Date   
Re: 2465A Repair Question

Chuck Harris
 

Hi Matthew,

The Feedback signal from U1371C leaves the one circuit board, and
passes through the "stab" connectors to the other circuit board.

At that point, it simply goes to the LED in the Opto Isolator U1040.

Measure the voltage at the Opto Isolator's pin 1, and it should be
about 2V... maybe a little more, maybe a little less.

Measure it at The 4.3K that connects to the stab connector and it
should be the same voltage as you measured on the opto's pin 1.

If the stab connector is missing from your re-cap, all sorts of
funny stuff will happen.

Opto isolators do go bad... not very often, but it can happen.

-Chuck Harris

Matthew Wilson wrote:

First of all, thank you for your expertise and help! As I mentioned, I've done a lot of work on tube gear but nothing in the solid state world this complex so I very much appreciate your patience and guidance!

I replaced the non-polarized electrolytic 1µf 50v caps that were in the unit with new 1µf WIMA film caps rated to 63v. So no - there were no WIMA caps in there to begin with. Sorry for the confusion on that.

I will leave the tantalum cap in there.

I will read the section on making the dummy load carefully and proceed with checking U1040. The diagnostic tree at this point simply says "Repair path through U1371C and U1040" so I will do this.



Re: 2465 DVS Repair - was; Re: [TekScopes] Wanted; Person to repair Tektronix 2465 DVS

jhalbrecht
 

Howdy Tektronix enthusiasts,

I'd like to publicly than Chuck Harris for all the help he has given me in my attempt to repair my Tektronix 2465 DVS Oscilloscope. Although I haven't finished the repair Chuck's instructions were clear and concise. I've moved on to other projects without finishing the 2465 but I value what I've learned in the process.

Chuck; Thank you so much for your time, patience, knowledge and sharing.

   - Jeff

On 9/15/2019 12:47 PM, Chuck Harris wrote:
It should be exactly 0.8Vp-p, with no offset. See the waveform
picture in the manual.

The scope's power on test routing attempts to measure the peaks
of that sine'ish waveform as a verification of the trigger and DAC
circuitry. Your scope is failing this test.

The first digit of the error code can be 0, 2, or 4.

4 means that the positive peak of the sinewave is too positive.

The second digit of the error code can be 0, 1, 2, or 4.

2 means that the negative peak is not negative enough.

That means, your sinewave appears to the controller as being
shifted up in the positive direction.

That is what you want to look for. Since the test signal goes
directly to the trigger chip, and if carefully measured will probably
be just right, the problem has to be that the trigger hybrid's
threshold is not being set correctly.

If your other knobs work ok when you press A/B and dismiss the error
message, the DAC has to be ok.

That leaves a bad MUX, or an opamp with a stuck output. I don't recall
which way a bad capacitor in the Sample gate goes, but you should be
able to see any of these errors, as they will stay stuck all of the
time.

-Chuck Harris

jhalbrecht wrote:
Assuming TP46 is the PCB edge side of R567 It has about 1VAC 60hz maybe a 20 ms dc
offset. It doesn't change as I exit the error message or _fiddle_ with the triggering
adjustments.

- Jeff

On 9/15/2019 6:39 AM, Chuck Harris wrote:
The power inside of the 2465 supplies is pretty dirty from
an RF point of view. It is pretty quiet from a 2x60Hz point
of view.

How can you tell the difference?

The RF noise is composed of sliver thin spikes that ride on
the top and bottom of the supply's DC waveform. They look like
a fuzzy caterpillar.

The 2x60Hz ripple will stand still when the scope is triggered
using the line mode.

Tek recommends you use the scope in bandwidth limit mode for
making these measurements.

The other failure that can happen to cause the Test05 Fail XX
failures is in the MUX and Sample and hold gates that the A5
board uses to feed the threshold signals to the trigger hybrid.

Typically one of three things happens (In approximately the
order of likelihood):

The MUX has an output that gets stuck high, or low (the message
gives a clue), or,

The sample and hold op amp gets stuck high or low, or,
The sample and hold capacitor gets leaky.

Trace back the TLA and TLB signals from the trigger hybrid to
the two sample and hold OPAMPS, and from there to the MUX.

And, it is conceivable that the AC Line signal that is supposed
to go from the power supply to the CHN5 input to the trigger hybrid
could be missing, or stuck... TP46 is your friend.

