Date   

Sick 7704A

jstanton@...
 

Hi,

I just bought a 7704A which works, but poorly. It only has a
bandwidth of 170MHz and the tube blooms badly at a low intensity. It
looks like it needs a new tube but does anyone know whether a weak
tube affects the bandwidth, or do I have other problems?

My other 7704A was tested at the same time and had a 240MHz bandwidth.

Is there a source for replacement tubes?

Can someone give me a few hints.

Just a small thing. I have a number of TM500 modules with broken
plastic edges which look ugly. I have started to fix them by cutting
a section from the hood of a DB25 connector with a matching color.
Glue it in place with cyanoacrylate plastic cement and the device
looks good again.

John Stanton


Cap source "7633"

Rick Davis <rdavis@...>
 

Looking for a source for the Sprague 68D series caps used on the
rectifier board of the 7633. Apparently Mallory made a cross at one
time.
I need the 9600uf for sure. I suspect there will be others one I get
the board out.

Thanks,
Rick


Re: replacement part?

parabus@...
 

--- In TekScopes@egroups.com, Hong F Du <feng@s...> wrote:
Hi All,

What will be the replacement part for 151-0487-00 ( a transistor)
from
the power supply of Tek scope 7603? Many thanks.

Regards,

feng
December 14, 2000.

The transister is Silicon...NPN.......2N3773...151-0487-00

Regards,
Bernard Lee


replacement part?

Hong F Du <feng@...>
 

Hi All,

What will be the replacement part for 151-0487-00 ( a transistor) from
the power supply of Tek scope 7603? Many thanks.

Regards,

feng


Re: Tek HV parts (570)

Stan or Patricia Griffiths <w7ni@...>
 

spam@fgm.com wrote:

My Tek model 570 vacuum tube curve tracer seems to have
lost the ability to keep the high voltage running. When
it is first powered on, I get a nice trace, but the HV
oscillator tube (6AQ5) looks like it's really unhappy
about it. In a minute or so, the high voltage goes
away with the usual dim expanding trace.

I've replaced the tubes, and don't see anywhere the
supply is overloaded, so I'm guessing a failed
capacitor or shorted turn in the transformer. Anyone
know where to get small quantities of the 1,2,3, and 4
kilovolt capacitors? I've found about half of them,
a couple apiece at five different vendors (I'd end up
spending 10 times more in shipping than in parts).
Are some capacitors more likely to fail than others?
I don't have a high voltage capacitor tester, though
I plan to go through it with the one I do have if I
can't just replace 'em all. And if I'm really unlucky,
anyone know where I can obtain a replacement HV transformer?

Failing all the above, can anyone recommend a place to have
classic Tek gear repaired?

-- Thanks,
John Rehwinkel
spam@fgm.com


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Hi John,

You can use just about any scope as a high voltage capacitor checker. You
just set the vertical input to DC coupling and some fairly sensitive range
like 0.1 volts/division. You then (carefully) connect some low ripple DC
(like the +500 volts from an older Tek scope) to one end of the cap and
touch the other end to the scope input. A very good cap will not leak DC
and the scope trace will return to the screen when the cap is charged. A
leaky cap will cause the trace to remain off screen. You can actually
measure the amount of leakage by realizing the scope is putting 1 megohm on
the end of the cap to ground and forming a DC divider with it. By measuring
the amount of DC deflection on the scope and knowing how much DC you are
applying to the cap, you can actually make a pretty good calculation of the
internal DC leakage resistance of the cap. It should be very very high in a
good cap . . . To get familiar with this testing technique, try some known
good mylar caps (very low leakage) and then try some older "black beauty"
type caps (usually quite high leakage). Make sure you don't apply more DC
than the cap is rated for. Less is OK but won't give you as good a test as
testing it near its rated voltage. The 500 volt supply in an older Tek
scope is DEADLY. BE CAREFUL.

I know of no source of good 570 High Voltage transformers although I know
one guy who rebuilds certain old Tek HV transformers. I am not sure he does
570 transformers, though. He is: Bill Schell, 10102 Winder Trail, Orlando,
FL 32817 Phone: (407) 282-4289.

I had a HV transformer failure in my early 570 and found that I could
substitute a HV transformer from an RM15. It provides a slightly different
CRT cathode voltage than the original but it was close and I think I can
make it work OK if I adjust it to keep the total CRT accellerating voltage
the same as it was originally. I have only partially restored my 570 so I
don't really know if this is a good solution or not.

Stan
w7ni@teleport.com


Re: Tek HV parts (570)

Michael Dunn <mdunn@...>
 

At 5:07 PM +0000 2000/12/07, spam@fgm.com wrote:
know where to get small quantities of the 1,2,3, and 4
kilovolt capacitors? I've found about half of them,
Digikey has a limited number of HV caps. You can always make series/parallel combinations too... You'd probably want equalizing resistors in the case of series strings.

p.s., I've probably asked before, but does anyone have an 8608 tube to spare?

