deflection is
reduced to about .25 divisions. I get the same results from a
couple
of known good 7A26 amps. I monitored the inputs to the vertical
amplifier and noted the DC shift and reduced amplitude waveform so
I'm thinking it's probably the vertical interface board. Any
insight
would be appreciated. - Dean Smith
This sound's as a defective vertical channel switch....
The same symptoms you would see on a 2445..2465 with a bad channel
switch.

I had a look at the 7704 model, and there the channel switch is made
out of ordinary components. I don't know if this is the case in the
7704A. If so, check for 1% resistors which have drifted, or try to
wiggle with the transistors on that board (vertical interconnect)

- Fred de Vries


7704A - Vertical non-linear depending on vertical position

Heather
 

Hello all - I'm trying to bring a 7704A back into service after
several years of downtime. Everything seems to be working with the
exception of the vertical non-linearity I'm seeing. For example - if
I input a signal and set up for 1 division of deflection near the top
of the screen and move the position knob on the vertical amp (7A26)
to move the trace to the bottom of the screen the deflection is
reduced to about .25 divisions. I get the same results from a couple
of known good 7A26 amps. I monitored the inputs to the vertical
amplifier and noted the DC shift and reduced amplitude waveform so
I'm thinking it's probably the vertical interface board. Any insight
would be appreciated. - Dean Smith


Re: Off subject, kind off: home brew spot welding NiCd batteries

gettingalongwouldbenice
 

--- In TekScopes@yahoogroups.com, "Miroslav Pokorni" <mpokorni2000@y...> wrote:
Hello everyone,

Does anyone have an experience with spot welding tabs on a subC size NiCd
batteries? I have a stack of ten batteries which were connected with nickel
plated iron (?) tabs, welded at four spots at each end of tab, but a tab
came loose on one cell.

I was thinking of using large cap (10,000 mictoF or so), charged to 50 V or
so, a suitable switch (perhaps mercury displacement) and short, thick and
solid wires as electrodes. I need to make only four welds, so 'electrodes'
can be consumable.

I do not intend to break any new grounds, looking for someone's prior
experience.

Thank you in advance,

Miroslav Pokorni
There's currently a thread in sci.electronics.design on the subject.
I posted some links to my spot welding experiments and some
commercial data.
mike


tek 2211 : adjusting vertical gain

nav0239
 

I need to know which pot needs to be adjusted or a pointer to where
to find the info.

Everything is fine with the scope, except that the vertical gain
calibration is off quite a bit. Both channels have the same gain.I
have tried but could not find a service manual.

Thanks a lot!
nav0239


Re: Another Tek tunnel diode pulser 017-086 - Manual, anyone?

Craig Sawyers <c.sawyers@...>
 

From Zenith's data sheet, the tunnel diode is a 152-0099-00, which is a
50mA/6pF device. Calculated switching time for this would be faster than
60ps - but it all depends on the layout. Any additional stray capacitance
would slow the time down. It says in the data sheet that it is on a
"circuit board assembly" which could add several pF and a few nH - hence the
specified <200ps rather than anything faster.

It is really neat though - compact and small.

The much larger 067-0513-00 has a diode in a tiny disc-like package (100mA,
6pF - so <30ps), incorporated into a GR air-line - a bit like the way it is
done in the 284. The aim is to make it think it is in a matched
transmission line. It goes like stink with a <30ps fall time (so no
performance degradation from layout) and is battery powered. There is one
on eBay at the moment.

Craig

-----Original Message-----
From: Cliff Carrie [mailto:cliffcarrie@hotmail.com]
Sent: 20 March 2004 20:36
To: TekScopes@yahoogroups.com
Subject: [TekScopes] Another Tek tunnel diode pulser 017-086 - Manual,
anyone?


I picked up a Tek 017-086 TD pulser a while back. It is self
contained and
about twice the size of its GR connector. Power is from 2 internal coin
cells. Risetime printed on it is <.2ns (200ps). It turns on
automatically
when a 50 ohm termination is present. I put it together with a GR
to BNCm 50
ohm feedthru termination. Plugs directly into a scope input. Of course it
can be put on a probe end with suitable adapters.

No muss, no fuss, no 100 volt input pulses needed.

Does anyone have a manual or data sheet for this pulser? I'm
curious about
flatness and aberrations. What product family was it intended for? It's
faster than most of the pulsers I've seen, except for my Tek 284,
and much
more convenient.

Regards,
Cliff

_________________________________________________________________
http://join.msn.com/?pgmarket=en-ca&page=byoa/prem&xAPID=1994&DI=1
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Re: Off subject, kind off: home brew spot welding NiCd batteries

Eric Schumacher <WB6KCN@...>
 

Hello Miro

Best deal is to use an activated flux (acid) you need so little flux on the tip of the solder that you can't even see it. Just tin the nickel plate or stainless of the cell and finish the job with the usual 63/37. The stainless conducts so poorly that it takes practically no heat (in calories) to get the job done. The admonishment not to solder to nicads must have been started by a guy who tried to do it with a 500 watt iron and rosin core solder, will never happen that way. Acid core solder doesn't work very well by the way but the flux that tastes like lemon juice (we use it on our SMT line) works great.

Eric

At 04:07 PM 3/20/04, Miroslav Pokorni wrote:
Hello everyone,

Does anyone have an experience with spot welding tabs on a subC size NiCd
batteries? I have a stack of ten batteries which were connected with nickel
plated iron (?) tabs, welded at four spots at each end of tab, but a tab
came loose on one cell.

I was thinking of using large cap (10,000 mictoF or so), charged to 50 V or
so, a suitable switch (perhaps mercury displacement) and short, thick and
solid wires as electrodes. I need to make only four welds, so 'electrodes'
can be consumable.

I do not intend to break any new grounds, looking for someone's prior
experience.

Thank you in advance,

Miroslav Pokorni




Yahoo! Groups Links




Re: Sticky Buttons

Miroslav Pokorni
 

Do not forget lubricant, it is amazing what a little bit of grease can do
for sliding. I am not sure what would be the best or recommended grease for
those switches, but I would try (thick) silicon grease, I do not think that
you can go very wrong with that choice. Spray silicone would not give you a
durable solution and there is a chance that vehicle in spray (solvent) can
attack plastic.

Regards

Miroslav Pokorni

----- Original Message -----
From: "jdpetrzelka" <j.petrzelka@verizon.net>
To: <TekScopes@yahoogroups.com>
Sent: Wednesday, March 10, 2004 7:02 AM
Subject: [TekScopes] Sticky Buttons


Working on a DM5010 multimeter it has a bunch of little square button
switches on the front panel, a few are sticky, should I try and clean
them or lubricate them ? And how with what ? I have it completely
apart they don't apear dirty, they are plastic, I beleive the same are
used on some later scopes. Thanks in advance for any wisdom on this
subject, Jon P.

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