Date   

Re: Hi all

morriso2002@...
 

--- In TekScopes@y..., Michael Dunn <mdunn@c...> 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?

I would love to have a 556. They are both massive double beam machines
but there are quite a few differences. The 556 is in one piece while
the 555 is quite a bit larger and has a separate power supply. The 555
has 4 plugins, 2 vertical and 2 special timebases while the 556 has
built in timebases. The 555 has twin distributed amplifiers and lumped
delay lines while I'm pretty sure the 556 has 549 type vertical amps
with a coaxial line and a pair of 8608s. They're different enough to
make them both desirable but unfortunately not many 556s made it down
here.


and many plugins including a homebrew spectrum analyzer built into
an
old plugin caracass
Please tell us something about your spectrum analyzer!
It's based on the unit described in QST in 1999 by Wes Hayward and
another fellow whose name escapes me. Wes (W7ZOI) has a website with
pictures of various versions including an early shot of mine before I
found an attenuator for it. You can probably find it by doing a
search. It goes up to 80 MHz and has 5 KHz resolution at its best. I
had to design an interface to the Tek plugin specification which works
quite well even if I say so myself.

Morris


Re: tek 475 vertical position pots - end of story!

pe1fbo@...
 

Thanks Emanuele for your extensive coverage for cleaning the pots of
an 475. I'm sure more people appreciate this nice stor, because it is
one of the most common failure's in 465, and 475 scopes, probably the
best scope line ever build by Tektronix.

Fred de Vries, Holland


Re: 454 with no vert. deflection

mtmpsmp@...
 

--- In TekScopes@y..., Stan or Patricia Griffiths <w7ni@e...> wrote:
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@e...
......................................................................
Stan,
Well I have located a manual, I bid on the one you had on Ebay but
it got out of hand in short order! ( I know you were happy!)
Anyway I have located my problems. (plural) turns out someone had
lifted the end of D388 to check it at some time and the choke on the
back side of the board had come off. Also Q388 was bad I replaced the
transistor and resoldered the choke and things got interesting! The
position controls were working but gain was still way off. I started
checking for gain in each stage from the delay line and
got as far as Q 464,364 at this point gain fell drastically! :( Well
I Pulled those and low and behold they were npn not the expected pnp,
I replaced with two 151-0193 and I have a new scope!!!!
(This scope came from IBM so I really don't Know what to think about
this?)
So in closing I want to thank you for all your help It was very nice
of you to take the time. Now I have this 2213 that the trace only
covers half of screen........
thanks. Mike Smith


Re: 454 with no vert. deflection

Stan or Patricia Griffiths <w7ni@...>
 

Hi Mike,

Good news! It is always great to hear of a success like yours.

More comments below . . .

mtmpsmp@yahoo.com wrote:

Stan,
Well I have located a manual, I bid on the one you had on Ebay but
it got out of hand in short order! ( I know you were happy!)
Anyway I have located my problems. (plural) turns out someone had
lifted the end of D388 to check it at some time and the choke on the
back side of the board had come off. Also Q388 was bad I replaced the
transistor and resoldered the choke and things got interesting! The
position controls were working but gain was still way off. I started
checking for gain in each stage from the delay line and
got as far as Q 464,364 at this point gain fell drastically! :( Well
I Pulled those and low and behold they were npn not the expected pnp,
I replaced with two 151-0193 and I have a new scope!!!!
(This scope came from IBM so I really don't Know what to think about
this?)
Well, there are marginal technicians in every company . . .

So in closing I want to thank you for all your help It was very nice
of you to take the time. Now I have this 2213 that the trace only
covers half of screen........
Half the screen horizontaly or vertically? I might have some ideas on this,
too, if you are stuck . . .

thanks. Mike Smith
OK, Mike. My pleasure.

Stan
w7ni@easystreet.com


Re: 454 with no vert. deflection

mtmpsmp@...
 

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

Good news! It is always great to hear of a success like yours.

More comments below . . .

mtmpsmp@y... wrote:

Stan,
Now I have this 2213 that the trace only
covers half of screen........
Half the screen horizontaly or vertically? I might have some ideas
on this,
too, if you are stuck . . .

thanks. Mike Smith
OK, Mike. My pleasure.

Stan
w7ni@e...
......................................................................
The trace starts on center of screen and runs to right side, Vertical
seems to be ok. The output transistors voltages are comparable but
signal on + plate is very weak. I don't have manual for this one but
layout looks very close to my 2235 .
although parts are numbered different.
Mike


Re: Manual Sources

Doug <carroll@...>
 

Thanks to everyone who replied,
I've contact several and am looking for the best price

Doug

--- In TekScopes@y..., "Doug" <carroll@u...> 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


7904 power supply

ke4dnk@...
 

