Date   

Re: Repairing my Tektronix 454 oscilloscope need some advice

Victor
 

Albert,
With the 454 energized today I could make some of your recommended test. I start with the "less risky test" and the results was far from my expectations. After follow your process I applied to Q1430 collector 1V pp and the voltage at the HV test point was only - 3 to - 4 V. I change the frequency from 23 kHz until 27 kHz and no results and no voltage increase to 77 V DC.
Otherwise: The current at F1437 measured is 0.22A. 
Also adjustment on pot R1401 give any variation on the HV test point.
The voltage on HV test point actually (in normal operation) is  - 64V. 
I could'nt make other test mentioned on your message on 02/17.
My test equipment is : scope TEK 7603, wave generator Sound Technology 3100A, meter Fluke 87III.
Any thought from your side ? 
Thank you 
Victor

-----Original Message-----
From: Albert Otten <aodiversen@concepts.nl>
To: TekScopes <TekScopes@groups.io>
Sent: Tue, Feb 18, 2020 5:44 pm
Subject: Re: [TekScopes] Repairing my Tektronix 454 oscilloscope need some advice

(continued)
I did an easier and less risky test. F1437 tied to GND, wire to "P" disconnected. Sine wave generator FG504, same GND , 50 ohm output applied to Q1430 collector (no other termination). Viewed waveform at Q1430 collector at a scope. Kept amplitude pp up to only  1 V so  Q1430 would never conduct.
Measurements:
Resonance at about 23 kHz, not very sharp but clear enough.
Amplitude 1 V pp at collector resulted in 77 V DC at the HV test point as measured with a 10M DMM.
Impedance was about 10 ohm.

Albert


Re: 5116+5D10 intensity problem

Yeun-Jung Wu
 

Hello every Tek expert:

I just finished a long reply for thank you all for a long list of helpful hints. Unfortunately my wi-fi connection was lost at the time I keyin "send" command. Everything was lost.

Here I reype my reply short. First I want to thank everyone on the help of HV probe and the dielectric fluid. HV measurement was still a lethal barrier I had not cross before. Probably it was also a basic skill every devoted Tek collector should master. This will be my next great lesson to learn.

I managed to tune down X/Y gain of 5D10 and vertical/horizontal gain of 5116 by marking their original position first. On 5D10 there was little effect even the gain was set to minimum. Setting 5116's gain of vertical/horizontal indeed shrunk the scale on bother direction back a little; last portion of character of top readout was barely visible. As Harris and other experts pointed out sideway deflection should increase since slower electron spent more time across those electrostatic plates. Trace was dim because final kinetic energy was less due to insufficient acceleration. Finally I returned all settings to their original position.

I went on to probe waveforms on A3 HV board. TP267 at HV oscillator measured 0.56V, exactly as manual described. TP24 had similar waveform with the same period (oscillator worked) but the amplitude was smalle; 100Vpp v.s. 400Vpp. TP25 I measured similar waveform and amplitude while manual indicate a positive half waveform. (TP25 was at the junction of CR245, C246, R246. C246 was a 10kOhm R29 away from TP24. at least there was discrepencies on waveforms.

68nF C248/C249, 1nF C241, 47nF C242 were all cylindrical polyester film capacitors. I wonder whether LCR meter would reveal any leakage at high voltage? I also ordered a 10kV, 5mA silicon diode CR247. But expect long sipping delay.

Filter capacitors C837, C839, C815, C810 were at correct capacitance and low serial resistance. I had not trace where larger than normal ripple of +30V was from.

I wish the transformer, as many of you explained, would be O.K. Digging through HV problem of 5000 series scope I spotted Dennis's post of replacement of 577 curvier tracer by older 5110's. I also bought a broken 577 from eBay several years ago. Brought it back to work a few days then the intensity control became inoperative, rendered storage mode not function. Since it still displayed curves I leave it as it was. Hopefully there will no epoxy problem.

Dennis post also reminds me about the possibility of displaying 5D10's screen on a big screen scope, eg. R7603?

