Date   
Re: Looking for guidelines for evaluating a 7904 + modules

Craig Sawyers <c.sawyers@...>
 

It's not directly part of your question but you will find that the 7B53A is not the ideal timebase
plugin
for the 7904. The 7B53A was designed for the 100MHz scopes
Indeed. The 7904 is a 500MHz mainframe when used with the correct plugins. Those are the timebase pair
7B80 and 7B85, and to get the full bandwidth you will need 50 ohm plugins - 7A19 single channel (which
will give the full 500MHz) or 7A24 dual channel (350MHz). Or if you want to get really esoteric there
is the 7A21N direct access plugin, which replaces the vertical amp and gives direct access to the
vertical deflection plates. That gives 1GHz bandwidth, but with fixed sensitivity of < 4V/div single
ended or <10V/div differential.

You can go non-50 ohm and use the 7A26, but that will only give you 200MHz.

Anyhow the classic configuration is 7A19, 7A19 (option 4, with variable delay), 7B85, 7B80

Craig

Re: Looking for guidelines for evaluating a 7904 + modules

Roger Evans
 

It's not directly part of your question but you will find that the 7B53A is not the ideal timebase plugin for the 7904. The 7B53A was designed for the 100MHz scopes which have a longer delay line and the trigger delay of the 7B53A is matched to this signal delay so that you do get to see the trigger point. The 7904 has a shorter signal delay because of the much higher bandwidth and you will not be able to see the trigger point with the 7B53A. It's not much of an issue for getting the system up to spec but becomes problematic if you want to use it in anger.

Roger

Re: Looking for guidelines for evaluating a 7904 + modules

nonIonizing EMF
 

On Fri, Sep 6, 2019 at 02:58 PM, Harvey White wrote:


With no real independent standards, all you can really do is to make sure that
the scope is self consistent.
The review of the scopes I've acquired 7904, TDS-520(B), TDS-540, TDS-744 and TDS-8000(B) qualifications/validations/calibrations led me into the situation where I am and last left off reviewing what are the most cost effective systems on the market. I determined I'd just invest in the modules recommended at first and still am. Then I observed I might, and I think am, able to make equivalent and better than or lets say equivalent to modules or devices more cost effectively.

This would be an interesting discussion to elaborate on more for the broke student, victim/disabled or retired with shady investment managers. For those that can afford, I say by more new equipment and give away your old equipment cost effectively or lets say free. B^)

To my amazement where not only the cost of the previously noted systems I invested in, the cost of equivalent or better than systems to use for standard references since there really isn't as much other than electrochemical standard reference materials that can be dirt cheap (I think) other than the frequency standards and components on the market that have improved in performance. Most more modern systems seem to be made to not last longer term, be repairable as easy and not meet the quantitative specifications.

Last I left off were diodes and who has cost effective diodes still on the market and where do we find or are there other more modern circuits for higher frequency/rate testing? The TDS-8000 design specs were still overwhelming me in study. Looking forward to getting back into this fall/winter with the PMI/Wavetek systems since those fit into the 5000 series mainframes (D10/D11/D14).

Re: Looking for guidelines for evaluating a 7904 + modules

Jean-Paul
 

Hello there

The plug-ins cal is easier if you can find or make a plug-in extender, the original TEK Extenders came in a black suitcase and there were both rigid and flat cable types The set of extenders is very rare to find and thus costs $$$ $ on epay.

Various DIY versions exist, finding the right connectors is the challange .

Without extenders, you remove the scope covers for limited access on one side of the plug-ins.
I was fortunate to find the original Tektronix extender set in its suitcase, at the time I didn't know of its existence and just got the suitcase out of curiosity.

Bon courage

Jon

Re: TN500 Plugin 067-0699-99

Dave Casey
 

Looks like the ohmeter probes are 2-pin Lemo similar to what Tek used in
other places with more pins. The connectors can still be bought, sometimes
at a decent price on eBay, so making up some probes should be pretty easy.

