Date   

Re: 067-0912-00 needed

Eric
 

Dave,

The board is weird. My understanding of this is all this board does is allow you to check the lights “I know mine are ok” and it passes analog signals to the tube amplifiers so you can calibrate the analog portions of the scope with out any of the digital circuits being installed.

Eric

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Dave Casey
Sent: Thursday, October 22, 2020 4:48 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] 067-0912-00 needed

That schematic has some curious idiosyncrasies. The logic is powered by
+5VD, but all the pull ups being used are to +5V. (The ones that are
+shown,
anyway; there are unused inputs on U420 and U520 that must also be pulled high for the board to work, but these aren't indicated in the schematic.) Also, the inputs from the mode switches on A2 are referenced to +5V (not
+5VD). +5V and +5VD are basically two copies of the same supply, powered
from the same output of the switcher, and their domains cross in a few places within the scope without any real decoupling. That spirit continues in the 067-0912-00 board.

The parts list and schematic do not appear to line up 1:1 (C621 on the schematic is very probably C620 on the parts list, but R520 is in the parts list and so far escapes detection on the schematic.

Another interesting observation is that the _FPR ("Front Panel Read", active low) signal is left floating when using the 067-0912-00, meaning that A2U61 and A2U62 are not guaranteed to be tri-stated and could be fighting U430 and U530 of the 067-0912-00 for D0:D8. I'm sort of surprised there's no pull-up on the A2 board, but the schematic shows that signal being driven directly by the MPU board (which would be absent when using the 067-0912-00).

Enough mysteries for tonight...


Dave Casey


On Wed, Oct 21, 2020 at 1:12 PM Dave Daniel <kc0wjn@gmail.com> wrote:

A schematic for the -00 version of the board is in the datasheet link
on the TekWiki page to which Dennis pointed.

DaveD


On Oct 21, 2020, at 13:45, Dennis Tillman W7pF <dennis@ridesoft.com>
wrote:

Hi Eric,
I can't help with a schematic, but there is some information on this
card on TekWiki at
http://w140.com/tekwiki/wiki/067-0912-00
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Eric
Sent: Wednesday, October 21, 2020 8:55 AM
To: TekScopes@groups.io
Subject: [TekScopes] 067-0912-00 needed

I am thinking about trying to tackle a calibration on my 7854. I
have
confirmed that the digital and analog sections are out of adjustment.
The digital section is about .8 division left of center. In looking
through the calibration document It seems I have everything I need to
do the calibration except the 067-0912-00 the analog test board. How
likely is this something that I am going to be able to acquire it does
not look too complex from the schematic just a few IC’s and a data bus.







--
Dennis Tillman W7pF
TekScopes Moderator









Re: Is it possible to test 2465B power supply boards outside of the scope?

Grayson Evans
 

Thanks Chuck. I looked in the back of the maintenance manual among the flow charts and all I can find to test the regulator board is this note:
"All regulators (except +10) required some load to regulate, the lower voltage supplies require greater loads. The regulators between +15 and -15 [+5, -8, -5?] may be loaded using 100 ohm resistors of the proper power rating. "
This seems to leave out the 87V and 42V outputs.
Is this what you are referring to or did I miss info somewhere else in the manual?


Re: smd precision resistor "paint layer" peeled off while soldering *** advice needed ***

Rogerio O
 

I forgot to ask what is the temperature coefficient of these resistors?
In the parts list it is listed as TC=T9.
Thank you


Re: smd precision resistor "paint layer" peeled off while soldering *** advice needed ***

Chuck Harris <cfharris@...>
 

I would make both resistors the same... besides, you can't buy
just one SMD resistor.

-Chuck Harris

Rogerio O wrote:

Thank you all for the replies.
I am not sure of what to use as a replacement part.
I have ordered the KOA RN732ETTD1002B25 part from Mouser, which was the closest to the spec I could find.
Is it adequate? Any other better replacement?
Do I have to replace both R2012 and R2013 or just the one that has been compromised?
Roger






Re: smd precision resistor "paint layer" peeled off while soldering *** advice needed ***

Rogerio O
 

Thank you all for the replies.
I am not sure of what to use as a replacement part.
I have ordered the KOA RN732ETTD1002B25 part from Mouser, which was the closest to the spec I could find.
Is it adequate? Any other better replacement?
Do I have to replace both R2012 and R2013 or just the one that has been compromised?
Roger


Re: 067-0912-00 needed

Dave Casey
 

That schematic has some curious idiosyncrasies. The logic is powered by
+5VD, but all the pull ups being used are to +5V. (The ones that are shown,
anyway; there are unused inputs on U420 and U520 that must also be pulled
high for the board to work, but these aren't indicated in the schematic.)
Also, the inputs from the mode switches on A2 are referenced to +5V (not
+5VD). +5V and +5VD are basically two copies of the same supply, powered
from the same output of the switcher, and their domains cross in a few
places within the scope without any real decoupling. That spirit continues
in the 067-0912-00 board.

The parts list and schematic do not appear to line up 1:1 (C621 on the
schematic is very probably C620 on the parts list, but R520 is in the parts
list and so far escapes detection on the schematic.

