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Thank you. I should have said I had joined that group There does not seem to be much there about my problem.

Again, I’m sorry I was not more through in my original post, larry

There is another groups.io group, "HP-Agilent-Keysight_equipment", that offers a level of information about HP ... equipment similar to the level on this (TekScopes) forum.

There is also a TekScopes2 group.io group.

DaveD

Dennis,

I welcome the change of topic. I felt like I "Hijacked" the 5xx thread. Here is my issue, I have a 577D2 (non-storage) and that is the one thing about it that I do miss and feel is most useful "different" feature of the 577. I wanted the D1 as my first choice, but the D2 presented itself at a good price, so I bought it, on the chance that I could fix it and resell later. I have several 5000 and 7000 series storage scopes, so I have worked with them enough to understand the limitations and finicky nature of the technology. I was looking at the schematics and was wondering if, push comes to shove, it is possible to "add" the storage function to the D2, using parts scavenged from a 5111/5103(D11)? It seems that the differences are very few between them. The simpler thing may be to just wait on the right 577D1 to pop up for repair? I am finding that repairing these instruments is not as difficult as learning to use them properly. I am leaning toward keeping both instruments, at least for the time being. Anyway, I appreciate your detailed answer and insights!

Sincerely,
--
Michael Lynch
Dardanelle, AR

Hi,

I’ve bought a Agilent E3630A power supply. It has not arrived yet, but the display does not work - according to the person from whom I bought it.

So, I'm looking for as much info as I can acquire so as to be ready to repair it. I presently have a HP 3312A function generator. It works fine but it is not in calibration. So again, while there seems to be “lots” of info about Tektronix text equipment, there seems to lesserly about HP…

Thanks larry

Take lots of pictures and video, while disassembling your scope and
notes...etc! Replace what is bad, don't fix that isn't broken!
These scopes are very good quality and few parts here and there are needing
attention but that is it!

Ed,

Appreciate your insights. I actually was able to buy 2 dead units and bring them both back to life. Since both work great after repair, it seems that the prudent thing to do is to keep them both and sell something else? After all, there is nothing else that can take the place of the TEKTRONIX curve tracer. I have found that they are essential in repairing all other forms of old electronic gear. I am interested as to what others say on the subject as I am trying to expand my knowledge of these instruments. Learning what these things can do is a more difficult task than the actual repair of the instruments.

Thanks Again!

--
Michael Lynch
Dardanelle, AR

I think he might need to shift the decimal point left one position.

There are no electrolytic capacitors that are critical. In my
opinion, the 180uf and 250uf were picked for size and voltage
rating, not for value back in the day. A little bigger causes
no harm, and reduces the noise a bit. I choose slightly higher
voltage capacitors because they are bigger, and can dissipate
more power. They also have have lower ESR's, longer life ratings,
and higher ripple current capabilities.

No transistors or rectifiers, in the power supply, are prone to
failure. Really, the only parts that are prone to failure is the
orange, or clear sleeved electrolytic capacitors (2465 and 2465A),
and the -15V inverter filter cap (all supplies). The yellow RIFA
0.068uf caps sometimes go bad in Europe, but not the US. They are
rated 250VAC, which is ample margin, on top of the already ample
margin built into the 250VAC rating, for US 120V instruments.

I do a complete recap because it is a pain to remove the supply,
and my customers would rather not be subject to that pain...

I've done it so many times, I don't notice the pain anymore.

-Chuck Harris

Jean-Paul wrote:

On Wed, Aug 14, 2019 at 11:24 AM, Dennis Tillman W7PF wrote:

EVERY Tek curve tracer, except for the limited plugin versions (7CT1N and
5CT1N) have two "sockets" to do A/B comparisons. This includes the 570 (vacuum
tube curve tracer), 575, 576, 577, and 370. The 576 and the 577 have similar
basic capabilities such as their maximum voltage (1,600V at 100mA, and 1,500V
at 200mA respectively), but differ significantly in other ways.

The 576 has an optional 176 high current "front porch" capable of testing
power transistors. The 576 has readouts (not on-screen) which assist casual
users in avoiding mistakes when making basic device measurements.

