开云体育

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. TekScopes
  2. Messages
Expanded Topics Messages Polls
Date
Tektronix 2712/2710/27XX 300Hz Filter F.S.

 

开云体育

Hello All:

?

I currently have a Tektronix 300Hz filter for the 27XX series Spectrum Analyzer's for sale. If interested please contact me off the reflector.

?

73


Rich, AJ3G
Re: 7603 no trace

 

David,

More for you below. Hope it helps:


Could also be C866 is shorted, but that would be extemely rare.
To eliminate that, pull one side up temporalialy, and power up and
re-measure R860 volts.
+69V with ref to ground.
I think you measured the "high" side of R860(the 130V supply line). Maybe I should have said measure the collector of Q860; this is the same as the base of Q869 and the low side of R860; or should be if connections are OK. Again, this would be with one end of C866 lifted.


I must thank you for your persistent help so far Jimmy, very explicit
instructions that are very easy to follow!
Thanks.


re cap ripple testing, do I put scope probes only on the cap pins of
each individual cap to test each cap?
First, did you see my earlier posting about measuring ripple with an old analog meter that has an "OUTPUT" terminal? Anyway...

Here's how I would check for excessive ripple using another (test) scope. This will work for all of the big filter caps that have one terminal connected to chassis ground. DO NOT use this method for the filter cap (C806) in the 130V supply because neither one of its terminals is connected to chassis ground:

<<<<<<Be carefully around the AC input/mains power!!!>>>>

1. Ground a 10X probe hooked to the test scope to chassis of problem scope. Use a good-quality clip lead to extend the probe's ground lead if the length of the ground lead is not enough for easy measurements, AND INSULATE the 2 alligators' connection with some black electrical tape so this won't short something out if it accidentally touches anything.
2. Set test scope channel to 50V/div. (Use 5V/div if you've got a scope that does not auto-sense probe attenuation). Be sure to use a 10X probe.
3. Set test scope channel to AC coupling and vertically center the sweep. (You can initially use DC coupling if you want to see the DC component also.)
4. Set test scope for Line trigger, and about 10mS/div. Adjust trigger for a steady sweep (flat line when probe tip is not connected to anything).
5. Carefully probe the "hot" side of each big filter cap. For most, the "hot" side is the "+" terminal. However, for some like C808 (1800 uF) for the -50V supply, it would be the "-" terminal.

If the cap is good, you should see a sweep that's still nearly flat. I'm thinking no peak-to-peak waveform on a filter cap should be more than about 3V. If necessary, increase vertical sensitivity to 5V/div, or less, so V peak-to-peak can be more accurately measured. You DON'T won't to overdrive the test scope's channel amp by using too much sensitivity (As a general rule, don't let the waveform go vertically too much off the top/bottom of the screen.) It is good to return the test scope's channel to the 50V/div before going on to the next cap!!!!!

To check filter cap C806 in the 130V supply use two 10X probes, two scope channels of the test scope, set one channel for "Invert" and use the "Add" vertical function. Make sure both channels have equal V/div settings, and they are adjusted for equal gain. This is basically a differential measurement. To verify test scope's settings (equal gains, etc.), probe a common signal point with both probes and make sure there's no (or very little) signal/ripple.

It will be good to post your ripple measurements.

Regards,
Jimmy
Re: Power supply problem with Tek 2220

Tan Chor Ming
 

开云体育

Hi Francis,

You are spot on. ?There is no stupid question.

?

After I downloaded the 2230 (as directed by Tom) and compared with the 2220/2230.

Immediately, I notice the difference.? The 2220/2230 has a thermal shutdown board which is not present in the 2235.

So, for my 2220 it is an indication that the thermal shutdown is working.?

I believe it is at working at the correct temperature because shutdown always happen when the chassis is burning hot (can hold for a 4 to 5 sec before it burns)

I will try to do a test to disconnect the shutdown and see it the shutdown happens again, just to locate the cause.

?

Comparison between 2220 and 2235 PS

???????????????????????????? ??2220??????????????????????? 2235????????????????? Comments

-5V supply ??????????????Yes???????????? ????????????No

R907????????????????????? ??549 ohm????????????????? 357 ohm??? ????????Current rating on +43V for 2220 is about 30% higher

Thermal shutdown?? ??Yes??????????????????????? No?

?

Rgds,

Chor Ming

From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Francis
Sent: Monday, January 23, 2012 4:41 AM
To: TekScopes@...
Subject: [TekScopes] Re: Power supply problem with Tek 2220

?