-Chuck Harris


jhalbrecht wrote:
O.K. tried without success to improve the ripple signal on the DC test points. I
don't have a dedicated ground on the Rigol nor on an old 15mhz B&K I aoso tried. I
tried with the banana clip between the 2464 ground jack and the ground of the test
signal on the rigol and on the outside of a BNC connector on CH2 of the Rigol. I
tried it like that with and without the addition of the probe ground too. Nothing got
me near to what I thought ripple might look like.

Is there any change the DC is that dirty?

I also tried swapping out the U300 trigger hybrid from the 2445 switch and knob
donor. Nope, same error Test 05 Fail 42

- Jeff


On 9/14/2019 4:59 AM, Chuck Harris wrote:
That won't do it!

You must connect a big fat banana plug terminated cable in the
2465's ground jack (near the calibrator) to the equivalent ground
on the front panel of the scope that is measuring the ripple.

Anything less will allow the ground loop current to pass through
the probe's shield, and the current through the probe's shield will
generate tens of millivolts (I2R) of unnecessary ground loop noise
in your signal.

We are dealing with a maximum of a few mv of signal here.

Strap the two scopes' grounds together!

-Chuck Harris


jhalbrecht wrote:
:-) yup. Connected the short ground clip from my probe to the solder ground lug on
the chassis / bnc of ch 1. Also set 20mhz bw filter too.

- Jeff


On 9/13/2019 9:11 PM, Chuck Harris wrote:
While doing the ripple measurement, you must connect the
grounds between the 2465 and the testing scope.

-Chuck Harris

jhalbrecht wrote:
Before trying the hybrid swap I got a bit more familiar with my 2465 by
testing the
voltages on J119 and comparing to table 5-1 in the adjustment procedure.

I used a Keithley 2000 Multimeter and a Rigol DS1054z oscilloscope with the extra
options enabled.

The measurements looked solid and stable well withing the published tolerances.

However I'm not confident on my procedures for measuring ripple. It seemed more
like
stray noise basically at 120Hz I tried with the Keithley on AC and the Rigol
with AC
coupling. All the ripple appeared well below 100mv but for instance on pin 6, 12
and
5 that exceeds the 15mv spec as well as the 10mv spec for pin 1.

Before actually physically swapping the trigger hybrid are there any other test
suggestions to try first?


- Jeff

On 9/12/2019 11:11 AM, Chuck Harris wrote:
Hi Jeff,

Usually, when I see Test05, Fail XX, and it isn't the A5 board
of a late model 2465B, it is due to a bad trigger hybrid. Try
removing one from one of your 2445's, and put it into your DVS.
I would bet it will fix the problem.

Note: Seat the chip by hand, making sure it goes all the way
to the PCB. Then while holding it, put nuts on diagonal corners,
and snug them finger tight. Then put on the other two nuts.

Tightness doesn't improve the contacts, it just breaks the board
and studs. No more than 1/8T beyond contact. Just enough to
make the lock washer grab, no more.

Do measure the power supply's voltages and ripple. Don't tweak
any adjustments, unless you want to do a complete recalibration.

The capacitors are almost certainly dead by now... especially
if the fan is stopped, or sluggish from lack of lubrication.

-Chuck Harris

jhalbrecht wrote:
I got the paddle switch out of the donor without incident.

Chuck and group,

Perhaps I could check some voltages on the 2465 dvs (original / first model) A5
board
next in an attempt to solve the "Test 05 Fail 42' triggering problem before
digging
into replacing the paddle switch into the 2465 switch board assembly.

- Jeff



Re: 2465A Repair Question

Matthew Wilson
 

First of all, thank you for your expertise and help! As I mentioned, I've done a lot of work on tube gear but nothing in the solid state world this complex so I very much appreciate your patience and guidance!

I replaced the non-polarized electrolytic 1µf 50v caps that were in the unit with new 1µf WIMA film caps rated to 63v. So no - there were no WIMA caps in there to begin with. Sorry for the confusion on that.

I will leave the tantalum cap in there.

I will read the section on making the dummy load carefully and proceed with checking U1040. The diagnostic tree at this point simply says "Repair path through U1371C and U1040" so I will do this.

Re: 2465A Repair Question

Chuck Harris
 

No, it doesn't mean U1371 is bad. It means that the
power supply output is low, and the feedback loop which
uses U1371 as its comparison element is trying as hard as
it can, but still can't force the supply up to 5V.

