Date   

Re: 1A5 - Usefulness, Experience

Stephen Hanselman
 

Roy,
Monday I’ll check my stock. I have a 6ft cabinet full of Tek probes If I have one it’s $25.00 plus shipping

Regards,

Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@...
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
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On Jan 5, 2019, at 18:59, Chuck Harris <cfharris@...> wrote:

The primary purpose of the 1A5 is to allow you to measure small
signals that are at large voltage offsets from ground.

For instance, measuring 1mv between two points in a circuit that
floats 150V above ground. If you tried to do that with a single
probe that was ground referenced, your scope would never have
enough dynamic range to even resolve that a signal was there.

If you tried to float the scope 150V above ground so that your
scope's ground clip could be attached to one of the points on the
circuit, you might kill yourself when you touched the front panel
of the scope.

-Chuck Harris

Roy Morgan wrote:
Tek Folks,

With the 547 I got not long ago, I got a 1A5 plug-in. Not being familiar with deferential measurements, or the 1A5, I have been reading the manual (RTFM, as they say!).

I do not yet have a differential probe such as the P6046, but I see that the thing has A and B inputs that I can use in the meantime. No doubt I can use this thing to good advantage without the specialized differentia amplifying probe.

Sooo … what is the experience and advice of the folks on the list -
- What are the likely uses for this plug-in?
- Will it help me analyze audio amplifier performance?
- How about balanced modulators in SSB radio receivers?
- Are there types of solid state circuits (digital or analog) that it will help me with?
- One channel of my 1A1 preamp has now gain - can I use the 1A5 (in the 545 that Is also here) to diagnose this problem?

- What measurement would I need the probe to make successfully?

- Are there known failures of points of weakness in the 1A5?

Thanks for any comments or suggestions.

Roy

Roy Morgan
K1LKY since 1958
k1lky68@...









Re: 1A5 - Usefulness, Experience

Chuck Harris <cfharris@...>
 

The primary purpose of the 1A5 is to allow you to measure small
signals that are at large voltage offsets from ground.

For instance, measuring 1mv between two points in a circuit that
floats 150V above ground. If you tried to do that with a single
probe that was ground referenced, your scope would never have
enough dynamic range to even resolve that a signal was there.

If you tried to float the scope 150V above ground so that your
scope's ground clip could be attached to one of the points on the
circuit, you might kill yourself when you touched the front panel
of the scope.

-Chuck Harris

Roy Morgan wrote:

Tek Folks,

With the 547 I got not long ago, I got a 1A5 plug-in. Not being familiar with deferential measurements, or the 1A5, I have been reading the manual (RTFM, as they say!).

I do not yet have a differential probe such as the P6046, but I see that the thing has A and B inputs that I can use in the meantime. No doubt I can use this thing to good advantage without the specialized differentia amplifying probe.

Sooo … what is the experience and advice of the folks on the list -
- What are the likely uses for this plug-in?
- Will it help me analyze audio amplifier performance?
- How about balanced modulators in SSB radio receivers?
- Are there types of solid state circuits (digital or analog) that it will help me with?
- One channel of my 1A1 preamp has now gain - can I use the 1A5 (in the 545 that Is also here) to diagnose this problem?

- What measurement would I need the probe to make successfully?

- Are there known failures of points of weakness in the 1A5?

Thanks for any comments or suggestions.

Roy

Roy Morgan
K1LKY since 1958
k1lky68@...








1A5 - Usefulness, Experience

Roy Morgan <k1lky68@...>
 

Tek Folks,

With the 547 I got not long ago, I got a 1A5 plug-in. Not being familiar with deferential measurements, or the 1A5, I have been reading the manual (RTFM, as they say!).

I do not yet have a differential probe such as the P6046, but I see that the thing has A and B inputs that I can use in the meantime. No doubt I can use this thing to good advantage without the specialized differentia amplifying probe.

Sooo … what is the experience and advice of the folks on the list -
- What are the likely uses for this plug-in?
- Will it help me analyze audio amplifier performance?
- How about balanced modulators in SSB radio receivers?
- Are there types of solid state circuits (digital or analog) that it will help me with?
- One channel of my 1A1 preamp has now gain - can I use the 1A5 (in the 545 that Is also here) to diagnose this problem?

