Topics

Tektronix 2465

Jose Alfredo
 

Hello everybody,

I just bought this Tektronix 2465 oscilloscope here in Brazil. When turned on, you can see blinking dots on both, upper and down fields, that show the unit status - see my video on https://youtu.be/NDc4gKDbCQI. Have any of you had any similar experience that could help me fixing it?

Thanks

Jose Alfredo C. Santos

Panos
 

Hi.
From your video I think that your Grid Bias setting is too high or out of range. The sure is that the dots in the bottom of the screen indicate a loss of your calibration settings. :-(

Panos

GerryR
 

One of the calibration procedures produces those series of dots when setting the vertical limits, if I remember correctly. It would appear that whatever initiates that procedure is somehow "stuck on." I'll try to find which procedure it is and report back.

GerryR
KK4GER

----- Original Message -----
From: "Jose Alfredo" <@jacs_bh>
To: <TekScopes@groups.io>
Sent: Thursday, December 26, 2019 3:38 PM
Subject: [TekScopes] Tektronix 2465


Hello everybody,

I just bought this Tektronix 2465 oscilloscope here in Brazil. When turned on, you can see blinking dots on both, upper and down fields, that show the unit status - see my video on https://youtu.be/NDc4gKDbCQI. Have any of you had any similar experience that could help me fixing it?

Thanks

Jose Alfredo C. Santos



Jose Alfredo
 

Tks for the feedback Panos, I'm afraid I'll have to go through the calibration process.

Em 26/12/2019 19:37, Panos escreveu:

Hi.
From your video I think that your Grid Bias setting is too high or out of range. The sure is that the dots in the bottom of the screen indicate a loss of your calibration settings. :-(

Panos

Panos
 

The most common tactic to start with this, is to measure the voltages for the correct levels on the main board connector J119.

Afterward it will need to replace all the electrolytic capacitors on both boards of your power supply. The same exist and for five yellow capacitors branded as Rifa there.
There is X and Y 275VAC types.

But think twice before you spent a penny for this!! Have you a way to do all the calibration by yourself? It need very specific and time consuming procedure for this, plus very expensive calibration tools.
There is also a case of needing some original TEK genuine spare parts.

I'm not trying to disappoint you. But I say things the way they are. ;-)

Jose Alfredo
 

Well, I am giving a try. I have a tektronix TBS1102 that could help me, for the #7 item in 4-2 table for required test equipment. For item #5 I have a B&K 4053B. I'm worried about the Time Maker (#6), the primary and secondary sine wave generators (#2 and #3). Just don't have any equipment to use.

Do you think I could use a pulse signal to generate the time marks?

I've seen a video, once, from w2aew channel on youtube, on witch he built a circuit for a fast ramp square wave generate. Don't know if I could adapt it for 200 MHz (and even 500 MHz) easily. Don't even know if it would be possible. I search through the procedures to verify where should I use it, and the frequencies I'll need.

Yesterday, I started the adjustment procedures. I adjusted the 10V as specified and the voltages and ripples were all ok. Also, I have done all the crt adjustments and stopped on the self cal procedures. I'll need to study them before going through.

Panos, do you think I'm going the wright way? Do you have any sugestions for the high frequencies I'll have to deal with?

Em 27/12/2019 01:44, Panos escreveu:

The most common tactic to start with this, is to measure the voltages for the correct levels on the main board connector J119.

Afterward it will need to replace all the electrolytic capacitors on both boards of your power supply. The same exist and for five yellow capacitors branded as Rifa there.
There is X and Y 275VAC types.

But think twice before you spent a penny for this!! Have you a way to do all the calibration by yourself? It need very specific and time consuming procedure for this, plus very expensive calibration tools.
There is also a case of needing some original TEK genuine spare parts.

I'm not trying to disappoint you. But I say things the way they are. ;-)

Jose Alfredo
 

Gerry, yesterday I adjusted the 10V voltage and runned through the crt adjustment procedures. The screen is now absolutely normal. It could, indeed, have been a previous attempt to calibrate the oscilloscope. Now I'm studing how to finish all the steps required to finish the calibration.

One thing I noticed is that the vertical readings are wrong. when I input a 2 Vpp saquare wave (or any other wave form), it shows something near 2.5 Vpp. I think the self call procedures will repair this. What do you think  about that?