Look down the line to U104o. It could be a bad connection,
it could be a bad opto, or it could be something wrong on
the Line side of the opto. Follow the diagnostics tree.

Do not replace any tantalum capacitors in the 2465A. Every
tantalum in this scope is conservatively rated, and needs
to be a tantalum capacitor.

There are no WIMA film capacitors of that value in the
power supply. If there were in yours, someone already
replaced the NP electrolytic capacitors.... or you have a
power supply unlike any I have ever seen, and I have seen
a lot of 2465 supplies.

You have to understand the electronic parts you are measuring
for the measurements to be useful.

An opamp can be thought of as being a differential amplifier
with essentially infinite gain. That means that the difference
between the "+" amd the "-" inputs is multiplied by essentially
infinity to make the output voltage. And, the output voltage
cannot go higher than the power supply rails no matter what
the input. So, if you can measure *any* difference between
the "+" and "-" input, the output should be as close as it
can get to the appropriate power supply rail.

You have to make a dummy load for the power supply, and work
on the supply outside of the scope. It is the only safe way.
In your poking and prodding, if your probe slips, you can burn
out your scope with a high voltage surge.

-Chuck Harris



Matthew Wilson wrote:

I tested the input voltages on U1371C:
Pin 9 = 4.23v
Pin 10 = 4.98v
As you can see, there definitely is more than 0v difference.

I also measured one of the other amps on that chip and also found a difference in input voltages:
Pin 12 = 2.502v
Pin 13 = 2.464v

This is testing voltage measured on pins with pos lead and with neg lead on chassis (ground).

The 1µf caps that I replaced were WIMA film caps - so non-polarized, yes. I did not replace C1034 - the 4.7 µf tantalum cap, as I forgot to order that one.

Does this then mean that U1371 is bad? Is there any other test I can run that might confirm this before I look into replacing it?

Or should I continue troubleshooting and follow to U1040? Accessing pins on that board will be very tricky.

Re: 2465A Repair Question

Matthew Wilson
 

I tested the input voltages on U1371C:
Pin 9 = 4.23v
Pin 10 = 4.98v
As you can see, there definitely is more than 0v difference.

I also measured one of the other amps on that chip and also found a difference in input voltages:
Pin 12 = 2.502v
Pin 13 = 2.464v

This is testing voltage measured on pins with pos lead and with neg lead on chassis (ground).

The 1µf caps that I replaced were WIMA film caps - so non-polarized, yes. I did not replace C1034 - the 4.7 µf tantalum cap, as I forgot to order that one.

Does this then mean that U1371 is bad? Is there any other test I can run that might confirm this before I look into replacing it?

Or should I continue troubleshooting and follow to U1040? Accessing pins on that board will be very tricky.

Re: 2465A Repair Question

Chuck Harris
 

I mistyped, 5.87V should be 4.87V.

-Chuck

Chuck Harris wrote:

When dealing with opamps that have negative feedback,
there should be exactly 0V between the + and -
inputs. If the voltage difference is even 1mV in
either direction, the output of the opamp will be
hard stuck at the appropriate power supply rail.

(opamps have open loop gains that are effectively
infinite.)

If you find the voltage between the + and - inputs
is truly zero, and the output is stuck at the rails,
the opamp is bad.

And, yes, they do go bad.

Looking at your circuit, the opamp is driving the
control for the inverter output, and the direction
of that stuck at the rails output shows that the
non-inverting input is higher than the inverting
input (eg. output is at positive rail), so that
means the measured 5V is lower than the reference
5V going into the "+" input. Which is exactly
what you should expect given that the 5V supply is
at 5.87V. <<<<<< 4.87V!

Follow the diagnostic routine's directions, and
follow the signal from the output of U1371C to the
Opto-isolator U1040.

Be careful! The transistor side of U1040 is on
the mains side of the power supply. You must not
ground anything on that side!

One thing, when you replaced the electrolytics, did
you use non polar electrolytics for the few 4.7uf
and 1uf NP electrolytics? It matters.

-Chuck Harris

Matthew Wilson wrote:
I am working through the diagnostic section and am on the "Regulator Troubleshooting Procedure" 12 and 13. I've got the boards back inside the unit all hooked up and am able to test voltages on the A2A1 board just fine.

