Hello, I just discovered this group and look forward to
participating.
Right now I can use some technical help, though.

I am wrestling with a TEK 465 in the 32xxx serial # range that seems
to work fine in all areas except vertical position display. Both
channels have the same symptom, that is they have what seems to be an
accurate display when the vertical position is centered, but when the
position control for either channel is moved to either the top or
bottom of the screen, the trace only goes as far as the next to last
graticule and the signal gets compressed in amplitude until it
disappears altogether. I have been spending most of my troubeshooting
time in the vertical amplifier module because it appears that at
least one stage may be driving into cutoff or just the oposite (too
low gain) because the voltages on the vertical deflection plates do
not show the movement that the manual indicates. I have not yet tried
adjusting the gain pot because I need to find a signal source
compatible with the manual procedure on this. The manual gives you
the process but not much theory to allow for deviation.

If anyone has seen this before or has any suggestions, I would
appreciate hearing it. BTW, I am using a 453 to troubleshoot which
has an intermittent high voltage supply. That will be the next
project. Thanks in advance, good to have found this group.

Bill Wollam

Hello,
I just found out about this group and decided to join. I've got an
interesting collection of Tek scopes and other stuff, consisting of
three RM561As, a 551, a 181A time mark generator, a 106 square wave
generator, about 12 plugins, HP 523DR (tube frequency counter!), two
HP122ARs (HP tube scope), North Atlantic Phase Angle Voltmeter, Fluke
Differential Voltmeter, Kepco Power Supply, Waveforms
Oscillator/voltmeter, 4 radios, 2 TVs (tube, one color, one B/W), an
organ (Estey, 1961), Sherwood AM/FM tuner, Dynaco PAS-2, home made
tube amp. I have a few other pieces of test equipment that are
solid-state. Not looking so much to increase the size of my
collection, more interested in keeping it all working and sharing
ideas and stories with others.

George

At 7:00 AM +0000 2001/4/10, morriso2002@yahoo.com.au wrote:

547 (my workhorse bench scope), 549, the enormous 555 scoposaurus, 575

Do you know how the 555 differs from that other monster, the 556?

and many plugins including a homebrew spectrum analyzer built into an
old plugin caracass and a Japanese commercial transistor testing

Please tell us something about your spectrum analyzer!

by it at the age of about 10. A few years later I saw my first Tek - a
549 with a 1A4 plugin - and it was a really mind blowing experience

At least 2 of us here have 549/1A4 combos! Yes, a nice piece of equipment...

Michael Dunn, listboss :-)

When I recently joined this group, I read alot of the old posts. I
saw in one the mention that Freon-TF, used to clean fans, wasn't
available anymore.

Where I work, they use something called "Freon TF" to clean sensors
on check-sorting equipment. The product says that "Freon is a
trademark of DuPont ... Contents: Trichlorotrifluoroethane".

Is this the same stuff you're talking about or is it a substitute.

If anyone is interested, I can give specifics on where to get it.

-Jim

Welcome aboard, Morris. I'm just a novice collector, and only have one scope (a late 535A, Scopemobile, and a few plugins). But, it's in almost mint condition and I have all the probes, cords, and manuals, even the little mini-manual under the popup hood on the top of the scope. The scope is a joy to use and works perfectly. Truly a tribute to good engineering and design. I like it because it's older than I am and is also the type of stuff that put America in space in the 60's. Think about it. We went to the moon over 30 years ago. Pocket calculators were just a dream. Amazing.

I digress...Enjoy the group and keep warm with your tubes!

Chris Beck
West Bend, Wisconsin.

TekScopes@yahoogroups.com wrote:

I'm very pleased to have found this group as I am a great lover and
collector of vacuum tube Tek scopes here in Melbourne Australia. My
collection includes examples of the 310A, 502, 524AD, 529, 533A, 535A,
547 (my workhorse bench scope), 549, the enormous 555 scoposaurus, 575
and many plugins including a homebrew spectrum analyzer built into an
old plugin caracass and a Japanese commercial transistor testing
plugin built into a Tek blank. I also have a number of other
manufacturers' scopes as well, and sundry other pieces of Tek
equipment and manuals.

My interests include restoration and using these wonderful machines. I
can remember the first time I saw an oscilloscope and being fascinated
by it at the age of about 10. A few years later I saw my first Tek - a
549 with a 1A4 plugin �- and it was a really mind blowing experience
compared to the sorts of scopes experimenters had access to in the
1960s. Now I'm very happy to be able to own some of these
instruments and fully understand their workings.

I hope I will be able to contribute to the discussions here, both in
the way of helping others and learning along the way.