Em 26/12/2019 21:09, GerryR escreveu:

One of the calibration procedures produces those series of dots when setting the vertical limits, if I remember correctly.  It would appear that whatever initiates that procedure is somehow "stuck on." I'll try to find which procedure it is and report back.

GerryR
KK4GER


----- Original Message ----- From: "Jose Alfredo" <@jacs_bh>
To: <TekScopes@groups.io>
Sent: Thursday, December 26, 2019 3:38 PM
Subject: [TekScopes] Tektronix 2465


Hello everybody,

I just bought this Tektronix 2465 oscilloscope here in Brazil. When turned on, you can see blinking dots on both, upper and down fields, that show the unit status - see my video on https://youtu.be/NDc4gKDbCQI. Have any of you had any similar experience that could help me fixing it?

Thanks

Jose Alfredo C. Santos





Jose Alfredo
 

Well, I've uploladed an update video from my 2465 oscilloscope. The blinking dots are gone but I still have an issue on the vertical scale of the waves.

link: https://www.youtube.com/watch?v=a_iodWcnQIw

Em 27/12/2019 01:44, Panos escreveu:

The most common tactic to start with this, is to measure the voltages for the correct levels on the main board connector J119.

Afterward it will need to replace all the electrolytic capacitors on both boards of your power supply. The same exist and for five yellow capacitors branded as Rifa there.
There is X and Y 275VAC types.

But think twice before you spent a penny for this!! Have you a way to do all the calibration by yourself? It need very specific and time consuming procedure for this, plus very expensive calibration tools.
There is also a case of needing some original TEK genuine spare parts.

I'm not trying to disappoint you. But I say things the way they are. ;-)

satbeginner
 

Hi,

a quick look at your movie makes me belief you have both a 50 Ohm terminator AND your input is set for 50 Ohm?
That would cause the levels to be off.

Un saludo,

Leo

GerryR
 

Jose,
I have the 2465A and have been through the calibration procedure a few times due to the fact that I messed up when trying to change the battery backup module, which I believe you do not have on the 2465; that's a blessing. The calibration procedure for the 2465A called for a PG506 Calibration Generator and a TG501 Marker Generator for doing the calibration. I looked up the output specs of each and ended up using a good frequency generator and a good pulse generator to duplicate the "standard" output signals of the PG506 and TG501. That worked fine. The test procedure also called for a tunnel diode pulser, which I downloaded the specs for and made one that was suitable enough to get the job done, but I believe that Leo Bodnar makes a pulser that is more than adequate to get the job done and can be purchased from him online. Once I got through all the cal procedures, everything worked fine and all measurements were on target. It was quite a learning experience, but was fun as well.

GerryR
KK4GER

----- Original Message -----
From: "Jose Alfredo" <@jacs_bh>
To: <TekScopes@groups.io>
Sent: Friday, December 27, 2019 5:16 AM
Subject: Re: [TekScopes] Tektronix 2465


Gerry, yesterday I adjusted the 10V voltage and runned through the crt
adjustment procedures. The screen is now absolutely normal. It could,
indeed, have been a previous attempt to calibrate the oscilloscope. Now
I'm studing how to finish all the steps required to finish the calibration.

One thing I noticed is that the vertical readings are wrong. when I
input a 2 Vpp saquare wave (or any other wave form), it shows something
near 2.5 Vpp. I think the self call procedures will repair this. What do
you think about that?

Em 26/12/2019 21:09, GerryR escreveu:
One of the calibration procedures produces those series of dots when setting the vertical limits, if I remember correctly. It would appear that whatever initiates that procedure is somehow "stuck on." I'll try to find which procedure it is and report back.

GerryR
KK4GER


----- Original Message ----- From: "Jose Alfredo" <@jacs_bh>
To: <TekScopes@groups.io>
Sent: Thursday, December 26, 2019 3:38 PM
Subject: [TekScopes] Tektronix 2465


Hello everybody,

I just bought this Tektronix 2465 oscilloscope here in Brazil. When turned on, you can see blinking dots on both, upper and down fields, that show the unit status - see my video on https://youtu.be/NDc4gKDbCQI. Have any of you had any similar experience that could help me fixing it?

