Date   

Re: TDS-520

Harvey White
 

On Thu, 04 Jan 2018 13:03:33 -0800, you wrote:

On Thu, Jan 4, 2018 at 12:38 pm, Harvey White wrote:


I look at most of the specs other than the 0 ohms and disregard them.
The physical size, of course, is an item to consider.
I was thinking to disregard the 0 Ohm specs.

Makes sense as option selectors. I wasn't sure as like with the electrolytic capacitors if there is some sort of fail safe mechanism where the cheaper component fails before a more expensive or harder to source component fails, albeit, the caps can create more long term business. :-|
About the only thing that would be a fail safe mechanism would be
either a small (10 ohm or so) resistor in series with a power line.
This adds a bit of filtering for low currents. If the current is
substantial, you lose 1 volt per 100 ma at that resistor value.
Generally, I have not seen anything that protects capacitors. The
inrush current is substantial and is likely to exceed the rating of a
fuse. There are thermistor inrush protectors (NTC resistors) that
were designed into older television sets. Haven't seen that in a more
modern piece of equipment.



In regards to size, SMD/SMT is new to me (I haven't done electronics circuit work, other than a little in an instrumental analysis course, since the early 90's SCIENCE PROBE projects) and I was wondering since noted as "1206" and I couldn't find 0.125W at that size. I ordered "0805" which are a little shorter, i.e. .04"
IIRC, the 1206 is 0.12 by 0.060. The 0805 is 0.08 by 0.05. My
experience is that you can, with a bit of difficulty, put an 0805 in
the space of a 1206, but the other way is more difficult.

I figure that 4 tenths of an inch can be made up in the avg of the two solder blobs widths.
not neatly, of course.

Harvey

Thanks for detailing Harvey.




Re: TDS-520

jafinch78 .
 

On Thu, Jan 4, 2018 at 12:57 pm, Artekmedia wrote:


It might be on the actual in house board assembly documentation which likely
does not exist anymore anyway
OK.

I was thinking I'll take the board out and check on the backside. Other than that, I don't see where that number string length is found on the top/front of the board. The closest number I see is a 1117 between J20 and J35.

For now I can go by what is on the board indicating, where U4 isn't present. Thanks Dave


Re: TDS-520

jafinch78 .
 

On Thu, Jan 4, 2018 at 12:38 pm, Harvey White wrote:


I look at most of the specs other than the 0 ohms and disregard them.
The physical size, of course, is an item to consider.
I was thinking to disregard the 0 Ohm specs.

Makes sense as option selectors. I wasn't sure as like with the electrolytic capacitors if there is some sort of fail safe mechanism where the cheaper component fails before a more expensive or harder to source component fails, albeit, the caps can create more long term business. :-|

In regards to size, SMD/SMT is new to me (I haven't done electronics circuit work, other than a little in an instrumental analysis course, since the early 90's SCIENCE PROBE projects) and I was wondering since noted as "1206" and I couldn't find 0.125W at that size. I ordered "0805" which are a little shorter, i.e. .04"

I figure that 4 tenths of an inch can be made up in the avg of the two solder blobs widths.

Thanks for detailing Harvey.


Re: TDS-520

ArtekManuals
 

On 1/4/2018 3:43 PM, jafinch78 . wrote:

I'm still not finding the board ID number on my board yet and haven't read in the manual where found.
I have NEVER, In any TEKTRONIX MANUAL, seen a note as to where the board part number is to be stamped. It might be on the actual in house board assembly documentation which likely does not exist anymore anyway
-DC
manuals@...

--
Dave
Manuals@...
www.ArtekManuals.com


Re: TDS-520

jafinch78 .
 

On Wed, Jan 3, 2018 at 06:31 am, Siggi wrote:


On which schematic page did you find R1999? To determine whether R1998 is a
strapping resistor, you might see whether one of the unused pads shares a
track with one end of R1999. If so, then it's likely that their purpose is
to select some kind of an alternative.
Like DC noted, there is a typo on the manual and the resistors are found at 11-12, not 11-14.