Dave Casey

On Fri, Sep 6, 2019 at 2:59 PM bobh@... <bobh@...> wrote:

These photos aren't good but give you an idea what it looks like
especially the front panel and connectors.?? I'll get some better pics
later for TekWiki.

https://groups.io/g/TekScopes/album?id=95106

Bob.


On 9/5/2019 8:30 PM, Craig Sawyers wrote:
Does anyone have any information on a Tektronix TM500 plugin
067-0699-99?
I think that Tek parts designators that ended in -99 were in-house
calibration units. So it is likely
you will find it difficult to find a manual, or even the specification.

But the point has already been made - take a good series of front panel,
and internal shots with the
covers off and post them to Tekwiki.

Craig






Re: Repair of TDS7x04 PSU Front End - schematic, parts, and notes

Glenn Little
 

If you replace all the electrolytics in the power supply, you have a 95+% probability of fixing the supply.
Replace the caps with 105 degree C parts and select parts that have the lowest ESR and will handle the highest ripple current.
You can verify the condition of the capacitors with a capacitance meter that will measure ESR.
These are available on EBay from China for very little money and a very useful piece of test equipment.

Glenn

On 9/6/2019 7:23 PM, Mlynch001 wrote:
John,

Very interesting! I have a TDS460A which has what I believe to be a bad LVPS. Turned it one one evening, turned it Off, went back the next day and nothing happens. No power whatsoever and the Service manual is very little help. The tests that they say to run all point toward an???bad??? LVPS. Of course, no one has a new one, except some person in China and they want $250 with shipping, and you will probably have import duties on top of that. There is nothing online or anywhere else that remotely resembles the SMPS in the 460A. I???m not experienced enough to pick my way through the thing without a schematic. SMPS repairs are just Greek to me.
--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"

Re: Tek 576 CT ... Replacement of HV transformer with a modern DC/DC HV converter module ?

Ed Breya
 

The cores on many HP scope HV transformers I have are the same size as the Tek ones too. I believe this was a standard size of big-window EE, for use in HV parts in this power level class. They are not optimized for best use of core volume for efficiency and power density, rather for plenty of clearance around the HV winding. Tek, HP, and others may have used the same parts. The ferrites may be the same or equivalent types, and the gaps (in the case of center-leg gapping) were probably standardized for various A sub-L values.

There are pluses and minuses associated with the various ways of providing the gap. Grinding the center leg adds cost, so using one regular and one ground is cheapest, strictly speaking. But, then there are multiple part numbers, and the possibility of getting them mixed up in production (three possible outcomes). Having half the gap in each core allows for all uniform, but slightly more expensive parts, and no chance of mix up. Using shims allows for using all un-gapped cores, and customizing A sub-L, but adds labor to assembly, extra part numbers for shims, and the chance of mix up or even core breakage. Technically, it's best to have the gap only in the middle, with a ground center leg. Shimmed cores divide the gap into three parts, and the outer legs emit more leakage flux.

The CC cores commonly used in higher voltage like flybacks for TVs, have even more clearance available (and are also sub-optimal otherwise), and have the gaps set with shims.

Anyway, you won't see these styles of cores used in "ordinary" power conversion applications - yup - because they are sub-optimal, and always have been. They really only are for HV and other more exotic uses, but I would think they're still made and available - just not so much as in the good old days. Even though CRTs have been in decline, there are still lots of other HV applications. I haven't needed to look for such items since I have lots already, but I believe including the high-voltiness aspect in the searching should show some useful hits. Maybe try "high voltage ferrite" and things along that line. Other terms that may help: flyback, clearance, opening, CRT, isolation, universal-wound, window, C-core, wide, etc - anything that may be descriptive or associated. BTW, a couple of the big makers of these, as I recall were Ferroxcube and TDK - forty or fifty years ago.

Getting back to my earlier post, when it come to searching for other HV transformers that may be usable, I'm not worried about the core too much, but the HV winding and its suitability for direct 4 kV use, and the possible range of turns on the other windings.