Thanks

Jose Alfredo C. Santos






Jose Alfredo
 

Leo, thanks for helping me. I removed the 50 ohms terminal and things go worse. See: https://youtu.be/JeFw-dr9V3M

Em 27/12/2019 09:04, satbeginner escreveu:

Hi,

a quick look at your movie makes me belief you have both a 50 Ohm terminator AND your input is set for 50 Ohm?
That would cause the levels to be off.

Un saludo,

Leo

Jose Alfredo
 

Thanks Gerry!

Yes. I don't have those equipments (TG501 and PG506). Leo Bodnar pulser can replace the diode and the specific TG501 and PG506 units?

Em 27/12/2019 09:17, GerryR escreveu:

Jose,
       I have the 2465A and have been through the calibration procedure a few times due to the fact that I messed up when trying to change the battery backup module, which I believe you do not have on the 2465; that's a blessing.  The calibration procedure for the 2465A called for a PG506 Calibration Generator and a TG501 Marker Generator for doing the calibration.  I looked up the output specs of each and ended up using a good frequency generator and a good pulse generator to duplicate the "standard" output signals of the PG506 and TG501.  That worked fine.  The test procedure also called for a tunnel diode pulser, which I downloaded the specs for and made one that was suitable enough to get the job done, but I believe that Leo Bodnar makes a pulser that is more than adequate to get the job done and can be purchased from him online.  Once I got through all the cal procedures, everything worked fine and all measurements were on target. It was quite a learning experience, but was fun as well.

GerryR
KK4GER


----- Original Message ----- From: "Jose Alfredo" <@jacs_bh>
To: <TekScopes@groups.io>
Sent: Friday, December 27, 2019 5:16 AM
Subject: Re: [TekScopes] Tektronix 2465


Gerry, yesterday I adjusted the 10V voltage and runned through the crt
adjustment procedures. The screen is now absolutely normal. It could,
indeed, have been a previous attempt to calibrate the oscilloscope. Now
I'm studing how to finish all the steps required to finish the calibration.

One thing I noticed is that the vertical readings are wrong. when I
input a 2 Vpp saquare wave (or any other wave form), it shows something
near 2.5 Vpp. I think the self call procedures will repair this. What do
you think about that?

Em 26/12/2019 21:09, GerryR escreveu:
One of the calibration procedures produces those series of dots when setting the vertical limits, if I remember correctly. It would appear that whatever initiates that procedure is somehow "stuck on." I'll try to find which procedure it is and report back.

GerryR
KK4GER


----- Original Message ----- From: "Jose Alfredo" <@jacs_bh>
To: <TekScopes@groups.io>
Sent: Thursday, December 26, 2019 3:38 PM
Subject: [TekScopes] Tektronix 2465


Hello everybody,

I just bought this Tektronix 2465 oscilloscope here in Brazil. When turned on, you can see blinking dots on both, upper and down fields, that show the unit status - see my video on https://youtu.be/NDc4gKDbCQI. Have any of you had any similar experience that could help me fixing it?

Thanks

Jose Alfredo C. Santos









amirb
 

GerryR,
what signal/pulse generators did you use specifically? specially to replace the PG506


I think somewhere there is a need for pulses with high amplitude like 25V or 50V, isn't it?

GerryR
 

Jose,
You need a good frequency generator to replace the PG506 calibration generator and a good pulse generator (variable duty cycle and fast rise time) to replace the TG501 Marker generator. The pulser is only used for one of the cal procedures.

GerryR
KK4GER

----- Original Message -----
From: "Jose Alfredo" <@jacs_bh>
To: <TekScopes@groups.io>
Sent: Friday, December 27, 2019 7:30 AM
Subject: Re: [TekScopes] Tektronix 2465


Thanks Gerry!

Yes. I don't have those equipments (TG501 and PG506). Leo Bodnar pulser
can replace the diode and the specific TG501 and PG506 units?

