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Re: Tek 465b focus issue

 

开云体育

Well, I don't know. But observing in the other scope the signals at the plates, you should see something as clean as you have? in the CH1 output BNC connector.

The right method for measuring at the plates is to use a differential probe (expensive) or 2 probes, one for each plate. Connect them to each input channel. One of the channels should be inverted and the input mode "Add". If your scope can't invert one input channel (yours seems to lack this capability) you can probe one plate at a time, if there is something strange over the desired signal you will see it.

Regards,

Ignacio


El 01/09/2022 a las 4:00, DG escribió:
This is very useful info. I'll forward it to my tech.?
Question, What level of ripple on the signal would you consider acceptable, measured at the deflection plates? I remember that he initially followed the signal path all the way to CRT and thought it was good. Is there a test point to take a trace with another scope at the deflection plates?
Sorry, I'm just trying to be a communication link. My tech doesn't have enough English to post here. I personally do not have any CRT knowledge, period.
Thanks for your help!
_._,_._,_


Libre de virus.
Re: Tek 465b focus issue

 

开云体育

Hi

?

More

?

I have the ruins of a 465 series scope, so, I might have parts if you need.

?

Jean? L? C? Ruelle

?

De?: [email protected] [mailto:[email protected]] De la part de DG
贰苍惫辞测é?: mercredi 31 ao?t 2022 18:15
??: [email protected]
Objet?: [TekScopes2] Tek 465b focus issue

?

Hello,

?

?

I'm a new?member here. I'm not a repair professional?but a vintage audio hobbyist and use a scope for?testing amplifiers and other audio gear I restore or build from scratch. Most of the equipment I work on is vacuum tube type.

?

I got this scope on ebay for not much more than the shipping charge. It is in very good cosmetic shape besides?broken?away?cable?wrap feet.
Initially, I couldn't get a trace out of it but noticed that many push switches do not return to "off" position on their own, so I started with cleaning the controls that are accessible. Some of the switches seem sealed but there were many that are not. After cleaning I was able to get a trace on both channels that responds to sine and square but it is not anywhere sharp as I'd expect it to be. I have a friend, who is a retired TV repairman. He was able to improve the scope sharpness by re-seating some transistors in their sockets but the trace is still fuzzy. It responds to Focus and Astigmatism adjustments but it just doesn't get sharp enough to use the scope for any kind of measurements. He seems to think the issue is CRT itself. I took a scope reading out of the rear BNC connection with my Tenma and it displayed a sharp trace.
Here are the examples. First is 1KHz from signal generator displayed by Tek and second is the same signal displayed by Tenma from Tek's rear BNC port:

?

?

?

I can reduce trace intensity to make it sharper but the trace becomes very difficult to see. Increasing intensity makes the trace?very fuzzy.

Does it look like the CRT is the culprit?

My tech checked Anode and Cathode voltages as well as Grid Bias.

All in specs. Focus adjustment passes through the best possible image in the middle of the control rotation. Any suggestions?

I have a service manual copy but it is not complete. Some pages are missing.

?

Thanks in advance.

DG


?
Re: Tek 465b focus issue

 

开云体育

Hi

?

Do you still work on audio on tubes??

I have a lot of Tek tubes from old scopes. As far I can remember from the times I used too to deal with audio and tubes, very many could be fine for you.

Am I right ?

?

What is the scope you did by and face some problems with ?

?

Regards

?

Jean? L C Ruelle

?

?

De?: [email protected] [mailto:[email protected]] De la part de DG
贰苍惫辞测é?: mercredi 31 ao?t 2022 18:15
??: [email protected]
Objet?: [TekScopes2] Tek 465b focus issue

?

Hello,

?

?

I'm a new?member here. I'm not a repair professional?but a vintage audio hobbyist and use a scope for?testing amplifiers and other audio gear I restore or build from scratch. Most of the equipment I work on is vacuum tube type.

?

I got this scope on ebay for not much more than the shipping charge. It is in very good cosmetic shape besides?broken?away?cable?wrap feet.
Initially, I couldn't get a trace out of it but noticed that many push switches do not return to "off" position on their own, so I started with cleaning the controls that are accessible. Some of the switches seem sealed but there were many that are not. After cleaning I was able to get a trace on both channels that responds to sine and square but it is not anywhere sharp as I'd expect it to be. I have a friend, who is a retired TV repairman. He was able to improve the scope sharpness by re-seating some transistors in their sockets but the trace is still fuzzy. It responds to Focus and Astigmatism adjustments but it just doesn't get sharp enough to use the scope for any kind of measurements. He seems to think the issue is CRT itself. I took a scope reading out of the rear BNC connection with my Tenma and it displayed a sharp trace.
Here are the examples. First is 1KHz from signal generator displayed by Tek and second is the same signal displayed by Tenma from Tek's rear BNC port:

?