Ed

Re: Repair of TDS7x04 PSU Front End - schematic, parts, and notes

Mlynch001
 

John,

Very interesting! I have a TDS460A which has what I believe to be a bad LVPS. Turned it one one evening, turned it Off, went back the next day and nothing happens. No power whatsoever and the Service manual is very little help. The tests that they say to run all point toward an”bad” LVPS. Of course, no one has a new one, except some person in China and they want $250 with shipping, and you will probably have import duties on top of that. There is nothing online or anywhere else that remotely resembles the SMPS in the 460A. I’m not experienced enough to pick my way through the thing without a schematic. SMPS repairs are just Greek to me.
--
Michael Lynch
Dardanelle, AR

Re: 535A CRT in a 575 - clever trick?

Mlynch001
 

You will appreciate the 10 cm vertical range. It makes the math so much easier. The 577 uses an 8 cm vertical x 10cm horizontal display graticule and this is noticeably smaller when compared side by side with the Type 576, which is a 10x10 graticule (with 12cm horizontal, total usable). Seems like a great way to go to me. Either way your calibration will need to compensate for the change in one axis or the other. I read a post from someone that stated that the 577 can be fitted with a 10x10 cm display from some special 5xxx series scope that had this special option and recalibrated accordingly. The 577 supposedly has sufficient trimmer range to accomplish this. I’m fairly confident that the 575 would be able to handle the change as well. All that being said, since a 575 CRT is almost unobtanium, I would sure go this route, rather than having a non-working instrument. Should be able to find a 535A CRT much easier than the 575.

--
Michael Lynch
Dardanelle, AR

Repair of TDS7x04 PSU Front End - schematic, parts, and notes

John Bennett
 

I just completed repair of the PSU of a dead TDS7404. SInce I could not find much on-line help, I thought my notes might be helpful to others.
Here is a link: https://groups.io/g/TekScopes/files/Repair%20of%20the%20TDS%207x04%20PSU%20Front%20End.pdf
Best,
john
AE0AM

Re: Wanted; Person to repair Tektronix 2465 DVS

jhalbrecht
 

On 9/6/2019 3:03 PM, Chuck Harris wrote:
The serial number is on the front panel.
s/n B030668

This is the hardest version of the 2465B scopes to work
on. It is packed full of boards and cables that most don't
have.

I repair them, but there is a premium for the pleasure of
dealing with all of the extra work required.

Contact me off group for rates, etc..

Honestly, most of the time Dave Jones is a great example of
what not to do in electronics repair.
The video does show me what I'm getting into before I decide to open it up.

 - Jeff


-Chuck Harris

jhalbrecht wrote:
On 9/6/2019 12:59 PM, Chuck Harris wrote:
Your scope is suffering from electrolyte leakage on the
A5 board most likely. If it is SNB050000 or greater, most
definitely.
Hi Chuck and channel,

s/n: Shoot on the inside I guess??

I added another image to the Dropbox collection of images, see IMG_5784.jpg. This one
of me hitting the Beam finder.

I found a video by Dave Jones with some teardown detail in case I decide to open it
up. I'm concerned that I'll start getting to deep into it, wind up with extra parts
and unable to cram the springy snake back into the peanut can.

#Tektronix <https://www.youtube.com/results?search_query=%23Tektronix>#2465B
<https://www.youtube.com/results?search_query=%232465B>#Repair
<https://www.youtube.com/results?search_query=%23Repair>


EEVblog #1203 - REPAIR: Tektronix 2465B Oscilloscope

https://www.youtube.com/watch?v=Rp-0FqxQkBw

Of the couple knobs for time base and the toggle for ch. 2 How deep will I have to
dig to replace that switch handle? The switch operates if I use a plastic choke
screwdriver to flip it....

- Jeff






-Chuck Harris

jhalbrecht wrote:
Hello Tektronix enthusiasts,

I originally posted this in
https://groups.io/g/Test-Equipment-For-Sale-Wanted-or-Exchange/message/1056 I'm
hoping for more exposure in this group specific to Tektronix.

I'm wondering if I might find someone that would like to do some repairs for me. I
want to save this 'scope for my collection of old computers and related equipment.
https://www.theretrowagon.com/the-retro-wagon-debut-at-desert-code-camp-2016/ I
can pay something, I'm not asking for free but I can't justify 'depot' prices.
Someone near Mesa Arizona, where I reside, might help reduce shipping costs.

