Re: Novice question - 475, what mode is this?
The Tek 475 is analog, with a CRT screen, so the tools for LCD screens will probably not work. The intensity knob may be turned down too low (as Bob mentions), but on my 475, if I turn down the intensity until I can barely see the trace on just the A sweep, and then go to Mix, I can still see the A trace along with the B trace. But when I turn it down further, the B trace is still visible as the A disappears. There may be a dirty Mix switch or some other switch.
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On 6/22/2018 8:27 AM, Jeff Urban wrote: On Thu, Jun 21, 2018 at 02:29 pm, Bob Albert wrote:
Is the intensity set too low?
Bob
Sounds like you are not seeing the left side of the trace. Couple possible reasons for this, one is that the brightness or pedestal on your monitor is set too low. There are monitor test programs for this, as it is hard to tell just where black is black but none of the grays are black. One such program is called ntest.exe, which is totally stand alone, would run off anything, like a CD or stick or whatever. One of the patterns is exactly for that and says adjust until you see some particular block in the pattern. That should eliminate any black clipping.
Another possibility is if you have an edge lit LCD monitor. As the viewing angle changes vertically in those, the brightness changes. This effect varies, some models are better/worse than others. Some are terrible and you only get a limited range or it does all kinds of funky crap like show a negative image or all the color disappears if you are too low or high, things like that.
The one I got - ntest.exe, is from Nokia. If you can't find a suitable program I can upload it or you can hit me up with an email and I can send it as an attachment in a reply.
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Re: was capacitors now about switches
Just want to make it clear that the "buttons" I referred to in the OP are the small, self-contained switches that solder onto the board individually - not the rubbery sheet kind that carry carbon films that make contact on patterns on the board. I've had plenty of troubles with the rubbery kind, but never a problem until now, with the discrete snap-action switches, as long as the "snap" was still good. I have had plenty that had mechanical failure from wearout or breakage, where the plastic actuators were deformed or bent off-axis (or even the whole switch unit popped open) from too much force, or the detent action was lost and the contact would either short or open permanently.
Ed
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Re: was capacitors now about switches
Hello,
PCB buttons can and do fail all the time. A fun example was the Vernee Apollo lite, where too tight manufacturing tolerances allowed sweat grease to accumulate.
I have summed it all up in a video, just in case anyone feels like taking a look:
Tam
--
With best regards
Tam Hanna
---
Enjoy electronics? Join 8300 other followers by visiting the Crazy Electronics Lab at
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Re: Novice question - 475, what mode is this?
On Thu, Jun 21, 2018 at 02:29 pm, Bob Albert wrote:
Is the intensity set too low?
Bob
Sounds like you are not seeing the left side of the trace. Couple possible reasons for this, one is that the brightness or pedestal on your monitor is set too low. There are monitor test programs for this, as it is hard to tell just where black is black but none of the grays are black. One such program is called ntest.exe, which is totally stand alone, would run off anything, like a CD or stick or whatever. One of the patterns is exactly for that and says adjust until you see some particular block in the pattern. That should eliminate any black clipping. Another possibility is if you have an edge lit LCD monitor. As the viewing angle changes vertically in those, the brightness changes. This effect varies, some models are better/worse than others. Some are terrible and you only get a limited range or it does all kinds of funky crap like show a negative image or all the color disappears if you are too low or high, things like that. The one I got - ntest.exe, is from Nokia. If you can't find a suitable program I can upload it or you can hit me up with an email and I can send it as an attachment in a reply.
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Re: Novice question - 475, what mode is this?
That's "MIX" - mixed mode. What it does is instead of intensifying the part of the trace to be expanded by the B timebase it simply switches to B timebase at that point of the sweep, wherever you set the delay control.
On the left you are going at at the slower A sweep on the right it actually is intensified but since the sweep is faster it needs that. Push the intensify button and you'll get the whole trace of the slower sweep where the sine waves look compressed but right where the B sweep starts in mixed mode it will be intensified. Looking at the mixed mode tell me that the intensified portion will only be a few cycles - a small version of what you see on the right. Then of course when you go to B sweep the whole screen gets the delayed part - which is currently on the right in mixed mode.
I hope you got that, sometimes I am not the best explainer in the world. The manual might do better, not sure.