My +10v reference is working fine, but the +5v at pin 1 of P232 only measures 4.25v. Varying R1292 does not vary this voltage reading at all.

Procedure advises "Repair path through U1371C and U1040"

First I went to U1371C and measured Pin 8 and 10.

Pin Spec Measured
8 +4.4v +12.27v
10 +5v +4.87v

The weird thing is that when I measure the voltage at R1284, which is directly connected to pin 10 of the U1371C, I see exactly 5v. Somehow by the time it gets to pin 10, we lose 0.13v?

How common is it to have U1371 go bad? From the parts list, this is an LM324J quad op amp.






Re: 465B fan question

Chuck Harris
 

The reason for non detergent oil recommendations is not really
important, but is as follows:

Detergents are added to keep dirt and wear products in suspension
so that in a pressure feed filtered oil lubrication system the
filter can remove them from the oil.

Applications without filters will circulate those products, and
that can, in theory, cause additional wear.

In practice, the wear products that detergent can suspend are much
smaller than the lubricating film thickness that floats the shaft
over the bearing... and they are for the most part much smaller
than the minimum particle size the oil filter can remove.

That is why your highly filtered engine drain oil is black.

For our purposes either type of oil works just fine.

-Chuck Harris

GerryR wrote:

They make special motor spindle oils like "Mobile Velocite No.10 Mineral Base Oil," which is used all the time in industrial environments for high-speed spindles and motors. It is a 5W non-detergent oil. You can get it at places like McMaster-Carr Supply, Granger, etc. They have other weights, but I find this to be good for most applications. I can't recall off-hand, but there is a reason they don't recommend a detergent type oil, like automotive oils, for motor spindles. If I remember, I'll post the reason. I also know from first-hand experience, that the synthetic automotive oils react with some stainless steels in negative fashion; I had the unfortunate experience to find that out when working on some SS pistol slides and frames, not that it is an issue in this case.

GerryR

Re: 2465A Repair Question

Chuck Harris
 

When dealing with opamps that have negative feedback,
there should be exactly 0V between the + and -
inputs. If the voltage difference is even 1mV in
either direction, the output of the opamp will be
hard stuck at the appropriate power supply rail.

(opamps have open loop gains that are effectively
infinite.)

If you find the voltage between the + and - inputs
is truly zero, and the output is stuck at the rails,
the opamp is bad.

And, yes, they do go bad.

Looking at your circuit, the opamp is driving the
control for the inverter output, and the direction
of that stuck at the rails output shows that the
non-inverting input is higher than the inverting
input (eg. output is at positive rail), so that
means the measured 5V is lower than the reference
5V going into the "+" input. Which is exactly
what you should expect given that the 5V supply is
at 5.87V.

Follow the diagnostic routine's directions, and
follow the signal from the output of U1371C to the
Opto-isolator U1040.

Be careful! The transistor side of U1040 is on
the mains side of the power supply. You must not
ground anything on that side!

One thing, when you replaced the electrolytics, did
you use non polar electrolytics for the few 4.7uf
and 1uf NP electrolytics? It matters.

-Chuck Harris

Matthew Wilson wrote:

I am working through the diagnostic section and am on the "Regulator Troubleshooting Procedure" 12 and 13. I've got the boards back inside the unit all hooked up and am able to test voltages on the A2A1 board just fine.

My +10v reference is working fine, but the +5v at pin 1 of P232 only measures 4.25v. Varying R1292 does not vary this voltage reading at all.

Procedure advises "Repair path through U1371C and U1040"

First I went to U1371C and measured Pin 8 and 10.

Pin Spec Measured
8 +4.4v +12.27v
10 +5v +4.87v

The weird thing is that when I measure the voltage at R1284, which is directly connected to pin 10 of the U1371C, I see exactly 5v. Somehow by the time it gets to pin 10, we lose 0.13v?

How common is it to have U1371 go bad? From the parts list, this is an LM324J quad op amp.




Re: 465B fan question

GerryR
 

They make special motor spindle oils like "Mobile Velocite No.10 Mineral Base Oil," which is used all the time in industrial environments for high-speed spindles and motors. It is a 5W non-detergent oil. You can get it at places like McMaster-Carr Supply, Granger, etc. They have other weights, but I find this to be good for most applications. I can't recall off-hand, but there is a reason they don't recommend a detergent type oil, like automotive oils, for motor spindles. If I remember, I'll post the reason. I also know from first-hand experience, that the synthetic automotive oils react with some stainless steels in negative fashion; I had the unfortunate experience to find that out when working on some SS pistol slides and frames, not that it is an issue in this case.

