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2430A System DAC values changing when aquisition mode changes to FISO

 

Hi,
The symptoms are that the display goes crazy when changing from 100 microsecs timebase to 50 microsecs or above but only when acquiring.

Using Special/ Force DAC to correct the Centring values (CT11/21)brings back a reasonable display. I can see this working on the 4051 chips pin3
however trying to write these to store fails and the old value comes back when TBase is 100microsecs or greater.
I cold start most times I start the scope to have a known base. Lithium Battery is fine, amazing.

I first rebuilt the Low voltage Power supply with new caps. Then all the electrolytic caps on the main board A10.

I am tempted to think that D7 of the data bus is being pulled by the waveform processor bus. Any ideas

Rob ( this is my wifes ID)
 

My 2440 behaved in a similar way after I improperly did the CCD
calibration. Maybe one of those many trimmer potentiometers is bad or
drifted. You need a tunable signal source like an SG503 and lots of
patience to perform that part of the calibration procedure.

On Tue, 20 Nov 2012 16:30:19 -0000, "marjoriehookham"
<marjoriehookham@...> wrote:

Hi,
The symptoms are that the display goes crazy when changing from 100 microsecs timebase to 50 microsecs or above but only when acquiring.

Using Special/ Force DAC to correct the Centring values (CT11/21)brings back a reasonable display. I can see this working on the 4051 chips pin3
however trying to write these to store fails and the old value comes back when TBase is 100microsecs or greater.
I cold start most times I start the scope to have a known base. Lithium Battery is fine, amazing.

I first rebuilt the Low voltage Power supply with new caps. Then all the electrolytic caps on the main board A10.

I am tempted to think that D7 of the data bus is being pulled by the waveform processor bus. Any ideas

Rob ( this is my wifes ID)
 

David,
Thanks for the reply but the values of CT11/21 actually change when the mode changes from SISO to FISO and come back when moved back to SISO mode. This changes the CCD outputs and is correctable by the force DAC routine.
Still think it is CCD calibration ?
Rob

--- In TekScopes@..., David <davidwhess@...> wrote:

My 2440 behaved in a similar way after I improperly did the CCD
calibration. Maybe one of those many trimmer potentiometers is bad or
drifted. You need a tunable signal source like an SG503 and lots of
patience to perform that part of the calibration procedure.

On Tue, 20 Nov 2012 16:30:19 -0000, "marjoriehookham"
<marjoriehookham@...> wrote:

Hi,
The symptoms are that the display goes crazy when changing from 100 microsecs timebase to 50 microsecs or above but only when acquiring.

Using Special/ Force DAC to correct the Centring values (CT11/21)brings back a reasonable display. I can see this working on the 4051 chips pin3
however trying to write these to store fails and the old value comes back when TBase is 100microsecs or greater.
I cold start most times I start the scope to have a known base. Lithium Battery is fine, amazing.

I first rebuilt the Low voltage Power supply with new caps. Then all the electrolytic caps on the main board A10.

I am tempted to think that D7 of the data bus is being pulled by the waveform processor bus. Any ideas

Rob ( this is my wifes ID)
 

I think it could be. Like I said, my 2440 acted like you describe
when I miscalibrated the CCD although I did not investigate in detail
at the time because I already knew the problem came from me screwing
up the procedure. Part of the CCD calibration procedure includes
switching to faster and slower sample rates to verify that they still
work correctly.

There are two different CCD calibration procedures for the 2440 based
on serial number and I got them swapped because a critical section was
split between non-facing pages in the manual I printed. It does not
help that the "best" CCD calibration settings are somewhat ambiguous.

On Tue, 20 Nov 2012 18:10:55 -0000, "marjoriehookham"
<marjoriehookham@...> wrote:

David,
Thanks for the reply but the values of CT11/21 actually change when the mode changes from SISO to FISO and come back when moved back to SISO mode. This changes the CCD outputs and is correctable by the force DAC routine.
Still think it is CCD calibration ?
Rob

--- In TekScopes@..., David <davidwhess@...> wrote:

My 2440 behaved in a similar way after I improperly did the CCD
calibration. Maybe one of those many trimmer potentiometers is bad or
drifted. You need a tunable signal source like an SG503 and lots of
patience to perform that part of the calibration procedure.

