Date   
Re: Tek 465 repair hints, svc manual? (fix story)

Mark Anton
 

In many types of equipment, I have found shorted disc and mylar caps just often enough to be aware that it happens. Not really frequent at all, but often enough to know that they never go bad.
Actually have found shorted discs where the voltage should not have been a problem at all. Like a 3 volt p-p signal riding on 6 volts of DC with a .01 50 volt disc. Where did my signal go? Took the cap out and measures 4 ohms. No stress there but the cap failed. So it dont suprise me either, but its not the first thing I go looking for either.

Mark.
----Original Message Follows----
From: E K <dataclue@...>
To: TekScopes@...
CC: E K <dataclue@...>
Subject: [TekScopes] Re: Tek 465 repair hints, svc manual? (fix story)
Date: Mon, 17 Feb 2003 18:58:13

-- the Z axis circuitry is coupled to the horizontal amp via R1475, so it was the latter after all.
Turns out the supply does not come back even with all the transistors removed!
7. There are very few possible paths between +110 and ground with the output transistors out of circuit, found a drop of several volts across R1283 (a 47Ohm resistor). Aha! It's connected to ground via C1283, a 0.01 uF 150V ceramic cap enough, removing it restores the supply. Once it's removed, I of course notice a small charred spot next to one of the leads, 8. Replacing the 0.01 uF cap brings back the supply and the horizontal sweep. You may have heard about the tantalum caps in these scopes, I know I did. But the ceramic caps must have also come from a bad batch or weren't really rated 150V.
.
E K <





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Re: Tek 465 repair hints, svc manual? (fix story)

E K
 

Got the 465 horizontal sweep fixed a couple of weeks ago, thanks to David DiGiacomo for a service manual. This didn't take very long, but had some interesting twists and turns.
1. Quickly verified that the over-current protection of the +110V power supply was kicking in (easily done by checking whether the smaller transistor is on).
2. Found the power supply isolation procedure thoughtfully included in the manual and disconnected the horizontal amplifier by desoldering four components (two feed resistors into the final output stage, a resistor for the X10 MAG neon light (!), and a 6.7V zener also connected to the output stage.
3. The power supply went up somewhat, to ~50V. Followed the second half of the isolation procedure, disconnecting the Z axis amplifier / CRT circuit. The supply cheerfully returned to 110V. Ok, it's not the horizontal amplifier after all!
4. Spent a some time chasing around the intensity amplifier, checking caps, removing some of the transistors, and trying to find the presumed short. This didn't lead anywhere.
5. Decided to reconnect the horizontal amplifier (with Z axis amp still disconnected) and the power supply dropped back down to below half of nominal. After a little bit of confusion, noticed the mistake -- the Z axis circuitry is coupled to the horizontal amp via R1475, so it was the latter after all.
6. Checking the various semiconductors and capacitors yields nothing, somewhat surprisingly. No obviously shorted caps, no shorted transistors or diodes. Turns out the supply does not come back even with all the transistors removed!
7. There are very few possible paths between +110 and ground with the output transistors out of circuit, found a drop of several volts across R1283 (a 47Ohm resistor). Aha! It's connected to ground via C1283, a 0.01 uF 150V ceramic cap that previously escaped suspicion. Sure enough, removing it restores the supply. Once it's removed, I of course notice a small charred spot next to one of the leads, and feel like an idiot -- should've noticed it a long time ago. Try to make myself feel better saying that the charring probably appeared over time as I was debugging. ;-)
8. Replacing the 0.01 uF cap and putting everything back together brings back the supply and the horizontal sweep. An astigmatism adjustment and the scope is ready for use, the only remaining problem being a flaky CH1 vertical position pot, to be fixed some other time.
9. You may have heard about the tantalum caps in these scopes, I know I did. But the ceramic caps must have also come from a bad batch or weren't really rated 150V.
All told, an investment in a service manual, a one cent capacitor and 8 total hours or so of fun yield a working 465 scope.
E K <dataclue@...> wrote:
Working on a Tek 465 with a horizontal deflection problem. Namely, no horizontal deflection under normal operation and no response to horizontal position adjustment. Limited horizontal deflection if "beam find" pressed, however. It seems that there is a sweep signal being generated, so expecting the problem to be further down the line. This is somewhat buttressed by the fact that a +110 testpoint reads about 40V, other easily checked voltages are normal (e.g., +15, -8).



---------------------------------
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Looking for probes

Tracy Nelson <tnelson158@attbi.com> <tnelson158@...>
 

I've got a couple of 310As and a 647. I'm trying to teach myself
something about electronics. Problem is, I've got a motley collection
of random probes, and I don't think any of them are impedence-matched
for my scopes. Two are so old and worn there isn't any manufacturers
information on them, and one says "RCA WG-400A". I'm not getting what
I think are proper readings from it, though, so I don't think it's one
I can use.