?

Hi,

I downloaded the 2230 manual (thanks Tom...) to see how the PS was
made, and then came to my mind a stupid question: is there a thermal
shutdown board on your scope, and did you check it?

Re: Tekscopes at the Computer History Museum

Brad Thompson
 

On 1/22/2012 8:29 PM, Thomas Miller wrote:
I worked at Bendix Communications Division from '66 to '71. Even had my
own 545 Tek scope. They were the days. DTL had just arrived and a lot of
military systems were just being converted to the pure digital domain.
It was around 1971 that the 8080 came out and the world was about to
really change.
Hello, Tom and the group--

IIRC, the 8080 was introduced in 1974; the 4004 was introduced in 1971.
In the early 1960s, I worked as a co-op student at a company that
manufactured magnetic-core logic (nonvolatile, radiation-resistant,
very low power consumption). Four bits per cubic inch.

73--

Brad AA1IP
Re: Tekscopes at the Computer History Museum

 

开云体育

I worked at Bendix Communications Division from '66 to '71. Even had my own 545 Tek scope. They were the days. DTL had just arrived and a lot of military systems were just being converted to the pure digital domain. It was around 1971 that the 8080 came out and the world was about to really change.
?
Regards.
Tom
?

----- Original Message -----
Sent: Sunday, January 22, 2012 7:35 PM
Subject: RE: [TekScopes] Re: Tekscopes at the Computer History Museum

?

In 1967 I worked at Bendix Aerospace and saw this F4 autopilot on the floor
of one of the factories. I believe Bendix designed it. It is indeed an
electromechanical monster. I always wondered how they figured it out it. It
must have been a nightmare with all those layers of rods, gears, actuators,
and servos.

All the autopilots I worked on at Bendix were analog computers. Fortunately
when I started there all the new designs use the new uA709 IC OpAmps. That
was a revolutionary leap in technology. But before I could fully appreciate
the beauty of OpAmps everything changed again.

2 years later autopilots were being designed with digital logic. The
Concorde autopilot used DTL.

Then they started building B52 subsystems with ROM lookup tables. I used to
have to blow out diodes in those tiny ROM packages one bit at a time.

They were exciting times to be in electronics.

Dennis

-----Original Message-----
From: phorphile, Sunday, January 22, 2012 9:22 AM

In the Navy in '65 I was treated to a visit inside an F4 Phantom simulator
trailor. That was one big analog electromechanical maise on wheels. Analog
computers laid the ground work for digital to take off from.

> ......They have heard of analog computers, sort of, but they're treated
like the redheaded stepchild. .......
Re: Tek 7k plug-in prices rising...

G. K.
 

China has finally re-valued its currency!

From: Aaron
To: TekScopes@...
Sent: Sunday, January 22, 2012 4:44 PM
Subject: [TekScopes] Re: Tek 7k plug-in prices rising...

?
> > Have you seen the BIN price for this?
> > Item 270788500453

> Perhaps that's in HK $ ??

They just forgot to put the decimal point in when typing the price. If you check the sales history, they sold one unit for almost exactly 1/100 of the price in that listing.

I wonder what the listing fee was for that ad...

Aaron
Re: Tekscopes at the Computer History Museum

 

I defer to your superior knowledge of the history of computers, Steve, but I think you contradicted yourself. During the Civil war the new battefield howitzers didn't have the help of digital computers to aim them. What was learned and the mathematics developed for ever more complex artillery aiming schemes, as an example, laid the groundwork for which digital technology later took over and refined the job. Sir Isacc Newton didn't have an Apple ;-)

Arden

While analog computers made some amazing advances for their day, I disagree with the comment that they laid the groundwork for modern digital computers. The early designs of digital computers did not leverage anything from analog computers, and took totally independent paths. Probably the only connection is that one of the early digital computers – ENIAC, was designed for the purpose of computing trajectory tables for large field artillery – a similar task the Nike flight path computer performed. The latter provided correction information in real time, while ENIAC actually computed tables of numbers that were published in field manuals.
Seeking 5L4N manual

 

Anyone know where I can download a manual for the 5L4N? Thanks, AL
Re: Need Manual for Type W, SN 4560 & 5336

 

Bernd and Egge,

I was aware of the change from Nuvistors to FETs in the 1A1, but didn't know a similar thing had happened to the Type W.