Em 27/12/2019 09:17, GerryR escreveu:
Jose,
I have the 2465A and have been through the calibration procedure a few times due to the fact that I messed up when trying to change the battery backup module, which I believe you do not have on the 2465; that's a blessing. The calibration procedure for the 2465A called for a PG506 Calibration Generator and a TG501 Marker Generator for doing the calibration. I looked up the output specs of each and ended up using a good frequency generator and a good pulse generator to duplicate the "standard" output signals of the PG506 and TG501. That worked fine. The test procedure also called for a tunnel diode pulser, which I downloaded the specs for and made one that was suitable enough to get the job done, but I believe that Leo Bodnar makes a pulser that is more than adequate to get the job done and can be purchased from him online. Once I got through all the cal procedures, everything worked fine and all measurements were on target. It was quite a learning experience, but was fun as well.

GerryR
KK4GER


----- Original Message ----- From: "Jose Alfredo" <@jacs_bh>
To: <TekScopes@groups.io>
Sent: Friday, December 27, 2019 5:16 AM
Subject: Re: [TekScopes] Tektronix 2465


Gerry, yesterday I adjusted the 10V voltage and runned through the crt
adjustment procedures. The screen is now absolutely normal. It could,
indeed, have been a previous attempt to calibrate the oscilloscope. Now
I'm studing how to finish all the steps required to finish the calibration.

One thing I noticed is that the vertical readings are wrong. when I
input a 2 Vpp saquare wave (or any other wave form), it shows something
near 2.5 Vpp. I think the self call procedures will repair this. What do
you think about that?

Em 26/12/2019 21:09, GerryR escreveu:
One of the calibration procedures produces those series of dots when setting the vertical limits, if I remember correctly. It would appear that whatever initiates that procedure is somehow "stuck on." I'll try to find which procedure it is and report back.

GerryR
KK4GER


----- Original Message ----- From: "Jose Alfredo" <@jacs_bh>
To: <TekScopes@groups.io>
Sent: Thursday, December 26, 2019 3:38 PM
Subject: [TekScopes] Tektronix 2465


Hello everybody,

I just bought this Tektronix 2465 oscilloscope here in Brazil. When turned on, you can see blinking dots on both, upper and down fields, that show the unit status - see my video on https://youtu.be/NDc4gKDbCQI. Have any of you had any similar experience that could help me fixing it?

Thanks

Jose Alfredo C. Santos










GerryR
 

The high-amplitude output is used to stimulate the Tek tunnel diode
pulser for Vertical Transient Response calibration. The unit I made to
replace the Tek Pulser operates at 10 V, so I didn't need the high-amplitude
output called out in the procedure.
The PG506 Cal Gen "standard" output is a 1 KHz square wave
adjustable form 100 uV to 5 V into a 50 ohm load. I used my BK Prec 4045B
Sig Gen for these outputs.
The markers were generated from my Wavetek 801 Pulse generator, good
to 50 MHz. I couldn't verify the 2 nS requirement in the cal procedure.
I used my Wavetek 1001A leveled sinewave RF sig gen to verify
flatness to 300 MHz; the procedure called for verification to 350 MHz.

GerryR
KK4GER

----- Original Message -----
From: "amirb" <@amirb>
To: <TekScopes@groups.io>
Sent: Friday, December 27, 2019 7:36 AM
Subject: Re: [TekScopes] Tektronix 2465


GerryR,
what signal/pulse generators did you use specifically? specially to replace
the PG506


I think somewhere there is a need for pulses with high amplitude like 25V
or 50V, isn't it?

Siggi
 

On Fri, Dec 27, 2019 at 07:25 Jose Alfredo <@jacs_bh> wrote:

Leo, thanks for helping me. I removed the 50 ohms terminal and things go
worse. See: https://youtu.be/JeFw-dr9V3M

You may have a bad or flaky input attenuator.
Set the scope to DC coupling, and measure the resistance from the inner
conductor of the input to the shell. It should be 1MOhm on the dot across
all vertical settings.
Set the coupling to AC, and you should measure infinite input resistance.
Set the coupling to 50Ohm and you should measure 50Ohm.
If any of those are off, the attenuator has problems.

The contacts on these attenuators can develop oxidation or other problems
that cause them to either not complete the connection, or to go high
resistance. It’s also possible that a previous user has burned out the
50Ohm termination resistor.

<https://youtu.be/JeFw-dr9V3M>

Chuck Harris
 

I recently fixed one customer scope whose attenuator
was not making 50 ohms in the 50 ohm position. The problem
turned out to be the latching relay in the attenuator section
had a "patina" on its gold plated coil pins, that was preventing
the coil from having continuity.

