Date   
Re: HV Probe and DMM Input Impedance

Robert Putala KE8UW
 

The answer to your question can be found in the attached pdf. Boat Anchors
Manual Archive has a manual for one model of EICO HV probe, and it shows
that different models have different resistor values for use with various
meters.

On Mon, Oct 28, 2019 at 9:36 AM n4buq <n4buq@...> wrote:

This last weekend, I found an EICO HV probe in very nice condition at an
estate sale. Opening it up, it contiains a 1.09G ohm resistor in series
with the tip and cable. I connected it to the input of my Fluke 27 DMM and
measured a low voltage source (all I had handy at that moment). From what
I could tell, the probe gives me a 100x scale factor (e.g 10VDC measured
0.1VDC). While I may need to measure some higher voltages to confirm
whether this is really accurate, it appears to be at least somewhat
accurate.

I have a question, though, regarding the theory of the way this works.
The Fluke has a 10M ohm input resistance which, if I'm thinking about this
correctly, makes the measuring circuit 1100M ohms of which 10M ohm is the
meter and the remaining resistance in the voltage divider network is the
probe's resistor; however, I'm having trouble with the math.

Intuitively, (for me, at least), to obtain a 1/100 divider, I would think
that ideally the probe resistance should be 0.990M ohms with the meter
providing the remainin 10M ohms. But I find it odd that the resistor has
that odd value which makes it seem like it was almost intended to work with
a 10M device.

If I'm not mistaken, those probes were intended to be used with a
particular device (meter) that provided the proper readings but not sure
about that either (not finding a lot of info on this probe).

Am I off base here? I know that some of the HV probes designed to work
with the Fluke are designed to connect differently and I think the meter is
used in mA mode with them but not sure about that.

Is it a false expectation that the meter give me a 1/100 reading when used
with the probe in that manner? Is it also possible that the 1090M ohm is
giving me a "close enough" with that low voltage test and the difference
would become more measurable with higher voltages?

Sorry - this should be simple but, for some reason, I can't make it make
sense to me at the moment.

Thanks,
Barry - N4BUQ



Re: LCD screen for CSA803 or 1180x

Leo Bodnar
 

I am not planning to do anything with LCD replacement.
It was just heads up for those with bad CRT or those with spare time on their hands.
It can be anything from simple scaler hack (it still took me two weeks to modify 8051 code to fit LCD into 89410A) to a fun project rewriting of video controller firmware. It's all i80186 so should be reasonably comfortable for most programmers.
Leo

Testing the linearity of the 11801 time base

Reginald Beardsley
 

I had concluded previously that nothing was lost in the NVRAM failure, but had not really developed a good test.

The post about enabling the FW debug option and discovering that the NVRAM is used to store diagnostic results prompted me to play around some more.

I'm using a Keysight 33622A which is specified a <1 ps jitter. I'm feeding a 100 kHz 250 mVpp square wave to the external trigger input and feeding a 200 mVpp ramp to an SD-26 and varying the ratio of the two frequencies.

A ramp with a 90 kHz frequency will sample the waveform at 9 points separated by the trigger rate + k*dT where k runs from 1-9 and dT is the time/div divided by 50. By changing the time/div and position you can inspect the linearity of the time sampling very closely using point accumulate mode. At 1 ps/div the lines are imperceptibly different from horizontal.

As I increase the time/div, the lines begin to slope. At 100 ns/div they slope noticeably and I catch samples on the falling edge of the ramp. If you have one of these I urge you to try it. It's rather mind bending, but an excellent test of the linearity of the time sampling. At 100 or 200 ns/div, you can see flat steps for samples that have been taken at the same time offset from the trigger with a voltage change less than the ADC step. The point accumulate mode allows you to build up a noise free picture of the sample timing.

At least for my unit, I can find nothing of significance that was lost because of the NVRAM failure. And from an engineering perspective, storing factory calibration constants in NVRAM is extremely poor practice. A small EPROM would be much more appropriate. My setup had a list of over $50K in the early '90s. A customer with a 5-6 year old instrument would be rather unhappy if failure of the NVRAM battery was a return to factory repair.

I have to pinch myself from time to time to convince myself that I own such a thing. I've still got quite a way to go understanding what it is telling me, but it's without question the most fascinating instrument I've ever played with.