On Tue, 20 Nov 2012 16:30:19 -0000, "marjoriehookham"
<marjoriehookham@...> wrote:

Hi,
The symptoms are that the display goes crazy when changing from 100 microsecs timebase to 50 microsecs or above but only when acquiring.

Using Special/ Force DAC to correct the Centring values (CT11/21)brings back a reasonable display. I can see this working on the 4051 chips pin3
however trying to write these to store fails and the old value comes back when TBase is 100microsecs or greater.
I cold start most times I start the scope to have a known base. Lithium Battery is fine, amazing.

I first rebuilt the Low voltage Power supply with new caps. Then all the electrolytic caps on the main board A10.

I am tempted to think that D7 of the data bus is being pulled by the waveform processor bus. Any ideas

Rob ( this is my wifes ID)
 

David,
Have fixed this problem . It was a cracked tracked on the Calibrator amplifier hybrid ?U610. I found it using hair dyer/freezer spray. The Calibration coefficients are set by the processor every time the autosetup is run and ?timebase or change gain switches are changed . Carefully observing the outputs of U610 shows loading similar to Attribute clock changes when front panel switches are changed.The input to U610 does not change.
The symptoms are then that the scope is stable until you change any setting. You could get any waveform from triangles to alternating dc offsets to just random. I could not find anything about dynamic calibration in the manual but I expect it will be true of most 2400 scopes.
CCD calibration is now possible and stable.
Rob

From: David
To: TekScopes@...
Sent: Tuesday, November 20, 2012 5:46 PM
Subject: Re: [TekScopes] 2430A System DAC values changing when aquisition mode changes to FISO

?
My 2440 behaved in a similar way after I improperly did the CCD
calibration. Maybe one of those many trimmer potentiometers is bad or
drifted. You need a tunable signal source like an SG503 and lots of
patience to perform that part of the calibration procedure.

On Tue, 20 Nov 2012 16:30:19 -0000, "marjoriehookham"
<marjoriehookham@...> wrote:

>Hi,
>The symptoms are that the display goes crazy when changing from 100 microsecs timebase to 50 microsecs or above but only when acquiring.
>
>Using Special/ Force DAC to correct the Centring values (CT11/21)brings back a reasonable display. I can see this working on the 4051 chips pin3
>however trying to write these to store fails and the old value comes back when TBase is 100microsecs or greater.
>I cold start most times I start the scope to have a known base. Lithium Battery is fine, amazing.
>
>I first rebuilt the Low voltage Power supply with new caps. Then all the electrolytic caps on the main board A10.
>
>I am tempted to think that D7 of the data bus is being pulled by the waveform processor bus. Any ideas
>
>Rob ( this is my wifes ID)
>
 

How did you repair the problem with U610? Did you replace it?

The 2440 CCD calibration has a procedure listed on page 5-13 of the
service manual which mentions the dynamic calibration I was thinking
of:

NOTE: Pushing A HORIZONTAL MODE causes the instrument to make firmware
corrections based on the new adjustment just made for the L clock.
These corrections may change the alignment slightly; in subparts j-n
[actually at least subparts j-q], repeatedly alternate between making
the adjustment and pushing A MODE until no change is noted when the
button is pushed.

On Wed, 26 Dec 2012 04:00:52 -0800 (PST), Marjorie Hookham
<marjoriehookham@...> wrote:

David,
Have fixed this problem . It was a cracked tracked on the Calibrator amplifier hybrid ?U610. I found it using hair dyer/freezer spray. The Calibration coefficients are set by the processor every time the autosetup is run and ?timebase or change gain switches are changed . Carefully observing the outputs of U610 shows loading similar to Attribute clock changes when front panel switches are changed.The input to U610 does not change.
The symptoms are then that the scope is stable until you change any setting. You could get any waveform from triangles to alternating dc offsets to just random. I could not find anything about dynamic calibration in the manual but I expect it will be true of most 2400 scopes.
CCD calibration is now possible and stable.
Rob

________________________________
From: David <davidwhess@...>
To: TekScopes@...
Sent: Tuesday, November 20, 2012 5:46 PM
Subject: Re: [TekScopes] 2430A System DAC values changing when aquisition mode changes to FISO
?
My 2440 behaved in a similar way after I improperly did the CCD
calibration. Maybe one of those many trimmer potentiometers is bad or
drifted. You need a tunable signal source like an SG503 and lots of
patience to perform that part of the calibration procedure.

