Date   

Re: Continued: 2465B CTT/HPIB/WR TEST 05 fail 42, all CTT fail

Jean-Paul
 

Chuck many thanks thought so,

Yes I have gone thru Calibrating CTT proceedure and aware of the specific requirements for the signal.

Have all the stuff needed to do it.

As I have mounted a subsitute A5 bd need to replace to the original and do a full CAL anyway.

However it means that the original OPT board has an issue that caused the other flaky tests as orig OPT bod ALL CTT tests fail.

Real puzzle,

Enjoy,


Jon


Hi! I am new, but have several Tek scopes

Steven Bender
 

Steven here,

New to this Group, but not new to Tektronix, or various repairs.

I have and love my working Sony/Tek 335, and Sony/Tek 336 small Oscopes, may they show traces forever! I also have (4) not working Tek 2445 scopes that I need to repair, and a dual trace LeCroy 9450A that shows a trace on only one channel (these are on my really long TO DO LIST). In this time of COVID, I recently got three units that are taking up my time and attention, besides those that are just hanging around.

The latest three acquisitions include an off topic set - a Rohde & Schwarz UPL, (nice for audio) this one powers up with a blank white screen, no dos, no boot, no bios, no beep, so it’s problem is not the usual CCFL Failure. I think it runs either a 486DX or maybe an early Pentium 100/133. It has an internal power supply connector blackened/burned, and several of those smt glass cased diodes across the 9! Vregs from output to input, are looking kinda dark, and suspicious, some might be blown. So likely a PS failure (and hopefully nothing else ended up blown, as this unit is just loaded with boards)... (Any UPL owners/users among us????)

The other two recently acquired sets are: a Sony/Tek 335, and also a 336, both with VG cosmetics, but neither one shows a trace. The 335 I noticed has a broken Ch2 position pot, (R222 AB) Tek part 311-1795-00, a front panel .075/.125 shaft 10k/10k ohm dual control. As far as symptoms, the 335 shows a “low line” led, but that’s about it. The 336 will light up some of its push buttons, but also nada in terms of a trace.

I could use some suggestions, help, and that dual pot, there have to be some 335 parts donors still in existence, knobs are OK, just the outer shaft doesn’t connect to the inside part of the control.

Thanks, and you all stay safe!

Steven


Re: NEW TOPIC: Outstanding Rockland Instruments 7000 Plugin; WAS: Slightly OT- Wavetek 7530B?

Steven Bender
 

Gentlemen,

The Rockland 7530A and 7530B are not seriously off topic, because they fit into a Tek 7633 or the 7603, two very popular and commonly found scope mainframe/power supply units

I have one of each Rockland boxes, and a Tek 7603. The 7530A is a working set, but it stressed the 7603’s power supply, such that the system would hang between 20 to 30 minutes after powering on. Eventually, I found that bad or failed solder joints on the several 2N3055 PS main pass transistors was the problem.

The 7530B unit doesn’t work, but after evaluating the innards, those six, (or was it seven) full length boards, seemed almost the same, so I switched one bunch with the other bunch in the 7530A, and the working set still worked! So it’s not the boards it’s something in the 7530B “box” that has failed. I forget which set of boards is currently in the working set, but I never quite finished with the 7603, as it’s so big and heavy, but Iagree, when working, it’s certainly a fantastic setup when evaluating equipment in the audio range.

Steven


Re: Vertical attenuator skirted knobs

 

Walter,

Group A-1 look like they are for the 465 (old-style, with the black ring insert).

Group B-3 appear to be "new style" knobs (without a black ring insert) for the 475 (NOT the 475A, which has a range of 5mV to 100V).

Group D, based on the style of the shafts, appear to be for some 2200-series scopes, not the 233x scopes that you have indicated. They are NOT for the 2213/2215 or the 2235/2236, but there are lots of other scopes in the 2200-series, and I'm not familiar with most of them.

-- Jeff Dutky


Re: Which probe is better suited for 2465B?