Have Fun!
Reg

Re: Brittle knobs-TDS210

guy232
 

Not sure if they are the same or similar as the smaller friction fit knobs on the 22xx series but if so: I read in some old posts that heating them up with hot air first was a trick for removing and installing them. The temperature was not mentioned. Also I would imagine it doesn't always work, so a backup plan like glue/epoxy etc would be wise.

Your PayPal reimbursement arrived...

Brad Thompson
 

Hello, Phil--

...Today (Tuesday, Oct. 29). I'll mail your package tomorrow (Wednesday, Oct. 30) and will forward the
 delivery date to you when it's issued.

Thank you, and 73--

Brad  AA1IP

Re: Brittle knobs-TDS210

Mark Jordan
 

My solution: super glue...  ;-)

    Mark Jordan, PY3SS

On 29-Oct-19 16:18, sittners wrote:
I had one of the position knobs suddenly break on my TDS210 and promptly ordered some replacements from Q service. The initial attempt at installing the new know resulted in it breaking as well so I attempted a second replacement with the same failure. Is anyone familiar with this issue and if so, have you found a solution?

regards,

Phil, KD6RM



Re: FW: [TekScopArc] Yahoo groups closing down. Find us on Facebook or Tapatalk.com soon.

guy232
 

+1 to hoping we don't have to rely on facebook.

Is the info on the archives still currently available for the time being or no?

I tried joining the yahoo group a couple months ago and was denied, Dennis informed me that all of the archived info was moved to the group here. Maybe my context was poor or I misunderstood him, maybe he just meant the tekscopes group was backed up but not the tekscopes archive groups? Kinda confused. Any info would be appreciated, I heard that there was quite a bit of 22xx series info there and I've been trying to track it down for months with no luck.

Re: FW: [TekScopArc] Yahoo groups closing down. Find us on Facebook or Tapatalk.com soon.

Dan Cordova <danny_cordov@...>
 

An early goodbye-  I don't have a facebook account and don't plan to have one. 
So- goodbye...
Dan

On Tuesday, October 29, 2019, 10:24:04 AM PDT, Chuck Harris <cfharris@...> wrote:

Wasn't TekScopeArchive set up as a patch to TekScopes running out
of file space?  And, wasn't it incorporated into the groups.io
site when we moved, and had no choice but to buy a Premium membership
with more file space?

-Chuck Harris

Roy Thistle wrote:
Hi Dennis:
Over the years, I tried to join TekScopArc… and never was able to... and never got a message from the moderator, as to why not.
Perhaps that somewhat explains the current situation?
I'd like to join TekScopArc... or at least know why I can't.
Best regards and wishes.
Roy



Re: TDS3044B repair

David Kuhn
 

I'm in central, PA, about 3 hours from you if you ever want to come up and
try it here with one of my VGA/GPIB modules.

Before that. Power it up while holding in the "B TRIG" button (might be
different on the TDS3014), which on my TDS3032's causes a RESET. I've had
that fix display issues after replacing the battery NVRAM in in the scope.

The display in the TDS3032, is the exact same LCD used in the GEIT Phasor
XS and USN60 instruments. I have worked on many. I have never seen the
LCD fail on those instrument where it's all white. Typical, if not broken,
is smeary displays that lines seems to go out of sync. Dim, of course with
broken backlight tubes.

Dave

On Mon, Oct 28, 2019 at 10:50 PM Tom B <tbryan@...> wrote:

Hi Rich (?),

Thanks. I am located in Maryland near Washington DC.

If anyone in the Washington DC area has a TDS3GV that I could come over
and quickly test my scope with, I would appreciate it.

Tom Bryan
N3AJA


On 10/28/2019 10:29 AM, Oz-in-DFW wrote:
I'd still remove and reseat both ends.

Where are you in the world? I have a VGA/serial/GPIB card in my 3014
that we might be able to mate with your scope briefly.


Re: Replacing TDS540B CRT with LCD?

Harvey White
 

Thank you, however, I have a 540A, and they are using B and above.

I may give it a try anyway.

Harvey

On 10/29/2019 2:46 PM, David C. Partridge wrote:
<https://www.eevblog.com/forum/repair/conversion-tektronix-tds500-to-tds700-color-oscilloscope/>

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Harvey White
Sent: 29 October 2019 16:53
To: TekScopes@groups.io
Subject: Re: [TekScopes] Replacing TDS540B CRT with LCD?

I'd love to have the details, if you please. I've got a "spare" 540CPU
that I could change. Already have the memory upgrade, I think.