I need a transformer or a working power supply for my 7904 scope.The
serial # is above B260000.

The transformer is T1310, part # 120-0742-00.

The power supply assembly is # 620-0461-00

Paul Lewis
1317 Kingston Ridge Rd.
Cary, NC 27511

1-919-467-2818

Please reply to ke4dnk@bellsouth.net


Re: Manual Sources

dhuster@...
 

Hi, Doug,

Check out the "Q&A" column in the February 2001 issue of "Poptronics"
magazine (formerly "Popular Electronics" and "Electronics Now"
magazines) for a list of manual sources. Also check out my post at
http://www.nostalgiaair.org/nostalgiaair/messageboard/newforum/840.htm
for manual source listings. Tek doesn't offer any manuals in paper
for older instruments, only on microfiche, but it's cheaper anyway.
Used 'fiche readers are cheap or many libraries have reader/printers
available.

Dean Huster
Contributing Editor, "Q&A"
"Poptronics Magazine"
q&a@gernsback.con
http://www.poptronics.com/forums/index.html


Re: 7904 power supply

Stan or Patricia Griffiths <w7ni@...>
 

Hi Paul,

I can't help you with this one. You might try Deane Kidd
<dektyr@teleport.com>

Stan
w7ni@easystreet.com

ke4dnk@yahoo.com wrote:

I need a transformer or a working power supply for my 7904 scope.The
serial # is above B260000.

The transformer is T1310, part # 120-0742-00.

The power supply assembly is # 620-0461-00

Paul Lewis
1317 Kingston Ridge Rd.
Cary, NC 27511

1-919-467-2818

Please reply to ke4dnk@bellsouth.net

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Re: Manual Sources

Stan or Patricia Griffiths <w7ni@...>
 

Hi Doug,

Are you really sure Tek still offers older manuals on microfiche? Last time
I checked I thought they had discontinued that, too.

Stan
w7ni@easystreet.com

dhuster@pb.k12.mo.us wrote:

Hi, Doug,

Check out the "Q&A" column in the February 2001 issue of "Poptronics"
magazine (formerly "Popular Electronics" and "Electronics Now"
magazines) for a list of manual sources. Also check out my post at
http://www.nostalgiaair.org/nostalgiaair/messageboard/newforum/840.htm
for manual source listings. Tek doesn't offer any manuals in paper
for older instruments, only on microfiche, but it's cheaper anyway.
Used 'fiche readers are cheap or many libraries have reader/printers
available.

Dean Huster
Contributing Editor, "Q&A"
"Poptronics Magazine"
q&a@gernsback.con
http://www.poptronics.com/forums/index.html

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127

morriso2002@...
 

I have picked up a 127 preamp power supply that is used to power a
couple of 1- or letter plugins for use as instrument amplifiers. It's
quite a boatanchor and seems to work OK but I want to replace the
selenium rectifiers in it with silicon for safety reasons.

There are 5 rectifiers in there. To save me a bit of measurement work,
does anybody have any info on function/ratings of the rectifiers or
whether Tek issued a bulletin on their replacement?

Morris


Re: 127

Stan or Patricia Griffiths <w7ni@...>
 

Hi Morris,

I am sure Tek made a silicon replacement kit for those seleniums. I am sure
I have a copy of it on microfiche. I will check that out at my next free
moment and see about taking my microfiche to the local library and making you
a hard copy of the mod instructions for you. I promise to keep the price of
my labor within reason . . .

Don't let me forget this . . . at age 62, things sometimes fall in the
cracks.

Stan
w7ni@easystreet.com

morriso2002@yahoo.com.au wrote:

I have picked up a 127 preamp power supply that is used to power a
couple of 1- or letter plugins for use as instrument amplifiers. It's
quite a boatanchor and seems to work OK but I want to replace the
selenium rectifiers in it with silicon for safety reasons.

There are 5 rectifiers in there. To save me a bit of measurement work,
does anybody have any info on function/ratings of the rectifiers or
whether Tek issued a bulletin on their replacement?

Morris

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Re: 8608

rdriggers@...
 

Hello, since you have a 556 you may be the one to know, i just picked
up for cheap a 556 that looked good, but when i got it home it looks
as if a rodent has eaten a lot of the wires and insulation on the
inside. Is this scope worth the effort to repair or maybe i should
use it for parts. I have a manual and all the parts are there, the
case looks good and is straight. I have a 545a and a 453 that i use
but i have not used a 556.