Roy Thistle
 

On Tue, Feb 23, 2021 at 10:56 AM, Giuseppe Marullo wrote:


Trying to get them from Ebay, I asked the seller specific conditions/photos
and I will claim the money back if they are not in good order. Anything
specific to ask to be checked, like the button or something similar?
I
If one searches the messages, for P6137, here on TekScopes... there is some discussion about these P6137 (and the other probes, in that family of probes.)
Those threads have some good discussion, about getting them from Ebay.
P6137 are known to be fragile.
Many of these on Ebay have obvious physical damage ( broken tip etc.)... but, some will also have damaged coax (common enough, and not obvious) That might make the probe intermittent... or cause it to become intermittent, with handling.
Unless you really need the P6137's bandwidth... older, lower bandwidth, more hardy, and less costly Tek probes... that can be compensated for the 2465B input capacitance... might server you better.


Re: 465B strange ripple

Mike Merigliano
 

Okay, you did all of the tests, but it was hard to tell given the reporting. For example, is the 55 VDC supply okay as far as ripple goes? I am not the only one to ask about this.

Also, using "ripple" for the trace on your 465B, and ripple on the testing scope screen when checking supplies, is confusing when the context is not clear.

Even though you have "two triggered traces", that does not mean it has to be a trigger problem, and using the trigger hold-off just helps stabilize the display. I use this a lot on my 475 when there are complex signals that are hard to trigger on.

Traces can be noisy even when a scope is working correctly (but not when the voltage switch is at GND - that's not good as you know). I get 1 mV 100-MHz fuzz on a trace even at much longer time divisions if I zoom in (say 10mV per division), but don't worry about it, as it is probably FM radio interference, because I can reduce it with better/shorter probe grounding. Reducing the bandwith with the button makes it disappear of course. Maybe this all makes sense to you.

It looks like you have 50-Hz noise, signal, ripple, or whatever you want to call it, "riding along" on the sweeped trace, and it is likely generated inside the scope somewhere. There were some suggestions on how to find where this is happening, and your recent posts look like you are back on that track.

There is quite a bit of instruction within tek documents etc. that could answer some of your questions, like how to use the Add and Invert function instead of a differential amp, and the disadvantage of doing so.

On 2/23/2021 12:04 PM, Stephen wrote:
Mike,

I DID all the recommended tests except for the one involving a diff amp, which I don’t have.
Ozan suggested that I use the “INVERT” and “ADD” trick, although it was not as good. I asked where I should probe for that, but got no answer. But that’s fine; everyone has their own stuff to do, and I understand that; that’s perfectly normal and understandable.

Anyway, I did all the other tests. And as far as the magnetic issue, I did mention that the problem occurs all the time. Even when the scope is inside it’s box. Even in broad daylight, when nothing is powered on, no incandescent lights, NOTHING is even up and running besides a FG that is not even plugged into the same wall socket. All the shields are also in place, and all the ground connections have been checked.
There is absolutely no visible ripple. Some are even a bit less than what the manual suggests. Some filter caps have been replaced as well. The rectifiers have been checked and are all good.
I have done everything that I could or knew how. I have also been carefully documenting within my posts and most of my pictures, all the voltages and sweep times. I don’t know how much clearer I can be...

Now, something I did notice earlier today, is that at lower sweep times.. I can somehow considerably slow down the ripple to “almost” nothing, when I turn the “HOLDOFF” pot clockwise... But it’s still there, and it makes the calibration of anything X10 related, very difficult, as I can see the pips from my Type 184 rocking horizontally back and forth... Or When trying to adjust “High Speed Timing”, for Example....

BTW, I’m not an EE either. Far from it even. Also self taught.




Re: Continued: 2465B CTT/HPIB/WR TEST 05 fail 42, all CTT fail

Chuck Harris <cfharris@...>
 

The Test81, Fail 03 is a combination of a Fail 02, and Fail 01,
which means that your reference oscillator is not calibrated.

The Test82, Fail 02 is hopefully spurious. Everything is closely
dependent on the oscillator being right. Let's just say that I have
seen it spuriously appear when the reference is uncalibrated, and
spuriously disappear after calibration.

Calibrating the CTT is easy, if you have a good clean frequency
standard that can make either a 50% duty cycle 1Vp-p square wave,
or a 1Vp-p low distortion sine wave at the correct frequency and
stability.