The 577 comes in a non-storage (577-D2) and storage 577-(D1) CRT version. It
has an optional 176 "front porch" which can test single, dual, or quad OpAmps,
SCRs, 3 Terminal Positive and Negative Voltage Regulators.

Both the 576 and the 577 were designed to make the majority of semiconductor
measurements that any circuit designer would be interested in quantifying. I
once asked Deane Kidd, when I was in his lab, which he recommended, 576 or
577. His answer was definitive: the 577 hands down. So that is what I found to
replace my 575 10 years ago. I have had both the 577-D2 and 577-D1 over the
years since and there is no question that the 577-D1 (storage) version has
more capabilities although the storage is tricky to adjust and is sometimes
annoying.

I am now fortunate to own both a 576 and a 577 and all the optional "front
porches" so I can test just about anything.

Sean: I believe you are thinking of the low cost adapter board I designed to
test vacuum tubes on a Tek semiconductor curve tracer. My adapter is not
limited to the 576. It works on ANY Tek curve tracer (575, 576, 577, 7CT1N,
and 5CT1N). Contact me OFF-LIST at "dennis at ridesoft dot com" if you would
like a copy of the paper I wrote about testing vacuum tubes on Tek curve
tracers.

Dennis Tillman W7PF
toggle quoted message Show quoted text ( #quoted-71260773 )

Thanks to you and Chuck above, I stand corrected. I'll shoot you a message later today.

Sean

On Wed, Aug 14, 2019 at 09:52 AM, Jason A. wrote:

I have a 535A that I just finished mostly refurbishing I would part with. It's
got all new tubes, almost all the capacitors replaced, one broken resistor
replaced in the vertical amp, and calibrated up (mostly) to the "B" plugin
inside it. I can attest the frequency and voltage displays are in-line with
reality, but may need some geometry true-up and probably wouldn't hurt to
adjust the delay line. I would also be willing to include a 1A1 plugin
(probably needing at minimum new capacitors and a calibration). I am in the
Atlanta area. The downside is that with all the parts I've just put into it,
I'll have to have what I have sunk into it for acquisition cost and parts. I
will even write off the labor as a labor of love keeping something as cool as
an old 5-series running.

Jason,

If I was closer, I would very interested. Shipping an irreplaceable 65 lb beast seems like it would be a bad idea.

Sean

Removing the supply is tricky, but straight forward.

First remove the case.

Then remove the upper shield. Usually that involves
simply removing the screws, including one on the left
edge, and on the back panel. Highly optioned scopes
have a card cage, which is full of cables, and little
pinned connectors, which makes everything difficult.

Next, remove three screws that fit between the transistors
on the bottom of the chassis.

Now to the back panel of the scope.

Remove the two screws that holds the black plastic insulator
that protects you from the mains, and then the insulator..

There are two spacers that go between the pc boards on the
supply, that hold the boards to the back panel... their
screws go next.

May as well unplug the ribbon that goes to the A5 board, from
the A5 board, and unplug the two groups of wires that go to
the middle of the power supply on the left... and any other
cables you see that unplug from the power supply... remember
where they go, there will be a test later ;-)

You also have to unplug the pink faston connectors that go
from the line entry filter to the board, and the 120/240V
switch to the board. These are tricky, and will require
something to help you install them later. I use a set of
lap sponge forceps, which is like a large hemostat with
curved jaws...

Now, we look at the back panel, and note that there are a
couple of screws that hold the right side of the back panel
to the rest of the chassis, these need to be removed so that
you can pull the back panel back and make a little more room
to remove the supply, which should now be free to lift up
and out.

Yes, it is a pain.. which is why I suggest recapping, rather
than just repairing the supply. No point in having to do this
more than once.

You should build a dummy load so you can test the supply on
the bench after you are done with your repairs. There used
to be some homemade units for sale ala Jerry Massengale

When you put the pink faston connectors back, you must be
sure they seat fully. When you put the two connectors back
into the middle of the supply, you must make sure they are
aligned correctly.

Be careful when removing the various spacers from between the
circuit boards. They break easily, as do the locks for the
pin clusters that connect the two boards together, as does
the braided ground that attaches to the center partition/
shield... may as well remove the aluminum spacer to protect
it.

Some like to unsolder the fan's power lead, I just work with
it attached... for recaps. I remove it for complex repairs.

