Date   

Re: 'Solder Rot'

EricJ
 

Hi Tam,

It is National Physical Laboratory's "Good Practice Guide #136."

--Eric

On Jan 6, 2020 10:04 AM, Tam Hanna <tamhan@...> wrote:




Hello Eric,
May I ask for you to provide me a link or reference to the paper?

Tam
---
With best regards
Tam HANNA (emailing on a BlackBerry PRIV)

Enjoy electronics? Join 14k other followers by visiting the Crazy
Electronics Lab at https://www.instagram.com/tam.hanna/






Re: 454 screen brightness issues?

 

Jack:

In my previous email, I unsuccessfully tried to transcribe the procedure
for CRT grid bias adjustment described on page 6-11 of the manual.  Grid
bias adjustment control R1447 does not directly affect the voltage at
TP1349. Refer to the manual (page 6-11) for the exact process; my
apologies for my error.  I suggest the following:

1.  Setup the scope's controls as described on page 6-8 and 6-9
"Preliminary Procedure".
2.  Try to adjust the INTENSITY control  to get +12V at TP1349, as per
page 6-11 "Adjust CRT Grid Bias."  If this cannot be done, there might
be a Z-axis problem. If you can get +12 volts, then go to step 3 below:
3.  Adjust CRT Grid Bias potentiometer R1447 per paragraph 6.d on page 6-11.
4.  Let us know what the results are. Although at this point I might be
at a loss as to further ideas.

It's also possible that there might be an issue with the grid bias
resistors/potentiometer (R1442 thru R1449) as others have suggested.  If
you have access to a ohmmeter (such as a VTVM) that can detect
variations of about 1.8 megohms in a total resistance of about 52
megohms, then you can check this by measuring the resistance (with power
down) from the CRT pin 3 to TP1349 while varying grid bias potentiometer
R1447 from fully CCW to fully CW.  You might get one measured value with
the ohm meter's leads in one position, and another with the meter leads
"reversed"; if so then go with the higher set of measurements, as the
lower set of measurements would be due to forward bias of D1440.

Mike D N4MWP

On 1/6/20 7:37 PM, Jack Ohme wrote:
Mike,

I have a copy of the manual in PDF and on paper. The intensity dial
correctly changes the voltage (although the screen brightness shows no
change), but the grid biasing potentiometer does not change the voltage at
TP1349, which stays at around 6.8v. I'm not sure whats happening here, if
this is the grid biasing pot that is broken or something nearby on the Z
axis board, but I will inspect the schematics. Let me know if you think of
anything to look for.

-Jack

On Mon, Jan 6, 2020 at 2:15 PM Albert Otten <aodiversen@...> wrote:

Hi Jack,
Where should I be looking for those DC restorers, in the -1920v?
The 454 has no DC restorers. The HV transformer has separate windings for
the grid and the cathode circuit. The rectified voltage for the grid can be
reduced somewhat by the grid bias pot R1447 (in the divider chain with
R1442-R1446) and is stacked on the voltage supplied by the Z-axis
amplifier.
When you follow Mike's suggestion and use a pdf of the manual, you will
note that the waveform at TP1349 is almost invisible. The blue picture in
the paper manual is also very faint. The voltage switches between the 2
written values 17.7 V and 6.75 V.

Albert




Re: Trying to bring back a AA501

Eric
 

Seems the 5V is leaking from the next chip up stream the MC14490E when removed the 5V goes away sence it has 5V coming out and input it is most likely bad as well

On 1/6/2020 9:21 PM, Chuck Harris wrote:
CMOS of that era can drive essentially nothing.

Therefore, I would think that the 5V on the empty
socket is muscling the output to 5V.

-Chuck Harris

Eric wrote:
OK so trouble shooting of the night. Voltage on pin 9 of U1410 is about 7.5 V, CR1412
tests as a diode. However, on the socket with the chip removed I do see the 4.95V
present. Also on pin 13 it looks like everything is behaving I think . The voltage
goes down as the frequency goes up so I think the op Amp U1610D is working as
expected. Or is at least changing it output. So I am still at a bad stage in U1410
specifically D. I have NOS ones on order about 10 of them so we will see what happens.