Harvey


On 10/29/2019 10:46 AM, David C. Partridge wrote:
It's not that hard to convert the board - move a 74F04 (IIRC) and add VRAM

D.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Harvey White
Sent: 29 October 2019 12:53
To: TekScopes@groups.io
Subject: Re: [TekScopes] Replacing TDS540B CRT with LCD?

From what I understand, for full color you'll need the CPU board
changed out from the monochrome version. Otherwise, you'll need to do
some trace cutting perhaps, and that's something I wouldn't want to do
without a supply of working CPU boards, if then.....

I think that the kits *may* offer a partial color, but it's not on a
per-trace basis.

Harvey


On 10/29/2019 8:03 AM, David Thomas wrote:
Hi David,
how about this one? I believe Hakan managed to fit a 7 inch
800x600 (actually the part number is very similar).
£45 plus import tax...

https://www.ebay.co.uk/itm/LCD-VGA-2AV-Controllers-with-Remote-Control-7inch-800x600-LCD-Display-A070SN01/263388878055?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D60272%26meid%3Db6714bdf1367445ba732eead2db547bf%26pid%3D100005%26rk%3D6%26rkt%3D12%26mehot%3Dpf%26sd%3D253979723396%26itm%3D263388878055%26pmt%3D1%26noa%3D0%26pg%3D2047675&_trksid=p2047675.c100005.m1851


These seem to be popular for car reversing cameras (note the 2 phono
sockets in the pictures) ...

I have a couple of monochrome 6xx series scopes that I would like to
convert - does anyone have any ideas about converting the mono display
to colour? (I think one of the kit suppliers does it using a bit of
programmable logic clamped over the DAC area of the PCB...)

DLT
(UK based)

On 28/10/2019 21:41, zenith5106 wrote:
On Mon, Oct 28, 2019 at 05:30 PM, David C. Partridge wrote:

If anyone has a pointer to a suitable panel (ideally cheap-ish) I'd be
grateful!
If you are prepared to to some work yourself as opposed to installing
a finished bolt-on-kit I can recommend this:

https://www.ebay.com/itm/VGA-LCD-Controller-Board-KYV-N2-V2-7-A070SN02-800x600-Lcd-Screen/360725515609


and this is how I did it on a TDS544A:
http://www.hakanh.com/dl/TDS_LCD.htm

/Håkan













Brittle knobs-TDS210

sittners
 

I had one of the position knobs suddenly break on my TDS210 and promptly ordered some replacements from Q service. The initial attempt at installing the new know resulted in it breaking as well so I attempted a second replacement with the same failure. Is anyone familiar with this issue and if so, have you found a solution?

regards,

Phil, KD6RM

Re: Replacing TDS540B CRT with LCD?

 

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Harvey White
Sent: 29 October 2019 16:53
To: TekScopes@groups.io
Subject: Re: [TekScopes] Replacing TDS540B CRT with LCD?

I'd love to have the details, if you please. I've got a "spare" 540CPU
that I could change. Already have the memory upgrade, I think.

Harvey


On 10/29/2019 10:46 AM, David C. Partridge wrote:
It's not that hard to convert the board - move a 74F04 (IIRC) and add VRAM

D.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Harvey White
Sent: 29 October 2019 12:53
To: TekScopes@groups.io
Subject: Re: [TekScopes] Replacing TDS540B CRT with LCD?

From what I understand, for full color you'll need the CPU board
changed out from the monochrome version. Otherwise, you'll need to do
some trace cutting perhaps, and that's something I wouldn't want to do
without a supply of working CPU boards, if then.....

I think that the kits *may* offer a partial color, but it's not on a
per-trace basis.

Harvey


On 10/29/2019 8:03 AM, David Thomas wrote:
Hi David,
how about this one? I believe Hakan managed to fit a 7 inch
800x600 (actually the part number is very similar).
£45 plus import tax...

https://www.ebay.co.uk/itm/LCD-VGA-2AV-Controllers-with-Remote-Control-7inch-800x600-LCD-Display-A070SN01/263388878055?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D60272%26meid%3Db6714bdf1367445ba732eead2db547bf%26pid%3D100005%26rk%3D6%26rkt%3D12%26mehot%3Dpf%26sd%3D253979723396%26itm%3D263388878055%26pmt%3D1%26noa%3D0%26pg%3D2047675&_trksid=p2047675.c100005.m1851


These seem to be popular for car reversing cameras (note the 2 phono
sockets in the pictures) ...