I am not sure of the usefulness of mixed mode, I can't think of a case where I would use it. Well effectively, I like playing around with such things so it is useful for that...:-)
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Re: was capacitors now about switches
Yes, that is a good way to return flexi-buttons to operation.
I use Caig Caikote, which is a conductive carbon coating, applied onto the old surface.
I clean the old surface with IPA first.
Menahem
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was capacitors now about switches
Greetings,
Allow me to add to the comments by Ed and Shailendra regarding push button switches.
I had the remote for an auto fail and drain the batteries.
Exploring the problem I first determined that the remote was not transmitting. From there I discovered that the conductive coating on the contact areas of the molded buttons had dislodged and made conductive paths (shorts) on the switch areas of the PCB.
After cleaning this residue away I was able to return the unit to proper function with a very neat little product from ¡°ButtonWorx¡±. They make different size peel and stick conductive buttons which stick to the PCB over the switch circuit area and below the molded button. Depressing the molded button in turn depresses the ¡°new¡± button.
I have no affiliation with ¡°ButtonWorx¡±, I¡¯m simply happy I discovered their product.
Regards,
Ken
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Re: Speaking of capacitor problems - it's not always their fault
On Thu, Jun 21, 2018 at 09:36 am, Ed Breya wrote:
With all this capacitor talk, I thought I'd relate a recent experience in
patching up a consumer item. When I took the shot CRT from that AT5005 SA
recently discussed here, to drop off at the recycling place, I noticed a guy
lugging a medium sized LCD TV out of his car. I was going to offer help in
chucking it in the bin, but instead said I could take it - it looked pretty
decent as a possible spare TV. He said it had a problem with the sound. So, it
went into my truck instead of to certain destruction. With stuff like this, I
can take a quick shot at fixing, but if no good, I'll strip out some parts,
and it ends up with the same fate on my next trip to recycling.
I powered it up, and quickly found that the "trouble with the sound" was that
the volume level insisted on going to maximum, regardless of pushing the
buttons on the small local control panel on the side. No other functions
worked - it was locked up because the volume up button seemed to be stuck. I
figured that a cap leaked somewhere and faulted the control interface. I
opened it up and found the insides quite clean, and there were no obvious
signs of problems with any of the usual suspects - the Al electrolytic caps.
In fact, there are none on the little button board, or anywhere around the uP
periphery that could be blamed for messing up the button signals. I pulled the
button board, and it seemed OK - the buttons all had good snap action. The
only thing a little weird was the solder mask looked kind of flakey, so maybe
there was some leakage. I was going to try washing it, but decided to first
make some resistance measurements for before and after comparison. I was
shocked to find that the real problem was the buttons themselves. Five out of
the seven had various low resistances in their "open" state - some so low that
the R didn't even change when pushed. I have never seen a problem in one of
these kind of buttons before, that wasn't an obvious mechanical failure.
Fortunately, I had some of the right kind in stock, so did the replacements,
put it all back together, and voila, it all worked - sound too.
The lesson here is that it's not necessarily always or only cap problems. I
was lucky on this one, because if there were any cap problems too, it could
have led to a wild goose chase fooling around with them, only to ultimately
encounter the button issue. After exhausting most of my patience on caps, I
likely would have assumed it was still cap juice somewhere, rather than
closely looking at those buttons, and the unit would have been tossed.
Ed
Hello Ed, I too have experienced the same kind of switch failure on several devices, including a LCD TV, a PC monitor, and music systems. The tiny tactile switches do fail after some time. It is worth checking them when the controls appear locked up, or a certain function is continuously active without pressing any button. Replacement is the best solution, but if you can't find a replacement, you can use a contact cleaner to soak the button for some time, and then exercise it to restore operation. Although the buttons appear sealed, some amount of liquid seeps in and helps make the switch work for some time. Eventually, you must replace the switch to get ling term fix. Regards Shailendra
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Michael A. Terrell
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-----Original Message----- From: Jon Batters <jonbatters32@...>
Hi Michael, How is the Display Module connected to the Base Module to measure values ? Can you hook an RMS meter and an averaging and this meter in parallel to determine if this meter is an RMS model and let us know. There is only the meter module, and a current transformer. It is connected across the AC line, and it uses a current transformer. This is shown in a photo in the listing. I haven't tested it, yet. None of my True RMS meters have a current reading function. They are Fluke 8920/8921/8922 series meters.