I use an HP3336B, with my GPS disciplined Rb lab standard as
the reference. The 3336B with the high stability option would
be fine by itself.

The HP is set to 1MHz, and makes a nice low distortion sine wave
referenced to the lab standard or internal reference.

-Chuck Harris

Jean-Paul wrote:

Chuck, with known good CTT board exchanged for the one in the failed scope, all cables properly reattached.

A5 board is know good and had no SMD leaky caps.

Only, partial success, CTT works but the following faults on self test:

Test 01 -06 PASS

CT TEST 81 Fail 03
CT Test 86 Fail 02
All others PASS

So really confusing results.

Your thoughts?

Jon







Re: Vertical attenuator skirted knobs

-
 

Walter's North of the Border packrat midden to the rescue!

On Tue, Feb 23, 2021 at 11:56 AM walter shawlee <walter2@sphere.bc.ca>
wrote:

Few things are as frustrating as when the vertical knob on a Tek scope is
damaged, by cleaning (hah, you didn't know the printing washed right off,
did you?) or mechanical wear or other damage. Many discussions have taken
place over printing new skirts, etc. but not many actual solutions have
turned up. I get a ton of requests for these, but mostly we are out of
stock.

However, I am a bad pack rat, I accumulate many odd but interesting
things, thinking "ah, these are really cool, I will figure out what these
are meant for later!". well, it doesn't always turn out as intended. I
found an ignored fat stock box full of these skirted knobs, many brand new,
but almost none with identifying information. Rats...

Photography to the rescue, and thanks to many pictures they are now up on
the stuff page, and YOU can figure out what they are if you need one.
Hopefully these can make some sad looking scopes out there look happy
again. They are from 400-series, 22xx-series, 5A-series and SC50x-series
units. Please look here:
https://www.sphere.bc.ca/test/stuffday.html#tekfans

all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.






Re: Which probe is better suited for 2465B?

Jim Ford
 

Totally makes sense.  I was refuting Jean-Paul's assumption that the 20 pF was across the 50 ohm input.  We agree.  Thanks, Tom.              JimSent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Tom Lee <tomlee@ee.stanford.edu> Date: 2/23/21 11:09 AM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] Which probe is better suited for 2465B? Hi Jim,Lower frequency scopes merely throw a 50 ohm terminator across the input to provide a 50 ohm mode, but the 485 has two separate attenuator sections, one for 1M, and a different one for 50 ohms, with a relay switching between them, as necessary. Because the entire 50 ohm signal path is different, the capacitance can be (and is) designed to be inherently lower, as it has to be to make the bandwidth spec.CheersTom-- Prof. Thomas H. LeeAllen Ctr., Rm. 205350 Jane Stanford WayStanford UniversityStanford, CA 94305-4070http://www-smirc.stanford.eduOn 2/23/2021 11:00, Jim Ford wrote:> Well, 20 pF is about 22.7 ohms at 350 MHz, so that would affect the 50 > ohm input.  So I assume Tek left the 20 pF shunt cap off the 50 ohm > input.>> Jim Ford>> ------ Original Message ------> From: "Jean-Paul" <jonpaul@ix.netcom.com>> To: TekScopes@groups.io> Sent: 2/23/2021 10:41:46 AM> Subject: Re: [TekScopes] Which probe is better suited for 2465B?>>> Rebonjour,  the 485 spec is 50 Ω /1 MΩ//20 pF>>>> https://w140.com/tekwiki/wiki/485>>>> I assume the 20 pF applies to either Zo.>>>> Best measurement of Cin is the classic TEK 130 LC meter, very easy to >> use and accurate, with a 1, 3 pF scale.>>>> We also use the HP 4232A LCR meter.>>>> Very interested to hear the 485 Cin actual data. I bet its >0 (:-:)>>>> Bon Journee>>>> Jon>>>>>>>>>>>>>> >>


Re: Continued: 2465B CTT/HPIB/WR TEST 05 fail 42, all CTT fail

 

On Tue, Feb 23, 2021 at 09:16 PM, Jean-Paul wrote:


Only, partial success, CTT works but the following faults on self test:

Test 01 -06 PASS

CT TEST 81 Fail 03
CT Test 86 Fail 02
All others PASS

So really confusing results.