I have a couple of monochrome 6xx series scopes that I would like to
convert - does anyone have any ideas about converting the mono display
to colour? (I think one of the kit suppliers does it using a bit of
programmable logic clamped over the DAC area of the PCB...)

DLT
(UK based)

On 28/10/2019 21:41, zenith5106 wrote:
On Mon, Oct 28, 2019 at 05:30 PM, David C. Partridge wrote:

If anyone has a pointer to a suitable panel (ideally cheap-ish) I'd be
grateful!
If you are prepared to to some work yourself as opposed to installing
a finished bolt-on-kit I can recommend this:

https://www.ebay.com/itm/VGA-LCD-Controller-Board-KYV-N2-V2-7-A070SN02-800x600-Lcd-Screen/360725515609


and this is how I did it on a TDS544A:
http://www.hakanh.com/dl/TDS_LCD.htm

/Håkan











Re: 260-2500-00 Encoder

Sergey Kubushyn
 

On Tue, 29 Oct 2019, Clark Foley wrote:

Unfortunately it is not long enough...

I'll work something out but it would be more mechanical work than expected.
No biggie but not a quick job either.

If the inner shaft is long enough, try to scavenge it from the unit that I
sent. After you tear into it, you can decide if it is possible to replace
the broken one. Have fun!
---
******************************************************************
* KSI@home KOI8 Net < > The impossible we do immediately. *
* Las Vegas NV, USA < > Miracles require 24-hour notice. *
******************************************************************

Re: 260-2500-00 Encoder

Clark Foley
 

If the inner shaft is long enough, try to scavenge it from the unit that I sent. After you tear into it, you can decide if it is possible to replace the broken one. Have fun!

Re: HV Probe and DMM Input Impedance

EB4APL
 

No, the common VTVMs have 10 Meg input resistance and on this input you plug the HV probe and it works, so leave the 1 Mg resistor away.

You are right that using a DVM you have to multiply the reading by 110, or insert and adapter made with common resistors and a pot so you get a 1/1000 division, which is easier to do mentally.

Ignacio

El 29/10/2019 a las 15:11, David M escribió:
Yupppp!!!!
Don't know why I couldn't have said it that way... Guess it was old age.
You're correct in that the meter's (VTVM usually) input circuitry has to be made to include the extra 1 Meg resistor into its scale factor.. A normal digital meter is designed to have a 10 Meg input impedance, and the probe's internal resistor would have to be changed accordingly.
The OP's best approach to using the probe is to get a VTVM having an 11 Meg input impedance and everything would be correct. I doubt that the resistors used in that old probe are still around, so its value is marginal.
As someone else suggested, in order to use the probe with a 10 Meg DMM, just remember to multiply the meter reading by 110 to get the correcct reading.

Dave M


On Mon, Oct 28, 2019 at 06:54 PM, johncharlesgord wrote:

Dave,
If I am interpreting the addition of the 1Meg resistor correctly, it will just
change the 1090 Meg probe resistor to a 1091 Meg value. That will make the
division ratio into the 10 Meg DVM 10/1101, not what is wanted.
--John

On Mon, Oct 28, 2019 at 03:20 PM, David M wrote:

You're absolutely correct about the 1 Meg resistor being in most VTVMs, but
the OP was asking about using the probe with his Fluke 27 DMM, having an
input
impedance of 10 Meg. In that case, adding a 1 Meg resistor would be
necessary
in order to get the correct divider ratio, and the correct DMM reading.
Modern digital multimeters are usually supplied with ordinary straight-wired
probes having no resistor inside the probes, making the additional resistor
necessary.

Cheers,
Dave M



On Mon, Oct 28, 2019 at 01:17 PM, johncharlesgord wrote:

Dave,
I don't think your "add 1M to the probe" will work. The 11Meg VTVMs had
1Meg
in the probe and 10Meg in the instrument, creating a 10/11 divider in
normal
operation. The instrument scaling compensated for that. Adding 1Meg to
the
HV probe will actually make the situation slightly worse. (The voltage at
the
hot end of the 1Meg will be 1/100th of the probe tip voltage, but the DVM
is
looking at the cold end of the 1Meg resistor.)
--John Gord

On Mon, Oct 28, 2019 at 09:06 AM, David M wrote:

Barry, the Eico (and other manufacturers as well) made those probes so
that
the resistor could be changed to accommodate the particular VTVM or
multimeter
you needed to use them with. In the case of the 1090 Meg resistor, it
was
to
be used with a meter having 11 Meg input resistance. That would
calculate
to
a 1000:1 divider.
So, to use your HV probe with a meter having a 10 Meg input, you would
need
to
add an additional 1 Meg resistor into the probe (or wherever you could
make
it
fit) so that the probe works into 11 Meg.