Is there a source for probes for instruments this old, and if so what
kind should I be looking for? Right now all I need is a
general-purpose probe, and maybe one for high-voltage work (one of my
310As isn't working on AC, so I thought I'd try to fix it once I know
enough).

Thanks!
-- Tracy Nelson

Differential probe

Marcello Pellerano
 

Hello all,
could you please give me the schematic of a differential probe?
I've seen some of them in various catalogues, but it seems to me that the price required is not so cheap, so I'd like to build one of these.
Thanks
Marcello

Re: 485 Repair Question

Jose V. Gavila <eb5agv@...>
 

Hi Dick,

I picked up a nice clean Tek 485 at Marlboro Saturday. I know it has
problems and thought it would make a good winter project (between
shoveling snow !).
Mine was also got as a winter project and ended as a nice working unit :-)!

First though, what is the procedure for removing the case ?
I am trying to locate a Service Manual, but want to look inside
without breaking anything in the process.
Remove the four screws inside the back plastic supports. I think there is
another screw on the bottom of the scope. Then slide carefully the green
cover and get the unit out of its case.

I have the service manual for it in case you need any detailed information.
As you probably know, usual troubles include the switching supply which is
not easy to work on (but not impossible :-)! )

Good luck!

Regards,

JOSE
----------------------------------------------------------------------
73 EB5AGV / EC5AAU - JOSE V. GAVILA
La Canyada - Valencia (SPAIN)

Vintage Radio: http://jvgavila.com
Vintage Test Equipment: http://jvgavila.com/testeq.htm
European Boatanchors List: http://groups.yahoo.com/group/euro_ba_swap

485 Repair Question

w1ksz <w1ksz@tiac.net> <w1ksz@...>
 

I picked up a nice clean Tek 485 at Marlboro Saturday. I know it has
problems and thought it would make a good winter project (between
shoveling snow !).
First though, what is the procedure for removing the case ?
I am trying to locate a Service Manual, but want to look inside
without breaking anything in the process.

Thanks, Dick, W1KSZ

Re: Tektronix 7M11 Delay Line plug-in

david@...
 

Anyone know what kind of coax cable is used in this delay line
unit... is it flexible or semi-rigid... or what?
It is flexible. Interestingly, it's not insulated - I guess otherwise
they wouldn't have been able to cram it all in.

485 part needed

Sam Reaves
 

I need a vertical attenuator switch assembly modules (with the PCB)
fpr a Tek 485. Someone used freon based or some other cleaned and
disolved and damaged the PCB.

Thanks

Sam

How to use YahooGroups.com?

John Herbster <herb-sci1@...>
 

I am writing this post to find out how to use yahoogroups. I want to review messages in the TekScopes group, but cannot "get there". Yahoo keeps saying my profile (what ever that is supposed to be) is invalid and will not accept any new profile that I enter. So I cannot see anything that is posted.

Does anyone know what could be wrong or can you refer me (by e-mail) to an explanation? --JohnH

Tektronix 7M11 Delay Line plug-in

konnylagarde2002
 

Anyone know what kind of coax cable is used in this delay line
unit... is it flexible or semi-rigid... or what?

THANKS for your help!!!

Konny

561s/766h

arthurok_2000 <arthurok_2000@yahoo.com> <arthurok_2000@...>
 

ibm service used alot of 561s scopes and it was concidered
much better then a fairchild dumont 766h
They were both replaced by 453 and 454 scopes

Anyone have a spare CRT?

vollumscope <perls@ime.net>
 

Howdy all--

I'm looking for a CRT for my TEK 549--

154-0498-00

Easy to identify:

5" round,
10cm X 6cm screen window in aluminized front for tube.

Any help appreciated.

Thanks!

Regards

Robert

Re: TDS-210 firmware upgrade?

pe1fbo <sh331182@12move.nl> <sh331182@...>
 

Hi Jose,

The firmware is probably located in an EPROM or Flash EPROM.
If your lucky you will spot a big chip, 28 or 32 pins with something
like 27C010 27C020 or an 27F010 27F020. If your less luck they have
used a PLCC (plasic lead chip carrier) soldered on the board with the
same type numbers. The bad thing is that Tek never provided diagrams
of the newer stuff, and not servicing them either after a few years
they went out of production.

- Fred

--- In TekScopes@..., "Jose V. Gavila" <eb5agv@c...>
wrote:
Hello!

I have a TDS-210 with an old (I think it is v1.1x) firmware. I have
access
to another unit with v2.03. Is there a way to copy it?. Is it
located in an
EPROM?

Thanks!

JOSE
--------------------------------------------------------------------
--
73 EB5AGV / EC5AAU - JOSE V. GAVILA
La Canyada - Valencia (SPAIN)

Vintage Radio: http://jvgavila.com
Vintage Test Equipment: http://jvgavila.com/testeq.htm
European Boatanchors List:
http://groups.yahoo.com/group/euro_ba_swap

Re: TDS-210 firmware upgrade?

zenith5106 <zenith@telia.com> <zenith@...>
 

--- In TekScopes@..., "Jose V. Gavila" <eb5agv@c...>
wrote:
Hello!