Your thoughts?
The 81 errors are related to CTT (non-)calibration. Not unexpected, since you replaced the option board. This was discussed a while ago in this group.
The 86 error quite likely is linked to the same.

Raymond


Re: Continued: 2465B CTT/HPIB/WR TEST 05 fail 42, all CTT fail

Jean-Paul
 

Chuck, with known good CTT board exchanged for the one in the failed scope, all cables properly reattached.

A5 board is know good and had no SMD leaky caps.

Only, partial success, CTT works but the following faults on self test:

Test 01 -06 PASS

CT TEST 81 Fail 03
CT Test 86 Fail 02
All others PASS

So really confusing results.

Your thoughts?

Jon


Re: Which probe is better suited for 2465B?

Jean-Paul
 

Sr. Marullo,

Keep scope inputs away from TX or exciter outputs, there are various techniques to monitor the modulatiion, power etc. using directional couples and splitters.

A power rated load may have a tap off, but a resistive attenuator could be built, say 100:1

Take care of the max and peak power rating of the scope at 50 Ohm.

The broadcast engineers among us can advise better,

Ciao,

Jon


Re: 465B strange ripple

Stephen
 

On Tue, Feb 23, 2021 at 08:40 AM, satbeginner wrote:


Ok,

I looked at the picture.

Could you try this:

Select Ch1 only, put the Ch1 input to GND, and at 5mV sensitivity.

Select Line trigger and set the timebase at 10ms/div.

Curious how that looks like.

Does the signal still moves?

Leo
https://groups.io/g/TekScopes/photo/260052/0?p=Created,,,50,2,0,0

Done. It’s there, but now it’s not moving no matter the position of the Hold-off knob.


Re: 465B strange ripple

satbeginner
 

Ok,

I looked at the picture.

Could you try this:

Select Ch1 only, put the Ch1 input to GND, and at 5mV sensitivity.

Select Line trigger and set the timebase at 10ms/div.

Curious how that looks like.

Does the signal still moves?

Leo


Re: 465B strange ripple

Stephen
 

On Tue, Feb 23, 2021 at 07:13 AM, satbeginner wrote:

Interleaved.


Hi,

A while back I asked you to put a temporary (very short) ground in between the
attenuator output and the amplifier input to find where the ripple is picked
up.
I did. Hmmm... Maybe I didn’t put the ground in the right place by fear of shorting something... Didn’t I report back on that?

I'm not sure if I saw feedback on this, I was busy, so I could have missed
this.
Maybe I didn’t report it then. I’m also busy with work (not retired).

If you have this temporary ground in place and the ripple is still there and
is still the same, it is save to say the ripple is picked up in the amplifier.

If it is gone, it should come from the attenuators.
I didn’t see it go. But I probably didn’t put it in the right place..


One other thought:

In one of your pictures it looks like there are two traces.

When you see this signal, can you play a bit with the trigger hold-off to see
if that makes a difference?
EXACTLY!! That’s what led me to believe it was trigger related. My long last post talks about that.

Now in this last picture: https://groups.io/g/TekScopes/photo/260052/0?p=Created,,,50,2,0,0

You can see a trace with NO INPUT at all. It’s DC coupled, 5mV/Div, 5ms/Div.
If you enlarge the image, you’ll be able to see thes little “blips” that, put together, seem to form a very low amplitude square wave. Now that square wave moves from left to right, or the opposite way, depending on the position of HOLD-OFF knob. In this picture, it’s at about 9 o’clock, and it’s steady. Otherwise it can get pretty fast...


Re: Which probe is better suited for 2465B?

Tom Gardner
 

On 23/02/21 16:56, Jean-Paul wrote:
Tom is the 485 input 50 Ohm free of any capacitance? Or just lower than the others?
The 485 has two attenuators, the normal 1Mohm attenuator used with traditional "high impedance" probes, and a separate 50ohm attenuator. A relay connects the input from the BNC socket to either one or the other attenuator.