If you are able to find the mod kit, would you mind scanning the modified schematic? I'm a complete beginner to electronics and chase enough dead ends even when I have a full manual in front of me. With incomplete schematics I find myself second-guessing everything. :-(

I checked eBay and Dave's(ArtekMedia) site but didn't see any manuals for SN >7000, although I sent an inquiry to the eBay listings that didn't show a part number or SN range for the manual.

What does PWB stand for, as mentioned in Egge's post below this?

Aaron

--- In TekScopes@..., "Egge Siert" <eggeja@...> wrote:
It seems that you have two Type W's with the FET-Frontend and the PWB for these. With SN 7000 and above this was standard. For this late versions a new Manual was printed. FET-Frontends (less drift) were used in late Type 1A1's (I don't for sure also 1A2's) and the 1A7A (which has the same circuit as the later 7A22).
Egge Siert
Re: Total beginner with newly acquired 475 with issues

 

Hi "newbarrie"'

There is far more expertise on this forum than mine but here are some points to get started with, but not specific to the 475:

Scopes (and all electronics) that have been sitting around unused for a long time develop not only visible "verdigris" but invisible oxidation and corrosion effects. Wherever two metals are mechanically opposed to pass an electric current is where you will find problems. Apply an electrical contact cleaner that contains a lubricating protectant (I recommend MG Chemicals Super Contact Cleaner) to all connectors, unseat and reseat them at least a couple of times. Plug-in intgrated circuits can also be a problem but leave them to a later level of diagnostics. With switches be a little more careful where you apply the contact cleaner, keep it only to the contacts as well as you can. You can apply cleaner with an artist's brush in tight spaces. Rotate switches several times to restore functioning. Check for loose hardware, tight screws and nuts are required at some points to insure good grounding. You may be surprised at the results you get by performing this procedure. Next, before attempting to do further diagnositics, get a service manual and make it a reading project until you have a good sense of what the scope is all about electronically and how to perform diagnostics and calibration. When you are ready to dig into the cause of particular failures here's the place to get help.

Arden

......I also have acquired through the ubiquitous Ebay a half dead Tek 475 scope to play with. ......
Re: Force DSA-602 to proceed past 11A34-induced POST error?

 

It looks like David and Javier were right and this plugin was just missing some sort of calibration constant, fixed by running EA on a good DSA 602 mainframe.

I have now been using it for one week, in various 11k mainframes, with no trouble at all.

Thanks again guys!

Aaron

--- In TekScopes@..., David <davidwhess@...> wrote:

This sounds familiar so maybe your sanity is safe. I remember reading
about this series of oscilloscopes and something about using a newer
model to refresh the calibration or initialization or something data
in a plug-in so that it would work with an older oscilloscope.

On Sun, 15 Jan 2012 13:53:15 -0000, "Aaron"
<ataylor@...> wrote:

Javier,

When I tried telling it to exit diagnostics before, it wouldn't do it, but it is 5am here, so I probably did something stupid, like bumping the touchscreen enable/disable button. Thank you for letting me know that it should work and I will definitely give that another try next time. Unfortunately, I can't test it at the moment(see below).

Now I'm really questioning my sanity. The mainframe I was using has very old firmware on it. Thinking that perhaps a newer firmware version would let me exit the diagnostics and continue on, I tried my second mainframe. In this mainframe, the plugin works fine and throws out zero errors. To make things even more odd, when I try it in the original mainframe, it now exhibits zero errors. So now the plugin works in both mainframes, with no errors, and all four channels take good measurements.

In another 15 minutes I will know if it will pass EA, although it already passed the partial EA that the newer mainframe insists on running every time the configuration changes.

I guess it is an intermittent problem.

Aaron



I've around a 11A34 with a failure in channel 4, and I've put it on a
DSA-602. It fails (as expected), but in the POST screen that appears,
when selecting "Exit Diagnostics" the DSA starts, and enables you to use
the other channels in the failing 11A34 (of course, it also throws
errors during EA).
I am trying to capture four channels simultaneously with my DSA-602,
which requires three plugins. Unfortunately, my third 11A34 is
misbehaving. When it is inserted, the mainframe fails POST with errors
about there being zero gain in channel four of the plugin.
...
wondering if anyone knows a way to force the mainframe to ignore the
errors so I can use channels 1-3?
Re: Tek 7k plug-in prices rising... 7L13/7L14

 

If the only thing wrong with the 7L13 is a broken knob, then I think $1k
is a reasonable price. Microwave spectrum analyzers are always
expensive. Though a 7L13 or 7L14 is on the low-end of the frequency
range, it might be OK for many people, without the $3k . . $5k . . .
expense of getting something with a higher frequency range.