I have a TDS-210 with an old (I think it is v1.1x) firmware. I have
access
to another unit with v2.03. Is there a way to copy it?. Is it
located in an
EPROM?

Thanks!

JOSE
--------------------------------------------------------------------
The TDS200 series with version 2.xx use a completely different
hardware than the older ones. On the older ones you'd have to replace
a ROM chip to upgrade and the newer ones use a FlashROM, updated by a
special fixture.
/Zenith

Tektronix 577 Curve Tracer Questions

drd_007
 

Hello,

I just purchased a Tektronix 577D2 Curve Tracer. It came with a user's manual and only the FET test fixture but no protective cover. (In order to sweep higher voltage ranges, I must manually override the safety switch) Here are several questions for the group:

1. Does anyone have some duplicate test fixtures they would care to sell or perhaps know of a source for these fixtures? I would also like to replace a couple of the labelled knobs.

2. Is there anyone out there who has made their own fixtures who could share information with me?

3. Does anyone know of a textbook containing in-depth explanations for the testing of various devices using this instrument? I did a search on Google and Amazon with no luck.

Regards,

Mike DiGirolamo, W4XN
Charlottesville, VA 22901-8810

Type 111 capacitor replacement

Craig Sawyers <c.sawyers@...>
 

Hi all

I've uploaded a couple of pics to the pictures section of the Tekscopes site
showing the replacement of the 40+40uF @ 450V smoothing cap in the Type 111
pretrigger pulse generator. The original was a Sprague unit, with a nylon
insulating sheath. At least one lister contacted me reporting a similar
failure with a Sprague cap in his oscilloscope, so perhaps this isn't
unusual with these Spragues.

The replacement is a JJ cap (Slovakian) that I got from a local supplier in
the UK (although they seem to be available in the US and elsewhere too, just
trawling google). JJ are a part of Tesla, who manufacture audio tubes.

I used a 50+50uF @ 500V cap, and is exactly the same diameter as the Sprague
unit, but a trifle shorter.

What I did was remove the old cap from the mounting plate by twisting the
locating tabs and pulling it off. I then trimmed the plastic sheath off the
new cap at the bottom revealing the metal can, and give the adhesive
something to grip to. Superglue was then used to glue the new cap to the
base.

As you can see, it almost looks as if it is original (which was part of the
exercise!).

JJ's site is at http://www.jj-electronic.sk/.

Craig

TDS-210 firmware upgrade?

Jose V. Gavila <eb5agv@...>
 

Hello!

I have a TDS-210 with an old (I think it is v1.1x) firmware. I have access
to another unit with v2.03. Is there a way to copy it?. Is it located in an
EPROM?

Thanks!

JOSE
----------------------------------------------------------------------
73 EB5AGV / EC5AAU - JOSE V. GAVILA
La Canyada - Valencia (SPAIN)

Vintage Radio: http://jvgavila.com
Vintage Test Equipment: http://jvgavila.com/testeq.htm
European Boatanchors List: http://groups.yahoo.com/group/euro_ba_swap

Nelson-Ross PSA011 Spectrum Analyzer Plugin for 53x/54x/55x Series

Jim Reese
 

Hello Group Members,

I have a Nelson-Ross model PSA011 audio spectrum analyzer plugin
available. The center frequency range is from 0-20 KHz and
dispersion is from 100Hz to 6 KHz. It is in excellent condition and
worked the last time it was checked several years ago. It fits the
53x/54x/55x series Tek scope mainframes. I have only seen the one of
this model and it was never listed in any old Tucker catalogs with
the other Nelson-Ross units. Before I put it on Ebay, I figure I will
offer it to group members as-is for $25 plus shipping to the first
one that wants it.

Let me know if you need any letter, 1, 2, or 3 series plugins. I am
going to start clearing out my over-stocked collection cheap ($10-$25
each as-is but complete).

Regards,

Jim

Need Manual for 453A-4

kevin_ka0i <kj558@yahoo.com>
 

I would like to have a copy of operator's manual or service manual
for my 453A-4. It does not have to be in paper form, .pdf file on
CD is ok too. I will gladly compensate for expenses. I realize I
can purchase one on CD via ebay. That is plan "B". Thanks.

Kevin Hunter
Willard, MO

Free Tektronix CRT

kevin_ka0i <kj558@yahoo.com>
 

I have a CRT that I removed from a piece of Tektronix medical
equipment. It may be useful to someone. The piece of equipment
was working when I dismantled it. This CRT had a clear, bright
trace. The number on top of the CRT appears to be 521 F 64. This
has been in my way for a couple of years. If no takers on here in
the next few days, it will go in the trash. You pay only
shipping. Please email if you want pictures, dimensions, etc.

Kevin Hunter
Willard, MO