Best Regards to all of you!

Yeun-Jung Wu


Re: New software-only method to extract 11801 or CSA803 series SRAM and other memory locations

Reginald Beardsley
 

Yes, It's stated in the service manual.

Reg


Re: 3D printable feet for TDS500/600/700

Tam Hanna
 

Hello,

in case anyone needs one printed in Europe: I am willing to give it a shot with my RF100 and some white or grey material I have left over.


Shipping also for free. But _ONLY_ via Slovak Federal (no Hungarian Governmental, no JewPost as both are pricey), strictly WHEN I HAVE TIME FOR IT (aka up to 2 weeks of wait), strictly UNINSURED. Offer limited to until I tire of printing them, no legal rights whatsoever, "Ersitzung" explicitly excluded.


Tam



--
With best regards
Tam HANNA

Enjoy electronics? Join 15k7 other followers by visiting the Crazy Electronics Lab at https://www.instagram.com/tam.hanna/


Re: 5116+5D10 intensity problem

Chuck Harris <cfharris@...>
 

I have never seen a fault on a 5000 series EHT before either.

The epoxy used on the 5000 series, and the 7000 series, EHT's
is very different from the epoxy I find on 547's, etal. It is
clear amber, and very hard. The epoxy on failed 547's is a
muddy, brownish red, and is much softer.

I am coming to the conclusion that the epoxy failure is some
sort of fire retardant failure... much like computer cases that
turn from white to brown over time.

-Chuck Harris

magnustoelle via Groups.Io wrote:

Good Day Yeun-Jung,
apart from the discussion on HV probing, my recommendation is to check the HV capacitors in the high volt section. I have seen a few which failed in other 5000 series oscilloscopes, but I have never seen a failed HV transformer in that family of devices. Faults might be spurious. If you have access to an insulation tester, that would be a relatively easy test, i.e. remove the board, unsolder the capacitors and test them. Carefully increase the test voltage while measuring the leakage current and follow the tester‘s manual.  Good luck,
Magnus




Re: 5116+5D10 intensity problem

magnustoelle
 

Good Day Yeun-Jung,
apart from the discussion on HV probing, my recommendation is to check the HV capacitors in the high volt section. I have seen a few which failed in other 5000 series oscilloscopes, but I have never seen a failed HV transformer in that family of devices. Faults might be spurious. If you have access to an insulation tester, that would be a relatively easy test, i.e. remove the board, unsolder the capacitors and test them. Carefully increase the test voltage while measuring the leakage current and follow the tester‘s manual.  Good luck,
Magnus


Re: 547 scope HV transformer problem. One practical solution.

Morris Odell
 

Hi Ernesto,

Thanks for the discussion which I found really interesting. I am also a 547 admirer and use one as my main bench scope with a 1A4 plugin. That combination really brings out the best in that scope and indeed is featured on the cover of Jim Willams' Analog Circuit Design book. I suspect the lack of a trigger connection to the plugin connector in the CA reflects its heritage when that wasn't part of the design of the older 500 series.

The switchable HV supply is a neat idea but you will eventually need to replace the HV transformer as they do deteriorate further with time. There is a drawing and specification for the transformer in the files section of this group. Chuck Harris made very fine replacements and hopefully he will start doing them again but with persistence you might also be able to do them. I have had quite a few scopes with the problem (549, 556, 547, 545B) and they are running nicely with a variety of rewound transformers. I also have a 547 with what looks like an original transformer that does not have the problem. It's worth reading through the extensive discussion in this group about the transformer before attempting it though.

Good luck and let us know how you get on,

Morris Odell
Melbourne, Australia


Re: New software-only method to extract 11801 or CSA803 series SRAM and other memory locations

Ragnar S
 

Hi,

Thanks a lot for this information!

Did you ever find out if 10000 .. 1FFFF actually is the the NVRAMs on the A5 board (U500 and U511)?