- What measurement would I need the probe to make successfully?

- Are there known failures of points of weakness in the 1A5?

Thanks for any comments or suggestions.

Roy

Roy Morgan
K1LKY since 1958
k1lky68@...


Re: Tektronix 465 Fan Motor not working! Help!

toby@...
 

On 2019-01-04 8:10 PM, ironcoder@... wrote:
I am guessing there is a 12 volt supply in the 465. A low volume computer fan sounds like a simple solution.
According to the service manual, +55, +15, +5, -8. (The original fan
motor is thermally controlled from the +15V supply.)




Re: 475A repair

ehsjr
 

On 1/4/2019 1:30 PM, satbeginner wrote:
Hi all,
for nostalgic reasons I wanted a 475A, just because it was the very first scope I ever touched in 1979.
My mentor at my first job made sure I would understood what a scope was, so he made me try, use and understand all features of this scope like delayed sweep, single sweep, add and subtract channels, etc.
Just before Christmas I found one that I could have shipped one in reasonable condition to me in Spain.
It was shown with two traces, so I felt confident about a possible repair.
When it arrived it was quite dirty, also it was very difficult to remove the cover, because it had several (small) dents in it, also the legs are crumbling already.
The surprise however was that the inside was remarkably clean :-)
No black soot near the high voltage cable, no dust, really clean actually.
There were signs of previous work, the cover of the channel two attenuator was missing, and also the cover over the high voltage board was removed and missing.
But still, when I turned it on, the traces appeared, like in the pictures, so not bad for a start.
I started cleaning the outside and I also cleaned all switches using alcohol and a brush, as described in the manual.
I also flushed the potmeters with alcohol, because they were very, very "touchy", just by looking at them traces would go everywhere.
I still need to lubricate them, but not quite sure what to use?
All this helped, and the traces became quite stable, but....
Now I could start testing the basic functionality, and it turned out that the delayed timebase was not working.
Tempted to go directly into that part of the scope, I did the smart thing (I think) , and started with the power supply voltages and ripple check.
Aha!! Funny thing number one!!
The -15V was down to -1,9V, while the rest of the voltages were very near, 50V was 49,9V , -8V was -7,98V, etc.
But: the scope (more-or-less) was working anyhow, regardless of the missing -15V??
Could this be a tantalum capacitor?? I checked the resistance as specified in the manual, and no, no shorts.
So I checked the transistors in that part of the power supply, and they were all OK, it turned out to be the relevant half of U1464, so U1464B.
I replaced it with a LM358 and behold, the -15V came back as -14,99V :-)
What about the delayed timebase? Hmmm, still not working.
Checking some stuff in that area revealed more broken parts:
The second broken part:
FET U930 had became a resistor, so I replaced that with a 2N5485 I had lying around.
And third:
Dual OpAmp U930 was gone as well, and yes, another LM358 brought the delayed sweep back to life. :-)
I will test further, and if and when everything looks OK, I will calibrate it.
Some pictures of my new scope can be found here: https://groups.io/g/TekScopes/album?id=81177
To be continued,
Leo
Nice. Sounds like you've got a good one. :-)

Ed


Re: 2213A recap & vertical jitter repair (attenuator fix)

Michael
 

My 2213A would show ripple on my workbench with the case off. I discovered it was nothing but the fluorescent shop light I was using, I did all kinds of things to track down that ripple. I turned off the shop light and went to lunch but left the scope running. I came back and no ripple. Turned on the shop light and ripple again. A lesson learned.


Re: 2213A recap & vertical jitter repair (attenuator fix)

tom jobe <tomjobe@...>
 

One more thought about your ripple on the lower voltage settings... are you putting the perforated metal cage back on the power supply section before you check to see how much ripple there is?
Without the metal cage the ripple doesn't look very good as I remember.

On 1/4/2019 12:32 PM, tekscopegroup@... wrote:
On Thu, Jan 3, 2019 at 05:01 PM, tom jobe wrote:

I have never changed any of those silvery axial capacitors, but then I
may have never done the 22XX re-cap job the way it should be done either.
Without changing those small tubular caps, by any chance do you remember if your traces where still showing any ripple (not thermal noise) on the lower 2-10mV ranges? As is mine are still showing about 0.4mV (one minor div) on the 2mV range. Looks like a small amplitude irregular square wave. And btw there is actually at least one capacitor (C715 22uF on the timing board) that is used to filter a reference voltage applied to the inverting input of U715, so getting that one replaced should probably be important as well.

