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Re: Free Tek 7000 scopes and plug in units

 

Tony, that's a great offer. I'm in Cambridge and could pick up the lot - I could really use much of that lot, even if it needs work, especially as my lab 2465 is poorly at the moment. I'm quite sure I'd end up redistributing some of it, too!

Chris

On 06/03/2013 11:16, Tony wrote:
Hello all,
I am moving and have to dispose of the following as a complete lot:

2x 7704A
3x 7A26
4x 7B53A
1x 7B92A
4x 7A13
1x 7A18

These are in various states of repair, though most have faults.
I paid ???150 for the lot from a local company that folded a few years ago.
I would rather sell them or give then away than send them to scrap.
I located close to Stanstead Airport.

Any takers?

Tony Sedivy
Re: 134 current amplifier replacement PSU

Albert
 

I opened a 230V 015-0059-00 and it definitively has just one single primary winding.
I have two of these 230V types and they have no brittle plastic at all. The hot (?) series resistors are located inside the alloy housing, not inside the plastic housing.

Albert

I have 3 of these supplies, 2 came from 115 countries and were were for
that voltage.

I had to convert them to 240v if possible. I opened up the transfs
and found that the primaries in all three were split into 2 x 115v halves.
Rewiring the two split primaries 115 ones in series gave me 230v line
units which have been working fine for years now.

Probably all the 134 power transformers were made that way in the
factory and the Tek numbers refer to those pre wired for the
Us and European etc markets.

John Byers
Re: 134 current amplifier replacement PSU

Stefan Trethan
 

I store probes and test leads that are shorter than 1.5 meters on comb
or rake type holders. I know the problem of not having any wall space
to hang them, so I just mounted a horizontal arm to one of the two
vertical posts carrying the beam with the fluorescent light over the
bench. On either side of the arm is a test lead comb with 25 slots. I
put the short leads on the bench side and the long ones on the outside
so they can go all the way to the floor.

There are two further horizontal arms below that carrying pliers and
screwdrivers - accessible from the short-lead side when seated at the
bench. It's just like a Christmas tree - the way I like them ;-)

Many probes or leads are longer than 1.5 meters and I hate kinking
coax so I hang them over large diameter plastic bobbins mounted to the
side of a cabinet. You can nest them by mounting the largest bobbin on
top and sequentially smaller sizes below, then the cables will not
interfere much.

There is something to be said for having plenty of space, but if you
can cram the same stuff in a smaller volume, while preserving ease of
access mind you, there's less running around and more chance of
putting things back after use.

ST
Re: 134 current amplifier replacement PSU

Rob
 

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Forgot to say…..”tell him Rob sent you”….or don’t *laugh*…. No real affiliation although a satisfied repeat customer and we chat from time to time…

?

From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Rob
Sent: Wednesday, March 06, 2013 12:00 PM
To: TekScopes@...
Subject: RE: [TekScopes] 134 current amplifier replacement PSU

?

?

Giving away all my secrets..... the labels and containers are here (bottom
of the page) at reasonable price.....



They do indeed work well for storage and retrieval as someone else pointed
out in the beginning of this thread. (Although I seriously thought I was the
only one who had thought of them being used in this way....small
world...and/or great minds think alike.)

May happy hunting and good deals follow you...
Rob

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] On Behalf
Of Mark Wendt
Sent: Wednesday, March 06, 2013 6:15 AM
To: TekScopes@...
Subject: Re: [TekScopes] 134 current amplifier replacement PSU

On 03/06/2013 06:56 AM, Craig Sawyers wrote:
>> ROFL! Yeah, my probe, cable and wiring collection has grown to the
>> point where it's getting unmanageable too. Stuffing them in the
>> scope cart
> drawer
>> worked when I got back into the swing of things, but I really need to
> start
>> figuring out a better storage system. I like the idea of the VHS boxes.
> Too
>> bad I tossed out all my VHS stuff many moons ago when I reconfigured
>> my video system to DVD, now BlueRay.
Re: 134 current amplifier replacement PSU

Rob
 

Giving away all my secrets..... the labels and containers are here (bottom
of the page) at reasonable price.....



They do indeed work well for storage and retrieval as someone else pointed
out in the beginning of this thread. (Although I seriously thought I was the
only one who had thought of them being used in this way....small
world...and/or great minds think alike.)