Ragnar


Re: Repairing my Tektronix 454 oscilloscope need some advice

Victor
 

Dave,
Thank you for the tip. I read and see the photo album and this is a great information and a great job ! I believe also that HV transformer is the same on 453 and 454.  Actually I am trying some additional test with the help of Albert Otten. If the test fail then I will be sure that my HV transformer is dead. Then I would like to ask you some additional information or details about your rewound. 
Thank you,Victor

-----Original Message-----
From: Dave Wise <david_wise@phoenix.com>
To: TekScopes@groups.io <TekScopes@groups.io>
Sent: Mon, Feb 17, 2020 9:05 pm
Subject: Re: [TekScopes] Repairing my Tektronix 454 oscilloscope need some advice

If I understand correctly, the 454 HV is similar to the 453.  I successfully rewound a 453 transformer using a low-tech process which I documented in topic and photo album titled "453 HV Transformer Rewind".

HTH,
Dave Wise
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Victor via Groups.Io <vmcfer=aol.com@groups.io>
Sent: Saturday, February 15, 2020 10:40 AM
To: TekScopes@groups.io
Subject: [TekScopes] Repairing my Tektronix 454 oscilloscope need some advice

Hi members,
I have since many years a tek 454. Few years ago the trace stop to show. Since I have more spare time to dedicate to my small lab I would like to repair it.
The first step was to repair the power supply witch is working now fine. Then I discover that the CRT circuit is not working (very low voltage on the TP 1469 (-1960V)) and no voltage on the CRT heater.
I test all the parts on the Z Axis circuit board feeding the HV voltage and I couldn't find any trouble. I open the plastic box containing the HV transformer for testing and all the parts seems fine except a 1 Mohm resistor which I replace it. Is not easy to work on this circuit with few information but I think the HV transformer is dead.
A very well know Canadian supplier for Tek parts doesn't have any spare available for the HV transformer. So I'm looking for some advice or any members experience on this scope or additional test to confirm my suspicion. Also any specs about the HV transformer will be welcome.
Thanks in advance.
Victor


Re: 547 scope HV transformer problem. One practical solution.

ykochcal
 

"I had never cleaned it from some dirt accumulated in 40 years through the
cover holes, many tubes are dirty, but I didn't dare to blow with
compressed air or... god forbid ...wash it."


After you get more comfortable, you might take some time to look up
washing/wash/clean in this group.

I think a little Compressed air can be good as long as it's the "oil less"
kind

John


Re: Repairing my Tektronix 454 oscilloscope need some advice

Victor
 

Albert,
Thank you for all that great tips that you sent yesterday and now.I was busy today with the  interference filter dead. I couldn't find any spare on the market with the same size as the original. So I decide in the mean time to install one found on my spares parts box. It will be out of the scope but temporary will be a solution to continue the job. Tomorrow morning I will be able to energize my 454 and make test. I will let you know about them.
Thank you,Victor

-----Original Message-----
From: Albert Otten <aodiversen@concepts.nl>
To: TekScopes <TekScopes@groups.io>
Sent: Tue, Feb 18, 2020 5:44 pm
Subject: Re: [TekScopes] Repairing my Tektronix 454 oscilloscope need some advice

(continued)
I did an easier and less risky test. F1437 tied to GND, wire to "P" disconnected. Sine wave generator FG504, same GND , 50 ohm output applied to Q1430 collector (no other termination). Viewed waveform at Q1430 collector at a scope. Kept amplitude pp up to only  1 V so  Q1430 would never conduct.
Measurements:
Resonance at about 23 kHz, not very sharp but clear enough.
Amplitude 1 V pp at collector resulted in 77 V DC at the HV test point as measured with a 10M DMM.
Impedance was about 10 ohm.

Albert


Re: 547 scope HV transformer problem. One practical solution.

 

Hi Albert, thank you for the information.