Cheers,

Morris Odell

__________________________________________________________________
Get your own FREE, personal Netscape Webmail account today at http://webmail.netscape.com/

I'm very pleased to have found this group as I am a great lover and
collector of vacuum tube Tek scopes here in Melbourne Australia. My
collection includes examples of the 310A, 502, 524AD, 529, 533A, 535A,
547 (my workhorse bench scope), 549, the enormous 555 scoposaurus, 575
and many plugins including a homebrew spectrum analyzer built into an
old plugin caracass and a Japanese commercial transistor testing
plugin built into a Tek blank. I also have a number of other
manufacturers' scopes as well, and sundry other pieces of Tek
equipment and manuals.

My interests include restoration and using these wonderful machines. I
can remember the first time I saw an oscilloscope and being fascinated
by it at the age of about 10. A few years later I saw my first Tek - a
549 with a 1A4 plugin - and it was a really mind blowing experience
compared to the sorts of scopes experimenters had access to in the
1960s. Now I'm very happy to be able to own some of these
instruments and fully understand their workings.

I hope I will be able to contribute to the discussions here, both in
the way of helping others and learning along the way.

Cheers,

Morris Odell

At 5:07 PM +0000 2001/4/08, Doug wrote:

Hi,
my name is Doug and I am looking for a User Manual and Service manual
for a Tek 454 Scope. I had seen a source on the web but can't seem
to find it now. Does anyone know were I might find these manuals?
I understand tek is very expensive for printed versions of the manual

Don't forget to monitor eBay!


-----------------------------------------------------------------
Michael Dunn | Surround Sound Decoder & Stereo Enhancer
Cantares | Self-Amplified Speakers, Test Equipment
74 George St. | Ambisonic Surround Sound CDs and Recording
Waterloo, Ont. | (519) 744-9395 (fax: 744-7129)
N2J 1K7 | mdunn@cantares.on.ca
Canada | http://www.cantares.on.ca/
-----------------------------------------------------------------

You may also want to look at www.big-list.com under "manual
dealers". I have had good luck finding manuals from several entries
in this list.

Jim

Hi Doug,

I doubt you could get that manual from Tek at any price these days. Anyway,
if you go to the following URL, you can find a list of companies and people
who can supply you with copies of Tek manuals:

<http://www.reprise.com> Click on the Tek reference section and keep looking
around. You will find the list you are looking for.

Stan
w7ni@easystreet.com

Doug wrote:

Try this one. Bill

http://used-line.com/cgi-bin/manuals/manuals.cfm

Doug wrote:

Hi,
my name is Doug and I am looking for a User Manual and Service manual
for a Tek 454 Scope. I had seen a source on the web but can't seem
to find it now. Does anyone know were I might find these manuals?
I understand tek is very expensive for printed versions of the manual

Thanks
DOug


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Hi,
my name is Doug and I am looking for a User Manual and Service manual
for a Tek 454 Scope. I had seen a source on the web but can't seem
to find it now. Does anyone know were I might find these manuals?
I understand tek is very expensive for printed versions of the manual

Thanks
DOug

Hi All

My old faithful 7904 has started to have a little problem with the display.

It will run for hours or days with no problem. Then it will start to drift
the display up and down, this is the trace/s and readouts as well. Note this
is not on oscillation up and down. It will shift up for awhile, then drop
down lower then it should be for awhile. I am talking about a 1/2 CM or so.
Everything is always on screen, it just gets annoying after awhile.

I found I can turn off the readouts and it will stop. Turn the readouts back
on, and it will be fine again for a few hours or days.

Any ideas what might be going on and where to start looking before I tear
into it.



Thanks,
Don

BTW Hi Mark Gurries glad to see you on the list.

Eventually I have got it!
The entire story is reported at
http://space.tin.it/clubnet/egirland/tek475/vpots/vpots.html
I want to thank you once again the group for the support and in
particular Mr. Fred de Vries who helped significantly.
Until next time, ciao.

Hi Michael,

Thanks for the rundown on the 7S14/5S14. I knew the 5S has come before the 7S and
that they had similar specifications, but since I have never seen a 7S version, I
did not know they were THAT similar!

Stan
w7ni@easystreet.com

Michael Dunn wrote:

Hi,

there is a 6CZ5 and a 2AS-15 in the regulation loop of the Tek 555
heater supply voltage. The 2AS-15 is probably the one you mean.
Quoting from the 555 manual:

I hope this helps.

Laurent Lamesch

Yep. That's just what I needed. Thanks much!