--- In TekScopes@y..., Michael Dunn <mdunn@c...> wrote:
Yoohoo. I got a pair of NOS, Tek-boxed 8608 tubes for the
vertical of my 556! They work great. Has anyone else had an 8608
fail on them. My bad one had a grid short. I noticed it because
the
vertical position knob acted like a light dimmer, making the tube
glow incandescent white depending on the setting!!!

Michael

-----------------------------------------------------------------
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@c...
Canada | http://www.cantares.on.ca/
-----------------------------------------------------------------


Re: Manual Sources

dhuster@...
 

Hi, Stan,

I was the one (Dean) who mentioned the manuals on 'fiche. I suppose
that I'm only assuming that they're doing that since they were so hot
to get all of us Service Center technicians to quit using paper
manuals and rely solely upon 'fiche for our documentation. It must
have been the same folks who did the mechanical design on the 434
that came up with that idea. In 1982, you could order the manual of
Tek's oldest scopes on 'fiche. I just assumed .....

It also makes me sick. I may have told you this story already.
Since I was the sole tech at the OKC Service Center, I got all
the 'fiche updates each week and dutifully made them. But I never
threw away the old 'fiche as it was replaced with the new. When I
left Tek, I had a nearly complete set of 'fiche from the oldest
instrument to the newest, through all the T&M, television, medical,
IDG (computer) and old catalogs and sales literature. I literally
gave it all away to a friend in Dallas who owned a cal lab there (a
lab that was sucking away an alarming amount of business from the
Dallas Service Center -- I'll have to tell you about Dale sometime)
in trade for a few pieces of older hp test equipment. I'll bet that
I could sell that 18" stack of 'fiche on eBay for an easy 4-figures
today, especially if Tek no longer produces it. I assume that
they've converted it all to PDF?

Dean


Re: 8608

Michael Dunn <mdunn@...>
 

At 12:24 PM +0000 2001/4/18, rdriggers@hitter.net wrote:
Hello, since you have a 556 you may be the one to know, i just picked
up for cheap a 556 that looked good, but when i got it home it looks
as if a rodent has eaten a lot of the wires and insulation on the
inside. Is this scope worth the effort to repair or maybe i should
use it for parts. I have a manual and all the parts are there, the
case looks good and is straight.

Well, if you have the room, it's quite the scope, don't you think? ;-) On the other hand, I would buy the manual from you!

Michael


Re: Manual Sources

Stan or Patricia Griffiths <w7ni@...>
 

dhuster@pb.k12.mo.us wrote:

Hi, Stan,

I was the one (Dean) who mentioned the manuals on 'fiche. I suppose
that I'm only assuming that they're doing that since they were so hot
to get all of us Service Center technicians to quit using paper
manuals and rely solely upon 'fiche for our documentation. It must
have been the same folks who did the mechanical design on the 434
that came up with that idea. In 1982, you could order the manual of
Tek's oldest scopes on 'fiche. I just assumed .....

It also makes me sick. I may have told you this story already.
Since I was the sole tech at the OKC Service Center, I got all
the 'fiche updates each week and dutifully made them. But I never
threw away the old 'fiche as it was replaced with the new. When I
left Tek, I had a nearly complete set of 'fiche from the oldest
instrument to the newest, through all the T&M, television, medical,
IDG (computer) and old catalogs and sales literature. I literally
gave it all away to a friend in Dallas who owned a cal lab there (a
lab that was sucking away an alarming amount of business from the
Dallas Service Center -- I'll have to tell you about Dale sometime)
in trade for a few pieces of older hp test equipment. I'll bet that
I could sell that 18" stack of 'fiche on eBay for an easy 4-figures
today, especially if Tek no longer produces it. I assume that
they've converted it all to PDF?

Dean

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Well, Tek USED to do exactly as you described . . . make all the old data
available on microfiche. I think they quit doing it a couple of years ago.
I am not familiar with the term "PDF" but I assume it is some form of
computer readable pages that would put the old microfiche images on your
computer screen. I am not aware that Tek has bothered to do that with any
but current instruments. I think all of the old data is simply "gone" as far
as Tek is concerned. And yes, that pile of old microfiche is probably worth
all of 4 figures today. Very sad . . .

Stan
w7ni@easystreet.com


100!!!

Michael Dunn <mdunn@...>
 

Congratulations TekGroup! We've hit 100 members!