GerryR

----- Original Message -----
From: "Robert Simpson via Groups.Io" <go_boating_fast=yahoo.com@groups.io>
To: <TekScopes@groups.io>
Sent: Sunday, October 13, 2019 12:26 AM
Subject: Re: [TekScopes] 465B fan question


The Mobil 1 5W30 sounds good.
Also, I ordered replacement parts which are scheduled to arrive later next week. It will be interesting to see how adding back in the thermistor makes in fan startup.
Bob

Re: 465B fan question

Robert Simpson
 

The Mobil 1 5W30 sounds good.
Also, I ordered replacement parts which are scheduled to arrive later next week. It will be interesting to see how adding back in the thermistor makes in fan startup.
Bob

Re: 2465A Repair Question

Matthew Wilson
 

I am working through the diagnostic section and am on the "Regulator Troubleshooting Procedure" 12 and 13. I've got the boards back inside the unit all hooked up and am able to test voltages on the A2A1 board just fine.

My +10v reference is working fine, but the +5v at pin 1 of P232 only measures 4.25v. Varying R1292 does not vary this voltage reading at all.

Procedure advises "Repair path through U1371C and U1040"

First I went to U1371C and measured Pin 8 and 10.

Pin Spec Measured
8 +4.4v +12.27v
10 +5v +4.87v

The weird thing is that when I measure the voltage at R1284, which is directly connected to pin 10 of the U1371C, I see exactly 5v. Somehow by the time it gets to pin 10, we lose 0.13v?

How common is it to have U1371 go bad? From the parts list, this is an LM324J quad op amp.

Re: 465B fan question

Chuck Harris
 

Nye makes very nice lubricants, not oils, but actually
liquid greases. They are designed for extremely slow
motion with high pressures... like are in watches,
clocks, and some instruments. Not so much electric
motors. The viscosity of a watch or clock oil/grease
is very much higher than a small motor needs.

I would think a good motor oil would be drastically
cheaper, and better for the high speed application.

-Chuck Harris

Ken Eckert wrote:

I have used a lubricant by Nye Lubricants. It was a watchmakers lubricant.
Nye is still in business

On Saturday, October 12, 2019, Chuck Harris <cfharris@...> wrote:

Hi Robert,

There are quite a few different varieties of silicone oil,
but one thing they all seem to have in common is they like
to creep. This time next year, you will probably find the
oil has coated the entire front and back ends of the motor,
and the circuit board. Not a big problem, except that it
attracts dust, and won't be in the bearing anymore.

Watchmakers had this problem with some of synthetic oils
that were used in lubricating watches. They had to dip the
various parts in steric acid to give them a coating that
would stop the oil's migration.

As an example, I have to keep my silicone oil based heatsink
compound in a double plastic zip lock bag. It is in a screw
top jar, but the oil creeps past the cardboard seal in the lid,
over the threads, and leaves oil rings on whatever surface
the jar is sitting upon. I don't like that in an oil.

Synthetic petroleum based oils last virtually forever, and
stay put in the bearing much better than silicone oils.

-Chuck Harris

Robert Simpson via Groups.Io wrote:
Chuck, yes Silicone Oil. Late evening typing has its risks. As to why
that product, years ago I wanted to fix some sleeve bearing house fans.
After some research, tried Silicone oil which has worked fine, and is
working at the moment in this fan motor. Is there some long term reason
that might be a problem?

Also, oh no, RT8038 is missing! I didn't remove it, somebody must have
tried something. Looks like another part to order. Kind of good news in a
way as the motor seems to be OK. Amazing its works at all.
Bob







Re: 465B fan question

Chuck Harris
 

I tend to use a couple of lubricants for this purpose.
Either Mobil 1, 5W30, or a turbine lube made by MARS,
which stands for "Motors and Armatures, Inc."
Mars 93240, in the "Zoom Spout" container.

I can't tell any difference in performance between
the two.