There is a note there also noting if 32K RAMS installed, do not place R1998. I'll assume for now that is what is installed, though will verify as I see discrepancies where other resistors are placed and chip is not, i.e. U4.

I'm still not finding the board ID number on my board yet and haven't read in the manual where found.


I noticed the board has room for larger chips where on 11-14 the chips are memory and note 128k. Is this for option 1M? I wonder if these can be increased? I'm guessing will have to study why, how and what the circuit for the memory will require, and existing board circuit capabilities.

Would be great if there was an replaceable electrical components part list as with the TDS-520B manual for the TDS-520.


Re: TDS-520

Harvey White
 

On Thu, 04 Jan 2018 12:08:23 -0800, you wrote:

On Thu, Jan 4, 2018 at 05:11 am, Raymond Domp Frank wrote:


Love that!
????

Yeah..., so..., I at first was thinking they act like MOV's or fuses. I'm still thinking that. I was almost going to just bridge to see what happens... then decided instead of waiting 20 days for the Digikey or Mouser order... I bought a 3,000+ reel for ~$15 more that will be here in a few days and I can resell the reel.
Actually, I've seen them as option selectors. I've used them on
double sided homemade boards to bridge a track when I did not wish to
put in a jumper.

I look at most of the specs other than the 0 ohms and disregard them.
The physical size, of course, is an item to consider.

When making a PC board, and having options to select, there are
several useful options:

1) posts and shorting jumpers
2) dip switches
3) solderable jumper pads
4) 0 ohm resistors

Of all of them, the only one that can be profitably automated for pick
and place machines is the 0 ohm resistor.

Harvey



Interesting asking around and learning about the differences in the board models also. I still need to read more into the board design I have and the different models options to see what this model A11 (as well as other) board(s) can be upgraded into.

I purchased the Artek manual and appears no different than what I found online or was able to receive from Tektronix when I contacted them. I forgot when I contacted their support, they gave me links to a few manuals they had.

The HP8640B OPT323 PDF is way awesome and saved me from requesting a FOIA Request from the USAF to hunt down which department/office has a hard copy. The actual manuals are neat to have and I am thinking I will still try to hunt an original hard copy down.



Re: Tek 547 A Sweep display during retrace

Dave Wise
 

Morris, I see that Q184 is operated in common-base mode with a low-impedance return through D182 when UNBLANKING GATE LOCKOUT from D481 is inactive (negative). In that state, almost anything will work for Q184. There's no speedup cap issue like there is with Q373.

There might be some sluggishness turning off the beam if the lockout goes active (positive) while Q184 is on. I don't know if that's the case; my guess is that Q184's emitter is de-energized first.

Since active lockout is only about +5V, you need not be concerned about zenering the B-E junction.

This offers a simple hack for a bad Q373: just replace it with Q184, then put whatever in Q184. That works until you lose the second 2N2207.

Thanks for the de-cap. I believe the white pasty stuff was for passivation, as there was no germanium process analogous to silicon dioxide. It was either vacuum or dunk it in gunk. When I was a kid I cut open a TO-1 package. It was full of a clear gel. Silicone oil?

Dave Wise
________________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Morris Odell <vilgotch@...>
Sent: Thursday, January 04, 2018 1:34 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tek 547 A Sweep display during retrace

I’ve come late to this thread but as it happened last week I had to deal with just this problem in the B sweep of my 547. The problem was a failure of Q184, a 2N2207 that amplifies the sweep intensification pulse for the B sweep. According to the schematic that transistor runs at a Vce of 67 volts. I replaced it with a BC640, all of 95cents from the local electronics emporium. It was the only higher voltage (80V) PNP they had with Cin = 110 pf, Cout = 9.0 pf, Ft = 150 MHz. The leads needed a bit of persuasion to fit the socket but hey, you’ve got to work with what you’ve got.



