开云体育

So... getting back to it... After replacing Q1418 with a unit from a 464 that I have (also has a CRT fault).

Q1416 shows very similar traces, all three the same (EBC), but now at about 150mV p-p (previously about 120mV p-p).

The big change is Q1418 traces. There's much more DC bias now on the collector. See here: /g/TekScopes/photo/49286/11?p=Name,,,20,1,0,0

Current through F1419 still about 160mA.

HV tp is around -72V.

So... ??? Not sure how to proceed.

Hmmm...I too was going to suggest annodizing in situ.First clean the surface, and perhaps sandblast or bead blast with e.g. walnut shells (if you have that option) to match the surface roughness.? ?Then build a dam with wax around the area to hold some anodizing solution, and anodize the fresh scratches.
?Anodization is a VOLTAGE limited process.? When you anodize something at a constant current, it builds up oxide on the aluminum surface, which increases proportionally with the voltage applied.? There are two consequences to this.? ?1) you can adjust the thickness of the anodization by adjusting the applied voltage, and 2) the process is uniform.? Freshly exposed metal (i.e. scratched) will anodize preferentially over the adjacent already anodized area, so in principle you might be able to build up the surface over the scratches a bit and have them blend in better.? ?
I would be curious to see if this truly works on a finished panel, and I would certainly practice on junk parts first.? Post pictures!
? Dan

Hi Evan,

I once had an aluminum panel from an old Dumont scope stripped and then
anodized and I applied Dry Transfer Lettering. It took weeks to do all of
this. I did it to make the scope look more "modern". I was 18 at the time.
The scope was to be a gift for a friend. I was very proud of what I was up
to at the time. I look back on this now and have to laugh. I did show it to
my Tek Field Engineer and he figured out pretty quickly that this I had the
'Scope Bug". That led to an interview and a job offer at Tek followed by a
suggestion that I finish college first.

I, too, have plugins where some *!@#$%* moron used an electric engraving
tool to write deep into the surface of the front panel. I don't think there
is anything that can be done once the extremely hard aluminum oxide surface
film created by the anodizing process has been penetrated. I have concluded,
unfortunately, that there is realistically nothing that can be done. I have
resisted suggestions like Harvey's because it creates far more problems than
it solves. For instance:

* This entire process will be extremely time consuming (and time is money).
* It may not be possible to remove enough aluminum to reach the depth of
penetration of the engraving marks.
* Once you have removed the anodized surface the underlying aluminum is soft
and paint is not as hard as anodizing.
* You will have to replace all of the labels, etc.

It is possible to do your own anodizing. I once anodized the top and bottom
covers I made for my dual Shugart 8" drives that I built for my S100
computer. I did it in my bathtub. It was very tricky getting the entire
covers in the tub and into the anodizing chemicals since they were 17"
across and about 20" deep. But I did it and they looked good when I was
done. Just one of the crazy things I have dome in my life.

Anodizing is a way to increase the natural oxide coating that forms on the
surface of all metals. Anodizing changes the microscopic texture of the
surface and the crystal structure of the metal near the surface. Anodized
aluminum surfaces are harder than aluminum but have low to moderate wear
resistance that can be improved with increasing thickness or by applying
suitable sealing substances. The film of anodized aluminum is a form of
aluminum oxide. Ceramics are also made of aluminum oxide and they are
extremely hard. The surface of anodized aluminum is much stronger and more
adherent than most types of paint and metal plating, but also more brittle.
It is less likely to crack and peel from aging and wear, but more
susceptible to cracking from thermal stress.

Dennis Tillman W7PF

TSP heh? They made a good margin on it then. Came in little packets to make 5 gal batch.


Sent from kjo iPhone

Hi Group,

I am working on fixing a 2215 scope I bought the other day.