-Chuck Harris



Jean-Paul wrote:

Carsten,

Just for reference those square posts are 25 thousanths of an inch (0.025"). Sometimes it's more appropriate to describe something in its original units for clarity and absolute accuracy. (A classic example is the connector pitch 3.96 mm which is more correctly 5/32" (actually 0.15625" and 3.96875 mm).

Brian.

Dear Chuck:

Many thanks you are again the expert!

1/ Any tips on removal of the PSU for a novice? I have seen the teardown posts but it seems rather difficult.

2/ Some posts mention a 100 uF cap that must be exactly 100 uF, yet lytics are normally wide tolerance, your comment?

3/ Besides recapping, are there transistors or rectifiers prone to failure?

Kind Regards,

Jon

The Australian military found that it caused the"rubber" flexible insulation to swell of connectors with inserted crimp pins so it was banned from use on connectors.

Regards,
Brian.

Yes, I think this is what I will do. The scope is obviously old enough that the caps will have leaked, so I'll go with that as a starting point. I'll let everybody know how it goes.

Thanks.

I have three 577s and two 576s, all working, more or less. Both kinds can get the job done, having similar capabilities. If I had to trim down to only one unit, I'd keep a 576. It's the "king" of old-school CTs, especially with the readout - that's the big convenience. To me, the 576 has a cleaner layout, and is easier to use and see the control functions. The downside is that it uses a unique CRT, and some units have the "bad HV transformer" issue (one of mine did, and needed serious repair). It also uses some of the long-obsolete Printact relays, which may be difficult to find if needed.

The 577 is a newer design, in style and components, and shares parts with the 5000 series scopes, including the CRT. One thing that the 577 can do that the 576 absolutely can not, is store a trace on screen - if you have the D1 storage version. This can make for convenient comparisons between DUTs. The downside of this is the storage CRT, which I think is also shared with 5000 series, so somewhat available, but storage tubes don't age well with use. I doubt that many of these tubes still work perfectly after all the years. One of my 577s has this. The CRT still sort of works and stores an image, but not very well.

These are just a few of the many differences between them, but what they have in common, that makes a big old CT still have good value and utility, is the bigness, and sometimes the oldness. The essential part is the collector supply, with wide ranges of operation, and durability. It's very simple in principle, but complicated to make all the operating modes work out. The big stuff and complicated arrangements of parts and switching and control and measurement made these pretty spendy to begin with, and their continued utility and longevity makes them still valuable to those who know what to do with them.

Now, even if their CRTs all burned out, these things could still be useful by tacking into the guts and using an external scope for X-Y display. The converse doesn't hold - if the big stuff severely craps out, it's pretty much useless, no matter how fine a display it has. Fortunately, the big old stuff holds up well (but not always or perfectly), so if we can keep our displays and minor parts working, these units can go for a very long time. I consider a CT a workhorse in the lab, and essential. Two workhorses are better than one (if one throws a shoe, for instance), and so on. Just like scopes, it's always good to have spares.

Ed

Hi Michael.
I changed the subject since it has been about the 500 series SCOPES and not CURVE TRACERS until now.
In the next few days there will probably be many replies to this question. I request that everyone keep the discussion dignified.

For 99% of our members the most important consideration will be which one you can get at an affordable price. They are both wonderful instruments especially if you have nothing else.

Since you are in the 1% category that owns both a 576 and a 577 (and so do I) 1 I will comment on which one meets my needs and why.

The first thing I think of, that I believe Deane also thought was important, was the storage capability of the 577-D1. It has a drawback as well - it can be annoying when it is not adjusted properly. I have followed the internal adjustment procedure carefully for adjusting the storage voltages with little success so I live with the occasional storage artifacts. Another reason I like the 577 is because I am also interested in testing the additional things my 178 "front porch" can test (OpAmps, Voltage Regulators, SCRs, etc).

I personally think the 576 is the most beautiful instrument with a CRT that Tek ever made (In that respect I'm a romantic). Many 576 owners love the readout which helps to avoid mistakes when measuring parameters. This is not something I need. Like my annoying storage, the fiber optic readouts have their own issues. Most 576s have some dark fibers by now and there are no replacement readouts that I know of. I don't think there is a practical way to repair individual fibers either. The 576 has its own specialized "front porch", the 176, for testing power transistors which is important for some users. The 576 was incredibly expensive to build and Tek did not make much, if any, profit on each they sold.