On 1/6/2020 12:01 PM, Eric via Groups.Io wrote:
I'll check tonight when I get back to the bench if there is voltage in the
socket with the ic removed. When I curve traced the outputs with the chip
out on a bread board referenced to ic ground point 1 2 and 4 showed a
diode. 3 showed nothing fully open circuit.

On Mon, Jan 6, 2020, 11:41 AM Dave Wise <david_wise@...> wrote:

That happened here a few weeks ago. Fluke 8000A DMM. After a transient,
it would only display even digits. Turned out the 7447 display driver
developed an internal short on its 1's input. The MOS A/D chip was fine.
Whew!

Dave Wise
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Chuck Harris
via Groups.Io <cfharris=erols.com@groups.io>
Sent: Sunday, January 05, 2020 10:36 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Trying to bring back a AA501

I am having trouble imagining how a 15V CMOS device could spontaneously
generate 5V on one of its outputs.... I can see ~0V, or ~15V, or even 7.5V,
but 5V is an odd value for a device that has no resistors in it.

Are you sure that it isn't being bullied around by whatever it is driving?
old style CMOS has very little drive capability.

-Chuck Harris









Re: Tektronix 570 Vacuum Tube Curve Tracer on eBay

Leon Robinson
 

We had receivers on the Navy ship I was on, WW2 vintage that had RF amps to prevent the
local oscillator radiation from leaking out the antenna and giving the ships position away.

Leon Robinson    K5JLR

Political Correctness is a Political Disease.

Politicians and Diapers should be changed
often and for the same reasons.

On Monday, January 6, 2020, 8:19:06 AM CST, Geoffrey Thomas <geoffreythomas@...> wrote:

I recall reading somewhere (years ago) that some military receivers were
running a few amps in the front end to protect against emp.
Anybody verify or was it an apocryphal tale/April fool article?

Geoff.

On 06/01/2020 01:59, Roy Thistle wrote:
On Sun, Jan  5, 2020 at 11:25 AM, Greg Muir wrote:


the vacuum tube equipment still possessed by the military for use when EMP
from a nuclear blast renders a portion of the solid-state hardware useless.
Hi Greg:
Although obviously I am privy to very little information about what the "military" has, or does not have... I am doubtful, if the military keeps any vacuum tube type equipment because of "transistorized" = solid state equipment failing due to NEMP. The reason I say this is that... at least the high EMF generated by the Type 1 pulse of a NEMP event requires relatively long conductors to couple energy. Small conducting paths; small inductor values, fully metallically shielded, and enclosed cases... besides other common EMP hardening measures... significantly null out NEMP effects.
That said... militaries are working on... and due claim to have... EMP weapons that act to produce extremely large local EMP pulse that can disable/destroy EMP hardened gear very locally... or so they say.
Cheers. Best regards and wishes.
Roy


Re: Trying to bring back a AA501

Chuck Harris
 

CMOS of that era can drive essentially nothing.

Therefore, I would think that the 5V on the empty
socket is muscling the output to 5V.

-Chuck Harris

Eric wrote:

OK so trouble shooting of the night. Voltage on pin 9 of U1410 is about 7.5 V, CR1412
tests as a diode. However, on the socket with the chip removed I do see the 4.95V
present. Also on pin 13 it looks like everything is behaving I think . The voltage
goes down as the frequency goes up so I think the op Amp U1610D is working as
expected. Or is at least changing it output. So I am still at a bad stage in U1410
specifically D. I have NOS ones on order about 10 of them so we will see what happens.


On 1/6/2020 12:01 PM, Eric via Groups.Io wrote:
I'll check tonight when I get back to the bench if there is voltage in the
socket with the ic removed. When I curve traced the outputs with the chip
out on a bread board referenced to ic ground point 1 2 and 4 showed a
diode. 3 showed nothing fully open circuit.

On Mon, Jan 6, 2020, 11:41 AM Dave Wise <david_wise@...> wrote:

That happened here a few weeks ago. Fluke 8000A DMM. After a transient,
it would only display even digits. Turned out the 7447 display driver
developed an internal short on its 1's input. The MOS A/D chip was fine.
Whew!

