Date   
Re: Tek 2467B

Sergey Kubushyn
 

On Wed, 10 Oct 2018, jmtfungus via Groups.Io wrote:

Ok thanks, I didn't realise that error code meant that the calibration
data had been lost permanently. So a dead the battery in the chip is the
most likely cause?
Almost 100%.

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Re: Tek 2467B

Jude Taylor
 

Ok thanks, I didn't realise that error code meant that the calibration data had been lost permanently. So a dead the battery in the chip is the most likely cause?

Re: Tek 2467B

Sergey Kubushyn
 

On Wed, 10 Oct 2018, jmtfungus via Groups.Io wrote:

Can anyone offer advice or instructions to read an expired DS1225 for
calibration data and write to a new replacement? I have acquired a Tek
2467B but it has a TEST 4 FAIL 10 error at power on. I was contemplating
buying a MiniPro TL866 Universal Programmer to do this but have never done
so before. Thanks Jude
There is nothing but garbage in that expired DS1225. There is no reason to
bother reading it. Replace the NVRAM with a fresh one (or FRAM) and
recalibrate.

It might've had sense if your scope was still in calibration so that NVRAM
had valid data but once it's lost there is absolutely nothing there worth
reading.

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* Las Vegas NV, USA < > Miracles require 24-hour notice. *
******************************************************************

Re: Tek 2467B

Chuck Harris
 

Given that you have an error code that is telling you
that your calibration is invalid; you need to get your scope
calibrated.

Calibration works just fine with a new blank NVRAM.

Using a NVRAM that is programmed with some other scope's
calibration constants is really never a good idea.

-Chuck Harris

jmtfungus via Groups.Io wrote:

Can anyone offer advice or instructions to read an expired DS1225 for calibration data and write to a new replacement? I have acquired a Tek 2467B but it has a TEST 4 FAIL 10 error at power on. I was contemplating buying a MiniPro TL866 Universal Programmer to do this but have never done so before. Thanks Jude



Re: Tek 2467B

Jude Taylor
 

Can anyone offer advice or instructions to read an expired DS1225 for calibration data and write to a new replacement? I have acquired a Tek 2467B but it has a TEST 4 FAIL 10 error at power on. I was contemplating buying a MiniPro TL866 Universal Programmer to do this but have never done so before. Thanks Jude

Re: 2465B SN 55xxx with TEST 05 FAIL 40

 

Option 46 is the designation for the military version of the scope (OS-288/G) that included option 10 IEEE-488 interface and 2 probes.

Manuel

Re: free - tek 453 scope manual printout

chuck
 

just confirmed my scope is pre "a" so the docs would need to be for the vanilla 453.
Thanks

Re: troubleshooting Tek453 Mod 210H

Fabio Trevisan
 

Hello Chuck,

On your finding of D940 opened, there is a screaming question... How did you tested it open?
H.V. diodes usually have a very large forward voltage drop (circa 20 volts), and they won't test right on a regular diode test.
Still, assuming your diagnostic is correct and D940 is indeed open, it's a Tek part number 152-0192-00, and the commercial part number is manufacturer specific, it's a VARO 7701-5X.
You can find its specs here:
http://w140.com/Tektronix_Xref_sm.pdf, page 12-2, line 8.
It's a 5kV diode, 50mA rated average forward current. and it has 15V forward voltage drop at the rated current.

Back in 2016, When I needed to diagnose a H.V. problem on my former 464, one of my first suspects were the H.V. diodes, and they're of this same vintage (not the same specs, but are also from VARO).
Back then, I sourced from a local electronics store, a few modern ESJA53-12. They are 12kV, low recovery time H.V. diodes, for currents up to 5mA and they worked fine on the 464, but the original parts on the 464 were 12kV 5mA (so the ESJA53-12 were a perfect match).

The ones on the 453, however, are 50mA, so I guess you will need to source different ones:
Either original parts (new old stock), and two reputable sources that users from Tekscopes group often resort to are:
Sphere: (http://www.sphere.bc.ca/) or...
QService: (https://www.qservice.tv/)...
(No affiliation though... just a happy customer)
Or you can try these folks here: http://hvstuff.com/
Never dealt with them, but they're almost the only source you can find on the net for H.V. oriented stuff.