Another interesting observation is that the _FPR ("Front Panel Read",
active low) signal is left floating when using the 067-0912-00, meaning
that A2U61 and A2U62 are not guaranteed to be tri-stated and could be
fighting U430 and U530 of the 067-0912-00 for D0:D8. I'm sort of surprised
there's no pull-up on the A2 board, but the schematic shows that signal
being driven directly by the MPU board (which would be absent when using
the 067-0912-00).

Enough mysteries for tonight...


Dave Casey

On Wed, Oct 21, 2020 at 1:12 PM Dave Daniel <kc0wjn@gmail.com> wrote:

A schematic for the -00 version of the board is in the datasheet link on
the TekWiki page to which Dennis pointed.

DaveD


On Oct 21, 2020, at 13:45, Dennis Tillman W7pF <dennis@ridesoft.com>
wrote:

Hi Eric,
I can't help with a schematic, but there is some information on this
card on TekWiki at
http://w140.com/tekwiki/wiki/067-0912-00
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Eric
Sent: Wednesday, October 21, 2020 8:55 AM
To: TekScopes@groups.io
Subject: [TekScopes] 067-0912-00 needed

I am thinking about trying to tackle a calibration on my 7854. I have
confirmed that the digital and analog sections are out of adjustment. The
digital section is about .8 division left of center. In looking through the
calibration document It seems I have everything I need to do the
calibration except the 067-0912-00 the analog test board. How likely is
this something that I am going to be able to acquire it does not look too
complex from the schematic just a few IC’s and a data bus.







--
Dennis Tillman W7pF
TekScopes Moderator









Re: Is it possible to test 2465B power supply boards outside of the scope?

Chuck Harris <cfharris@...>
 

I do that all the time. You would be committing a very
dangerous act if you were to work on the power supply while
it was installed in the scope.

To make the supply work, you need a dummy load. The manual
tells you the resister values necessary in the back where the
trouble shooting flow charts are..

-Chuck Harris

Grayson Evans wrote:

Wondering if anyone has been able to test the 2465B power supply boards (A1A2, A3) together, without reinstalling into the scope?
This would allow checking the supply voltages and ripple to at least make sure the mods/fixes worked.
I can't tell by looking at the schematic if the regulators require a load in order to work properly, or some circuit path needs to be connected.
The maintenance manual shows test points throughout the power supply schematic with waveforms, but I don't see how in the world to access these locations if the unit is installed in the scope.
Thanks,






Is it possible to test 2465B power supply boards outside of the scope?

Grayson Evans
 

Wondering if anyone has been able to test the 2465B power supply boards (A1A2, A3) together, without reinstalling into the scope?
This would allow checking the supply voltages and ripple to at least make sure the mods/fixes worked.
I can't tell by looking at the schematic if the regulators require a load in order to work properly, or some circuit path needs to be connected.
The maintenance manual shows test points throughout the power supply schematic with waveforms, but I don't see how in the world to access these locations if the unit is installed in the scope.
Thanks,


Re: smd precision resistor "paint layer" peeled off while soldering *** advice needed ***

Chuck Harris <cfharris@...>
 

Oh, I missed that it was the resistor's paint. They are toast,
and must be replaced. I thought he was talking about the solder
mask paint.

-Chuck Harris

Ed Breya via groups.io wrote:

If the over-coating on these SMDs has floated or burned off, then it's likely due to being undercut by the corrosive, leaked electrolyte. This stuff can travel considerable distance by capillary action on the surfaces. From your description of the resistors affected, they are fairly high precision, metal film types. The paint flaking off indicates the metal films have been compromised by the corrosion, so may be out of spec - they would tend to be higher in resistance due to missing some of the metal. Try to measure the values in-circuit, as accurately as possible, considering the associated circuitry.

If you get everything properly cleaned up and working again, you can measure the operating voltages in that section, and assess whether the resistors are still OK. If good, just leave them alone.

Ed






Re: smd precision resistor "paint layer" peeled off while soldering *** advice needed ***

Ed Breya
 

If the over-coating on these SMDs has floated or burned off, then it's likely due to being undercut by the corrosive, leaked electrolyte. This stuff can travel considerable distance by capillary action on the surfaces. From your description of the resistors affected, they are fairly high precision, metal film types. The paint flaking off indicates the metal films have been compromised by the corrosion, so may be out of spec - they would tend to be higher in resistance due to missing some of the metal. Try to measure the values in-circuit, as accurately as possible, considering the associated circuitry.

If you get everything properly cleaned up and working again, you can measure the operating voltages in that section, and assess whether the resistors are still OK. If good, just leave them alone.

Ed


Re: 7A26 edge distortion

 

On Wed, Oct 21, 2020 at 02:49 PM, Raymond Domp Frank wrote:


I temporarily put some small caps (3 - 10 pF) in parallel with one trimmer-cap
at a time and so far, I've found 5 (yes, five) that immediately made the pulse
steeper, without overdoing it, in both channels!
I'm afraid this is going to exhaust my donor supply...
The problem was indeed caused by defective trimcaps: I started by replacing 4 (four !) open trimcaps in Ch2, made preliminary adjustments and took another picture. See album.