Dave Wise
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Chuck Harris
via Groups.Io <cfharris=erols.com@groups.io>
Sent: Sunday, January 05, 2020 10:36 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Trying to bring back a AA501

I am having trouble imagining how a 15V CMOS device could spontaneously
generate 5V on one of its outputs.... I can see ~0V, or ~15V, or even 7.5V,
but 5V is an odd value for a device that has no resistors in it.

Are you sure that it isn't being bullied around by whatever it is driving?
old style CMOS has very little drive capability.

-Chuck Harris










Re: Trying to bring back a AA501

Chuck Harris
 

7447 is now a CMOS part?

CMOS is free of dissipation elements, like resistors, and
analog region transistors.

How would it find 5V from a 15V supply? To get 7.5V, it would
have to get really, really hot, as two transistors in a totem
pole pair were both turned on at the same time...

5V would be pretty much the same thing, with the lower of the
two transistors (N type) being slightly stronger than the upper.

Point is, it would be very hot.

-Chuck Harris

Dave Wise wrote:

That happened here a few weeks ago. Fluke 8000A DMM. After a transient, it would only display even digits. Turned out the 7447 display driver developed an internal short on its 1's input. The MOS A/D chip was fine. Whew!

Dave Wise
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Chuck Harris via Groups.Io <cfharris=erols.com@groups.io>
Sent: Sunday, January 05, 2020 10:36 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Trying to bring back a AA501

I am having trouble imagining how a 15V CMOS device could spontaneously
generate 5V on one of its outputs.... I can see ~0V, or ~15V, or even 7.5V,
but 5V is an odd value for a device that has no resistors in it.

Are you sure that it isn't being bullied around by whatever it is driving?
old style CMOS has very little drive capability.

-Chuck Harris







Re: Tek 576 Curve Tracer USB port to a cpu ... ?

Eric
 

Arduino has potential Pi is too much like a computer... well is a computer. I have had this rolling around in my head for a while as to how to do this, I was even thinking of omitting all the HV stuff tapping off the CRT driver pins digitizing the inputs and driving a VGA port with them. Some challenges I have come across already. computer monitors are raster driven. Not X-Y driven so we would need to time the raster. Not TOO huge a deal with a curve tracer but a scope the sweeps are WAY to fast for a computer monitor. Color not really an issue due to the curve tracers being monochrome. You can just set some values and make it a color. The 576 has a sweep rate of 60Hz so it would lend its self to a conversion however the BIG one is how to get the grid lines on the image. These would have to be driven digitally given they are etched in to the glass. So not sure how to do that part yet but I think an Arduino has 1024 value ADC full scale. Then of course can we get it through a calibration process to aline everything. We would need about 60FPS at a res of 1024x768 monochrome with and adjustable persistence as a possible feature upgrade to aid in the matching of transistors. By REALLY being able to over lay the traces. But I really like the idea of a 576 with a 19 inch screen.

On 1/6/2020 6:40 PM, Mlynch001 wrote:
Seems like they are getting a premium for their interface. But they are also the only game in town. If you want to play, I suppose one should prepare to pay dearly? I wish some of the brilliant minds in the group would come up with something reasonable. Arduino or Raspberry Pi seem to have potential, I am not at all familiar with either.


Re: Trying to bring back a AA501

Eric
 

OK so trouble shooting of the night. Voltage on pin 9 of U1410 is about 7.5 V, CR1412 tests as a diode. However, on the socket with the chip removed I do see the 4.95V present. Also on pin 13 it looks like everything is behaving I think . The voltage goes down as the frequency goes up so I think the op Amp U1610D is working as expected. Or is at least changing it output. So I am still at a bad stage in U1410 specifically D. I have NOS ones on order about 10 of them so we will see what happens.

On 1/6/2020 12:01 PM, Eric via Groups.Io wrote:
I'll check tonight when I get back to the bench if there is voltage in the
socket with the ic removed. When I curve traced the outputs with the chip
out on a bread board referenced to ic ground point 1 2 and 4 showed a
diode. 3 showed nothing fully open circuit.