Didn't power up.. that's now fixed, was a dodgy Zener diode in the pre-regulator board of the SMPS. While waiting for new caps to arrive to recap the SMPS, I thought I would give it a good clean and pamper it. I need a little help finding a little mechanical part that broke.. :-/

It's the "screw" (not the usual lateral/set screw arrangement, but the central/concentric type screw) that holds the delayed sweep knob onto its shaft :

;attach=453070;image

Knob itself is fine. It's just the metal piece/"chuck", tapered, threaded, that bites the splined shaft when tightening the central nut... that I need. This appears to be made of the softest metal Tek could get... no, I swear I didn't use a hammer to tighten it... but still, the threaded part broke.

So if someone has a box of old stuff and maybe have this little part that would save this knob (from a different scope model possibly ?)... I would be very grateful indeed ! :-)

With some luck, does anyone know if this might possibly be some generic piece of hardware, that one could buy from god knows what hardware vendor on-line ? (any links appreciated ! )

What would be a correct name/terminology to describe this part, so I can use the appropriate keyword to try to find some ?
Hopefully one can get one made from a stronger metal...

Thanks for reading anyway....


Regards,


Vincent Trouilliez

On Thu, 14 Jun 2018 19:08:41 +0000 (UTC), you wrote:

Probably best to sand it down and come up with some kind of paint to make it look decent.? I know of no patch for anodize finish that would have a chance of blending in.

If the gouges have material above the surface (don't we adore customer
property retention departments?), then you might remove the panel and
try to roll (or very gently tap with a flat block) the material back
into the grooves. That may help a little.

I'd also sand it as smooth as possible, that can give you a decent
finish. Naturally, that removes the anodize. You may be able to
anodize the exposed aluminum, but I'm not sure, haven't tried any of
this.

Another possibility would be to tap the gouges flat as above, then put
in a completely non-original but perhaps stylish Tektronix logo over
the disfigurement.

It's not a bug, it's a feature.

Harvey

Bob
On Thursday, June 14, 2018, 10:43:07 AM PDT, <thespin@...> wrote:

Hey all,

I've just gotten a 1A4 plugin that has some numbers gouged deep into front. I'd like to do something to make it look better than having the numbers gouged in the front. Does anyone have any suggestions for how to cover up or remove scratches in aluminum anodize? It also looks like under the anodize, it's bead blasted or sand blasted or something to give the uniform finish. Not sure how to replicate this. Any suggestions?

Best,
Evan




| | Virus-free. www.avast.com |

But, alas, what you say is not true. It once was, back when
electrolytic capacitors used rather caustic electrolytes that
ate away the aluminum oxide dielectric layer, but that hasn't
been the case for about 30 years.

It is just fine to raise the voltage rating of an electrolytic
capacitor used as a decoupling cap, filter, bypass, whatever.

It is also just fine to buy only 10uf 160V caps, and use them
to replace both the 10uf 100V caps, and the 10uf 160V cap in
the 2465's power supply.

Just like it was fine when you specified 330uf 50V caps to
replace both the 250uf 20V and the 180uf 40V caps in the
power supply.

This isn't audio gear where you have to worry about how the
end user might "feel" about your choice. You can use valid
technical reasons.

If you need some evidence to back my assertions, grab any old
bag of electrolytic capacitors that have been sitting on the
shelf for years, and measure the capacitance. They will all
measure at the nominal value... after years of being operated
at the extremely low voltage of 0V. I have just such a bag
of nichicons from a project where I overbought the caps. This
was back in the 1970's. They all still read 2200uf +/- 10%.

-Chuck Harris

M Yachad wrote:

Probably best to sand it down and come up with some kind of paint to make it look decent.? I know of no patch for anodize finish that would have a chance of blending in.
Bob

Let's get some clarity on this.

A decoupling cap can USUALLY have the CAPACITANCE increased, but NOT the voltage rating.
Sometimes the cap's VOLTAGE rating should even be decreased, according to the actual circuit voltage.
I hope that's clear!

On these 180uf/40V, the optimum substitute IN THIS CIRCUIT is a 330uF or 470uF/50V, preferably Nichicon PW or HE, but DEFINITELY NOT Panasonic EB. That "updated" list is completely misleading, by listing Panasonic EB caps as "suitable".