I'd never have thought that practically (?) all trimcaps of the problem-type would be defective in the one unit but then again, it *is* a systemic problem.

Thanks to John and Roger for your help and suggestions!

Raymond


Re: Tek 4654M; No Trace, No +5V, No +95V; Help

adesilva_1999@...
 

I understand and I figured out what made me think otherwise. It is the generic picture of a multiplier they have on the semiconductor manual at the top of that page! Lesson learnt.


Re: 067-0912-00 needed

Clark Foley
 

Dennis,

Did you ever make duplicates of that early 7804N conversion board (K7-1286-XA)?

Clark


Re: 577D1 Phantom base current

Michael W. Lynch
 

DW,

My "ZERO Line trace" stays flat, right against the bottom of the CRT graticule. When testing a transistor with the steps set to 1, I see two lines, the first is that "zero line trace" at the very bottom of the CRT and when increasing the collector voltage this line always moves straight across from left to right, with no perceptible vertical deflection. The next line or trace would be the single trace that you would expect to get. As the collector voltage knob is increased, that trace moves left and up from the corner of the graticule, as one would expect. Of course, this is indicating increased voltage as well as the presence of current. The ZERO line is always present , representing the collector voltage knob position, regardless of the number of steps selected, except when the collector voltage knob is set to zero; when it becomes a single dot. Hope this answers your question.

--
Michael Lynch
Dardanelle, AR


Re: 577D1 Phantom base current

DW
 

Michael,

Thanks for the reply. From what you observed I am not getting the same results. The phenomenon I am experiencing seems to be an issue with improper biasing on the base terminal.

When you set the set the step generator to the single setting, do you notice when raising the collector voltage there appears to be current increase initially then levels off horizontally across the display. And when setting the step amplitude higher or lower this will affect how how much vertical deflection until the line goes horizontal again. Or does it just stay flat at 0. I hope this makes sense.


Re: 067-0912-00 needed

Dave Daniel
 

A schematic for the -00 version of the board is in the datasheet link on the TekWiki page to which Dennis pointed.

DaveD

On Oct 21, 2020, at 13:45, Dennis Tillman W7pF <dennis@ridesoft.com> wrote:

Hi Eric,
I can't help with a schematic, but there is some information on this card on TekWiki at
http://w140.com/tekwiki/wiki/067-0912-00
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Eric
Sent: Wednesday, October 21, 2020 8:55 AM
To: TekScopes@groups.io
Subject: [TekScopes] 067-0912-00 needed

I am thinking about trying to tackle a calibration on my 7854. I have confirmed that the digital and analog sections are out of adjustment. The digital section is about .8 division left of center. In looking through the calibration document It seems I have everything I need to do the calibration except the 067-0912-00 the analog test board. How likely is this something that I am going to be able to acquire it does not look too complex from the schematic just a few IC’s and a data bus.







--
Dennis Tillman W7pF
TekScopes Moderator





Re: 067-0912-00 needed

 

Hi Eric,
I can't help with a schematic, but there is some information on this card on TekWiki at
http://w140.com/tekwiki/wiki/067-0912-00
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Eric
Sent: Wednesday, October 21, 2020 8:55 AM
To: TekScopes@groups.io
Subject: [TekScopes] 067-0912-00 needed

I am thinking about trying to tackle a calibration on my 7854. I have confirmed that the digital and analog sections are out of adjustment. The digital section is about .8 division left of center. In looking through the calibration document It seems I have everything I need to do the calibration except the 067-0912-00 the analog test board. How likely is this something that I am going to be able to acquire it does not look too complex from the schematic just a few IC’s and a data bus.







--
Dennis Tillman W7pF
TekScopes Moderator


067-0912-00 needed

Eric
 

I am thinking about trying to tackle a calibration on my 7854. I have confirmed that the digital and analog sections are out of adjustment. The digital section is about .8 division left of center. In looking through the calibration document It seems I have everything I need to do the calibration except the 067-0912-00 the analog test board. How likely is this something that I am going to be able to acquire it does not look too complex from the schematic just a few IC’s and a data bus.


Re: Tek 4654M; No Trace, No +5V, No +95V; Help

Michael W. Lynch
 

On Tue, Oct 20, 2020 at 11:20 PM, <adesilva_1999@yahoo.com> wrote:


I wonder what made them use the same part number for two entirely different
things - one with the tripler and the rest of the HV circuitry and one that
has just the tripler!
They did not use the same part number for two different parts. The 455 and 465M both use the U550 designation in their schematics, both use the identical TEK part # 152-0635-00. 152-0635-00 is the "all in one" HV Multiplier along with other circuitry.

The 465(not "M)/465B/475 , on the other hand, use the 152-0552-01, which is the stand alone "6 stage" Multiplier, not usable in the 455/465M. This series of scopes has the other circuitry externally, on the main board. Much easier to fix, but less manufacturing friendly.

--
Michael Lynch
Dardanelle, AR


Re: smd precision resistor "paint layer" peeled off while soldering *** advice needed ***

Richard in Edenton NC
 

Thanks Chuck

73 Richard W4MCD

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