?

?

I can reduce trace intensity to make it sharper but the trace becomes very difficult to see. Increasing intensity makes the trace?very fuzzy.

Does it look like the CRT is the culprit?

My tech checked Anode and Cathode voltages as well as Grid Bias.

All in specs. Focus adjustment passes through the best possible image in the middle of the control rotation. Any suggestions?

I have a service manual copy but it is not complete. Some pages are missing.

?

Thanks in advance.

DG


?
Re: Tek 465b focus issue

 

Rebonjour à tous my first portable Tektronix was 454, then 485, in 1970s 465,475, 465B.

Fine machines,, some are still running....brings back memories.....

1. 465, 465B are indeed very different. Tekwiki has the history, manuals, révisions for all TEK vintage scopes. Another forums is the EEVBLOG in repair, test equipment sub groupe


2. Artech makes excellent reproduction manuals in paper or CD ROM.

3. CRT HV de focusing is easily distinguished from amplifier noise. I would not use VERT CH 1 out BNC, or mess with deflection plate signals ( danger of cracking CRT seal) for this issue.

4. XY dot test or GRD input and slow sweep AUTO, gives a dot, best for focus/ astigmatism adjustment
Beware of intensity, burning

5. always check LV PSU busses and then HV CRT section. Beware of the HV anode usually -2500V
No need to measure the Ultor CRT dag 15 kV yet.

just the ramblings of an old retired EE

Bon chance

Jon
Re: Tek 465b focus issue

 

开云体育

CRT deflection factors are generally given in volts/inch (or perhaps volts/cm).? That says what the voltage difference between the two plates will deflect the beam a certain difference.? The actual number varies with a lot of factors.

What you may be seeing is that the internal noise of the amplifier perturbs the beam enough that your spot is the actual (smaller spot) dithering around the right location.? That dithering is due to noise.

put the scope on XY mode.? Set the horizontal and vertical gain to the maximum volts/division (least sensitivity).?

Defocus the scope so that you get a large circle.? Adjust the astigmatism so that the spot is as round as possible.?

As you adjust the focus, you may need to adjust the astigmatism to get the sharpest spot.?

as you adjust the focus, decrease the intensity so that the spot is not too bright.?

once you get a reasonable spot, with not a lot of brightness, you should get a sharp spot.? If the spot isn't focusing to a sharp spot, then turn on the sweep and see if you can see a waveform of some sort (because it could be interference from some other part of the scope).

if you see a waveform at all, it's interference.

Harvey



On 8/31/2022 10:00 PM, DG wrote:

This is very useful info. I'll forward it to my tech.?
Question, What level of ripple on the signal would you consider acceptable, measured at the deflection plates? I remember that he initially followed the signal path all the way to CRT and thought it was good. Is there a test point to take a trace with another scope at the deflection plates?
Sorry, I'm just trying to be a communication link. My tech doesn't have enough English to post here. I personally do not have any CRT knowledge, period.
Thanks for your help!

Re: Tek 465b focus issue

 

That's the one
--
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Re: Tek 465b focus issue

DG
 

On Wed, Aug 31, 2022 at 09:49 PM, Paul Amaranth wrote:
Artek
artekmanuals.com?
Re: Tek 465b focus issue

DG
 

This is very useful info. I'll forward it to my tech.?
Question, What level of ripple on the signal would you consider acceptable, measured at the deflection plates? I remember that he initially followed the signal path all the way to CRT and thought it was good. Is there a test point to take a trace with another scope at the deflection plates?
Sorry, I'm just trying to be a communication link. My tech doesn't have enough English to post here. I personally do not have any CRT knowledge, period.
Thanks for your help!
Re: Tek 465b focus issue

 

You should be able to get the correct manual from Artek for a nominal cost.
His scans are excellent and well worth the small cost. I often print
schematics from his scans on a D size plotter with excellent results.