Cheers,
Dave M
--
El software de antivirus Avast ha analizado este correo electrónico en busca de virus.
https://www.avast.com/antivirus

Re: LCD screen for CSA803 or 1180x

Reginald Beardsley
 

Please send me the scripts or point me to the right page in the programming manual for reading waveforms.

I checked all the Lithium batteries when I got the scope. All were >3.0 V which I found very impressive after 30 years.

I very much hope that Leo decides to offer a replacement touchscreen LCD for these. The existing touch interface is horrible.

Reg

Re: FW: [TekScopArc] Yahoo groups closing down. Find us on Facebook or Tapatalk.com soon.

Chuck Harris
 

Wasn't TekScopeArchive set up as a patch to TekScopes running out
of file space? And, wasn't it incorporated into the groups.io
site when we moved, and had no choice but to buy a Premium membership
with more file space?

-Chuck Harris

Roy Thistle wrote:

Hi Dennis:
Over the years, I tried to join TekScopArc… and never was able to... and never got a message from the moderator, as to why not.
Perhaps that somewhat explains the current situation?
I'd like to join TekScopArc... or at least know why I can't.
Best regards and wishes.
Roy



Re: FW: [TekScopArc] Yahoo groups closing down. Find us on Facebook or Tapatalk.com soon.

Roy Thistle
 

Hi Dennis:
Over the years, I tried to join TekScopArc… and never was able to... and never got a message from the moderator, as to why not.
Perhaps that somewhat explains the current situation?
I'd like to join TekScopArc... or at least know why I can't.
Best regards and wishes.
Roy

Re: Replacing TDS540B CRT with LCD?

Harvey White
 

I'd love to have the details, if you please.  I've got a "spare" 540CPU that I could change.  Already have the memory upgrade, I think.

Harvey

On 10/29/2019 10:46 AM, David C. Partridge wrote:
It's not that hard to convert the board - move a 74F04 (IIRC) and add VRAM

D.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Harvey White
Sent: 29 October 2019 12:53
To: TekScopes@groups.io
Subject: Re: [TekScopes] Replacing TDS540B CRT with LCD?

From what I understand, for full color you'll need the CPU board
changed out from the monochrome version. Otherwise, you'll need to do
some trace cutting perhaps, and that's something I wouldn't want to do
without a supply of working CPU boards, if then.....

I think that the kits *may* offer a partial color, but it's not on a
per-trace basis.

Harvey


On 10/29/2019 8:03 AM, David Thomas wrote:
Hi David,
how about this one? I believe Hakan managed to fit a 7 inch
800x600 (actually the part number is very similar).
£45 plus import tax...

https://www.ebay.co.uk/itm/LCD-VGA-2AV-Controllers-with-Remote-Control-7inch-800x600-LCD-Display-A070SN01/263388878055?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D1%26asc%3D60272%26meid%3Db6714bdf1367445ba732eead2db547bf%26pid%3D100005%26rk%3D6%26rkt%3D12%26mehot%3Dpf%26sd%3D253979723396%26itm%3D263388878055%26pmt%3D1%26noa%3D0%26pg%3D2047675&_trksid=p2047675.c100005.m1851


These seem to be popular for car reversing cameras (note the 2 phono
sockets in the pictures) ...

I have a couple of monochrome 6xx series scopes that I would like to
convert - does anyone have any ideas about converting the mono display
to colour? (I think one of the kit suppliers does it using a bit of
programmable logic clamped over the DAC area of the PCB...)

DLT
(UK based)

On 28/10/2019 21:41, zenith5106 wrote:
On Mon, Oct 28, 2019 at 05:30 PM, David C. Partridge wrote:

If anyone has a pointer to a suitable panel (ideally cheap-ish) I'd be
grateful!
If you are prepared to to some work yourself as opposed to installing
a finished bolt-on-kit I can recommend this:

https://www.ebay.com/itm/VGA-LCD-Controller-Board-KYV-N2-V2-7-A070SN02-800x600-Lcd-Screen/360725515609


and this is how I did it on a TDS544A:
http://www.hakanh.com/dl/TDS_LCD.htm

/Håkan










Re: 260-2500-00 Encoder

Clark Foley
 

Pity