On the 10uF/100V caps, with about 80VDC going through them, you do NOT install a 10uF/160V to save money, by buying 10/160's for both the 10/100 and 10/160. You put the correct-rated cap in the correct place.

C1115 and 1132 are WRONG in the manual.
What you pulled out, is EXACTLY what you reinstall.
The 250uF/20V caps are replaced with 330uF or 470uF/25V. PW or HE. Nothing else.

The Film caps as follows - all VISHAY, and ALL confirmed available from Mouser.
I do NOT know about Digikey.
2.2nF BFC233660222 Qty 2
10nF BFC233660103 Qty 1
56nF BFC237241563 Qty 1
68nF BFC233810683 Qty 2

These all have the correct lead pitch, and all fit PERFECTLY, both physically and electrically.

And a last word of caution - if you're looking at other brands/models to save a few cents, then DON'T!
The headaches are NOT worth it.
"Only a rich man can afford to buy cheap"

If somebody would like to take it upon himself to update the "updated 2018" cap list onsite here with regard to these salient points, it would save a lot of newbies and hobbyists headaches, as they trust the knowledge of the men who put this list together, and there should NOT be any errors in that list.

Best of luck!

Menahem Yachad
Jerusalem Israel

Congratulations, Albert!
Must give you that well-known satisfaction that makes us spend so much time on these instruments!

Raymond

Thank you for posting your findings.? Here is a complete answer with rationale for some of my choices.? Hope this helps.

You wrote:>

C1065??? .056 ?F???250??? MTLZD??? ??? .056?F??? 300??? Vishay Polyester?Film??? 399-7635-ND?
The lead spacing is to wide for the replacementpart.? Should be 7.62mm but the part is 14.50mm. I could not find a partthat fits from Kemet or Vishay @ Digi-key.

You are right.? I am sorry I still have that information inthe list.? I gave up trying to fit thatlarge cap and accepted one from Panasonic:?P12080-ND I think it’s a decentchoice but not perfect.

You wrote:>

C1050??? 0.22 ?F???400??? PLSTC??? ???0.22??? 400??? Kemet Polyester???495-4473-ND
The lead spacing is not far enough, are you addingtinned copper wire to lengthen the lead or is this a mistake?

That is a dilemma.? The original fitment is an axial capacitorwith the leads spaced about 33 mm.? Icould find one from Illinois Capacitors 1572-1684-ND ?with a body that is 29 mmlong. ??It costs 1.14 USD and will workwell.? There is also one from Vishay BC2609-NDThat is 31 mm long for 3.48 USD.?I chose to add leads to a radial cap by TDK 495-4473-ND This only cost 0.82 USD but it was not a good choice.? My next recap will be either the Illinois Capacitor or the Vishay.? They might be abit long but there is ample room to raise them from the board and bend theleads back to fit the holes. ?

You wrote>

C1130??? 10 ?F???100??? ELCTLT??? ??? 10?F??? 160??? Nichicon PW???493-11888-3-ND
Link bring up minimum quantity of 500, I think youcan use this link instead? ?
FYI I ordered these and they sent the wrong part.I will find out sometime tomorrow if they have corrected the issue and post anupdate.

Sorry for the confusion.? Digikey corrected my order (from 493-11888-3-ND to 493-11888-1-ND) but I did notcorrect the list.? I meant instead 493-11888-1-ND which is the same cap in small quantities.? I prefer it over your suggestion because ithas a much higher life rating (5000 hours) but only costs 0.08 USD more. ?

You wrote>

For C1120??? 10 ?F???100??? ELCTLT??? ? -->???? 10 ?F??? 160? ,
Can I use is there some benefit to using a 160V cap??

The choice of 160 Volt caps was done years ago bysomeone who made the original list.? Ionly updated it to get longer life.? Multiplemembers of the forum have used 160 Volt substitutes with no reports ofproblems.? I have not looked for 100 voltparts with long life ratings.? But Iprefer my suggestion over the ones you linked to because of the lifetimeratings.