I verified the action of the negative pulse by R562, C562 on power up of the -150V that shifts the trace to the right. I could do something similar when the 325 unreg is applied to the HV supply. This works to protect the visible screen's phosphorous, but I am not sure what other transients occur at the electrodes of the CRT. The specs list a -200V maximum between grid and cathode, and I am inclined to put two neon tubes in series between these two electrodes to protect the cathode (when my CRT is blanked out there are -85V between them. With this protection, I would try to add another blanking pulse to the floating supply where the (un)blanking signals from the sweep generators come in. In this way, the trace would turn on already stabilized and nice looking. But for the time being, by raising slowly the supply to the HV the initial brightening is reduced, and I will tackle this after further investigating the HV transformer issue


Re: 547 scope HV transformer problem. One practical solution.

 

It is not only the enjoyment of the scope working, but also of the challenge of going around its HV problem.
I had incorrectly written that the plug-in on my scope is the 1A1, but it turns out the that one I have is the CA, an honorable senior dual-trace made 100% with vacuum tubes. I really like its design and the way it works competently. At the beginning waking up from the 40 years hybernation it was full of quirks, in part due to the old switches and the two gain potentiometers cracked and intermittently open. I shorted them out and I am waiting for replacements. But the more I use it the more quiet and behaved it becomes. This is the same with the whole 547. I had never cleaned it from some dirt accumulated in 40 years through the cover holes, many tubes are dirty, but I didn't dare to blow with compressed air or... god forbid ...wash it. But all by itself it is recovering from some shortcomings. The two time bases work fine, I can get delayed triggers, B intensified by A, trace separation, etc. etc. Retrace blanking and chopped blanking work fine. What a wonderful instrument!

One feature missing in the CA is a trigger signal from one of the channels so that one can use the alternate and chopped functions without having to trigger the scope externally. So I brought out the signal from the first stage of channel A, at the cathode of V3323, to the connector pin 5 through a 1K resistor, and this connects in the scope to the "Plug In" trigger input. This works fine, although as soon as I get a high voltage signal transistor or FET I will boost this added signal at the source with an emitter or source follower and send the signal with low impedance. Now the CA plug-in is perfect, it is all I need and I would not use an 1A4 if I had it. I don't know WHY Tektronix didn't add this single channel tool-module trigger, so easy to implement.


Re: 5116+5D10 intensity problem

Chuck Harris <cfharris@...>
 

The manuals on the internet are the old 1963 versions of
the P6015 manual. If you look at the picture, you should
notice that the connector on the compensation box is an
old PL259 UHF connector, like was used on the early 500
series scopes.

The manual that came with my P6015 is APR 87, and it has
two curves, one with Freon, and one without. The curve
with Freon shows 20KVDC or RMS from DC to 1MHz. With air
is 13KVDC or RMS from DC to 1MHz.

The old probe shows the same curve as mine, only it limits
the probe to 28KV, at less than 100KHz.

I am pretty sure that if you over voltage the probe, it
has a spark gap that will arc over before the probe is
ruined. Obviously, the spark gap will arc over at a higher
voltage with freon, and a lower voltage with air.

The patent indicates that R12 is suitable if the probe is
to be used and stored below 10C.

If I had a probe that was sans fluid, and I couldn't buy
more R114, I would either live with the 13KV limit, or
try another refrigerant with a high boiling point...
probably butane. SF6 is also bound to work.

[Please don't bother mentioning how butane is flammable.
Everyone already knows that. They should also know that
it isn't if there is no air in the probe... If you
fill the probe with liquid in the probe, you won't be
able to screw on the probe's cap before the butane has
boiled enough to totally displace the air.]

With SF6, you would have to fill with vapor only, as its
liquification pressure is too high.

-Chuck Harris


Harvey White wrote:

Ok, several things after searching the  manuals.

1) the liquid is fluorocarbon 114.  SF6 is used in the AWACS transmitter unless they
rebuilt it.

2) the P6015 has the liquid, the P6015A has a silicone filler and no liquid.

3) the P6013 (IIRC) may have neither and is rated for about 12KV or so, while the
P6015 is rated from 20KV to 30KV depending on circumstances.