May happy hunting and good deals follow you...
Rob

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] On Behalf
Of Mark Wendt
Sent: Wednesday, March 06, 2013 6:15 AM
To: TekScopes@...
Subject: Re: [TekScopes] 134 current amplifier replacement PSU

On 03/06/2013 06:56 AM, Craig Sawyers wrote:
ROFL! Yeah, my probe, cable and wiring collection has grown to the
point where it's getting unmanageable too. Stuffing them in the
scope cart
drawer
worked when I got back into the swing of things, but I really need to
start
figuring out a better storage system. I like the idea of the VHS boxes.
Too
bad I tossed out all my VHS stuff many moons ago when I reconfigured
my video system to DVD, now BlueRay.
Re: 531a manual

nicmatfr
 

Hello Ed
(and hello all, I'm a new member)

I also have a 531A I wish to repair but I am fortunate enough ot have the manual.
I recently found scans of the schematics here
I don't know about the 535 but the parts numbers have changed between 531 and 531A so it's not that easy to locate the actual parts if you don't have the exact schematics

Nicolas

--- In TekScopes@..., "e_eng_ed" <edsparkie@...> wrote:

Steve, This is great info! It really gives me a head start. I picked this up a few weeks ago. It worked briefly then the trace died. I was planning on cleaning the whole thing anyway. Hopefully with your info I can get it working.

Ed

--- In TekScopes@..., "Steve" <ditter2@> wrote:

--- In TekScopes@..., "e_eng_ed" <edsparkie@> wrote:

Does anyone know if there is a free download of the 531a operation and service manual. I found the 531 on BAMA but would like to find the 531a.

Thanks,

Ed
Ed,

I had the same problem looking for information to repair a 541A. In my case, I have a manual – 531A/541A that is supposed to cover both models. However it lacks all service information for the 541A.

You can get all the information you need by using a 535A manual which is available on the BAMA site. The only difference is the additional B time base. So if you ignore three pages of schematics – the B trigger, B Time Base and B Time Base Timing Switch, the schematics are almost identical.

There only difference is some additional options in the wiring of the Horizontal Display switch, and the added Delay Pick-Off circuitry. Compare this with the 531 manual you have already downloaded, as this part of the circuit is identical between the A and non-A models.

For that matter, you will find the majority of the circuits have not changed between the original 531 and the 531A. The only major change between the 531 and 531A (as well as the 541 and 541A) is the timing switch. The original scope used two switches to set the time base. One set the time/div range in decades (by powers of 10^3), while the second was a multiplier. This is a holdover from the original Tek non-plug-in scopes. Obviously this arrangement is a pain for the user, as most people simply turn the knob until they get the correct number of cycles or time resolution they want to see on the screen, then look at the knob to see what the time/div is.

Some of the tube types may have been updated in the A model, but the circuit wiring is identical. The original 531 used selenium plate rectifiers which were changed to silicon diodes during its production run. The 531A started out with silicon diodes. Early 531 manuals will not show the silicon version, which requires additional resistors in series to account for the higher resistive loss of the selenium rectifiers. But the power supplies in the 531A and 535A are identical, so again a 535A manual will cover your needs.

- Steve
Re: It works! It works!

Don Black
 

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I'd be worried about doing this in case there's any loose particles in the CRT. There could be debris such as glass chips, tiny pieces of metal, etc. which in the vacuum can crash into the screen, mesh, etc. and destroy the tube. I don't know about Tektronix but some special tubes such as camera tubes had a telltale in the carton to show if it had been turned face down for just this reason.

Don Black.

On 07-Mar-13 2:10 AM, HankC wrote:

?
Easiest way to remove the case on most portables:
-Put the front cover on
-Stand the scope on its face.
-Remove the screws & slide the case straight up.

HankC, Boston
WA1HOS
Re: Current rating of P6042

Mark Wendt
 

Stefan,

Thanks for the explanation. Yet again, I've learned something new from this list!

Mark

On 03/06/2013 10:49 AM, Stefan Trethan wrote:
I'm sure Steve would do a better job, but I'll try anyway:

The current probe is basically a transformer.
So you have a magnetically conductive core (which can be opened with
the slider to clamp onto a wire), and a number of coils wound on that
core.

The most basic current probe would have two coils, one having several
turns, connected to the scope, and one having just one turn, your wire
you clamp on.

Any ferromagnetic material can only carry so much flux before it
saturates, flux is caused by current, so you are quite limited in the
amplitude of current you can measure.
If you happen to measure a small AC current riding on a large DC
current you might want to "null out" the DC component.
This is possible by inserting one more winding onto the transformer,
and applying an equal and opposite DC current to that winding (divided
by the turns ratio).

The opposing current cancels out the flux caused in the core, reducing
the overall sum of flux into the range the core can carry, if all goes
well.

This is the method the DC current probes use to measure the DC
component (the flux is detected by a hall sensor).
It's also the method used by some of the CT* current transformers to
extend DC tolerance, where you can get a separate bucking coil to slip
on.


ST


On Wed, Mar 6, 2013 at 11:52 AM, Mark Wendt <mark.wendt@...> wrote:

Steve,

Been following this thread with interest, and noted something that's
been mentioned a few times - bucking current.

