Date   

Re: TM506

Stephen
 

On Wed, Jul 22, 2020 at 02:00 AM, <scm@...> wrote:


It looks like both R680 and R682 overheated. This implies that C680 might be
bad or there might be a short or other problem associated with the transistor
in the mainframe . If just R682 had gone, I'd suspect CR680. Note that any
excess current in the -20V bus should be limited by R695/Q660 current limiting
circuitry to under 1 A if the mainframe transistor (and its wiring) were OK
and Q660 was doing it's job. If C680 doesn't look shorted with the module
unplugged, suspect the mainframe transistor, its wiring (E-B interchanged?) or
a wiring short.
I don’t see any R695.


Re: TM506

SCMenasian
 

It looks like both R680 and R682 overheated. This implies that C680 might be bad or there might be a short or other problem associated with the transistor in the mainframe . If just R682 had gone, I'd suspect CR680. Note that any excess current in the -20V bus should be limited by R695/Q660 current limiting circuitry to under 1 A if the mainframe transistor (and its wiring) were OK and Q660 was doing it's job. If C680 doesn't look shorted with the module unplugged, suspect the mainframe transistor, its wiring (E-B interchanged?) or a wiring short.


Re: 485 Cordwrap Feet

Michael W. Lynch
 

On Tue, Jul 21, 2020 at 11:47 PM, Daveolla wrote:


If the fellow read the "6" in 465 as an "8" he would get 485.
That is the only explanation that I can imagine.

--
Michael Lynch
Dardanelle, AR


Re: TM506

Stephen
 

No voltage at pin 1 on any of the slots. Schematic shows 24.8V RMS.


Re: TM506

Stephen
 

On Tue, Jul 21, 2020 at 02:08 PM, Harvey White wrote:


On that transistor?

It's dead, Jim.

unless it's wiring, something nasty happened.

Now, what?  why?

Harvey
I replaced the dead NPN transistor with a TIP35C. I powered the unit on. No smoke, no arc... And the fuse didn’t blow either.
I turned it off and plugged in the DC power supply plugin. Only half (the negative portion) turned on. And this is how it was after the 7.5A fuse blew. However, it was functioning properly before that happened. In other words, nothing had changed.

So I went ahead and also the paired PNP. And just these 2, for slot #5. I powered the unit ON with no plugins.
Everything seemed ok. I plugged in the DC supply, and nothing. No power to it at all. I tried the AM503 Current Probe Amplifier, still nothing. I rechecked the fuses, the pins to the connector, and all was ok. I don’t think I inverted anything. I’ve rechecked everything several times over with the schematic.
Then I tried the FG502 Function Generator plugin. BOOM, an arc and smoke. 2 resistors blew up.

Picture: https://groups.io/g/TekScopes/photo/250733/0?p=Created,,,100,2,0,0

I’m baffled 😕


Re: TDS794D with broken Hard drive

Holger Lübben
 

Hi Reginald,
Thanks for your generous offer. But you're right - it's not woth to ship them over the Atlantic ;-)

Holger


Re: TDS540B switches during boot VGA output from color to monochrome

Tam Hanna
 

Afaik normal behavior. The color 7xx has more memory. But there is a tutorial on eevblog how to work around it.
---
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: TDS794D with broken Hard drive

Holger Lübben
 

Hi dave and Valentin,
Both tipps sound like a good improvement.
Do you know the maximum capacity which will be accepted by the scope?

Holger


Re: 485 Cordwrap Feet

Daveolla
 

If the fellow read the "6" in 465 as an "8" he would get 485.

Dave

At 11:34 PM 7/21/2020, you wrote:
Jeff,

I don’t see any way that a 485 could use cordwrap feet like a 465/475. The area where these mount to the scope is very narrow. Too narrow for the footprint of the 465/475 type of foot. It would take a hybrid design, sort of a melding of the 465 foot with the 485 foot.

I would ask the customer for a picture of the back and front of the scope.

I would be very interested to see what they have.

Thanks

Michael W. Lynch
11993 Wildcat Hollow Road
Dardanelle, AR
72834

From My I-Pad
479-477-1115
479-229-0126

On Jul 21, 2020, at 16:27, Jeff Davis <n0dyjeff@...> wrote:

Hi Michael,

Thanks for the photo - that's what I pictured
from the drawing in the service manual. I'm still mystified how my customer's 485 came by the feet he sent me.