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Re: - Early Telequipment 'Scope
Hi Adrian,
Thanks for your reply. So far, you are the only group member who has
expressed interest.
I attach photograph of the S31. You may be able to see that the input
connector has been changed (by the previous owner) to the more conventional
BNC type. Otherwise, I don't think there are any changes.
It is not obvious how the case can be removed, but it seems to be
constructed from 6 sections. I think that the rear panel must clip on
somehow and hold the sides in place which, in turn, hold the top and bottom
vented panels in place.
Hope the photo is of interest and you could certainly have the scope if you
don't mind travelling up to Yorkshire sometime. No rush, since the scope
has just been stored in the loft for the past 40 years!
Just let me know if you decide not to have it and I will also let you know
if there is any other interest.
Ken.
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On 19:42, Thu, 21 Jun 2018 Adrian, <Adrian@...> wrote: Hi Ken,
I would be interested if nobody nearer to you pops up - bit of a drive
from Eastern Anglia.
Does it have its case by any chance? Mine does not and I'm trying to
re-create one based on a very tiny, badly scanned image from a copy of a
1957 Wireless World, and struggling! All I can deduce at the moment is
that it may have been constructed more like the single '5-sided box'
design of the later S51 than the three piece 'clam shell' design of the
face-lifted S31 because it is missing all the fixing holes it would need
to hold the base part of that on. I would really appreciate a pic!
All the best, Adrian
On 6/21/2018 1:35 PM, Ken wrote:
Hi Adrian and group,
I have an early S31 model (also pre-facelift) which I would like to give away to anyone who is interested. I also have the full, original manual
with it - including parts lists, voltages and schematics. The oscilloscope
basically works, producing a dispayed waveform from the CAL signal, but
there are some issues with X and Y shift range and timebase linearity. The
serial number on the chassis appears to 810 and the number on the
transformer is 68810.
This would have to be by collection only - location West Yorkshire, UK.
Let me know if you are interested.
Ken.
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Re: Novice question - 475, what mode is this?
Is the intensity set too low?
Bob
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On Thursday, June 21, 2018, 1:45:58 PM PDT, Dmitri Shuev <dshuev@...> wrote: Hello, everybody: I am about to test a 475 that I have acquired for my radio alignment projects, and since I am relatively new to the oscilloscopes, I wonder if I am missing something... I am trying to replicate what I think is a Delayed Sweep combination trace, but for some reason rotating the Time/Delay Time control, and trying to move the switch point with the Delay Time Position pot does not result in the combination curve ( sample here - /g/TekScopes/photo/60634/0?p=Name,,,20,1,0,0) - all I am getting is a blank on the left before the trace begins... Am I understanding this mode correctly? Something is wrong with timebase control? Or am I missing something fundamental? Thank you, Dmitri
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Novice question - 475, what mode is this?
Hello, everybody: I am about to test a 475 that I have acquired for my radio alignment projects, and since I am relatively new to the oscilloscopes, I wonder if I am missing something... I am trying to replicate what I think is a Delayed Sweep combination trace, but for some reason rotating the Time/Delay Time control, and trying to move the switch point with the Delay Time Position pot does not result in the combination curve ( sample here - /g/TekScopes/photo/60634/0?p=Name,,,20,1,0,0) - all I am getting is a blank on the left before the trace begins... Am I understanding this mode correctly? Something is wrong with timebase control? Or am I missing something fundamental? Thank you, Dmitri
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On 2018-06-21 12:51 PM, musicamex@... wrote: Albert and LolPol,
Thank you for your input. Somehow i missed this download. I found LV test points and values in section 6 of this manual. I'll report my findings this weekend when i have some time to get back to testing....maybe sooner. The monsoon season here has started and my 4 hectares eats up allot of my free time in the lab, but green is beautiful compared to dry brown winters at our 1200 m elevation.
I also found allot of info in the charts and schematics in the last part of the 465 late .pdf. The display troubleshooting will be of help hopefully once i verify my LV test points. I dont have a HV probe for my VOM and don't have the source here for the appropriate resistors to build an appropriate voltage divider, so I'm hoping the solution is something in the LV circuit.