The 577 was designed to fix that problem. Tek engineers borrowed heavily where they could to keep costs down. For example, the entire display section was borrowed from the 5000 series of scopes. My principal complaint about the 577 is due directly to this lineage: there is no Graticule Illumination. That is problematic when I want to take a photo of the curves on the screen and the graticule lines do not show up in the photo so it is almost impossible to know what the V & I of each curve is. Instead I discovered an alternative way to add a graticule overlay after I take the photo of the semiconductor characteristic curves. But this is still an annoying oversight from Tek. One final thing in the 577's favor: it was released several years after the 576 and in the intervening years several new types of semiconductor devices were developed and the design team made sure the 577 could test those devices.

You are probably wondering why I find the storage of the 577-D1 to be essential. Here are four examples:
1) Junction (bipolar) FETs are notoriously temperature sensitive in a curious way. Below a certain bias point the temperature coefficient is negative, above this bias point the temp coefficient is positive. So display a FET on a non-storage 577-D2, pick some typical gate bias voltage steps, and look at the curves you get. You can't tell where the gate bias point is exactly at the midpoint between the positive and negative temp coefficients. If you do the same thing with the 577-D1 and turn the storage on all you have to do is change the temperature of the FET by applying a little heat to the FET and the curves above the critical bias point will move up and curves below this point will move down. The storage displays the bias point where nothing moved and that is the critical zero Temp coefficient bias point you should design for.

2) With storage turned on put a transistor in the left socket and another one in the right socket and toggle left to right and you can immediately tell if they match and by how much. The curves won't overlap unless they are matched.

3) This is a little trickier but I have used storage to find two power transistors (one NPN and one PNP) that had Beta close enough to make a near perfect class B output stage. I had the NPN in the left socket and I displayed the curves for it in the upper right quadrant of the 577-D1. Zero collector voltage and current was located at the exact center of the screen. Then I stored the top half of the screen. Next I did a similar thing with the PNP which was in the right socket. Again zero voltage and current were set to the center of the screen and its curves were positioned into the lower left quadrant. Then I stored the bottom half of the screen. There was a perfectly linear load line from the negative PNP collector voltages and currents on the bottom left of the screen to the positive NPN collector voltages and currents in the upper right part of the screen.

4) At extremely low collector currents Miller capacitance, socket capacitance, transistor noise, and AC (hum) pickup distort each collector V vs. I curve into a noisy loop. As you switch to more sensitive ranges the loops occupy a larger portion of each step until the steps themselves are totally obscured by the capacitance, transistor noise, and AC pickup. The solution is to switch to manual +DC or -DC and use the display filter to reduce the noise. With storage you can vary the collector voltage manually and trace out the entire set of characteristic curves just fine on the CRT no matter how sensitive the range you select. With a 576 or a 577-D2 you would have to use a grease pencil to mark your progress on the CRT to see the curves.

Dennis Tillman W7PF

Hi Brad,

I would like to buy your resistors... email me paypal address off list and I will pay immediately.

Phil

Hello--
I'm offering FS a small batch of NOS replacement resistors. These are sealed in plastic envelopes along with
a Tektronix round-face CRT trademark and a label listing quantity, value, power dissipation and tolerance.
The resistors' body length is approximately 1/2 inch, and they're likely of metal- or carbon-film construction.
Here's what's available:

2.26 K, 1/4 watt,? 1%, 20 pcs.
3.01 K, 1/4 watt,? 1%, 12 pcs. (opened envelope)
5.49 K, 1/4 watt,? 1%, 10 pcs.
7.15 K, 1/4 watt,? 1%, 10 pcs.
8.06 K, 1/4 watt,? 1%, 10 pcs.

I don't recall when the Tek logo went from showing a round CRT to a square CRT, but these parts
are likely? from the 5xx era.

I'm asking $10.00 for the whole batch, which includes USPS mail postage to U.S. locations.

Questions welcomed, PayPal honored

Thanks, and 73--

Brad? AA1IP