A clean up with deOxit red straightened out the problem.

-Chuck Harris

Siggi wrote:

On Fri, Dec 27, 2019 at 07:25 Jose Alfredo <@jacs_bh> wrote:

Leo, thanks for helping me. I removed the 50 ohms terminal and things go
worse. See: https://youtu.be/JeFw-dr9V3M

You may have a bad or flaky input attenuator.
Set the scope to DC coupling, and measure the resistance from the inner
conductor of the input to the shell. It should be 1MOhm on the dot across
all vertical settings.
Set the coupling to AC, and you should measure infinite input resistance.
Set the coupling to 50Ohm and you should measure 50Ohm.
If any of those are off, the attenuator has problems.

The contacts on these attenuators can develop oxidation or other problems
that cause them to either not complete the connection, or to go high
resistance. It’s also possible that a previous user has burned out the
50Ohm termination resistor.

<https://youtu.be/JeFw-dr9V3M>


satbeginner
 

Hi,

There is something wrong with either just the input 50 Ohm resistor, and/or the input attenuator box.

The change when you remove the external 50 Ohm is as expected, a rise in amplitude when you remove it.

However, the fact there is no change when you switch off the internal 50 Ohm terminator, indicates there is a problem there.

Such damage does happen when a too high voltage was inserted while set at internal terminator, that resistor usually is damaged, and, if the voltage was really high, the variable attenuator box behind that resistor is damaged too.

Can you check the same things on Ch2?

Un saludo,
Leo

Chuck Harris
 

The 50 ohm load resistor in the 2465 is a metal film
resistor that is deposited on the ceramic substrate
of the attenuator module. It is covered with
a temperature sensor film thermistor, and when it
reports that it is too warm, the CPU cuts it out of the
circuit.

To blow it, you have to do something really egregious,
like connect it to a high current supply that can
get the resistor really hot, really quickly.

I would guess that it can protect itself from an insult
in the several watt range. I have never felt the urge
to test it, though.

The manual has this obscure phrase:

5V rms; 0.5W-seconds during any 1-s interval for instantaneous
voltage from 5V to 50V.

Note that 5V -> 0.5W, and 50V -> 50W.

So, I think they are saying it can take 5Vrms for 1 second,
and 50V for 1/100th of a second.

If you can stand a little change in performance, it would not
be impossible to attach a SMD 50 ohm resistor in its place.

As I said earlier, the relays are common problem areas.. both
their contact regions, and the socketed coil pins.

It is a little difficult to remove the attenuator, you have to
remove the bezel, CRT knobs, and front panel assembly, and
several screws reachable from the hole where the front panel
assembly goes, and below the attenuator's bezel extension, and
unsolder a lead from a trimmer cap, and the vertical hybrid...

But, once you have it out of the circuit, everything likely to
be bad can be checked with a DVM. Take it easy on the gold.

-Chuck Harris

satbeginner wrote:

Hi,

There is something wrong with either just the input 50 Ohm resistor, and/or the input attenuator box.

The change when you remove the external 50 Ohm is as expected, a rise in amplitude when you remove it.

However, the fact there is no change when you switch off the internal 50 Ohm terminator, indicates there is a problem there.

Such damage does happen when a too high voltage was inserted while set at internal terminator, that resistor usually is damaged, and, if the voltage was really high, the variable attenuator box behind that resistor is damaged too.

Can you check the same things on Ch2?

Un saludo,
Leo



Reginald Beardsley
 

Jose,

You didn't state a budget. The lowest cost and actually very good option is to buy an ADF4351 based VFO with simple interface such as:

https://www.ebay.com/itm/US-35-4000MHz-RF-Signal-Simple-Generator-Signal-Source-ADF4351-VFO-HXY-D6-V1-02/202853156592

It's entirely adequate and in a nice case, a very useful piece of T&M kit.

If you want really top notch quality calibration references, I'd like to suggest getting the following two items:

http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=124&products_id=295

http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=107&products_id=301

Those will meet your immediate need and also provide metrology grade references for rise time and frequency for many years to come.

Have Fun!
Reg