C906 and C940 are of course on the A list. But I will definitively change out all the smaller blue radial caps as well and see how the ripple looks. If anything visible is still wiggling on the traces after that, then maybe I'll go for the small shiny axial caps as well. Thing is to get to some of these, the whole timing and input attenuator boards will have to come off to access that area of A1. And maybe even the CRT.


Re: 2213A recap & vertical jitter repair (attenuator fix)

tom jobe <tomjobe@...>
 

I have a 2215A I have been working from time to time that I'm going to give to a friend who works on magnetos used in some forms of motor racing.
It was a scope with many-many problems that now works fairly well.
On the side of it I had written a list of most of what has been done to it so far.
It has almost no ripple in the trace at @2mV and the trace itself when the scope is set to "ground" on the AC-GND-DC switch is a little under one half of a small division wide. I should have rechecked the "focus" setting before I took some photos when I got home today, but I think the photos will answer your question as they are. I tried to figure out what your email address is to send the photos to you directly but failed. I also tried to figure out my own email address from looking at my own post and failed too.
If you or anyone else would like to see these photos send me a note at tomjobe@... and they will be on their way.
If there is anything different I should be showing in the photos let me know and I will take some using your suggestions.
The fact that this 2215A has minimal ripple does not mean anything more than I got lucky, and it certainly does not mean I know anything about what I'm doing!

On 1/4/2019 12:32 PM, tekscopegroup@... wrote:
On Thu, Jan 3, 2019 at 05:01 PM, tom jobe wrote:

I have never changed any of those silvery axial capacitors, but then I
may have never done the 22XX re-cap job the way it should be done either.
Without changing those small tubular caps, by any chance do you remember if your traces where still showing any ripple (not thermal noise) on the lower 2-10mV ranges? As is mine are still showing about 0.4mV (one minor div) on the 2mV range. Looks like a small amplitude irregular square wave. And btw there is actually at least one capacitor (C715 22uF on the timing board) that is used to filter a reference voltage applied to the inverting input of U715, so getting that one replaced should probably be important as well.

C906 and C940 are of course on the A list. But I will definitively change out all the smaller blue radial caps as well and see how the ripple looks. If anything visible is still wiggling on the traces after that, then maybe I'll go for the small shiny axial caps as well. Thing is to get to some of these, the whole timing and input attenuator boards will have to come off to access that area of A1. And maybe even the CRT.


Re: 2213A recap & vertical jitter repair (attenuator fix)

Michael
 

Yes, all good information. I have a 2213 I bought in 1980. It is still used. I did get dirty horizontal sweep size potentiometer inside on the board. I used deoxit and it is still working years later. I have two 465s. The 2213 is far easier to repair.


Re: Tektronix 465 Fan Motor not working! Help!

Michael
 

I am guessing there is a 12 volt supply in the 465. A low volume computer fan sounds like a simple solution.


Re: 2213A recap & vertical jitter repair (attenuator fix)

tom jobe <tomjobe@...>
 

Yes! Those are the only three of concern in the common 22xx scopes as far as I know. (Where I live the 2213 and 2215 are not common, and not included in my definition of common 22xx scopes)
I doubt those Rifa capacitors know what they are used in <G>, and the problem seems more like what 30 years has done to that brand and era of film capacitors.
If you are in a 120 VAC part of the planet those bad caps are less of a problem than if you are in a 240 VAC part of the planet.
The worst horror stories about those kind of capacitors seem to come from the 240 VAC areas.
The same goes for those Schafnner AC inlet filters. You can almost get away with using them on 120 VAC, but not on 240 VAC for very long when they get this old.
Thank you everyone for taking an interest in my favorite Tektronix Oscilloscopes... the common 22xx's such as the 2213A, 2215A, 2235, etc!
tom jobe...