Is there a source for pdf or other format files of the foldout pages in unchopped original layout? It would make reading them much easier. I guess that I could print/splice/tape the ones i need.... I've scanned the 465 manual with all foldouts in one piece, not stitched. I uploaded it to Tekwiki: --Toby
Thanks again! I feel the cloud lifting!
Russ
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This the the rise time now at 5mV. I could probably get it better but but my bnc cables and 50ohm terminator are not great quality. Should I keep working at it? /g/TekScopes/photo/59361/4?p=Name,,,20,1,0,0
On Thu, Jun 21, 2018 at 12:00 pm, Fabio Trevisan wrote:
Hello lop pol,
I've followed up this topic from the start, without having actually jumped in,
hoping since the beginning that someone would ask or make remarks about two or
three important things (to check, or to be aware of).
1. That's a question... What type of Vertical Output board does your 465 have.
the one discrete or the one with the custom Tek IC?
It's important because the High Freq. compensation networks are different from
one type of board to the other and since your problem manifests in both
channels, there's a great likelihood the problem is located on the Vertical
Output Amplifier board, instead of on the pre-amplifier. Without that
information is difficult to advise further.
2. If your vertical amplifier is of the "Teck IC" kind, look also to the BIAS
trimpot. If the wiper is open, the amplifier may be operating on the wrong
bias point and that is supposed to impact the high-frequency performance.
Since the procedure for calibrating the bias calls for applying a 100Mhz
signal and adjusting the bias for the highest p-p display, from there we
deduct it has a marked effect on the low nanosecond time constant, which is
exactly where your issue lies.
3. Besides what Raymond already mentioned, that is not uncommon for some of
those trimmer caps fail open (I had 3 of those failed on my 464), I want to
bring to your attention that ALL the trimpots that are used on the H.F.
compensation networks are connected as "rheostats" so, a false contact or open
wiper will make any of them appear open, or in the best case, the full
trimpot's resistance, which will be just as bad for the step response.
Since many of them are in series with trimmer caps, it's easy to check them in
circuit, without needing to lift any leg, or remove any component.
Last but not least, despite your problem clearly doesn't seem to be on the
pre-amplifiers, when you find out the culprit and eventually replace one
faulty trimmer cap or faulty trimmer resistor, you will eventually need to go
through the Vertical High Frequency step response calibration, and for that,
it's important that you follow the procedure, and from your description, I
think you're already doing wrong...
While choosing for the right input level / input attenuator (pass-through) and
vertical attenuator settings, it's important to do all the High-Frequency
calibration with the oscilloscope set to the most sensitive setting... i.e.:
5mV/div (not 10mV, not 100mV... and not 200mV/div).
In other words, you need to source 25mVpp to the oscilloscope's input (for a 5
division display).
This is what will assure you that none of the high impedance input attenuators
are upsetting the subtle high frequency adjustments and artifacts.
While - in theory - the high-impedance input attenuators shouldn't degrade the
step response of the osciloscope, they're not perfect and they do cause some
minor disturbances and aberrations to the step response (and they can also be
misadjusted, something that you will only correct at a later stage) so, to
make a "clean" H.F. calibration, you need to make sure you got them (the high
impedance input attenuators) out of the way.
The only compromise to that rule is the input probe itself... If you intend to
use the oscilloscope with a particular probe (let's say, a 10:1), then you
need to connect that probe to the input, use the scope set to 5mV/div, and
apply, accordingly, a 250mVpp signal to the probe (if it's a 10:1 probe). This
will assure you will compensate in the scope, for the probe's H.F.
inaccuracies or artifacts.
Yet on this topic, you need to be sure to "source" that signal (regardless if
directly to the input or through your preferred probe), from a low impedance
source (50Ohm).
The latter is important because you don't want the frequency response of the
incoming signal to be affected by variations caused by the 'scope's input
capacitance, or your probe's input capacitance.
The lower the impedance of the source signal, the less the input capacitance
will matter and, of course, you will also want to assure the interconnect
cable is properly terminated.