On Mon, Jan 6, 2020, 11:41 AM Dave Wise <david_wise@...> wrote:

That happened here a few weeks ago. Fluke 8000A DMM. After a transient,
it would only display even digits. Turned out the 7447 display driver
developed an internal short on its 1's input. The MOS A/D chip was fine.
Whew!

Dave Wise
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Chuck Harris
via Groups.Io <cfharris=erols.com@groups.io>
Sent: Sunday, January 05, 2020 10:36 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Trying to bring back a AA501

I am having trouble imagining how a 15V CMOS device could spontaneously
generate 5V on one of its outputs.... I can see ~0V, or ~15V, or even 7.5V,
but 5V is an odd value for a device that has no resistors in it.

Are you sure that it isn't being bullied around by whatever it is driving?
old style CMOS has very little drive capability.

-Chuck Harris







Re: Tek 576 Curve Tracer solid state replacement for relays ?

Brad Thompson
 

garp66 wrote on 1/6/2020 6:03 PM:

hi

Still I wonder if *any* of the Tek 576 relays could be replaced with power Mosfets.
I am curious if some Hexfet / Mosfet relay replacement(s) might then be more reliable ?

Brad:
Are all of the relays in the Tek 576 that you are referring to susceptible to the issue you have brought up ?

I have used a number of different power Hexfets , Mosfets made by IR ( IRF.com ) , having very low "On" resistances ( 0.0001 Ohms ) at various voltages. These Fets are capable of being turned 'on' via the output of a single TTL gate, without issue. I have also placed these in series or parallel (D-S) to achieve a wider ranges of specification with good results.
Hello, Rick--

Thank you for your comments. I have an ailing 577 awaiting attention, but I haven't studied its
schematic with an eye toward replacing relays with MOSFETs nor have I done the same with a 576.
Thus I'd be guessing about the feasibility of making *any* replacements.

It would be interesting to hear from someone who was involved with design of Tek's more-recent
curve tracers. Are there reliability issues that would justify the time spent in reverse-engineering the relays
followed by forward-engineering the MOSFET replacements?

73--

Brad  AA1IP


Re: 454 screen brightness issues?

Jack Ohme
 

Mike,

I have a copy of the manual in PDF and on paper. The intensity dial
correctly changes the voltage (although the screen brightness shows no
change), but the grid biasing potentiometer does not change the voltage at
TP1349, which stays at around 6.8v. I'm not sure whats happening here, if
this is the grid biasing pot that is broken or something nearby on the Z
axis board, but I will inspect the schematics. Let me know if you think of
anything to look for.

-Jack

On Mon, Jan 6, 2020 at 2:15 PM Albert Otten <aodiversen@...> wrote:

Hi Jack,

Where should I be looking for those DC restorers, in the -1920v?
The 454 has no DC restorers. The HV transformer has separate windings for
the grid and the cathode circuit. The rectified voltage for the grid can be
reduced somewhat by the grid bias pot R1447 (in the divider chain with
R1442-R1446) and is stacked on the voltage supplied by the Z-axis
amplifier.
When you follow Mike's suggestion and use a pdf of the manual, you will
note that the waveform at TP1349 is almost invisible. The blue picture in
the paper manual is also very faint. The voltage switches between the 2
written values 17.7 V and 6.75 V.

Albert




Re: Tektronix 532 LV rail shorted

John Williams
 

It has been a while since I had to fix a 503-series power supply. But when C640 blows it shorts and blows the 10 ohm fuse resistor. If there are solid state rectifiers one or more of them could also be blown. If there is a tube rectifier you can pull the tube and see if it will power up. There is also an electrolytic on the top by the hv supply which filters the -150. It could also be somewhere else that is shorting the -150. There is a lot of interconnection.


Re: Tek 576 Curve Tracer solid state replacement for relays ?

Jim Ford
 

Yeah, a tenth of a milliohm raised my eyebrow!Jim Ford Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: garp66 <@green> Date: 1/6/20 3:10 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] Tek 576 Curve Tracer solid state replacement for relays ? Sorry,   typo correction:   Not 0.0001 OhmRDS of 0.001Ohms   Or  1 mili Ohme.g.)  IR's  family of StrongIRFET as an example.