Jeff

________________________________
From: TekScopes@groups.io
<TekScopes@groups.io> on behalf of Michael W. Lynch via groups.io <mlynch003=yahoo.com@groups.io>
Sent: Tuesday, July 21, 2020 1:46 PM
To: TekScopes@groups.io <TekScopes@groups.io>
Subject: Re: [TekScopes] 485 Cordwrap Feet

Jeff,

My 485 does not have cordwrap feet as
such. I suppose it just has something like the 2465 series? I posted a picture in the photo section.

Here:

https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgroups.io%2Fg%2FTekScopes%2Falbum%3Fid%3D250894&amp;data=02%7C01%7C%7C547ce97c1b73422019b808d82db71f2d%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637309611805858729&amp;sdata=DZOMfXYDeyeHixyq0T8JvYoC%2F18Ysvd3Z47aI7iAr9g%3D&amp;reserved=0

Hope this helps.

--
Michael Lynch
Dardanelle, AR







--
Michael Lynch
Dardanelle, AR


Re: 485 Cordwrap Feet

Michael W. Lynch
 

Jeff,

I don’t see any way that a 485 could use cordwrap feet like a 465/475. The area where these mount to the scope is very narrow. Too narrow for the footprint of the 465/475 type of foot. It would take a hybrid design, sort of a melding of the 465 foot with the 485 foot.

I would ask the customer for a picture of the back and front of the scope.

I would be very interested to see what they have.

Thanks

Michael W. Lynch
11993 Wildcat Hollow Road
Dardanelle, AR
72834

From My I-Pad
479-477-1115
479-229-0126

On Jul 21, 2020, at 16:27, Jeff Davis <n0dyjeff@...> wrote:

Hi Michael,

Thanks for the photo - that's what I pictured from the drawing in the service manual. I'm still mystified how my customer's 485 came by the feet he sent me.

Jeff

________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Michael W. Lynch via groups.io <mlynch003=yahoo.com@groups.io>
Sent: Tuesday, July 21, 2020 1:46 PM
To: TekScopes@groups.io <TekScopes@groups.io>
Subject: Re: [TekScopes] 485 Cordwrap Feet

Jeff,

My 485 does not have cordwrap feet as such. I suppose it just has something like the 2465 series? I posted a picture in the photo section.

Here:

https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgroups.io%2Fg%2FTekScopes%2Falbum%3Fid%3D250894&amp;data=02%7C01%7C%7C547ce97c1b73422019b808d82db71f2d%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637309611805858729&amp;sdata=DZOMfXYDeyeHixyq0T8JvYoC%2F18Ysvd3Z47aI7iAr9g%3D&amp;reserved=0

Hope this helps.

--
Michael Lynch
Dardanelle, AR





--
Michael Lynch
Dardanelle, AR


Re: 11801 diagnostic help

Jim Ford
 

I second that.  Years ago I had a similar problem with an HP 54120 scope.   Too much delay added excessive jitter to the edges.Jim Ford Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: "John Gord via groups.io" <johngord=verizon.net@groups.io> Date: 7/21/20 3:18 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] 11801 diagnostic help Per,It looks like you are using a very long delay (30us or so).  Can you use a much shorter delay?  You may just be seeing the actual jitter of the signal from one edge to another edge 30us later, or you might be seeing the jitter of the delay generator in the CSA 803A.--John GordOn Tue, Jul 21, 2020 at 08:04 AM, Perdad wrote:>> Hi,> > New to this forum and I have tried to search it for relevant answers but> without luck. This thread seems to have a lot people knowling a lot so trying> my luck.> > Just bougth an CSA 803A on eBay. The units works fine in that i passes Self> Test and Extended Diagnostics without any error.> I have a SD-14 and a SD-24 head. Using external trigger or using the internal> Pulse Generator for TDR works fine.> > The problem is the Calibrator and Clock outputs that have a very severe noise.> See picture:> https://www.dropbox.com/s/1577fnl5d48iui2/Calibrator_Jitter_CSA803C.jpg?dl=0> Tracing back it looks as if the 'Strobe Drive Board' is the problem. Any> guidance would be helpful.> > )) Per>


Re: TM506

Harvey White
 

On that transistor?

It's dead, Jim.

unless it's wiring, something nasty happened.

Now, what?  why?

Harvey

On 7/21/2020 8:27 PM, Stephen wrote:
On Tue, Jul 21, 2020 at 09:20 AM, Harvey White wrote:

Aha, tactical problem easily fixed.

There's lots of ways the connectors can be numbered, generally all
confusing.  What you're looking at is the connector maker's nomenclature.