Good luck with that,
Krgrds,
Fabio
On Sun, Jun 17, 2018 at 06:47 pm, lop pol wrote:
Hey guys. I have done a lot of work to this 465. I had initially planned on
selling it to help me buy some plugins for my 7633. I decided I don't want
to
sell it and am keeping it. Today I checked its rise time with a pg506 fast
rise. Both channel 1 and 2 closely resemble each other and they are not close
to right. Before I start trying to calibrate this thing, does it look like
there is some type of component issue left to fix? I am thinking since both
channels are so alike there is something wrong besides just out of
calibration. Thanks guys.
here are some pictures
/g/TekScopes/photo/59361/0?p=Name,,,20,1,0,0
/g/TekScopes/photo/59361/1?p=Name,,,20,1,0,0
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Re: Up to date capacitor list for Tek 2465A and 2465B scopes (2018)
Hello,
In principle, Menachems approach works - looks like this:
However, be careful of vibration and inductance - SMD parts tend to be better in both of these regards.
--
With best regards
Tam HANNA (emailing on a keyboard-less handset, sorry for spelling mistakes and brevity)
|
Hello lop pol,
I've followed up this topic from the start, without having actually jumped in, hoping since the beginning that someone would ask or make remarks about two or three important things (to check, or to be aware of).
1. That's a question... What type of Vertical Output board does your 465 have. the one discrete or the one with the custom Tek IC?
It's important because the High Freq. compensation networks are different from one type of board to the other and since your problem manifests in both channels, there's a great likelihood the problem is located on the Vertical Output Amplifier board, instead of on the pre-amplifier. Without that information is difficult to advise further.
2. If your vertical amplifier is of the "Teck IC" kind, look also to the BIAS trimpot. If the wiper is open, the amplifier may be operating on the wrong bias point and that is supposed to impact the high-frequency performance.
Since the procedure for calibrating the bias calls for applying a 100Mhz signal and adjusting the bias for the highest p-p display, from there we deduct it has a marked effect on the low nanosecond time constant, which is exactly where your issue lies.
3. Besides what Raymond already mentioned, that is not uncommon for some of those trimmer caps fail open (I had 3 of those failed on my 464), I want to bring to your attention that ALL the trimpots that are used on the H.F. compensation networks are connected as "rheostats" so, a false contact or open wiper will make any of them appear open, or in the best case, the full trimpot's resistance, which will be just as bad for the step response.
Since many of them are in series with trimmer caps, it's easy to check them in circuit, without needing to lift any leg, or remove any component.
Last but not least, despite your problem clearly doesn't seem to be on the pre-amplifiers, when you find out the culprit and eventually replace one faulty trimmer cap or faulty trimmer resistor, you will eventually need to go through the Vertical High Frequency step response calibration, and for that, it's important that you follow the procedure, and from your description, I think you're already doing wrong...
While choosing for the right input level / input attenuator (pass-through) and vertical attenuator settings, it's important to do all the High-Frequency calibration with the oscilloscope set to the most sensitive setting... i.e.: 5mV/div (not 10mV, not 100mV... and not 200mV/div).
In other words, you need to source 25mVpp to the oscilloscope's input (for a 5 division display).
This is what will assure you that none of the high impedance input attenuators are upsetting the subtle high frequency adjustments and artifacts.
While - in theory - the high-impedance input attenuators shouldn't degrade the step response of the osciloscope, they're not perfect and they do cause some minor disturbances and aberrations to the step response (and they can also be misadjusted, something that you will only correct at a later stage) so, to make a "clean" H.F. calibration, you need to make sure you got them (the high impedance input attenuators) out of the way.
The only compromise to that rule is the input probe itself... If you intend to use the oscilloscope with a particular probe (let's say, a 10:1), then you need to connect that probe to the input, use the scope set to 5mV/div, and apply, accordingly, a 250mVpp signal to the probe (if it's a 10:1 probe). This will assure you will compensate in the scope, for the probe's H.F. inaccuracies or artifacts.
Yet on this topic, you need to be sure to "source" that signal (regardless if directly to the input or through your preferred probe), from a low impedance source (50Ohm).
The latter is important because you don't want the frequency response of the incoming signal to be affected by variations caused by the 'scope's input capacitance, or your probe's input capacitance.