Krgrds,

Fabio

On Wed, Oct 10, 2018 at 05:16 PM, chuck wrote:


hi folks,
Just confirmed this is a 453 pre A version.
Found D940 was open and when I looked at the two versions of this circuit
there is considerable differences.
D940 is the biggest diode I've ever seen so I guess a 1n911 is not going to do
the job. I haven't had a chance to look at the BOM but if any one knows the
commercial P/N would be appreciated. Also stray thought what blew the diode?
Everything else in the grid bias ckt seems to be alive and well. Any thoughts?
Thanks for your help been a great learning experience for me.
Chuck

Re: 2465B SN 55xxx with TEST 05 FAIL 40

Chuck Harris
 

Tektronix wrote high option numbers, like OPT46, to show things,
like including 4 probes, when they usually only included 2, or
including a carry pouch, or adding a Japanese mains power cord,
..., stuff like that.

Other options were mnemonic to what the option provided, like
OPT14 being for P14 phosphor on some scopes.

However, I don't see 46 listed in any of the literature I have.

-Chuck Harris

tekscopegroup@... wrote:

Right you are, only 4 SMD problem caps total. I need to have the board in front of me for facts to start falling in place. Definitively will carefully chop apart the caps before attempting removal. I did not intend to disturb any tantalums, unless really necessary. I've also read that the 20K trimmer pot near the DAC sometimes gets also damaged and needs to be replaced before the ref voltages are correct again. Maybe just order it too along the caps, just in case.

Your cleaning procedure makes a lot of sense, something I've not seen explained in detail anywhere else. Usually one would cringe at the idea of splashing water on a board like this, but now I am reassured it will be the best thing to do, even if corrosion damage appears to be light (due to fumes spreading on all nearby surfaces) its worth doing it right.

Do you by any chance know what Option 46 would be for this scope? Its the only field on the rear panel that has a punched hole in it.

Thanks.



Re: troubleshooting Tek453 Mod 210H

chuck
 

hi folks,
Just confirmed this is a 453 pre A version.
Found D940 was open and when I looked at the two versions of this circuit there is considerable differences.
D940 is the biggest diode I've ever seen so I guess a 1n911 is not going to do the job. I haven't had a chance to look at the BOM but if any one knows the commercial P/N would be appreciated. Also stray thought what blew the diode? Everything else in the grid bias ckt seems to be alive and well. Any thoughts?
Thanks for your help been a great learning experience for me.
Chuck

Re: 2445A calibration

Chuck Harris
 

R618 adjusts a balance between the two output sections of the
vertical amplifier. It will affect the overall gain of the output
amplifier, somewhat.

C105 and 205 will affect the corner accuracy of the 1KHz calibration
waveform. They probably won't affect the overall CAL02 calibration.

It is good to do what they tell you to do. The code running in the
internal calibration routines is a black box, and I doubt anyone outside
of the tektronix engineers that wrote it knows exactly what it is doing.

-Chuck Harris

maxim.vlasov@... wrote:

Chuck,

Sorry for the typo:

not super symmetric: -1,236 for CCW and -1.265 for CW.
to be read as "not super symmetric: -1,236 for CCW and +1.265 for CW."

Also one more thing. Just realized that I have skipped the C105 and C205 adjustment together with R618. Could it cause the problem, what do you think?

Thanks again,

Maxim

Re: 2445A calibration

Chuck Harris
 

Ack!

A rule of thumb is that when calibrating, is you need to use references
that are a minimum of 10x more precise and accurate than what you are
calibrating.

The scope you are using to measure the Arbitrary Waveform Generator, is
likely no better than +/-1%, assuming it was recently calibrated.

To that end, the PG506 is specified to be within +/-0.25%, which is
not quite 10x more precise and accurate than the 2445A is capable, but
certainly a lot better than what you are doing.