-----------------------------------------------------------------
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: Tek HV parts (570)

 

spam@fgm.com wrote:

My Tek model 570 vacuum tube curve tracer seems to have
lost the ability to keep the high voltage running. When
it is first powered on, I get a nice trace, but the HV
oscillator tube (6AQ5) looks like it's really unhappy
about it. In a minute or so, the high voltage goes
away with the usual dim expanding trace.

I've replaced the tubes, and don't see anywhere the
supply is overloaded, so I'm guessing a failed
capacitor or shorted turn in the transformer.
If this unit uses those little oil-filled caps in the HV supply,
try hitting them with some freeze spray. My RM545B did this
(as well as smoking the 6AU5 cathode resistor) due to electrical
leakage in the .001 uF 1KV oscillator tank cap. Chilling this
cap made the problem go away temporarily. I replaced it with
a ceramic disc with the same value and rating.

--
Dan Kerl
dlkerl@knology.net

PS- looking for a 577


Tek HV parts (570)

spam@...
 

My Tek model 570 vacuum tube curve tracer seems to have
lost the ability to keep the high voltage running. When
it is first powered on, I get a nice trace, but the HV
oscillator tube (6AQ5) looks like it's really unhappy
about it. In a minute or so, the high voltage goes
away with the usual dim expanding trace.

I've replaced the tubes, and don't see anywhere the
supply is overloaded, so I'm guessing a failed
capacitor or shorted turn in the transformer. Anyone
know where to get small quantities of the 1,2,3, and 4
kilovolt capacitors? I've found about half of them,
a couple apiece at five different vendors (I'd end up
spending 10 times more in shipping than in parts).
Are some capacitors more likely to fail than others?
I don't have a high voltage capacitor tester, though
I plan to go through it with the one I do have if I
can't just replace 'em all. And if I'm really unlucky,
anyone know where I can obtain a replacement HV transformer?

Failing all the above, can anyone recommend a place to have
classic Tek gear repaired?

-- Thanks,
John Rehwinkel
spam@fgm.com


Mod 3 cart scope lock down assembly

Don Crano <donc@...>
 

I am looking for the 'lock down assembly' for a TEK MOD-3 scope mobile cart.

I am using a TEK R217 rack cart and would like to mount a lock down for my
7904.

Anyone have a spare or any idea where I might find one.

Thanks,
Don


Re: 1A5, 1A7

Stan or Patricia Griffiths <w7ni@...>
 

I was going to suggest that maybe, with questions like that, you could use a
copy of my book (OSCILLOSCOPES--Selecting and Restoring a Classic) that is
full of such descriptions and includes both the 1A5 and 1A7. However, I see
that Bernard Lee has written you a response that is almost an exact copy of
what I wrote so I can say that you can rely on his answer.

Stan
w7ni@teleport.com

Michael Dunn wrote:

Does anyone know the difference between the 1A5 and 1A7
differential plug ins?

thx

-----------------------------------------------------------------
Michael Dunn | Surround Sound Decoder & Stereo Enhancement
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/
-----------------------------------------------------------------


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Re: 1A5, 1A7

parabus@...
 

--- In TekScopes@egroups.com, Michael Dunn <mdunn@c...> wrote:
Does anyone know the difference between the 1A5 and 1A7
differential plug ins?

thx

-----------------------------------------------------------------
Michael Dunn | Surround Sound Decoder & Stereo Enhancement
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/
----------------------------------------------
1A5 is an amplifier with differential inputs and up to 50 Mhz
bandpass, depending on sensitivity. It has an input for a special
differential probe P6046 and also has a comparison power supply built
in which may be connected to one of the differential inputs and
subtracted from the signal connected to the other differential input.
1A7 is an extremely high gain differential amplifier. It has a
bandpass of 500 Khz and a maximun sensitivity of of 10 uv/ division.

Regards, Bernard Lee


1A5, 1A7

Michael Dunn <mdunn@...>
 

Does anyone know the difference between the 1A5 and 1A7 differential plug ins?

thx

-----------------------------------------------------------------
Michael Dunn | Surround Sound Decoder & Stereo Enhancement
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: What to do with a pile of 7A16P's? CADC?

Michael Dunn <mdunn@...>
 

At 4:24 PM +0000 2000/11/09, walter shawlee wrote:
We have a pile of 7A16P's, the programmable version of the 7A16, used
Other than landfill, any suggestions?
Strip off any easily strippable parts, hardware, knobs, etc, and sell grab bags of Tek parts.


Also have about 150 pounds of partial and failed 5K/7K plug ins we
are scrapping. Free to anybody that wants to pay the freight. We
are also looking for CRT's, nixie tubes and HP repair parts.
Tempting :-) Could you post a rough list of 7000 modules...? Any particularly "interesting" ones? (7C,D,L,M,Snn)

BTW, is the 5000 series a successor to the 7000, or concurrent? What's the difference? I'm quite amazed at the tube/SS overlap - the 7000 series started to happen in the late 60s, yet tube units were produced till perhaps 1973(?).

Semi-related question for Canadians out there: Anyone know if CADC (Crown Assets Disposal Corp) or a successor is still in operation? I used to get all sorts of interesting junk through them.