Re: Tektronix 570 Vacuum Tube Curve Tracer on eBay

John Williams
 

There are a huge number of tubes that were produced and never used. I remember meeting a guy at a hamfest who told me that he had 4 semitrailers in his yard full to their roofs with new vacuum tubes. He offered me them for free if I would come over and get them. No chance. Radio Electric supply says they have over 2 million in stock. Crazy.


Re: Tektronix 570 Vacuum Tube Curve Tracer on eBay

Dan Cordova <danny_cordov@...>
 

Can't speak for the submarines, and I've been out of the military since Gulf War I, but other than some TWT's and a couple other EW jamming tubes- I can't remember seeing any vacuum tubes in military aircraft.  
I wondered myself what tubes were used in the bomb radar mentioned in an earlier email, never found out.  Those tubes would be in bonded storage, with limited access.  Not even sure what happens to those tubes once the weapon system that used the tubes is upgraded?
Maybe somewhere in the USA there's a big building with thousands of 300B vacuum tubes and other sought after vacuum tubes?

On Monday, January 6, 2020, 3:08:52 PM PST, John Williams <books4you@...> wrote:

I remember selling a number of vacuum tube items to contractors for the military. They bought a bunch of 160 series indicators, power supplies and such. I was told that they were still in use in submarines and never were replaced, I suppose if it works, keep it. I can imagine that there is a lot of tube equipment out there for the same reason. It’s a nice feeling actually.


Re: Tektronix 2465 for sale ...

Abc Xyz
 

Shipping to Florida wouldn't be too bad.

On Mon, Jan 6, 2020, 6:05 AM Ancel <@Protofabtt> wrote:

In the Caribbean




Re: Tek 576 Curve Tracer USB port to a cpu ... ?

Mlynch001
 

Seems like they are getting a premium for their interface. But they are also the only game in town. If you want to play, I suppose one should prepare to pay dearly? I wish some of the brilliant minds in the group would come up with something reasonable. Arduino or Raspberry Pi seem to have potential, I am not at all familiar with either.

--
Michael Lynch
Dardanelle, AR


Re: Tek 576 Curve Tracer solid state replacement for relays ?

garp66
 

Sorry, typo correction: Not 0.0001 Ohm

RDS of 0.001Ohms Or 1 mili Ohm

e.g.) IR's family of StrongIRFET as an example.


Re: Tektronix 570 Vacuum Tube Curve Tracer on eBay

John Williams
 

I remember selling a number of vacuum tube items to contractors for the military. They bought a bunch of 160 series indicators, power supplies and such. I was told that they were still in use in submarines and never were replaced, I suppose if it works, keep it. I can imagine that there is a lot of tube equipment out there for the same reason. It’s a nice feeling actually.


Re: Tek 576 Curve Tracer solid state replacement for relays ?

garp66
 

hi

Still I wonder if *any* of the Tek 576 relays could be replaced with power Mosfets.
I am curious if some Hexfet / Mosfet relay replacement(s) might then be more reliable ?

Brad:
Are all of the relays in the Tek 576 that you are referring to susceptible to the issue you have brought up ?

I have used a number of different power Hexfets , Mosfets made by IR ( IRF.com ) , having very low "On" resistances ( 0.0001 Ohms ) at various voltages. These Fets are capable of being turned 'on' via the output of a single TTL gate, without issue. I have also placed these in series or parallel (D-S) to achieve a wider ranges of specification with good results.

rick


Re: 454 screen brightness issues?

Albert Otten
 

Hi Jack,

Where should I be looking for those DC restorers, in the -1920v?
The 454 has no DC restorers. The HV transformer has separate windings for the grid and the cathode circuit. The rectified voltage for the grid can be reduced somewhat by the grid bias pot R1447 (in the divider chain with R1442-R1446) and is stacked on the voltage supplied by the Z-axis amplifier.
When you follow Mike's suggestion and use a pdf of the manual, you will note that the waveform at TP1349 is almost invisible. The blue picture in the paper manual is also very faint. The voltage switches between the 2 written values 17.7 V and 6.75 V.

Albert