I tried to autopsy the 2N2207 to see if I could see whiskers or anything else abnormal under a microscope. After decapitating it I found it was full of white pasty material resembling dried up thermal heatsink compound. I couldn’t clean it all out properly to see the innards so it went in the bin. The 547 is as good as new and still my favourite scope.



Morris







Re: Tek 547 A Sweep display during retrace
From: Dave Wise <mailto:david_wise@...?subject=Re:%20Tek%20547%20A%20Sweep%20display%20during%20retrace>
Date: Wed, 03 Jan 2018 17:22:21 PST

BC556 + 220pF is 55ns/30ns, the same on-time as the 2N2207. The Pro-Electron C-B-E pinout makes it easier to use than KSA992.

Two more base-in-the-middle parts:
MPSA56 + 470pF is 55/30.
PN2907A + 470pF is 60/30.

And there's a laugh - the PN2907A was what I tried something like ten years ago and gave up!



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Re: TDS-520

jafinch78 .
 

On Thu, Jan 4, 2018 at 05:11 am, Raymond Domp Frank wrote:


Love that!
????

Yeah..., so..., I at first was thinking they act like MOV's or fuses. I'm still thinking that. I was almost going to just bridge to see what happens... then decided instead of waiting 20 days for the Digikey or Mouser order... I bought a 3,000+ reel for ~$15 more that will be here in a few days and I can resell the reel.

Interesting asking around and learning about the differences in the board models also. I still need to read more into the board design I have and the different models options to see what this model A11 (as well as other) board(s) can be upgraded into.

I purchased the Artek manual and appears no different than what I found online or was able to receive from Tektronix when I contacted them. I forgot when I contacted their support, they gave me links to a few manuals they had.

The HP8640B OPT323 PDF is way awesome and saved me from requesting a FOIA Request from the USAF to hunt down which department/office has a hard copy. The actual manuals are neat to have and I am thinking I will still try to hunt an original hard copy down.


Re: 2465B CTT calibration question

 

Thanks to those that replied. I was able to perform the calibration by just using a 1MHz 1v peak to peak signal from a TXCO.


Re: TDS-520

 

Also, are the 0 Ohm resistors 1%, 0.125W, TC=100PPM, 1206, T&R like on the TDS-520B?
Love that!

Raymond


Re: Tek 2465b with down shifted display..

Siggi
 

On Wed, Jan 3, 2018 at 16:20 Mark Hatch <mark2382@...> wrote:

Siggi

Thank you for the reply! The 2456b did arrive and it now appears to have
what appears to be classical u400 failure. Channels 3 and 4 are fine and
when you put a sine wave into either channel 1 or 2 and move vertical
position up down, it gets compressed vertically at top and bottom.

The only thing that I am still a little worried about is that the output
text is shifted down. Wasn’t clear from other u400 reports whether that was
a symptom or not.

Any thought whether I am guessing right on the u400?

Sounds like a reasonable guess, though without seeing the problem first
hand it’s hard to say. Maybe you could post a video for posterity and the
groups edumafication?
Note that problems in the readout switching can also affect CH1/2 and the
readout. See e.g. https://groups.io/g/TekScopes/message/117824.

Have a used one on the way and planned to put it in after doing a quick
voltage and ripple test for anything that could fry the new u400


Re: Tek 547 A Sweep display during retrace

Morris Odell
 

I’ve come late to this thread but as it happened last week I had to deal with just this problem in the B sweep of my 547. The problem was a failure of Q184, a 2N2207 that amplifies the sweep intensification pulse for the B sweep. According to the schematic that transistor runs at a Vce of 67 volts. I replaced it with a BC640, all of 95cents from the local electronics emporium. It was the only higher voltage (80V) PNP they had with Cin = 110 pf, Cout = 9.0 pf, Ft = 150 MHz. The leads needed a bit of persuasion to fit the socket but hey, you’ve got to work with what you’ve got.