-----------------------------------------------------------------
Michael Dunn | Surround Sound Decoder & Stereo Enhancement
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/
-----------------------------------------------------------------


What to do with a pile of 7A16P's?

 

We have a pile of 7A16P's, the programmable version of the 7A16, used
in waveform digitizers like the 7912D and 7612AD. Unfortunately, we
have no digitizers, so these are worthless to us, and do NOT work in
regular frames. Rats.

Other than landfill, any suggestions? Note that we have lots of
other mor useful Tek items, parts and CRTs on our website here:
http://www.sphere.bc.ca/test/index.html

Also have about 150 pounds of partial and failed 5K/7K plug ins we
are scrapping. Free to anybody that wants to pay the freight. We
are also looking for CRT's, nixie tubes and HP repair parts.

all the best,
walter

walter2@sphere.bc.ca


looking for part

Hong F Du <feng@...>
 

Hi All,
Where can I get parts for Textronix 7104 scope? I need the vertical
channel switch IC. The component number is U668. Thank you in advanced.


Feng


Re: Tek 7B87 Question

Stan or Patricia Griffiths <w7ni@...>
 

HI Don,

The 7B87 can be used in any 7000 series main frame, including the 7904.

Stan
w7ni@teleport.com

Don Crano wrote:

I know the 7B87 plug in is designed to support the features of the 7854
frame, but can it be used in a 7904 frame, or is it strictly for the 7854
frame?

Thanks,
Don

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Re: Tek 7B87 Question

mhaubmann@...
 

Dear Don!

The 7B87 is a timebase that features a pretrigger aquire clock to
enable a pretrigger otion in the digital storage mode of the 7854.

It works in all other 7k scopes i own.

The main disadvantage of this timebase is that it does not have the
delta delay or normal delay for a delayed timebase. Also the
independent/runs after delay/triggerable after delay button is not
available because it will control the pretrigger operation.

When You use it as delayed timebase (eg with a 7B15 or 7B85) it will
work fine. (similar to a 7B80)

Michael B. Haubmann
mhaubmann@haubmann.at


--- In TekScopes@egroups.com, "Don Crano" <donc@s...> wrote:
I know the 7B87 plug in is designed to support the features of the
7854
frame, but can it be used in a 7904 frame, or is it strictly for
the 7854
frame?

Thanks,
Don


Tek 7B87 Question

Don Crano <donc@...>
 

I know the 7B87 plug in is designed to support the features of the 7854
frame, but can it be used in a 7904 frame, or is it strictly for the 7854
frame?

Thanks,
Don


Re: FS/For Trash? Type 502 Dual Beam Oscilloscope

mwcpc7@...
 

In a message dated 11/03/2000 9:56:55 PM Eastern Standard Time,
w7ni@teleport.com writes:

It is hard to guess what will happen on eBay. Here is my guess at
what it is worth: If it looks dead with no trace when you plug it in and
turn it on: $10.00. If it has a trace and appears to work: $25.00. A
little more if it has a manual and/or probes or a scope cart. I already
have two of them plus two 502A models but I would still find a place for it
here to save it from the landfill if it was close to here and I could get
it
just for picking it up.

Stan
w7ni@teleport.com
My experience is about the same. I have 5 or 6 502s and would really like to
have one operating on each bench that I use for audio work, but they really
need thorough servicing and recapping. I burned out two transformers before
I learned not to turn them on. I have paid $0.00 to $25.00 for them.


I would pick up any similar vintage Tek equipment that are available for the
hauling within 50 miles of Rochester, NY or $5 to $15 for one that sits in
front of me at a Hamfest. At that rate I get about all I can handle.

Mike Csontos


Re: FS/For Trash? Type 502 Dual Beam Oscilloscope

Stan or Patricia Griffiths <w7ni@...>
 

Hi Jeramy,

An old Tek scope like a 502 always has SOME value but whether it is worth
the cost the box and ship it is a good question. It is always a good idea
to offer these things to the list but it would be helpful to know WHERE it
is located to know if one could pick it up without boxing and shipping. As
to what it might be worth on eBay . . . good question. I have sold tons of
stuff on eBay and I have really been surprised at what some of it went for.
I have also put some stuff up for auction that never got a single bid . . .
sometimes I have relisted a "no bid" item and gotten good bids on the second
try. It is hard to guess what will happen on eBay. Here is my guess at
what it is worth: If it looks dead with no trace when you plug it in and
turn it on: $10.00. If it has a trace and appears to work: $25.00. A
little more if it has a manual and/or probes or a scope cart. I already
have two of them plus two 502A models but I would still find a place for it
here to save it from the landfill if it was close to here and I could get it
just for picking it up.

Stan
w7ni@teleport.com

Jeramy Ashlock wrote:

Hello, I just rescued an old 502 Dual Beam Oscilloscope that
was about to be thrown out, tubes and all. It is in
slightly beat up shape. I am wondering if it would have any
value to anyone here, or should I just trash it?

What do you think I could I get for this thing on ebay?


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