I bought a large lot of vintage computer equipment and amongst the mostly junk
were some diamonds in the rough. I think this Tektronix 2465 DVS is pretty cool.
Unfortunately it suffers from 'Test 05 Fail 42' which I believe is a triggering
problem, I haven't been able to get a trace. I also have some donor 2445 and a
bunch of repair manuals. Lots of pictures on dropbox;
https://www.dropbox.com/sh/ul4i0xnaakb01gf/AADPNQDCigzyeN9vELEndWNJa?dl=0

I think it would be a nice exhibit in my collection. I guess these are for sale if
I can't find someone to repair the 2465 DVS.

- Jeff

KF7CRU @jhalbrecht @TheRetroWagon





Re: TN500 Plugin 067-0699-99

Bob Headrick
 

This is way off topic, but RG-174 is 50 Ohms. RG-179 is a similar size but
75 Ohms.

Folks offering RG-174 as 75 Ohm should probably be avoided....

In this application it does not matter, the instrument in question is DC
levels.

- Bob W7OV

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Daveolla
Sent: Friday, September 6, 2019 10:03 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] TN500 Plugin 067-0699-99

It does not seem like a goof as it is printed right on the cable RG174 75
ohms SEE ENCLOSED PIC If you google RG174 75 ohms you will see it
referenced.
[snip]

Re: red "paint" on nuts of old Tektronix chassis hardware

 

Unless there is some curious thing going on here they are there to lock the nuts and indicate if they’ve been moved

On 6 Sep 2019, at 22:13, Jamie Ostrowski <jamie.ostrowski@...> wrote:



The nuts that hold the capacitors and tube sockets onto the chassis of the 500 series scopes have red material on them. Looks like it could be paint marks. Or is it some kind of thread-locking compound? Does anyone know what those markings are for or what chemical they are made from (ie a lacquer paint)?


Re: Wanted; Person to repair Tektronix 2465 DVS

Chuck Harris
 

The serial number is on the front panel.

This is the hardest version of the 2465B scopes to work
on. It is packed full of boards and cables that most don't
have.

I repair them, but there is a premium for the pleasure of
dealing with all of the extra work required.

Contact me off group for rates, etc..

Honestly, most of the time Dave Jones is a great example of
what not to do in electronics repair.

-Chuck Harris

jhalbrecht wrote:

On 9/6/2019 12:59 PM, Chuck Harris wrote:
Your scope is suffering from electrolyte leakage on the
A5 board most likely. If it is SNB050000 or greater, most
definitely.
Hi Chuck and channel,

s/n: Shoot on the inside I guess??

I added another image to the Dropbox collection of images, see IMG_5784.jpg. This one
of me hitting the Beam finder.

I found a video by Dave Jones with some teardown detail in case I decide to open it
up. I'm concerned that I'll start getting to deep into it, wind up with extra parts
and unable to cram the springy snake back into the peanut can.

#Tektronix <https://www.youtube.com/results?search_query=%23Tektronix>#2465B
<https://www.youtube.com/results?search_query=%232465B>#Repair
<https://www.youtube.com/results?search_query=%23Repair>


EEVblog #1203 - REPAIR: Tektronix 2465B Oscilloscope

https://www.youtube.com/watch?v=Rp-0FqxQkBw

Of the couple knobs for time base and the toggle for ch. 2 How deep will I have to
dig to replace that switch handle? The switch operates if I use a plastic choke
screwdriver to flip it....

- Jeff







-Chuck Harris

jhalbrecht wrote:
Hello Tektronix enthusiasts,

I originally posted this in
https://groups.io/g/Test-Equipment-For-Sale-Wanted-or-Exchange/message/1056 I'm
hoping for more exposure in this group specific to Tektronix.

I'm wondering if I might find someone that would like to do some repairs for me. I
want to save this 'scope for my collection of old computers and related equipment.
https://www.theretrowagon.com/the-retro-wagon-debut-at-desert-code-camp-2016/ I
can pay something, I'm not asking for free but I can't justify 'depot' prices.
Someone near Mesa Arizona, where I reside, might help reduce shipping costs.