-- John Rehwinkel

I need someone to refresh my memory. The old Tek scopes with
the separate power supplies (555 and similar) had an unusual
filament voltage regulator that operated with a saturable core
reactor. Part of the feedback circuit involved a tube that (I
think) was very sensitive to its filament voltage. I have a
clear mental image of the tube, it was a glass octal type with
a horizontal filament and a cylindrical plate around it. I'm
looking for the type number of this tube. Anybody know offhand
or have a manual with this info? Otherwise, I'll probably have
to wait 'til the next hamfest and see if one of the Tek manual
vendors will let me have a peek.

-- Thanks,
John Rehwinkel KG4L
spam@fgm.com

Hi,

there is a 6CZ5 and a 2AS-15 in the regulation loop of the
Tek 555 heater supply voltage. The 2AS-15 is probably the one
you mean.
Quoting from the 555 manual:
'The circuit operates by regulating the voltage applied to
the primary winding of the [heater supply] transformer [T750].
Any variation in the amplitude of the ac output from T750
appears across the secondary winding between terminals 11
and 12 of the transformer and is applied to the heater of
the special diode tube, V799 [2AS-15]. The amplitude variation
causes the diode to conduct more or less current, depending on
the direction of the change, and produces a voltage change in
the plate circuit of V799.'

I hope this helps.

Laurent Lamesch

John Rehwinkel wrote:

At 6:52 PM -0800 2001/3/31, dd@adobe.com wrote:

> For example, my 7S14

has a sticker on it that says 5S14 too.

For that plugin the guts are the same (originally a 5000 series plugin).
Is there some kind of adapter board in the back that has the 7000 edge
connectors on it?

Sure enough, each edge connector is a small card with some components.


At 6:49 PM -0800 2001/3/31, Stan or Patricia Griffiths wrote:

and found that that very seller had just a few weeks before that purchased a
known dead HP-01 for about $200. I further found out that he had purchased a

What a story!

> has a sticker on it that says 5S14 too.

I wonder what that is all about . . . ?? Just a quick look will tell you
that a 5000 Series plugin will not fit a 7000 series mainframe and vice-versa
and they are not electrically compatible, either.

See above.

And, Michael H. sent me the following information:

The 7S14 was originally designed as 5S14 and because of the fact that the plugins for the 7k Series are longer,
TEK Integrated it in a 7k Scopes housing and added some adapter prints to make it 7k scope compatible.
This plgin was the "poor peoples" Sampler especially for the Lower Bandwith 100 and 200 MHz Mainframes.

Take care with this plugin: it contains little battery cells in the sampling stage that may be empty.

This is actually the only plugin that i know that contains 5k Series Technology (and i own quite a complete collection).

The 7k Scopes interface differs mechanically and electrically a lot from the 5k scopes. the 5k scopes actually use a mechanics that is mechanically identical to the TM 500 System.

Do you think maybe a bad output transistor? thanks for your help.
Mike

Maybe, Mike. Looking at my 454 manual, I see that the collector

voltage on

both Q394 and Q494 should be about 41-42 volts measured with a

voltmeter.

Also, I don't think the voltmeter should "load" the circuit such

that the

voltage changes very much because of attaching the voltmeter.

There are TWO

sets of vertical deflection plate pins. Are you sure all FOUR pins

are

connected?

A good troubleshooting method for balanced circuits like vertical

amplifiers

is to short together like points such as the upper and lower CRT

deflection

plates in order to force them to be at the same voltage. This

should force

the trace to be centered vertcially and should not damage the

circuitry. If

the trace is centered with the CRT vertical deflection plates

shorted

together (this is also the same as shorting the collectors of the

vertical

output stage transistors together), it is a very good indication

that the CRT

itself is good.

Next, you can remove the short and move it to the emitters of Q394

and Q494.

If the trace is once again centered vertically, most likely Q394

and Q494 are

good. Next, move the short to the base of Q374 and the base of

Q474. If the

trace is once again centered, most likely Q374 and Q474 are good.

You can

work your way a stage at a time through the vertical amplifier this

way until

you do not get a centered trace. Now you are very close to the

problem and

it is time to check for shorted or open transistors in this

immediate area.

Be careful not to brush ground with the loose end of the short wire

while the

instrument is powered up and the other end is connected because you

will have

a LOT of destroyed transistors if you do that . . . Also, be sure

BOTH ends

of the short wire are disconnected before connecting one end to

another part

of the circuit . . .

Let me know how this works for you.

