--- In TekScopes@..., "Albert" <aodiversen@> wrote:

Thanks Bob,

I still don't understand it. Today I measured DC developed between the

In a good 564 there was also some 0.3-0.4 V DC between the plates, and

Albert

I would be careful about making assumptions on potential difference

What I don't understand is why the 56x series uses BOTH deflection

So why did Tek design deflection based blanking into the 56x series, and

- Steve

My R7603 has developed a problem where the readouts jump around a lot based on the input signal frequency and amplitude, signal trace is fine. With no input, readouts are steady. This readout problem occurs with several different vertical and horizontal plugins, problem appears to be in the 7603 frame.

Power supplies measure well and look good on scope, dont think they are involved. I have been unable to determine if the readout board or the vertical or horizontal amp board is involved as I do not have spares.

Has anyone seen this problem and resolved it?

Larry

----- Original Message -----

From: KenS

To: TekScopes@...

Sent: Friday, July 13, 2012 3:11 PM

Subject: [TekScopes] Polish out scratches in blue filter

?

Hi,

I have a 2467 with some minor scratches in the blue filter. I found out the hard way with another Tek scope that you can easily make problems worse if you try to remove scratches with a plastic polish, so I am cautious. There appear no sources of NOS blue filters out there. Anybody know of any that wouldn't come up in Google? Or, a sure-fire way to polish out scratches from these blue filters?

Thanks!

- Ken

"There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy"

Hamlet

--- In TekScopes@..., "Albert" <aodiversen@> wrote:

I swapped the CRT of this 564 with the CRT of a known to be good 564. Lo and behold, both 'scopes worked fine now! Then I moved the CRTs back to their original positions and again both 'scopes worked fine.
Spontaneous self-healing of a loose contact inside the CRT?

Albert

I have one. 20 dollars + shipping? = 25 total?


--- In TekScopes@..., Michael Dunn <mdunn@> wrote:

Hi. Does anyone have any 8608 tubes? (med power pentodes with
plate cap, used for vertical deflection on some Tek scopes (eg, 556,
549))

I'm willing to pay a reasonable amount for 1 or several, but not
an exorbitant price.

-----------------------------------------------------------------
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Cantares | Self-Amplified Speakers, Test Equipment
74 George St. | Ambisonic Surround Sound CDs and Recording
Waterloo, Ont. | (519) 744-9395 (fax: 744-7129)
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I swapped the CRT of this 564 with the CRT of a known to be good 564. Lo and behold, both 'scopes worked fine now! Then I moved the CRTs back to their original positions and again both 'scopes worked fine.
Spontaneous self-healing of a loose contact inside the CRT?

Albert

--- In TekScopes@..., "Steve" <ditter2@> wrote:

--- In TekScopes@..., "Albert" <aodiversen@> wrote:

Thanks Bob,

I still don't understand it. Today I measured DC developed between the blanking plates (across the 570k resistor) with no plugins installed. There is DC, rising to about 0.4 V after some warming up. So there seems to be at least "some" connection to pins 5 and 7 internally. But there was no response in intensity whatsoever when I supplied 20 V DC between those plates, using a floating DC supply.
In a good 564 there was also some 0.3-0.4 V DC between the plates, and 20 V was sufficient to make the dot disappear.

Albert

I would be careful about making assumptions on potential difference between the plates, generated by a floating supply. While it is true that the field difference between the plates bends the beam, there is a component that needs to be referenced to the relative charge of the electrons at the point in time they pass the plates – in other words a DC bias on both plates relative to ground.
What I don't understand is why the 56x series uses BOTH deflection unblanking AND a DC coupled grid control. I have seen deflection blanking used when the grid is AC coupled to the intensity blanking / control, and DC biased directly from the cathode. In these cases, deflection blanking is needed for very long blanking intervals, as the time constant in an capacitor coupled system can only remain off for the time constant. But the 56x uses the more complicated DC system, which uses dedicated HV windings for both the cathode and grid bias, eliminating any time constants and the need for another blanking system.
So why did Tek design deflection based blanking into the 56x series, and why do the time bases use it, with the DC grid control only used for intensify in dual time bases?
- Steve

--- In TekScopes@..., "Albert" <aodiversen@> wrote:

Thanks Bob,

I still don't understand it. Today I measured DC developed between the blanking plates (across the 570k resistor) with no plugins installed. There is DC, rising to about 0.4 V after some warming up. So there seems to be at least "some" connection to pins 5 and 7 internally. But there was no response in intensity whatsoever when I supplied 20 V DC between those plates, using a floating DC supply.
In a good 564 there was also some 0.3-0.4 V DC between the plates, and 20 V was sufficient to make the dot disappear.

Albert

I would be careful about making assumptions on potential difference between the plates, generated by a floating supply. While it is true that the field difference between the plates bends the beam, there is a component that needs to be referenced to the relative charge of the electrons at the point in time they pass the plates – in other words a DC bias on both plates relative to ground.
What I don't understand is why the 56x series uses BOTH deflection unblanking AND a DC coupled grid control. I have seen deflection blanking used when the grid is AC coupled to the intensity blanking / control, and DC biased directly from the cathode. In these cases, deflection blanking is needed for very long blanking intervals, as the time constant in an capacitor coupled system can only remain off for the time constant. But the 56x uses the more complicated DC system, which uses dedicated HV windings for both the cathode and grid bias, eliminating any time constants and the need for another blanking system.
So why did Tek design deflection based blanking into the 56x series, and why do the time bases use it, with the DC grid control only used for intensify in dual time bases?
- Steve

--- In TekScopes@..., "mattko87" <matt8@> wrote:

That ist right.
585, 581 are a epic technologiy.
high bandwith, distributed deflection and tunneldiode -base triggering

IMO, Tunnel diode trigging in the A models is a VERY IMPORTANT difference.

Not much of a fan of 4 division vertical as well. The 545 and 545A shared

The design is interesting for its day, but I don't find them too useful as

- Steve

13/07/2012 11:27

Is the astigmatism adjustment internal on these David? If I look
closely it almost appears to be trying to show two numerals / letters
at the same time, possibly the figure 1 (one)? As it's otherwise 100%
and new old stock I'd quite like to get this facet of its operation
fixed. Thanks.

--
Best Regards,
Chris Wilson.
mailto: chris@...



------------------------------------

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Hi Jay,
   Thanks for your suggestion but it didn't work. I am pretty sure power supply is the problem. Maybe something has to do with start up circuit, since power supply tries to start and then shuts off. One thing I noticed is that the voltage on the input bulk cap (470uF, 450V) is not stable and jumps ups and down(should have been stable DC). Maybe something has to do with power factor correction circuit. not sure need to do further investigation. Maybe something not working in the OV and OC protection circuit.


mickey