Further, the PG506's output impedance, when in voltage calibration mode,
is not 50 ohms, it is about as close to zero ohms as was humanly possible
in its day. To wit, its specified accuracy is +/-.25% +/-1uV for loads
of 1M *and* of 50 ohms.

The AWG most likely has a near zero ohm source with an internal 50 ohm
series resistance, put there to prevent reflections, from reflections
at the load end of the cable.

If 0.5Vp-p is showing as 0.55Vp-p, something is very wrong.

As to the DAC swing, it is not supposed to be symmetric about ground.
It must be 2.500V +/-1mv swing when the DELTA control is turned from
the fully CW position to the fully CCW position.

-Chuck Harris



maxim.vlasov@... wrote:

Hello Chuck,

I have started from the beginning. Replaced 4 aluminum caps on the A5 board (checked the ESR and capacity and they were fine). Then borrowed two 6.5 digit Agilent multimeters (to make sure about the readings) and set the 10V reference voltage to 10.0001V (can't do any better, the resistor is crusty). To measure things I use the ground hole under the calibrator output for the banana plug and pointy probe to measure things on J119.
Then I've continued to set the DAC reference voltage. The whole band is 2.501 volt, however it's not super symmetric: -1,236 for CCW and -1.265 for CW.
Then without touching anything else and re-running the CAL01 I've jumped on CAL02. Unfortunately CAL02 fails in the same fashion -> LIMIT ERROR.
Also noticed, that the gain of the scope is a little bit higher. I.e. instead of getting 0.5V p-p for 500mV calibration signal I get 0.55V. I wonder if it needs some fixing before going to CAL02.

For the vertical calibration I don't have the calibrator module like PG506. I substitute for that the AWG. The signal is 1KHz 50% duty cycle. Low level is 0V, HIGH level is what menu asks for into 50 Ohm, i.e. for 500mV required the AWG is set to provide LO=0V HI=0.5V into 50 Ohm. The output was tested on the "reference" scopes terminated to 50 Ohm.

I'm a bit lost in what could go wrong. I'll try checking the voltage ripple at the output of the power rails.

I just wonder if CAL02 would be affected by bad CAL01?

Thank you!

Best wishes,

Maxim



Re: 2445A calibration

maxim.vlasov@...
 

Chuck,

Sorry for the typo:

not super symmetric: -1,236 for CCW and -1.265 for CW.
to be read as "not super symmetric: -1,236 for CCW and +1.265 for CW."

Also one more thing. Just realized that I have skipped the C105 and C205 adjustment together with R618. Could it cause the problem, what do you think?

Thanks again,

Maxim

Re: 2445A calibration

maxim.vlasov@...
 

Hello Chuck,

I have started from the beginning. Replaced 4 aluminum caps on the A5 board (checked the ESR and capacity and they were fine). Then borrowed two 6.5 digit Agilent multimeters (to make sure about the readings) and set the 10V reference voltage to 10.0001V (can't do any better, the resistor is crusty). To measure things I use the ground hole under the calibrator output for the banana plug and pointy probe to measure things on J119.
Then I've continued to set the DAC reference voltage. The whole band is 2.501 volt, however it's not super symmetric: -1,236 for CCW and -1.265 for CW.
Then without touching anything else and re-running the CAL01 I've jumped on CAL02. Unfortunately CAL02 fails in the same fashion -> LIMIT ERROR.
Also noticed, that the gain of the scope is a little bit higher. I.e. instead of getting 0.5V p-p for 500mV calibration signal I get 0.55V. I wonder if it needs some fixing before going to CAL02.

For the vertical calibration I don't have the calibrator module like PG506. I substitute for that the AWG. The signal is 1KHz 50% duty cycle. Low level is 0V, HIGH level is what menu asks for into 50 Ohm, i.e. for 500mV required the AWG is set to provide LO=0V HI=0.5V into 50 Ohm. The output was tested on the "reference" scopes terminated to 50 Ohm.

I'm a bit lost in what could go wrong. I'll try checking the voltage ripple at the output of the power rails.

I just wonder if CAL02 would be affected by bad CAL01?

Thank you!