I tried to autopsy the 2N2207 to see if I could see whiskers or anything else abnormal under a microscope. After decapitating it I found it was full of white pasty material resembling dried up thermal heatsink compound. I couldn’t clean it all out properly to see the innards so it went in the bin. The 547 is as good as new and still my favourite scope.



Morris







Re: Tek 547 A Sweep display during retrace
From: Dave Wise <mailto:david_wise@...?subject=Re:%20Tek%20547%20A%20Sweep%20display%20during%20retrace>
Date: Wed, 03 Jan 2018 17:22:21 PST

BC556 + 220pF is 55ns/30ns, the same on-time as the 2N2207. The Pro-Electron C-B-E pinout makes it easier to use than KSA992.

Two more base-in-the-middle parts:
MPSA56 + 470pF is 55/30.
PN2907A + 470pF is 60/30.

And there's a laugh - the PN2907A was what I tried something like ten years ago and gave up!



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http://www.avg.com


Re: 5440 No Trace

magnustoelle
 

Good Day,

Rick, I am glad to hear you have fixed this by replacing R410. Nice to hear that another 5440 is back to operation.

Cheers,

Magnus

On 04/01/2018 03:22, Rick wrote:
You would think after all the time you guys have spent with me on this repair I'd learn a thing or two. I should have known exactly what the consequences shunting R410, the 3.3 ohm 1/2 watt resistor to the chassis. The first thing I did was confirm it still had the 44v supply to it and saw the voltage drop across down to 10mV. That was a give away because the current draw from the short would burn open the resistor. At 3.3 ohms that 13 watts and that was clearly pointed out to me 10 messages ago. I missed it. Q400 is good. I realized there was no way that resister couldn't not be 100% open especially since it showed no sign of burns. I replaced it and bingo all works perfectly. Still in calibration. All I needed was the new HV Multiplier and a proper install. I did use several layers of heat activated glue heatshrink.

Thank you to all that chimed in. I promise I won't forget what I learned this time. The beauty is it is always something very simple if you can clear you head and listen to learn from advice.

I have several more Tek projects. I still want to fix the excessively high SG505 output and make a notch filter fixture to calibrate it. Also I have an extra AA501 I need to get working. I'll be back.

Rick


Re: Tek 2465b with down shifted display..

Chuck Harris
 

Good advice for the 500 series, the 453, 454, 455, 465, 7000, ...
scopes of that era, but the 2465 family doesn't have any discrete
transistors in the vertical amplifier signal path.

And...

The signal path connections between the various hybrid stages are
all underneath the A1 board, and as such aren't readily reachable.

-Chuck Harris

HankC, Boston, WA1HOS via Groups.Io wrote:

Mark,
I did not see your original post but, as another member suggested, one side of your vertical amp is DOA.Are both channels affected in the same way? If so, the problem is after the channel switch.
This is easily isolated by shorting opposite sides of the amplifier to each other with a short jumper.
If the trace centers up, the problem is prior to the short location.Move the short one stage towards the input until the trace no longer centers.That stage is where the problem is; in all likelihood, one of the transistors in that stage is defective.If you swap those transistors, and the problem shifts the other direction, you have found your problem.It is best to return transistors to their original sockets so you will minimize the affects on the calibration.
HankC, Boston WA1HOS


Re: Tek 2465b with down shifted display..

 

Mark,
I did not see your original post but, as another member suggested, one side of your vertical amp is DOA.Are both channels affected in the same way?  If so, the problem is after the channel switch.
This is easily isolated by shorting opposite sides of the amplifier to each other with a short jumper.
If the trace centers up, the problem is prior to the short location.Move the short one stage towards the input until the trace no longer centers.That stage is where the problem is; in all likelihood, one of the transistors in that stage is defective.If you swap those transistors, and the problem shifts the other direction, you have found your problem.It is best to return transistors to their original sockets so you will minimize the affects on the calibration.
 HankC, Boston WA1HOS