Paul

On Wed, Aug 31, 2022 at 06:40:16PM -0700, DG wrote:
K04BB shows only one SM for 465b, regardless of the Serial Number.
TekWiki shows several variations of Serial Number manuals for 465 but not for "b" version. I know "b" is not the same as the original 465 model.
Am I missing something?
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix/Linux - We don't do windows
Re: Tek 465b focus issue

DG
 

K04BB shows only one SM for 465b, regardless of the Serial Number.
TekWiki shows several variations of Serial Number manuals for 465 but not for "b" version. I know "b" is not the same as the original 465 model.
Am I missing something?
Re: Tek 465b focus issue

 

The CH1 vertical output connector at the back of the scope is not the final signal that goes to the deflection plates. When you get the service manual you can see that this output is taken from the CH1 preamp, so there is plenty of circuitry after that able to pickup noise, oscillations or just ripple.

El 31/08/2022 a las 21:26, DG escribió:
Are you able to see two photos I uploaded into the folder named "Tek 465b focus issue"?
One of the pictures shows what the Tek is displaying with the probe on the Signal Generator output.
Another picture shows my functional 20MHz Tenma scope displaying the same signal taken from the BNC connector in the back of the misbehaving Tek.
As my Tech friend explained, the signal at the rear BNC is what feeds the CRT
--
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Re: Tek 465b focus issue

 

Yep, always screw that up.

On Wed, Aug 31, 2022 at 06:33:57PM -0400, Tom Miller wrote:
no, it is KO4BB.com letter Oh

On 8/31/2022 6:35 PM, Paul Amaranth wrote:
Try K04bb (that's zero - four) as in www.k04bb.com

On Wed, Aug 31, 2022 at 03:33:53PM -0700, DG wrote:
On Wed, Aug 31, 2022 at 05:00 PM, Froggie the Gremlin wrote:

KOBB
Do you have a web address for COBB? Many irrelevant sites pop up in search.

--
This email has been checked for viruses by Avast antivirus software.
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!DSPAM:630fe2ab199641972242101!
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix/Linux - We don't do windows
Re: Tek 465b focus issue

Tom Miller
 

no, it is KO4BB.com letter Oh

On 8/31/2022 6:35 PM, Paul Amaranth wrote:
Try K04bb (that's zero - four) as in www.k04bb.com

On Wed, Aug 31, 2022 at 03:33:53PM -0700, DG wrote:
On Wed, Aug 31, 2022 at 05:00 PM, Froggie the Gremlin wrote:

KOBB
Do you have a web address for COBB? Many irrelevant sites pop up in search.

--
This email has been checked for viruses by Avast antivirus software.
www.avast.com
Re: Tek 465b focus issue

Tom Miller
 

开云体育

KO4BB.com



On 8/31/2022 6:33 PM, DG wrote:
On Wed, Aug 31, 2022 at 05:00 PM, Froggie the Gremlin wrote:
KOBB

Do you have a web address for COBB? Many irrelevant sites pop up in search.

Virus-free.
Re: Tek 465b focus issue

 

Try K04bb (that's zero - four) as in www.k04bb.com

On Wed, Aug 31, 2022 at 03:33:53PM -0700, DG wrote:
On Wed, Aug 31, 2022 at 05:00 PM, Froggie the Gremlin wrote:


KOBB
Do you have a web address for COBB? Many irrelevant sites pop up in search.

--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix/Linux - We don't do windows
Re: Tek 465b focus issue

DG
 

On Wed, Aug 31, 2022 at 05:00 PM, Froggie the Gremlin wrote:
KOBB

Do you have a web address for COBB? Many irrelevant sites pop up in search.
Re: Tek 465b focus issue

DG
 

Is the probe supposed to be hooked up to anything?
Without the probe, the scope displays nothing.
Re: Tek 465b focus issue

 

Get service manual for SN you have

Tekwiki or KOBB

see CRT ckt, adjustment

Check voltages, PSU

use both focus and astigmatism controls.

jon
Re: Tek 465b focus issue

 

Try this.? Set the input coupling to GND, VOLTS/DIV to 10mV, horizontal sweep to 2mS/div, trigger mode to AUTO, source to LINE, and coupling to AC.
What do you see?
Re: Updated album Tek 465b focus issue #photo-notice

 

Try this.? Set the input coupling to GND, VOLTS/DIV to 10mV, horizontal sweep to 2mS/div, trigger mode to AUTO, source to LINE, and coupling to AC.
What do you see??
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