On 1/4/2019 1:09 PM, tekscopegroup@... wrote:
On Thu, Jan 3, 2019 at 05:01 PM, tom jobe wrote:
Thank you for the 2213A reply!
As far as I know, all of the aluminum electrolytic capacitor are
suspect, as well as the the X2 and Y2 film capacitors that see the input AC.
Tom, these would be C900 0.15uF, and C902/C903 0.0022uF correct?
And I thought explosive Rifa caps where only limited to the 2465x scopes.


Re: power supply PS2521G

Jim Ford
 

Yeah, pet peave of mine: not being able to see voltage and current for all supplies simultaneously.  All power supplies should have this ability.
Jim F


Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Siggi <siggi@...> Date: 1/4/19 7:02 AM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] power supply PS2521G
On Fri, Jan 4, 2019 at 8:37 AM Antoan1 via Groups.Io <Antoan1=
yahoo.com@groups.io> wrote:

  I just wounder if the right group for the PSD2521G power supply.
Hi Antoan,

I believe the PS2520/2521 supplies were OEM from GW Instek. The GW PPT-3615
looks identical to my PS2520.
I was never able to scare up a schematic for it, but with the hints and
tips from this EEVBlog repair thread <
https://www.eevblog.com/forum/testgear/tektronix-ps2520-triple-output-power-supply-repair-and-calibration/>
and some persistence, I was able to work through the problems in mine.
Seems the DACs are a weak point in these, plus I had logic supply and
opto-coupler problems with mine.
I'm not super-fond of this supply, the UI is quite horrendous and it can
only display read-back for a single channel at a time.

Siggi


Tek 2782 Schematics Uploaded to KO4BB

Bob Koller <testtech@...>
 

FYI, I have just uploaded the schematics for the Tek 2782 spectrum analyzer to KO4BB. It may be awhile until they are posted.
These are scans from the 11"X17" set I have, sorry I don't have anything else.

Enjoy!


Re: 2213A recap & vertical jitter repair (attenuator fix)

Alex
 

On Thu, Jan 3, 2019 at 05:01 PM, tom jobe wrote:
Thank you for the 2213A reply!
As far as I know, all of the aluminum electrolytic capacitor are
suspect, as well as the the X2 and Y2 film capacitors that see the input AC.
Tom, these would be C900 0.15uF, and C902/C903 0.0022uF correct?
And I thought explosive Rifa caps where only limited to the 2465x scopes.


Re: 2213A recap & vertical jitter repair (attenuator fix)

Alex
 

On Thu, Jan 3, 2019 at 05:01 PM, tom jobe wrote:

I have never changed any of those silvery axial capacitors, but then I
may have never done the 22XX re-cap job the way it should be done either.
Without changing those small tubular caps, by any chance do you remember if your traces where still showing any ripple (not thermal noise) on the lower 2-10mV ranges? As is mine are still showing about 0.4mV (one minor div) on the 2mV range. Looks like a small amplitude irregular square wave. And btw there is actually at least one capacitor (C715 22uF on the timing board) that is used to filter a reference voltage applied to the inverting input of U715, so getting that one replaced should probably be important as well.

C906 and C940 are of course on the A list. But I will definitively change out all the smaller blue radial caps as well and see how the ripple looks. If anything visible is still wiggling on the traces after that, then maybe I'll go for the small shiny axial caps as well. Thing is to get to some of these, the whole timing and input attenuator boards will have to come off to access that area of A1. And maybe even the CRT.


Re: 2213A recap & vertical jitter repair (attenuator fix)

Alex
 

On Thu, Jan 3, 2019 at 05:01 PM, tom jobe wrote:
-snip-
I saw where someone asked if all of your discussion applies to the
2215... which it may very well do... but the 2213 and 2215 are very
different oscilloscopes in many ways to the common 2213A. 2215A, 2235's,
2236's etc. family that many of us are more familiar with, so be careful.
Thanks again!
tom jobe...
Good catch Tom. I am so used to hear the similarities in power supply topology between the 2215a and 2213a that somehow my mind went on autopilot and assumed that the input attenuator boards must be the same or similar as well, since both are 60MHz scopes. Thanks for the correction.


Re: 475A repair

satbeginner
 

Sorry, one typo:

The FET has number Q920.