Re: 5440 No Trace

Rick
 

You would think after all the time you guys have spent with me on this repair I'd learn a thing or two. I should have known exactly what the consequences shunting R410, the 3.3 ohm 1/2 watt resistor to the chassis. The first thing I did was confirm it still had the 44v supply to it and saw the voltage drop across down to 10mV. That was a give away because the current draw from the short would burn open the resistor. At 3.3 ohms that 13 watts and that was clearly pointed out to me 10 messages ago. I missed it. Q400 is good. I realized there was no way that resister couldn't not be 100% open especially since it showed no sign of burns. I replaced it and bingo all works perfectly. Still in calibration. All I needed was the new HV Multiplier and a proper install. I did use several layers of heat activated glue heatshrink.

Thank you to all that chimed in. I promise I won't forget what I learned this time. The beauty is it is always something very simple if you can clear you head and listen to learn from advice.

I have several more Tek projects. I still want to fix the excessively high SG505 output and make a notch filter fixture to calibrate it. Also I have an extra AA501 I need to get working. I'll be back.

Rick


Re: Tek 547 A Sweep display during retrace

Dave Wise
 

BC556 + 220pF is 55ns/30ns, the same on-time as the 2N2207. The Pro-Electron C-B-E pinout makes it easier to use than KSA992.

Two more base-in-the-middle parts:
MPSA56 + 470pF is 55/30.
PN2907A + 470pF is 60/30.

And there's a laugh - the PN2907A was what I tried something like ten years ago and gave up!


Re: First draft of the Tek knob visual index project

Dano
 

On Sun, Dec 31, 2017 at 09:39 pm, Richard Knoppow wrote:

[snipped]
    I think there are some people who do not have a mail server that
Thunderbird or other mail clients can connect to. I agree its much
better to use a mail client for mailing lists and I happen to use
Thunderbird also.
[snipped]

Yes, that's precisely my issue. I have many domains with domain level rules, and no modern mobile email client can handle it correctly. Therefore, it's just much simpler to login to a webpage. I use any device that's near me or on me to read emails, but I have to wait to get to a PC in order to reply. It's a PITA, but redoing a bunch of domain rules just to make that work, isn't something I'm interested in doing right now. (can't stand typing on mobile devices anyhow, lol.)

Thanks for all the suggestions, they will help down the road!

-Dano

(some of you may remember Eudora, wonder whatever happened to them...)


Re: Tektronix PS280

Twig
 

The link from W140.com that tom jobe posted above does indeed have schematics. That is the good news. The bad news is that the schematics are riddled with errors, as I found when doing some troubleshooting a while ago. Best to take them with a grain of salt if you find something that does not make sense.


Re: First draft of the Tek knob visual index project

Dano
 

On Tue, Jan 2, 2018 at 08:55 am, tronix_cal wrote:

Are you using the Common Design Parts Catalog for any part of the project?
While it doesn't have the useable on code (Knob to Model number) listing, the
dimensions, logos, labeling, method of manufacture (molded/machined) and ID/OD
info is all there, with a directory of drawings. I know of a hard copy I
could borrow. The data could be extracted, without outright copying of the
entire content, couldn't it?
I have that manual, and am planning on scanning in the section with knobs to send to Walter. Just a FYI, in case you don't have easy access to it.

I'm still trying to find ANYONE who has more of those volumes, I'd like to get them scanned in and make them available (hopefully without stepping on toes). I realize they, either don't exist, or they do, and no one wants to part with them. Will have to figure out that hurdle, but no one has responded to my prior request, so that's the first step. Anyone willing to work with me? I have a high speed scanner, however it's only 8.5" x Unlimited, so folded pages will be tougher since they're typically 11x~17.

I have Volume 2 (1988 release), but that's it. I'd love to see those microfiche get scanned in too!

I'll start a new thread when I've got my system(s) setup better for scanning workflow. Feel free to response in the meantime though.

Cheers!

-Dano