The lower the impedance of the source signal, the less the input capacitance will matter and, of course, you will also want to assure the interconnect cable is properly terminated.
Good luck with that,
Krgrds,
Fabio
toggle quoted message
Show quoted text
On Sun, Jun 17, 2018 at 06:47 pm, lop pol wrote:
Hey guys. I have done a lot of work to this 465. I had initially planned on
selling it to help me buy some plugins for my 7633. I decided I don't want to
sell it and am keeping it. Today I checked its rise time with a pg506 fast
rise. Both channel 1 and 2 closely resemble each other and they are not close
to right. Before I start trying to calibrate this thing, does it look like
there is some type of component issue left to fix? I am thinking since both
channels are so alike there is something wrong besides just out of
calibration. Thanks guys.
here are some pictures
/g/TekScopes/photo/59361/0?p=Name,,,20,1,0,0
/g/TekScopes/photo/59361/1?p=Name,,,20,1,0,0
|
Look in the Databases section of this group for manoman.sqhill.com links; there you'll find lots of Tek manuals, all with "stitched" schematics.
|
Re: - Early Telequipment 'Scope
Hi Ken,
I would be interested if nobody nearer to you pops up - bit of a drive from Eastern Anglia.
Does it have its case by any chance? Mine does not and I'm trying to re-create one based on a very tiny, badly scanned image from a copy of a 1957 Wireless World, and struggling! All I can deduce at the moment is that it may have been constructed more like the single '5-sided box' design of the later S51 than the three piece 'clam shell' design of the face-lifted S31 because it is missing all the fixing holes it would need to hold the base part of that on. I would really appreciate a pic!
All the best, Adrian
toggle quoted message
Show quoted text
On 6/21/2018 1:35 PM, Ken wrote: Hi Adrian and group,
I have an early S31 model (also pre-facelift) which I would like to give away to anyone who is interested. I also have the full, original manual with it - including parts lists, voltages and schematics. The oscilloscope basically works, producing a dispayed waveform from the CAL signal, but there are some issues with X and Y shift range and timebase linearity. The serial number on the chassis appears to 810 and the number on the transformer is 68810.
This would have to be by collection only - location West Yorkshire, UK. Let me know if you are interested.
Ken.
|
Albert and LolPol,
Thank you for your input. Somehow i missed this download. I found LV test points and values in section 6 of this manual. I'll report my findings this weekend when i have some time to get back to testing....maybe sooner. The monsoon season here has started and my 4 hectares eats up allot of my free time in the lab, but green is beautiful compared to dry brown winters at our 1200 m elevation.
I also found allot of info in the charts and schematics in the last part of the 465 late .pdf. The display troubleshooting will be of help hopefully once i verify my LV test points. I dont have a HV probe for my VOM and don't have the source here for the appropriate resistors to build an appropriate voltage divider, so I'm hoping the solution is something in the LV circuit.
Is there a source for pdf or other format files of the foldout pages in unchopped original layout? It would make reading them much easier. I guess that I could print/splice/tape the ones i need....
Thanks again! I feel the cloud lifting!
Russ
|
Re: Up to date capacitor list for Tek 2465A and 2465B scopes (2018)
On Thu, Jun 21, 2018 at 09:37 am, machineguy59 wrote:
OUCH!! Yahoo email to groups.io lost context. So here is the message again.
Menahem,
Thanks for the information. I was not clear in expressing my concern. I will clarify my problem. The A5 boards I have suffered severe electrolyte damage. One of them (my current project) lost three pads and two traces to the etching of spilled electrolyte. I replace these pads with pads cut from foil and glued to the board with CW2500 epoxy. You can see an example of this process here:
Although my hand cut pads are not as perfect as his machine cut pads. I get pretty close. Also, my hand cut traces are not as narrow as original. I will try to post pictures of my work next time I have the scope opened up. I did not take "before" pictures. Its tedious but it works and saves the board without using jumper wires or gluing parts to the board. My concern is that CW2500 epoxy is great stuff but still not as good as original for strength. The weight of a leaded part leveraged by the leads would very likely wrench my replacement pads from the board.
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Jeff Urban
Michael A. Terrell
Fabio Trevisan
Shannon Hill