475A repair

satbeginner
 

Hi all,

for nostalgic reasons I wanted a 475A, just because it was the very first scope I ever touched in 1979.
My mentor at my first job made sure I would understood what a scope was, so he made me try, use and understand all features of this scope like delayed sweep, single sweep, add and subtract channels, etc.

Just before Christmas I found one that I could have shipped one in reasonable condition to me in Spain.
It was shown with two traces, so I felt confident about a possible repair.

When it arrived it was quite dirty, also it was very difficult to remove the cover, because it had several (small) dents in it, also the legs are crumbling already.
The surprise however was that the inside was remarkably clean :-)
No black soot near the high voltage cable, no dust, really clean actually.

There were signs of previous work, the cover of the channel two attenuator was missing, and also the cover over the high voltage board was removed and missing.
But still, when I turned it on, the traces appeared, like in the pictures, so not bad for a start.

I started cleaning the outside and I also cleaned all switches using alcohol and a brush, as described in the manual.
I also flushed the potmeters with alcohol, because they were very, very "touchy", just by looking at them traces would go everywhere.
I still need to lubricate them, but not quite sure what to use?

All this helped, and the traces became quite stable, but....

Now I could start testing the basic functionality, and it turned out that the delayed timebase was not working.
Tempted to go directly into that part of the scope, I did the smart thing (I think) , and started with the power supply voltages and ripple check.

Aha!! Funny thing number one!!

The -15V was down to -1,9V, while the rest of the voltages were very near, 50V was 49,9V , -8V was -7,98V, etc.
But: the scope (more-or-less) was working anyhow, regardless of the missing -15V??
Could this be a tantalum capacitor?? I checked the resistance as specified in the manual, and no, no shorts.

So I checked the transistors in that part of the power supply, and they were all OK, it turned out to be the relevant half of U1464, so U1464B.
I replaced it with a LM358 and behold, the -15V came back as -14,99V :-)

What about the delayed timebase? Hmmm, still not working.

Checking some stuff in that area revealed more broken parts:

The second broken part:
FET U930 had became a resistor, so I replaced that with a 2N5485 I had lying around.

And third:
Dual OpAmp U930 was gone as well, and yes, another LM358 brought the delayed sweep back to life. :-)

I will test further, and if and when everything looks OK, I will calibrate it.

Some pictures of my new scope can be found here: https://groups.io/g/TekScopes/album?id=81177

To be continued,

Leo


Re: 22XX Newbie. Preparing for the arrival of my 2213A, parts/documents/questions

tom jobe <tomjobe@...>
 

The issue you list about the transformer is for the 2213 and 2215 which are very different scopes (as hard as that might be to believe) and does not apply to your 2213A
Look in the TekScopes group message archive for ideas about the focus string of resistors. The amount of voltage each focus resistor has to drop is around the maximum it can handle, and there are several fixes discussed to help this problem
Definitely change the Schaffner AC inlet and the X2 and Y2 film caps if you have any of them

On Jan 1, 2019, at 5:54 PM, guy232 <gry.russel@...> wrote:

I have just bought my first scope from ebay, tek 2213A (Ser. B020545). Wanting to use this for working on 70s/80s solid state audio stereo amplifiers.


Have done a bunch of searching on old forums and on here aswell once I found this group (used to be a yahoo group i believe?)


I'm wondering if it would be wise to buy any parts in advance? I have compiled the following list of things I found via search:


1) a chain of 510k ohm 0.5watt carbon composition "focus" resistors

2) Check if the transformer winding has been altered/wire dressed for a crt longevity official fix

3) Scaffner power plug "IEC" can be explosive and should be replaced?

4) a few "RIFA" capacitors can be explosive and need replaced

5) Test LVPS first before making changes

Does there happen to be a more thorough list and/or suggested maintenance parts list that I have overlooked?


I have the following documents collected so far:

2213A SM + OM

2215A SM

050-2242-03 pdf about scr, fet, converter transistor replacement

troubleshooting tips on 2200 .pdf hakan

2200 PS noise pdf


Excited to start this project, glad I found this place and will be continuing to search around here, will update if I answer my own question.


Cheers




Re: 465B: Basic Restoration Tasks List For Long Life?

bbortnick@...
 

Hey that's great, I'm doing the same for a 465! How did you access the pots for lubing?

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