I bought a large lot of vintage computer equipment and amongst the mostly junk
were some diamonds in the rough. I think this Tektronix 2465 DVS is pretty cool.
Unfortunately it suffers from 'Test 05 Fail 42' which I believe is a triggering
problem, I haven't been able to get a trace. I also have some donor 2445 and a
bunch of repair manuals. Lots of pictures on dropbox;
https://www.dropbox.com/sh/ul4i0xnaakb01gf/AADPNQDCigzyeN9vELEndWNJa?dl=0

I think it would be a nice exhibit in my collection. I guess these are for sale if
I can't find someone to repair the 2465 DVS.

- Jeff

KF7CRU @jhalbrecht @TheRetroWagon






Re: Tek 576 CT ... Replacement of HV transformer with a modern DC/DC HV converter module ?

Chuck Harris
 

The cores on just about everything tektronix are the same,
nominally.

I have rewound 545B transformers on cores from pretty much
everything at one point. I am pretty sure that even the
2465 HV core would work, as would any of the 5000 series.
They have notches to handle a different form of clamping,
but that doesn't matter.

Tek was a big customer of Allen-Bradley Magnetics Division.
TDK Magnetics bought AB Magnetics, and as far as I can tell,
scrapped them.

%he 576, and indeed all of the 500 series used an AB,
W5 type ferrite, core, E1960S011A (no gap) and E1960S021A
(0.015" gap).

In later scopes, the gap was on both halves, and 0.007".

Dimensions are:

Outside: 1.960" +/- 0.050"
Inside : 1.408"
Center: 0.488 +/- 0.010"
Width: 0.520" +/- 0.015"
1/2 Height: 0.625" +/- 0.010"

The legs and cross section are rectangular, and the center
post is octagonal in shape approximating a circle.

As far as I can tell there is nothing like it in the world
available new.

I have all of the spec sheets.

-Chuck Harris

John Williams wrote:

Hi Ed. I was wondering if you had explored the possibility that the 575 hv transformer is similar or even the same as used in other models. As it used a common crt, I wonder if they also used a common transformer? Maybe another option?



Re: Looking for guidelines for evaluating a 7904 + modules

Harvey White
 

On 9/6/2019 2:16 PM, John Hudak via Groups.Io wrote:
I acquired a 7904 with the following modules: 2 - 7A26, 7A19, and 7B53AFor the most part, the scope seems to work OK.  It has been sitting unused in a bedroom for 15+ years. Prior to that it was in a lab, used quite a bit in the 80s and not much from there on.  Ironically, this is the scope I bought for my lab in 1979. (Deja vu all over again...)

I have the manuals for the base unit and all the plugins and have read the calibration procedure for the 7904 base unit.  My goal is to calibrate the scope and bring it to spec.
I have a few questions regarding procedure:1) Is it better to check/align each plugin by itself and then integrate them into the mainframe and then do an overall calibration, or  do the calibration of the overall unit?
No, as mentioned, calibrate the frame first, then the plugins. You'd *like* an input standardizer, get the one for the 500 mhz scopes.  The input standardizer will allow you to work independently of the plugins.  It's most useful when you have multiple mainframes.

What you *can* do (and this requires some specialized equipment), is to calibrate one plugin and the 7B53A.  Calibrate the other vertical plugins to the resulting standard.  Make sure that the two vertical and horizontal plugin slots are complete.

With no real independent standards, all you can really do is to make sure that the scope is self consistent.  If you had the input standardizer, you can get repeatable results across mainframes.

There's an entire slew of equipment intended to calibrate tek scopes, look at the TM500 or TM5000 modules, although there are some older pieces of tek tube equipment.