Stan

w7ni@e................................................................
......................................................................
Stan,
I got no farther than Q374 and Q474,
I replaced both transistors and the output transistors collector
voltage dropped to 40.5 and 35.2 volts. The trace is now in the upper
half of screen and I have a small deflection of a square wave signal
so gain is poor. Should Q374and Q474 be a matched duo?
This thing about having to touch the collectors to start the
transistors to conduct is really odd, you don't have to leave the
probe on just make a momentary contact with deflection pin or
collector.
I don't have a manual for this thing so I'm working mostly in the
dark. I would like to thank you very much for all the help you have
given me. mike

Hi Mike,

You really need a 454 manual. The one I was using to remind me of the Q
numbers was the one I now have up for sale on eBay right now. You should
look at auction #1226363944 and think about bidding on it.

You probably have found at least one bad transistor, or maybe two. You can
test those for most defects with an ohmmeter right on the bench.

The next thing I would do is short the emitters of Q394 and Q494 and see if
this forces the trace to the center of the screen. If it does, then I would
say Q394 and Q494 are good and you need to progress with the shorting process
to the previous stage, etc.

You really need the manual . . .

Stan
w7ni@easystreet.com

--- In TekScopes@y..., Stan or Patricia Griffiths <w7ni@e...> wrote:

mtmpsmp@y... wrote:

--- In TekScopes@y..., Stan or Patricia Griffiths <w7ni@e...>

wrote:

mtmpsmp@y... wrote:

I have a 454 that has no vertical deflection on ch1 or ch2,

using

another scope I am able to trace signal from the preamps to

the

deflection plates. The sweep appears to be in good shape and

the

trace is centered on crt. ( position controls have no effect

on

trace) What I don't understand is that I have a voltage

imbalance

on

vertical plates and the trace is still centered!

Boy! I don't understand that either. I have to wonder if the

voltage

unbalance is actually getting to the deflection plates inside

the

CRT.

Perhaps there is a broken connection INSIDE the CRT. If the

unbalance is

actually on the CRT plates, I don't see how the trace can be

centered

vertically . . .

Stan
w7ni@e...

.....................................................................

....................................................................

..

Stan,
Upon further investigation I have found that when the scope is
turned on the collector voltage is the same (74.6 volts) on each
output device. The voltage will stay in that condition ( flat
centered trace) until I start making voltage measurements with my
voltmeter ( high impedance digital) then the top connecter drops

to

56.8 -62.0 volts and the bottom to 32.5 -29.8 volts, the voltage

of

course being determined by position control. The trace is at this
point off screen in all modes ( chop, add ect) I can seem only to
bring this condition on by taking voltage measurement on either

vert

plate.
Do you think maybe a bad output transistor? thanks for your help.
Mike

Maybe, Mike. Looking at my 454 manual, I see that the collector

voltage on

both Q394 and Q494 should be about 41-42 volts measured with a

voltmeter.

Also, I don't think the voltmeter should "load" the circuit such

that the

voltage changes very much because of attaching the voltmeter.

There are TWO

sets of vertical deflection plate pins. Are you sure all FOUR pins

are

connected?

A good troubleshooting method for balanced circuits like vertical

amplifiers

is to short together like points such as the upper and lower CRT

deflection

plates in order to force them to be at the same voltage. This

should force

the trace to be centered vertcially and should not damage the

circuitry. If

the trace is centered with the CRT vertical deflection plates

shorted

together (this is also the same as shorting the collectors of the

vertical

output stage transistors together), it is a very good indication

that the CRT

itself is good.

Next, you can remove the short and move it to the emitters of Q394

and Q494.

If the trace is once again centered vertically, most likely Q394

and Q494 are

good. Next, move the short to the base of Q374 and the base of

Q474. If the

trace is once again centered, most likely Q374 and Q474 are good.

You can

work your way a stage at a time through the vertical amplifier this

way until

you do not get a centered trace. Now you are very close to the

problem and

it is time to check for shorted or open transistors in this

immediate area.

Be careful not to brush ground with the loose end of the short wire

while the

instrument is powered up and the other end is connected because you

will have

a LOT of destroyed transistors if you do that . . . Also, be sure

BOTH ends

of the short wire are disconnected before connecting one end to

another part

of the circuit . . .

Let me know how this works for you.

Stan

w7ni@e................................................................
......................................................................
Stan,
I got no farther than Q374 and Q474,
I replaced both transistors and the output transistors collector
voltage dropped to 40.5 and 35.2 volts. The trace is now in the upper
half of screen and I have a small deflection of a square wave signal
so gain is poor. Should Q374and Q474 be a matched duo?
This thing about having to touch the collectors to start the
transistors to conduct is really odd, you don't have to leave the
probe on just make a momentary contact with deflection pin or
collector.
I don't have a manual for this thing so I'm working mostly in the
dark. I would like to thank you very much for all the help you have
given me. mike