-----------------------------------------------------------------
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/
-----------------------------------------------------------------


Re: 127

Stan or Patricia Griffiths <w7ni@...>
 

Hi Morris,

Well, Tek made TWO different silicon mod kits for the 127, depending upon the
serial number of your instrument. For Serial Number 100-357, it is 040-0217-00
and for Serial Number 358-1409, it is 040-0282-00. There are about 8 pages in
each instruction set. So, if you tell me your Serial Number, I will get a copy
of the appropriate kit instructions for you. It will cost you about $2 plus
postage.

Stan
w7ni@easystreet.com

Stan or Patricia Griffiths wrote:

Hi Morris,

I am sure Tek made a silicon replacement kit for those seleniums. I am sure
I have a copy of it on microfiche. I will check that out at my next free
moment and see about taking my microfiche to the local library and making you
a hard copy of the mod instructions for you. I promise to keep the price of
my labor within reason . . .

Don't let me forget this . . . at age 62, things sometimes fall in the
cracks.

Stan
w7ni@easystreet.com

morriso2002@yahoo.com.au wrote:

I have picked up a 127 preamp power supply that is used to power a
couple of 1- or letter plugins for use as instrument amplifiers. It's
quite a boatanchor and seems to work OK but I want to replace the
selenium rectifiers in it with silicon for safety reasons.

There are 5 rectifiers in there. To save me a bit of measurement work,
does anybody have any info on function/ratings of the rectifiers or
whether Tek issued a bulletin on their replacement?

Morris

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Re: Tek 7904 Display Problem

Mark Gurries <gurriesm@...>
 

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

Been watching the list for a while. It was from one of your email on the
DCC list that I learned about this list. Anyway...

I told Jim Williams here at Linear Tech about this list. (My Lab bench
is next to his.) But he is not one to use PC's. That Jim for ya. For
those who are not familiar with Jim, he is one of out treasured assets at
the company. Hi writes many application notes for our IC and tackling
problems and parts that cause most of us to glaze over our eyes in terms
of the accuracy or noise level requirements. Things like how do you
verify all 24 bits of a 24 bit DAC!

The trick around here to getting a Tek scope fixed and checked out by Jim
Williams is to get an old 500 or 400 series scope in the lab. Tell Jim
about it, and the fact that it does not work annoys Jim to no end.
Before you know it, he is digging into the scope and fixing everything.
Not that we cannot fix out own scopes mind you, but, Jim does a faster
and better job than anyone I know. It fun to watch him and of course you
learn along the way the history and debug tricks.

We have about every make of Tek scope at the company labs. We have lots
of 547's working in parallel with the latest Tek Scopes. We just got
around to setting up an old 556 dual beam on another engineers lab bench.
454's are another favorite. A few of the guys have 7K stuff like yours.
One of my employees has every 7K plug in made including some test
adapters if I recall correctly. It amazing to see the latest scopes
setup right next to an old classic. The biggest reason we like the old
400 and 500 series scopes is the very fine trace and excellent noise
floor. When Jim sets up his 556 with two 1A4 plugins showing 8 traces
that are all beautifully detailed (4 of the traces are on a different
time base to boot) published in a App note, we sometimes get letters and
calls about the scope photo alone! How did you do that?

We think that our lab is one of the biggest consumers of electricity in
Silicon Valley with all these Tube Tek scopes on and possibly the source
of all the blackouts here in California. We already went though one air
conditioner! ;-0


Best Regards,

Mark Gurries
gurriesm@macconnect.com

---------------------------------------------------------
Promotor of the DCC Standard for Model trains.
Model Railroad Club and NMRA DCC presentations are at:
http://www.falken.net/dave/svl
--------------------------------------------------------
Audio Enthusiast (Love SAE equipment)
http://members.ebay.com/aboutme/gurriesm/
http://www.wardsweb.org/audio/index_audio.html
----------------------------------------------------------


Tek 7104 readout problem

dd@...
 

I have a 7104 and now a 7103 that have the same readout problem. The
readout is not visible unless the intensity knob is turned CW to the
"pulsed" position and then pushed against the stop.

On the 7104, I found that the TP1925 voltage was at -6.3V in the full CW
position, and I could make the readout go on by pulling it to about -11V,
so I tacked in a couple of resistors to change the range of the readout
intensity control. (Note, another problem this scope has is that the A/B
intensity knob indicator lamps don't activate properly, but I have no idea
if that's related.)

I wasn't totally happy with the above hack, and now that I have a 7103
with the exact same problem, I would really like to find the underlying
cause... has anyone seen/fixed this?

Thanks...

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