You wrote>

C1132??? 10 ?F???160??? ELCTLT??? ??? 10 ?F???160??? Nichicon PW
I pulled out a 250uf 20v from this location

C1115??? 250?F??? 20??? ELCTLT?????? 330 ?F??? 50??? Panasonic EB
I pulled out a 10uf 160v from this location

I seem to remember reading this is also an error in thedocumentation.

Actually, Tektronix documentation is incorrecthere.? You pulled a 20 volt cap from thelocation MARKED C1132 and a 160 volt cap from a location MARKED C1115.? The markings are interchanged by Tek on everydocument I find for these power supplies.??Take care when putting things back.?Use your Ohm Meter to check that C1115 is connected to L1115.

You wrote>

Also can I use a 20v 10uf cap for C1115 or is the 50V better?I'm just remembering what Menahem said about larger caps... I'm justremembering what Menahem said about larger caps...

The 50 Volt capacitor had a better lifeexpectancy.? Menachem has a good pointabout ESR of higher voltage caps.? But Ithink you will find that in these lower voltages there is little difference inESR between 20 volts and 50 volts.? So Ichose for other reasons.? Sometimes justto make a bulk order of one part number, sometimes because it looked moreuniform on the completed board.? Butalways for higher life and higher capacitance.?(Take note, higher capacitance is not always a good thing so check theapplication before deviating from spec.)

My CSA803 now passes the Self test and Extended diagnostics test.
In an earlier message I wrote that some if the 5 IR sensor groups were never selected during a full scan cycle. It appeared that this was due to a faulty 3-to-8 line decoder 74LS138. I replaced this IC and bingo.
In hindsight I am not 100% sure that it was the IC itself, or a bad solder joint to one of the 3 input lines. After replacement the operation of this IC was not stable. I resoldered the 3 input pins and that cured the problem. Previously I had checked everything for continuity with an ohmmeter and found no bad joints, but now with a probe I saw that the slightest pressure on the pins or on the board changed the results.

The repair time was nothing compared to the total time I spent to find the problem. I nearly completely reconstructed the schematics of the A9 Front Panel Control board and A10 Front Panel board, and the way all circuits are operating. Interesting and "on the fly" I got more insight in the CSA803. Once you know where and what to probe it's fairly simple to detect non-functioning IR pairs.
A silly mistake: after resoldering, all horizontal pairs worked well but still a few of the vertical pairs didn't. Then I realized that the distance from IR Led to sensor is much larger for vertical pairs than for horizontal pairs, and I used the bare board -- without the frame of "lenses" which are supposed to concentrate an IR Led light better on the corresponding sensor. With that frame in place all pairs worked fine.

Hey all,

I've just gotten a 1A4 plugin that has some numbers gouged deep into front. I'd like to do something to make it look better than having the numbers gouged in the front. Does anyone have any suggestions for how to cover up or remove scratches in aluminum anodize? It also looks like under the anodize, it's bead blasted or sand blasted or something to give the uniform finish. Not sure how to replicate this. Any suggestions?

Best,
Evan

Thanks Rich, I'd appreciate that info.

Unfortunately, this one's a goner. I decided to do a "quick" CRT check and rejuvenation attempt, since I found a correct socket on-hand. I wired it up and hit it with a B&K 470. It was unresponsive - so much so that I thought the 470 wasn't working right, which led to a wild goose chase of checking and rechecking the 470 and the wiring, but all seemed normal. The CRT had virtually no K emission at all, and was even dimmer yet when put back in-circuit, so the process did not help, but definitely did something to it. The CRT was too far gone, or too skimpy on K coating anyway. This is the first CRT I've tried that didn't show at least some improvement.

I'll be saving some of the RF sections and parts for possible re-use, so it's good to have schematics, etc for reference. I've already popped the CRT vacuum and put it in the e-waste box for the next recycling run, and the carcass will be stripped soon. Oh well, good thing it was only ten bucks, so no big loss. I got another rejuvenation data point, and some parts out of the deal.