Tektronix (go the the TEK WIKI and get LOTS of documentation on the
frames), started at 1 and went to 28 ON BOTH SIDES.  The board parts
side is side A, and the mostly trace side (bottom) is side B.

Pins 1 (A and B) are at the bottom of the module as seen with normal
module insertion.
I figured it out. The ones I bought (TIP35C and 36C) have the collector in the middle,
but the base and emitter reversed from the ones already installed. I’ll run wires.

The NPN pass transistor for slot 5 (the one before the High Power slot) has all pins shorted. That would be 6A, 7A, and 7B on the connector.



Re: TM506

Harvey White
 

interleaved as I like to do......

On 7/21/2020 8:42 PM, Stephen wrote:
On Tue, Jul 21, 2020 at 10:49 AM, Hugh Vartanian wrote:

Hey, Stephen,

No need to invoke any deities here (to the "praying" sign-off in a recent
post), or to threaten your new instrument with re-incarnation as a paper
weight! As previously stated, no rocket science is involved.
Everything you’re familiar with seems simple. I’m obviously out of my comfort zone, and I admit it.
That's ok.  If I got something new, the first thing I'd be doing is to analyze it so that I could relate it to something I knew about.  Then I'd go through and see how it's different (and it would be).

Not sure how much "we" are ever in our comfort zone.  (If that's a good thing).



If you can build guitar amps and handle logical/conditional functions in software,
this will all yield to you!
Yes, that’s easy for me.
I added a reverb to a gibson (old one) guitar amp.  It was tubes.  Don't quite remember the things I did, but I suspect I stole some circuitry ideas from someone else's guitar amp, and the reverb line (one of the spring ones, IIRC).



Same with the transistors in the mainframe. Know that the "don't fix
anything that isn't broken" adage ought not be scoffed at. It will be
better to understand and troubleshoot what you have with some directed
surgical intervention to start, rather than draining your time and energy
changing a bunch of stuff that doesn't need changing, or breaking other
things that aren't now broken, but for the intervention.....
I get the point, and I would usually agree with that. I just want to replace them to start fresh.
Starting fresh is not the thing here, but it's more like "what was working still works, what wasn't working is now fixed."

Doing that would mean, in a plugin, for example:

1) replacing all the tantalum capacitors (and you could argue some of it, but not all).

2) replacing the older semiconductors (maybe.....)

3) replacing the old 7400 series ICs (but what with?  Maybe 74LS, but that can have problems).

4) replacing all the sockets (and it depends on what kind and how they're made)

5) replacing (in some scopes) carbon composition resistors with film (depends where).

6) replacing hard to find hybrid circuits with even harder to find identical replacement hybrids.....

None of this makes sense unless you have parts (and there are some) that have a limited life due to:

1) bad manufacturing (some tantalum caps)

2) bad circuit design (some tantalum caps rated for too small a voltage for their use... they didn't know better at the time)

3) some ICS that have known failure modes due to bad manufacturing

4) some things that just didn't need to be designed like that (somewhat rare in Tektronix, but possible).

So what am I saying?

1) fix what's broken

2) within reason, fix what will break

3) do no harm (yes, I know where that comes from, and it's valid here)

4) restore it to good operating order where possible.

Go back through the archives and read or ask "do I need to replace this and why?"  (seriously)

some will replace anything that they think might fail.  Some will replace only those things that have failed (I might be guilty here).  And some take an approach where "what do I need to make it work best for the longest time" ?

I think I like the latter approach.

Keep asking questions, though.  Some people will stumble on this thread and perhaps learn a lot.

Harvey



Caveats to this judicious change-them-all strategy, surely are the "known"
failure rate of certain components based on history, and whether you are
close to something known to be an issue (i.e. 4 hours into mechanical
disassembly).
Agreed

(I confess to being, within reason, an all-or-nothing
capacitor changer!)
So am I in 50yo guitar tube amps.

Good luck, keep doing the research (multiplexed displays, linear power
supplies, transistors, tek manuals and circuit descriptions, this group and
its history, etc.), ask questions when you are stuck, etc. The problems
will yield.
Thank you.



Re: 11A16 Problem

Steve C
 

Hi Egge,

Thanks for the reply.

I checked the 11301 mainframe firmware and is version 2.4. Also, the 11A16 User Manual say for 11301/11302 the firmware version should be 2.4 or later, so it is compatible.
It seems that this is not the issue.

Thanks,
Steve


Re: TM506

Stephen
 

On Tue, Jul 21, 2020 at 10:49 AM, Hugh Vartanian wrote:


Hey, Stephen,

No need to invoke any deities here (to the "praying" sign-off in a recent
post), or to threaten your new instrument with re-incarnation as a paper
weight! As previously stated, no rocket science is involved.
Everything you’re familiar with seems simple. I’m obviously out of my comfort zone, and I admit it.