On Tue, 20 Nov 2012 16:30:19 -0000, "marjoriehookham"
<marjoriehookham@...> wrote:

Hi,
The symptoms are that the display goes crazy when changing from 100 microsecs timebase to 50 microsecs or above but only when acquiring.

Using Special/ Force DAC to correct the Centring values (CT11/21)brings back a reasonable display. I can see this working on the 4051 chips pin3
however trying to write these to store fails and the old value comes back when TBase is 100microsecs or greater.
I cold start most times I start the scope to have a known base. Lithium Battery is fine, amazing.

I first rebuilt the Low voltage Power supply with new caps. Then all the electrolytic caps on the main board A10.

I am tempted to think that D7 of the data bus is being pulled by the waveform processor bus. Any ideas

Rob ( this is my wifes ID)
 

David,
I bought a new ceramic hybrid U610 from Qservice in Greece.
I found the very small (but massive impact for debugging) mention of dynamic calibration today in the 2430 service manual The Military 2430A manual has it in 6.2.
Great fun
Rob

--- In TekScopes@..., David wrote:

How did you repair the problem with U610? Did you replace it?

The 2440 CCD calibration has a procedure listed on page 5-13 of the
service manual which mentions the dynamic calibration I was thinking
of:

NOTE: Pushing A HORIZONTAL MODE causes the instrument to make firmware
corrections based on the new adjustment just made for the L clock.
These corrections may change the alignment slightly; in subparts j-n
[actually at least subparts j-q], repeatedly alternate between making
the adjustment and pushing A MODE until no change is noted when the
button is pushed.

On Wed, 26 Dec 2012 04:00:52 -0800 (PST), Marjorie Hookham
wrote:

David,
Have fixed this problem . It was a cracked tracked on the Calibrator amplifier hybrid ?U610. I found it using hair dyer/freezer spray. The Calibration coefficients are set by the processor every time the autosetup is run and ?timebase or change gain switches are changed . Carefully observing the outputs of U610 shows loading similar to Attribute clock changes when front panel switches are changed.The input to U610 does not change.
The symptoms are then that the scope is stable until you change any setting. You could get any waveform from triangles to alternating dc offsets to just random. I could not find anything about dynamic calibration in the manual but I expect it will be true of most 2400 scopes.
CCD calibration is now possible and stable.
Rob

________________________________
From: David
To: TekScopes@...
Sent: Tuesday, November 20, 2012 5:46 PM
Subject: Re: [TekScopes] 2430A System DAC values changing when aquisition mode changes to FISO
?
My 2440 behaved in a similar way after I improperly did the CCD
calibration. Maybe one of those many trimmer potentiometers is bad or
drifted. You need a tunable signal source like an SG503 and lots of
patience to perform that part of the calibration procedure.

On Tue, 20 Nov 2012 16:30:19 -0000, "marjoriehookham"
wrote:

Hi,
The symptoms are that the display goes crazy when changing from 100 microsecs timebase to 50 microsecs or above but only when acquiring.

Using Special/ Force DAC to correct the Centring values (CT11/21)brings back a reasonable display. I can see this working on the 4051 chips pin3
however trying to write these to store fails and the old value comes back when TBase is 100microsecs or greater.
I cold start most times I start the scope to have a known base. Lithium Battery is fine, amazing.

I first rebuilt the Low voltage Power supply with new caps. Then all the electrolytic caps on the main board A10.

I am tempted to think that D7 of the data bus is being pulled by the waveform processor bus. Any ideas

Rob ( this is my wifes ID)

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