Harvey



2) Are there any websites that explain/describe the procedure and any 'tricks' to use or pitfalls to be aware of?
I am a EE and do embedded systems hw and sw design and have not really gone down the road of restoring/calibrating tek scopes, so any pointers would be very helpful.ThanksBest regards,J



Re: Wanted; Person to repair Tektronix 2465 DVS

jhalbrecht
 

On 9/6/2019 12:59 PM, Chuck Harris wrote:
Your scope is suffering from electrolyte leakage on the
A5 board most likely. If it is SNB050000 or greater, most
definitely.
Hi Chuck and channel,

s/n:  Shoot on the inside I guess??

I added another image to the Dropbox collection of images, see IMG_5784.jpg. This one of me hitting the Beam finder.

I found a video by Dave Jones with some teardown detail in case I decide to open it up. I'm concerned that I'll start getting to deep into it, wind up with extra parts and unable to cram the springy snake back into the peanut can.

#Tektronix <https://www.youtube.com/results?search_query=%23Tektronix>#2465B <https://www.youtube.com/results?search_query=%232465B>#Repair <https://www.youtube.com/results?search_query=%23Repair>


EEVblog #1203 - REPAIR: Tektronix 2465B Oscilloscope

https://www.youtube.com/watch?v=Rp-0FqxQkBw

Of the couple knobs for time base and the toggle for ch. 2 How deep will I have to dig to replace that switch handle? The switch operates if I use a plastic choke screwdriver to flip it....

- Jeff







-Chuck Harris

jhalbrecht wrote:
Hello Tektronix enthusiasts,

I originally posted this in https://groups.io/g/Test-Equipment-For-Sale-Wanted-or-Exchange/message/1056 I'm hoping for more exposure in this group specific to Tektronix.

I'm wondering if I might find someone that would like to do some repairs for me. I want to save this 'scope for my collection of old computers and related equipment. https://www.theretrowagon.com/the-retro-wagon-debut-at-desert-code-camp-2016/ I can pay something, I'm not asking for free but I can't justify 'depot' prices. Someone near Mesa Arizona, where I reside, might help reduce shipping costs.

I bought a large lot of vintage computer equipment and amongst the mostly junk were some diamonds in the rough. I think this Tektronix 2465 DVS is pretty cool. Unfortunately it suffers from 'Test 05 Fail 42' which I believe is a triggering problem, I haven't been able to get a trace. I also have some donor 2445 and a bunch of repair manuals. Lots of pictures on dropbox; https://www.dropbox.com/sh/ul4i0xnaakb01gf/AADPNQDCigzyeN9vELEndWNJa?dl=0

I think it would be a nice exhibit in my collection. I guess these are for sale if I can't find someone to repair the 2465 DVS.

- Jeff

KF7CRU @jhalbrecht @TheRetroWagon



Re: red "paint" on nuts of old Tektronix chassis hardware

Chuck Harris
 

It is most probably red glyptol, which is a red paint used
to lock nuts to screws, and as a marking agent.

It's an enamel, I think.

It kept tektronix from having to deal with customers that had
scopes arrive dead on arrival because a nut loosened and dropped
into something important.

-Chuck Harris

Jamie Ostrowski wrote:



The nuts that hold the capacitors and tube sockets onto the chassis of the 500 series scopes have red material on them. Looks like it could be paint marks. Or is it some kind of thread-locking compound? Does anyone know what those markings are for or what chemical they are made from (ie a lacquer paint)?



Re: Tek 576 CT ... Replacement of HV transformer with a modern DC/DC HV converter module ?

Ed Breya
 

No, I have not looked at the 575 transformer, for two reasons. First, I don't have one, and second, for a substitute in a rare or high-value thing like a 576, you don't want to sacrifice a different rare or high-value thing. The best candidates would be among units that are common, cheap, and plentiful. If you happen to have such parts anyway, then no big deal.

I have a bunch of mostly old Tek and HP HV transformers saved over the years, so started with what's on hand.

Ed

red "paint" on nuts of old Tektronix chassis hardware

Jamie Ostrowski
 

The nuts that hold the capacitors and tube sockets onto the chassis of the 500 series scopes have red material on them. Looks like it could be paint marks. Or is it some kind of thread-locking compound? Does anyone know what those markings are for or what chemical they are made from (ie a lacquer paint)?