In the scanned service manual available at the usual places, have a look as the /two/ diagrams <1> for the "Ch1 attenuators (Hi Z)" and "Ch1 attenuators (Lo Z)". The relay is K151.

Other scopes' 50ohm input is merely a 50ohm resistor connected across the "Hi Z" attenuator with 1Mohm/15pF input.


Re: Which probe is better suited for 2465B?

Tom Gardner
 

On 23/02/21 18:56, Giuseppe Marullo wrote:

For 50 Ohms use a coax like RG/198/U on a BNC.
Ok, this is easy...but what about high power stuff, like 100W RF or similar? Probably a T plus a dummy load but then high impedance probe, right?
A high power through attenuator (probably with cooling fins!), or a 20dB coupler which taps off 1% of the power going through it.


Re: 7A26 no signal

 

Thanks Tom,

Just repeated my measurements with the 7603 frame.
2.5ns is more correct value (timebase calibration issue with fastest sweep and 10X). This corresponds to 140MHz.
I measured also frame 3dB bandwidth and got 140MHz.

7603+7A26 combination gave 3ns rise time (correct timebase).
7603+7A26 3dB bandwidth was 100-110 MHz. These gave 3ns rise time (correct timebase).

I am happy with the results. Now I have 4ch 100MHz ”old school” scope in my lab.

Regards,
Jouko


Re: Which probe is better suited for 2465B?

Tom Lee
 

Hi Jim,

Lower frequency scopes merely throw a 50 ohm terminator across the input to provide a 50 ohm mode, but the 485 has two separate attenuator sections, one for 1M, and a different one for 50 ohms, with a relay switching between them, as necessary. Because the entire 50 ohm signal path is different, the capacitance can be (and is) designed to be inherently lower, as it has to be to make the bandwidth spec.

Cheers
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 2/23/2021 11:00, Jim Ford wrote:
Well, 20 pF is about 22.7 ohms at 350 MHz, so that would affect the 50 ohm input.  So I assume Tek left the 20 pF shunt cap off the 50 ohm input.

Jim Ford

------ Original Message ------
From: "Jean-Paul" <jonpaul@ix.netcom.com>
To: TekScopes@groups.io
Sent: 2/23/2021 10:41:46 AM
Subject: Re: [TekScopes] Which probe is better suited for 2465B?

Rebonjour,  the 485 spec is 50 Ω /1 MΩ//20 pF

https://w140.com/tekwiki/wiki/485

I assume the 20 pF applies to either Zo.

Best measurement of Cin is the classic TEK 130 LC meter, very easy to use and accurate, with a 1, 3 pF scale.

We also use the HP 4232A LCR meter.

Very interested to hear the 485 Cin actual data. I bet its >0 (:-:)

Bon Journee

Jon








Re: 465B strange ripple

Stephen
 

Mike,

I DID all the recommended tests except for the one involving a diff amp, which I don’t have.
Ozan suggested that I use the “INVERT” and “ADD” trick, although it was not as good. I asked where I should probe for that, but got no answer. But that’s fine; everyone has their own stuff to do, and I understand that; that’s perfectly normal and understandable.

Anyway, I did all the other tests. And as far as the magnetic issue, I did mention that the problem occurs all the time. Even when the scope is inside it’s box. Even in broad daylight, when nothing is powered on, no incandescent lights, NOTHING is even up and running besides a FG that is not even plugged into the same wall socket. All the shields are also in place, and all the ground connections have been checked.
There is absolutely no visible ripple. Some are even a bit less than what the manual suggests. Some filter caps have been replaced as well. The rectifiers have been checked and are all good.
I have done everything that I could or knew how. I have also been carefully documenting within my posts and most of my pictures, all the voltages and sweep times. I don’t know how much clearer I can be...

Now, something I did notice earlier today, is that at lower sweep times.. I can somehow considerably slow down the ripple to “almost” nothing, when I turn the “HOLDOFF” pot clockwise... But it’s still there, and it makes the calibration of anything X10 related, very difficult, as I can see the pips from my Type 184 rocking horizontally back and forth... Or When trying to adjust “High Speed Timing”, for Example....

BTW, I’m not an EE either. Far from it even. Also self taught.

4601 - 4620 of 183627