One potential advantage of the 7L13/14 is that the schematics are
available and there is no power supply or display electronics to worry
about. I think more modern or similar vintage but more capable spectrum
analyzers which are not 7000 series plugins would have a lot more
electronics to go wrong, including power supplies, firmware-based
microprocessor stuff, CRT displays etc.

I recently bought a 7L14, in the 2.5GHz version (without a 1.8GHz LPF
and input limiter) for $650 or so. I knew it had problems, and I fixed
some of them - multiple dead tantalum capacitors. I now suspect its
input mixer needs its diodes replacing, since its sensitivity was very
low, and there needs to be quite a lot of work to make the displayed
frequency match what the device was actually responding to. At present
it is not responding to any signal. Now I know more about these
devices, I realize I need the 1.8GHz LPF, but fortunately MiniCircuits
make one which should work OK - and the cost is under $50.

I have now acquired three of John Griessen's <john@...>
excellent 7000 series extender kits:



so I will be able to work on this beast. Its not for everyone, but I
liken this introduction to microwave electronics to buying my first
vehicle - a clapped out 1961 VW Kombi van - and the years of learning
experiences as I rebuilt various engines, always imperfectly, and
successfully refurbished the gearbox and many other parts.

It can't be ruled out that I am crazy too, but I only bid this because
someone else was ready to bid a little lower. One fellow in Western
Australia has a 7L14 (1.8GHz version) with the TR502 tracking generator
- bought on the understanding it was fully working for ~$1.5k. That
seems reasonable to me, but it turns out that it is lacking sensitivity
and so probably in need of diode replacement in the input mixer, plus
potentially other faults.

- Robin


Magnus wrote:

The winning bid for this one leaves me stunning. It comes with no
warranty and has a broken knob as per the item description...
I have no disbelief in the 7L13 spectrum analyser's quality and
capabilities. And I am aware that these are offered rarely - but...

The buyer was willing to pay _1 grand _USD as you US chaps might put it.
Re: Tek 7k plug-in prices rising...

 

Have you seen the BIN price for this?
Item 270788500453
Perhaps that's in HK $ ??
They just forgot to put the decimal point in when typing the price. If you check the sales history, they sold one unit for almost exactly 1/100 of the price in that listing.

I wonder what the listing fee was for that ad...

Aaron
Re: Tekscopes at the Computer History Museum

 

In 1967 I worked at Bendix Aerospace and saw this F4 autopilot on the floor
of one of the factories. I believe Bendix designed it. It is indeed an
electromechanical monster. I always wondered how they figured it out it. It
must have been a nightmare with all those layers of rods, gears, actuators,
and servos.

All the autopilots I worked on at Bendix were analog computers. Fortunately
when I started there all the new designs use the new uA709 IC OpAmps. That
was a revolutionary leap in technology. But before I could fully appreciate
the beauty of OpAmps everything changed again.

2 years later autopilots were being designed with digital logic. The
Concorde autopilot used DTL.

Then they started building B52 subsystems with ROM lookup tables. I used to
have to blow out diodes in those tiny ROM packages one bit at a time.

They were exciting times to be in electronics.

Dennis

-----Original Message-----
From: phorphile, Sunday, January 22, 2012 9:22 AM


In the Navy in '65 I was treated to a visit inside an F4 Phantom simulator
trailor. That was one big analog electromechanical maise on wheels. Analog
computers laid the ground work for digital to take off from.

......They have heard of analog computers, sort of, but they're treated
like the redheaded stepchild. .......
Re: Tek 7k plug-in prices rising...

Richard Solomon
 

Perhaps that's in HK $ ??

73, Dick, W1KSZ


On Sun, Jan 22, 2012 at 5:05 PM, J. L. Trantham <jltran@...> wrote:
?

Have you seen the BIN price for this?

?

Item? 270788500453

?

Joe

?

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] On Behalf Of HP
Sent: Sunday, January 22, 2012 5:51 PM
To: TekScopes@...
Subject: [TekScopes] Re: Tek 7k plug-in prices rising...

?

?


Magnus, don't worry, maybe the prices in the past was to low ???

just found:

7L14 Spectrum Analyzer: ONLY $1,499! (SOLD!)
from a US used electronic seller

So, they expect more, keep your eyes open ;-)

Peter
==============================0
> Hello,
> The winning bid for this one leaves me stunning. It comes with no
> warranty and has a broken knob as per the item description...
> I have no disbelief in the 7L13 spectrum analyser's quality and
> capabilities. And I am aware that these are offered rarely - but...
> The buyer was willing to pay 1 grand USD as you US chaps might put it.
Magnus
Re: Tek 7k plug-in prices rising...