4) I did not find the specs on the 6015 without dielectric fluid, not in the internet
material I have at the moment.


Harvey


On 2/17/2020 3:26 AM, Paul Cohen wrote:
Or maybe SF6 (nasty) gas which is used in HV

בתאריך יום ב׳, 17 בפבר׳ 2020, 10:22, מאת Yeun-Jung Wu ‏<
B0190@mail.ntou.edu.tw>:

Hello Harvey:

Thank you for your hint on future diagnosis. I will start collecting more
information on epoxy coated transformer first.

5D10 seemed to work fine except read out information had been expanded
outside the screen. Now I understand why red LED "possible under-sampling"
would lit: I was using slow time base to watch two nearly identical 7kHz
since wave superimposed together to form a nice envelope. There were lot of
wave form variation during long accuqsition time but the available memory
space for storing waveform was limited. When I select faster time base such
that several cycles was within the range of one horizontal division that
warning went away.

More than 5 year's ago I bought a Tek high voltage probe from eBay. There
was an empty can supposed to contain liquid with high dielectric strength,
something similar to banned CFC freon. For 4.5kV maybe I can fill some
other liquid and give it a try.

Best Regards,

Yeun-Jung Wu







Re: 3D printable feet for TDS500/600/700

Mlynch001
 

Monty,

I will add my complement, you did an awesome job on that design. I just made some of the little "Bottom" feet for the 4XX series, I had a 465 that was missing some of those as well. I find all sorts of uses for the 3D Printer around that workshop and home.

Thank You for sharing!

--
Michael Lynch
Dardanelle, AR


Re: 3D printable feet for TDS500/600/700

Abc Xyz
 

Gulp!

On Tue, Feb 18, 2020, 8:43 AM Mlynch001 <mlynch002@gmail.com> wrote:

JR,

I slice the STL file with CURA 4.4.1. Print in PETG, Nylon or ABS (I use
PETG with great success). Print "laid down" on one side so that minimal
support is needed.

Hope this helps.

--
Michael Lynch
Dardanelle, AR




Re: Repairing my Tektronix 454 oscilloscope need some advice

Albert Otten
 

(continued)
I did an easier and less risky test. F1437 tied to GND, wire to "P" disconnected. Sine wave generator FG504, same GND , 50 ohm output applied to Q1430 collector (no other termination). Viewed waveform at Q1430 collector at a scope. Kept amplitude pp up to only 1 V so Q1430 would never conduct.
Measurements:
Resonance at about 23 kHz, not very sharp but clear enough.
Amplitude 1 V pp at collector resulted in 77 V DC at the HV test point as measured with a 10M DMM.
Impedance was about 10 ohm.

Albert


Re: 3D printable feet for TDS500/600/700

Mlynch001
 

JR,

I slice the STL file with CURA 4.4.1. Print in PETG, Nylon or ABS (I use PETG with great success). Print "laid down" on one side so that minimal support is needed.

Hope this helps.

--
Michael Lynch
Dardanelle, AR


Re: 3D printable feet for TDS500/600/700

Monty Montgomery
 

Oh good. I was about to say I couldn't help with the 465 :-)

Thanks others for the compliments.

Cheers,
Monty


Re: 3D printable feet for TDS500/600/700

Abc Xyz
 

Thanks Mike! :)

On Tue, Feb 18, 2020, 8:34 AM Mlynch001 <mlynch002@gmail.com> wrote:

On Tue, Feb 18, 2020 at 10:19 AM, Abc Xyz wrote:


Monty,

Great Job in those Feet! Now if I just had a File for 465 Feet...
JR

You need a file for the cordwrap feet of the 465 Series? That file is on
THINGIVERSE.

HERE: https://www.thingiverse.com/thing:1410827

I can e-mail you the STL File, as I have that as well.

I have printed dozens of these for my various 4XX Series scopes plus some
for my brother as well.

Hope this helps.


--
Michael Lynch
Dardanelle, AR



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