Best wishes,

Maxim

Re: 2465B SN 55xxx with TEST 05 FAIL 40

Tom Gardner
 

My technique, which I used to replace the capacitors and one SMD resistor in the middle of the others, was:

* play a soldering station's hot air gun over the relevant component until the
solder melts and it blows away (do a few experiments to see which
temperature/velocity works best, and use a narrow nozzle)
* protect the surrounding components by loosely covering them with
kapton/polyimide adhesive tape, to deflect the hot air away
* clean the pads etc by any means you choose; I used IPA
* dab solder paste on the pads
* place replacement components, using solder paste as an "adhesive"
* use hot air gun to reflow that component
* remove polyimide tape

On 10/10/18 17:02, tekscopegroup@... wrote:
Right you are, only 4 SMD problem caps total. I need to have the board in front of me for facts to start falling in place. Definitively will carefully chop apart the caps before attempting removal. I did not intend to disturb any tantalums, unless really necessary. I've also read that the 20K trimmer pot near the DAC sometimes gets also damaged and needs to be replaced before the ref voltages are correct again. Maybe just order it too along the caps, just in case.

Your cleaning procedure makes a lot of sense, something I've not seen explained in detail anywhere else. Usually one would cringe at the idea of splashing water on a board like this, but now I am reassured it will be the best thing to do, even if corrosion damage appears to be light (due to fumes spreading on all nearby surfaces) its worth doing it right.

Do you by any chance know what Option 46 would be for this scope? Its the only field on the rear panel that has a punched hole in it.

Thanks.

Re: troubleshooting Tek453 Mod 210H

Dale H. Cook
 

At 11:53 AM 10/10/2018, chuck wrote:

Second serial number is 005652 so I guess this monster is pre A.
Do you have Nuvistors in the front end and on the trigger board? If so you need the early 453 manual (serials below 20,000). It is at TekWiki:

http://w140.com/mmm/tek-453.pdf

Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA
https://plymouthcolony.net/starcity/radios/index.html

Re: troubleshooting Tek453 Mod 210H

Brendan
 

On Wed, Oct 10, 2018 at 08:55 AM, chuck wrote:

just bought a 453 and of course there are problems. The trace is fat! Using the 1Khz internal signal when I put it on either channel the trace is out of focus and really hi intensity. The focus knob works to an extent but the intensity knob does nothing.

Fabio,
Just thought of something.
So far I have yet to see a tube. Have only lifted the Z amp so far but
everything is Xstrs.
There will be two rectifier tubes inside the HV box unless someone has made mods, and if you have a below 20,000 serial # the other "tubes" will be nuvistors. The A version has a larger screen than the non-A version. I have 2 non-A 453s one nuvistor and the other is all transistor minus rectifier tubes, both have a screen size of 3 1/2 inches wide by 2 1/4 tall.

Re: 2465B SN 55xxx with TEST 05 FAIL 40

tekscopegroup@...
 

Right you are, only 4 SMD problem caps total. I need to have the board in front of me for facts to start falling in place. Definitively will carefully chop apart the caps before attempting removal. I did not intend to disturb any tantalums, unless really necessary. I've also read that the 20K trimmer pot near the DAC sometimes gets also damaged and needs to be replaced before the ref voltages are correct again. Maybe just order it too along the caps, just in case.

Your cleaning procedure makes a lot of sense, something I've not seen explained in detail anywhere else. Usually one would cringe at the idea of splashing water on a board like this, but now I am reassured it will be the best thing to do, even if corrosion damage appears to be light (due to fumes spreading on all nearby surfaces) its worth doing it right.

Do you by any chance know what Option 46 would be for this scope? Its the only field on the rear panel that has a punched hole in it.

Thanks.

Re: troubleshooting Tek453 Mod 210H

chuck
 

Kevin,
Thanks for your tip. Will check these out once I get the courage to get into the CRT circuit. LOL

Re: troubleshooting Tek453 Mod 210H

chuck
 

Fabio,
Just thought of something.
So far I have yet to see a tube. Have only lifted the Z amp so far but everything is Xstrs.