-Chuck Harris

Robert Simpson via Groups.Io wrote:

Chuck,
What oil do you recommend? I would like to try some.
Bob



Re: 465B fan question

Ken Eckert
 

I have used a lubricant by Nye Lubricants. It was a watchmakers lubricant.
Nye is still in business

On Saturday, October 12, 2019, Chuck Harris <cfharris@...> wrote:

Hi Robert,

There are quite a few different varieties of silicone oil,
but one thing they all seem to have in common is they like
to creep. This time next year, you will probably find the
oil has coated the entire front and back ends of the motor,
and the circuit board. Not a big problem, except that it
attracts dust, and won't be in the bearing anymore.

Watchmakers had this problem with some of synthetic oils
that were used in lubricating watches. They had to dip the
various parts in steric acid to give them a coating that
would stop the oil's migration.

As an example, I have to keep my silicone oil based heatsink
compound in a double plastic zip lock bag. It is in a screw
top jar, but the oil creeps past the cardboard seal in the lid,
over the threads, and leaves oil rings on whatever surface
the jar is sitting upon. I don't like that in an oil.

Synthetic petroleum based oils last virtually forever, and
stay put in the bearing much better than silicone oils.

-Chuck Harris

Robert Simpson via Groups.Io wrote:
Chuck, yes Silicone Oil. Late evening typing has its risks. As to why
that product, years ago I wanted to fix some sleeve bearing house fans.
After some research, tried Silicone oil which has worked fine, and is
working at the moment in this fan motor. Is there some long term reason
that might be a problem?

Also, oh no, RT8038 is missing! I didn't remove it, somebody must have
tried something. Looks like another part to order. Kind of good news in a
way as the motor seems to be OK. Amazing its works at all.
Bob





Re: 2445 display problems

Jan Kolek
 

Pete,

Do you have any display on the CRT? If so, what? If not, maybe that's where you need to start troubleshooting.

As I read the 2445 service manual (and as I observe my own 2445 operation), under normal operation you should see a swept trace (or traces) for input signals, plus characters at the bottom of the screen indicating vertical gain setting and sweep time, as well as cursors (lines) and characters at the top of the screen if you have the delta-V and/or delta-T measurements enabled. If not normal, you should be seeing characters at screen bottom generated by the built-in self test indicating clues as to the source of a problem.

Regards,

Jan Kolek

Jan Kolek

Re: 465B fan question

Robert Simpson
 

Re: 465B fan question

Robert Simpson
 

Chuck,
What oil do you recommend? I would like to try some.
Bob

Re: 465B fan question

Chuck Harris
 

Hi Robert,

There are quite a few different varieties of silicone oil,
but one thing they all seem to have in common is they like
to creep. This time next year, you will probably find the
oil has coated the entire front and back ends of the motor,
and the circuit board. Not a big problem, except that it
attracts dust, and won't be in the bearing anymore.

Watchmakers had this problem with some of synthetic oils
that were used in lubricating watches. They had to dip the
various parts in steric acid to give them a coating that
would stop the oil's migration.

As an example, I have to keep my silicone oil based heatsink
compound in a double plastic zip lock bag. It is in a screw
top jar, but the oil creeps past the cardboard seal in the lid,
over the threads, and leaves oil rings on whatever surface
the jar is sitting upon. I don't like that in an oil.

Synthetic petroleum based oils last virtually forever, and
stay put in the bearing much better than silicone oils.

-Chuck Harris

Robert Simpson via Groups.Io wrote:

Chuck, yes Silicone Oil. Late evening typing has its risks. As to why that product, years ago I wanted to fix some sleeve bearing house fans. After some research, tried Silicone oil which has worked fine, and is working at the moment in this fan motor. Is there some long term reason that might be a problem?

Also, oh no, RT8038 is missing! I didn't remove it, somebody must have tried something. Looks like another part to order. Kind of good news in a way as the motor seems to be OK. Amazing its works at all.
Bob



Re: 465B fan question

Robert Simpson
 

A careful check shows only the other resisters. Does anyone know the operating parameter of this part (1D1618, tek 307-124-00) ?

0542-99 level sine generator questions

bill K7WXW
 

I started working on this signal generator today. It is in pretty good shape and has a number of changes from the schematics I have and the documentation available is pretty limited. I found the schematics and factory cal manual but the latter is missing p. 5. I am wondering if anyone here has the complete calibration document and would be wiling to share it?

And... if anyone here has worked on one of these units, I have a couple of questions. For example, what are the 10V and 3V adjustments referenced to?

Thanks,
Bill