 

开云体育

Have you seen the BIN price for this?

?

Item? 270788500453

?

Joe

?

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] On Behalf Of HP
Sent: Sunday, January 22, 2012 5:51 PM
To: TekScopes@...
Subject: [TekScopes] Re: Tek 7k plug-in prices rising...

?

?


Magnus, don't worry, maybe the prices in the past was to low ???

just found:

7L14 Spectrum Analyzer: ONLY $1,499! (SOLD!)
from a US used electronic seller

So, they expect more, keep your eyes open ;-)

Peter
==============================0
> Hello,
> The winning bid for this one leaves me stunning. It comes with no
> warranty and has a broken knob as per the item description...
> I have no disbelief in the 7L13 spectrum analyser's quality and
> capabilities. And I am aware that these are offered rarely - but...
> The buyer was willing to pay 1 grand USD as you US chaps might put it.
Magnus
Re: Tek 7k plug-in prices rising...

 

Magnus, don't worry, maybe the prices in the past was to low ???

just found:

7L14 Spectrum Analyzer: ONLY $1,499! (SOLD!)
from a US used electronic seller

So, they expect more, keep your eyes open ;-)


Peter
==============================0
Hello,
The winning bid for this one leaves me stunning. It comes with no
warranty and has a broken knob as per the item description...
I have no disbelief in the 7L13 spectrum analyser's quality and
capabilities. And I am aware that these are offered rarely - but...
The buyer was willing to pay 1 grand USD as you US chaps might put it.
Magnus
Tek 7k plug-in prices rising...

 

Hello,

The winning bid for this one leaves me stunning. It comes with no warranty and has a broken knob as per the item description...
?I have no disbelief in the 7L13 spectrum analyser's quality and capabilities. And I am aware that these are offered rarely - but...

The buyer was willing to pay 1 grand USD as you US chaps might put it.

See ?

Cheers,

Magnus
Re: 7603 no trace

David Miles
 

开云体育

On 22/01/2012 02:34, jtjewell83 wrote:
?

David and Magnus,

I'm thinking Q872 and the other 2 transistors are OK. There's just not quite enough base current to turn on Q872, and the others. The collector of Q860 is only 2 volts. It should be about 52V when things are normal (+50V supply + drops of 3 transistors' B-E junctions).

R860 (680K ohms) may be open. David, can you measure the volts ACROSS that resistor.

-67.6V

Based on your previous measurements of the +130V supply, you should measure about 70V. Or you should get about 71.5V on side of that resistor, referenced to ground.

71.8V ( no sign of cracked solder pads.)

Inspect for cracked solder joints around that area. Also, wiht the scope OFF, measure R860 ohms.

R860 = 12KOhms ( with R860 in place on pcb )


Could also be C866 is shorted, but that would be extemely rare. To eliminate that, pull one side up temporalialy, and power up and re-measure R860 volts.

+69V with ref to ground.

I must thank you for your persistent help so far Jimmy, very explicit instructions that are very easy to follow!

re cap ripple testing, do I put scope probes only on the cap pins of each individual cap to test each cap?

Thanks.

David.
ps. I have found what looks like a mistake in the service manual A11 low voltage regulator board,I think that R860 and R866 are mixed up. I have ignored the print out and concentrated on looking at the colour codes to find the correct resistor.


I'm thinking Q860 is OK.

We've getting close!!!

Jimmy


Re: 7603 no trace

 

Good Day,

Quote: - I'm thinking Q872 and the other 2 transistors are OK.? There's just not quite enough base current to turn on Q872, and the others.? The collector of Q860 is only 2 volts.? It should be about 52V when things are normal (+50V supply + drops of 3 transistors' B-E junctions).

Ah, yes - of course - you are raising a good point here Jimmy.? Plus some small drop across R875, of course. Too obvious. I should not try to understand voltage readings and schematics when it's getting late....

David, simply follow Jimmy's advice.? As your - 50V DC voltage reads off, you also might want to check if Q908 is on and Q909 is off during operation. See the description on page 4-30.

By the way: I have just seen that Tektronix has followed their own, good tradition and they have use sockets for all small transistors on the 7603's A11 Low Level Regulator board hardware. That should make any potential replacement work or tests easy, if necessary.

Cheers,

Magnus
138561 - 138580 of 208738