Ed

Kevin wrote:

"This topic brought back memories from an unrelated area of my past. Years ago I was an avid home brewer and wine maker, and needed to recycle bottles with labels. I used a product called Straight-A Label Remover. 2tbsp/gal hot water and soak overnight. Even the most stubborn label would have sluffed off of its own weight by morning! Never was sure what was in it, but but it had that slick feel. Maybe highly ionic or something."

It was likely trisodium phosphate (TSP), a very common cleaner for water-based washing.

Ed

On Thu, Jun 14, 2018 at 06:03 am, zenith5106 wrote:

H?kan

Hi H?kan,

Thanks for the response and link - much appreciated. You are absolutely correct but.before replacing the IC I removed and cleaned the IC Socket (with switch cleaner). The original IC was then re-inserted with the same results. The fault only cleared after replacing the IC I obtained from a cannibalised Tek 465B. Note that I have also cleaned and re-inserted most of the transistors and IC's (sockets - took a long time!) due to possible poor contact, plus cleaned all the switches.

Edward Thomas

This topic brought back memories from an unrelated area of my past. Years ago I was an avid home brewer and wine maker, and needed to recycle bottles with labels. I used a product called Straight-A Label Remover. 2tbsp/gal hot water and soak overnight. Even the most stubborn label would have sluffed off of its own weight by morning! Never was sure what was in it, but but it had that slick feel. Maybe highly ionic or something.

Kjo

On Thu, Jun 14, 2018 at 01:53 am, <edward@...> wrote:

Hi Dieter,

Thanks to Fabio's detailed and clever reasoning (you're very gifted Fabio), I
have found the issue with the Alt mode. The problem turned out to be a
defective U4391 (74LS02) that can be found on diagram 8 (Horizontal Display
Logic A&B Sweep Generator). When measuring pin 3 on this IC there was no
change in state (stayed low) when operating the ALT button in the "Horiz
display" section on the front control panel (after checking the switch first).
Replacing this IC from a butchered 465B restored the Alt mode and the scope
now reliably displays two traces :)

Note that your problem might be caused by a different component failure or
break in the Vert Alt Sync path, but if you follow Fabio's excellent
diagnostics, you will find the problem. Good luck, and another big THANKS to
Fabio, I owe you a drink!

Regards,

Edward Thomas.

Off course you could be right that the IC really was bad. Did you put the original back to confirm ?
Another likely culprit would be bad IC sockets which are known to cause various intermittent problems.
465B from that time are known to have them and if not replaced more problems will probably occur in the future.
To identify the sockets check here:
Note that some of the text and the large picture is incorrect. The smaller pics are right.
/H?kan

I only have a short minute but want to post this.? I will comment more on your other posts later when I have more time.
All Tektronix documentation has the physical locations of C1115 and C1132 interchanged.? You may want to update your documentation of PCB layout to show these two capacitors interchanged.? The power supply will not work if you install new capacitors based on the Tektronix documentation for these two parts.? You can verify the proper positions with your ohm meter.? C1115 positive terminal must connect to L1115.

Hi Dieter,

Thanks to Fabio's detailed and clever reasoning (you're very gifted Fabio), I have found the issue with the Alt mode. The problem turned out to be a defective U4391 (74LS02) that can be found on diagram 8 (Horizontal Display Logic A&B Sweep Generator). When measuring pin 3 on this IC there was no change in state (stayed low) when operating the ALT button in the "Horiz display" section on the front control panel (after checking the switch first). Replacing this IC from a butchered 465B restored the Alt mode and the scope now reliably displays two traces :)

Note that your problem might be caused by a different component failure or break in the Vert Alt Sync path, but if you follow Fabio's excellent diagnostics, you will find the problem. Good luck, and another big THANKS to Fabio, I owe you a drink!

Regards,

Edward Thomas.