If you can build guitar amps and handle logical/conditional functions in software,
this will all yield to you!
Yes, that’s easy for me.

Same with the transistors in the mainframe. Know that the "don't fix
anything that isn't broken" adage ought not be scoffed at. It will be
better to understand and troubleshoot what you have with some directed
surgical intervention to start, rather than draining your time and energy
changing a bunch of stuff that doesn't need changing, or breaking other
things that aren't now broken, but for the intervention.....
I get the point, and I would usually agree with that. I just want to replace them to start fresh.

Caveats to this judicious change-them-all strategy, surely are the "known"
failure rate of certain components based on history, and whether you are
close to something known to be an issue (i.e. 4 hours into mechanical
disassembly).
Agreed

(I confess to being, within reason, an all-or-nothing
capacitor changer!)
So am I in 50yo guitar tube amps.


Good luck, keep doing the research (multiplexed displays, linear power
supplies, transistors, tek manuals and circuit descriptions, this group and
its history, etc.), ask questions when you are stuck, etc. The problems
will yield.
Thank you.


Re: TM506

Stephen
 

On Tue, Jul 21, 2020 at 09:20 AM, Harvey White wrote:


Aha, tactical problem easily fixed.

There's lots of ways the connectors can be numbered, generally all
confusing.  What you're looking at is the connector maker's nomenclature.

Tektronix (go the the TEK WIKI and get LOTS of documentation on the
frames), started at 1 and went to 28 ON BOTH SIDES.  The board parts
side is side A, and the mostly trace side (bottom) is side B.

Pins 1 (A and B) are at the bottom of the module as seen with normal
module insertion.
I figured it out. The ones I bought (TIP35C and 36C) have the collector in the middle,
but the base and emitter reversed from the ones already installed. I’ll run wires.

The NPN pass transistor for slot 5 (the one before the High Power slot) has all pins shorted. That would be 6A, 7A, and 7B on the connector.


Re: TDS794D with broken Hard drive

Reginald Beardsley
 

I've got a similar size (2-6 GB) IDE drive you can have for shipping, however, I'm in the US, so it may not be worthwhile. When I swap drives I put the old ones in trays so I can swap them. I've got a couple dozen with various operating systems on them (Plan 9 anyone?). I rarely use the small ones now as nothing will fit on them.

Reg


Re: RM545B Looking for a good home (Austin, TX)

Reginald Beardsley
 

And I have an RM545A Tek manual for media rate postage.

Reg


Re: 11801 diagnostic help

Reginald Beardsley
 

Do an auto setup, That display is symptomatic of a bug in the 11801. I see it *all* the time. When I do, I do an auto setup and then reset things. Sometimes it requires an "initialize". Quite annoying.

I still haven't figured out what setting causes it after *many* hours with my 11801.

I just coughed >$$$ to chipxs for an SD-30, but also lucked out and snagged an SD-24 for <$90 all up.

And this is *all* Leo Bodnar's fault! If he hadn't sent me a CSA803A plot with the pulser I bought from him I would never have done this ;-)

You might want to check out this thread:

https://www.eevblog.com/forum/rf-microwave/testing-rf-connectors-and-cables/msg2640531/#msg2640531

Lots of TDR porn.

Have Fun!
Reg


Re: 11801 diagnostic help

John Gord
 

Per,
It looks like you are using a very long delay (30us or so). Can you use a much shorter delay? You may just be seeing the actual jitter of the signal from one edge to another edge 30us later, or you might be seeing the jitter of the delay generator in the CSA 803A.

--John Gord

On Tue, Jul 21, 2020 at 08:04 AM, Perdad wrote:


Hi,

New to this forum and I have tried to search it for relevant answers but
without luck. This thread seems to have a lot people knowling a lot so trying
my luck.

Just bougth an CSA 803A on eBay. The units works fine in that i passes Self
Test and Extended Diagnostics without any error.
I have a SD-14 and a SD-24 head. Using external trigger or using the internal
Pulse Generator for TDR works fine.

The problem is the Calibrator and Clock outputs that have a very severe noise.
See picture:
https://www.dropbox.com/s/1577fnl5d48iui2/Calibrator_Jitter_CSA803C.jpg?dl=0
Tracing back it looks as if the 'Strobe Drive Board' is the problem. Any
guidance would be helpful.

)) Per