I'm not an engineer, don't play one on TV, and didn't stay last night in
Motel 6. Could someone explain in technician (read: layman's) terms
what bucking current is?

Thanks,
Mark

------------------------------------

Yahoo! Groups Links
Re: Current rating of P6042

Stefan Trethan
 

I'm sure Steve would do a better job, but I'll try anyway:

The current probe is basically a transformer.
So you have a magnetically conductive core (which can be opened with
the slider to clamp onto a wire), and a number of coils wound on that
core.

The most basic current probe would have two coils, one having several
turns, connected to the scope, and one having just one turn, your wire
you clamp on.

Any ferromagnetic material can only carry so much flux before it
saturates, flux is caused by current, so you are quite limited in the
amplitude of current you can measure.
If you happen to measure a small AC current riding on a large DC
current you might want to "null out" the DC component.
This is possible by inserting one more winding onto the transformer,
and applying an equal and opposite DC current to that winding (divided
by the turns ratio).

The opposing current cancels out the flux caused in the core, reducing
the overall sum of flux into the range the core can carry, if all goes
well.

This is the method the DC current probes use to measure the DC
component (the flux is detected by a hall sensor).
It's also the method used by some of the CT* current transformers to
extend DC tolerance, where you can get a separate bucking coil to slip
on.


ST

On Wed, Mar 6, 2013 at 11:52 AM, Mark Wendt <mark.wendt@...> wrote:

Steve,

Been following this thread with interest, and noted something that's
been mentioned a few times - bucking current.

I'm not an engineer, don't play one on TV, and didn't stay last night in
Motel 6. Could someone explain in technician (read: layman's) terms
what bucking current is?

Thanks,
Mark
Re: Would anyone have a U800 heatsink they'd sell me?

 

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I use a very thin layer of JB weld epoxy. Also, I trim about 1/8 inch off so the package does not hit the mounting nut for the package. There may be other methods if you search the message archives. I know it has been discussed in the past.
?
Tom
?
?

----- Original Message -----
From: tonyp2422
Sent: Wednesday, March 06, 2013 8:25 AM
Subject: [TekScopes] Re: Would anyone have a U800 heatsink they'd sell me?

?

Thanks Tom! One is now on the way. Can I use adhesive thermal pad for this or do I have to use thermal "glue"?

--- In TekScopes@..., "Tom Miller" wrote:
>
>
>
>
> ----- Original Message -----
> From: tonyp2422
> To: TekScopes@...
> Sent: Tuesday, March 05, 2013 9:37 PM
> Subject: [TekScopes] Would anyone have a U800 heatsink they'd sell me?
>
>
>
> Of the type found in the U800 folder in the Files section here.
>
Re: It works! It works!

 

Easiest way to remove the case on most portables:
-Put the front cover on
-Stand the scope on its face.
-Remove the screws & slide the case straight up.

HankC, Boston
WA1HOS
Re: 134 current amplifier replacement PSU

 

PA4Tim said
"There are two power supplies: 015-0058-0x is the 115V supply and 015-0059-0x is the 230V supply."

I have 3 of these supplies, 2 came from 115 countries and were were for that voltage.

I had to convert them to 240v if possible. I opened up the transfs
and found that the primaries in all three were split into 2 x 115v halves.
Rewiring the two split primaries 115 ones in series gave me 230v line units which have been working fine for years now.

Probably all the 134 power transformers were made that way in the factory and the Tek numbers refer to those pre wired for the
Us and European etc markets.

John Byers
Re: Would anyone have a U800 heatsink they'd sell me?

 

Thanks Tom! One is now on the way. Can I use adhesive thermal pad for this or do I have to use thermal "glue"?

--- In TekScopes@..., "Tom Miller" <tmiller11147@...> wrote:




----- Original Message -----
From: tonyp2422
To: TekScopes@...
Sent: Tuesday, March 05, 2013 9:37 PM
Subject: [TekScopes] Would anyone have a U800 heatsink they'd sell me?



Of the type found in the U800 folder in the Files section here.
Re: It works! It works!

Craig Sawyers
 

Thanks Craig. Should I be concerned with that many hours on it? I see no
blooming or burning on the display.
I think that answers the question... I'd guess that my scopes have at least
that on the clock, if they had a clock to measure it!

Craig
Re: It works! It works!

 

--- In TekScopes@..., "Craig Sawyers" <c.sawyers@...> wrote:

I ran Exer 05 and I don't think they played with the numbers. The CRT has
11,000+ hours on it, and the power cycle count is 787. Is that a lot of
hours for
a 2465A CRT? Seems like a lot, but the traces look pretty darn good.
That works out at 14 (13.98) hours per power cycle. Looks like it was
somewhere where the whole lab woke up with a power breaker, and then was
shut off 14 hours later for three or four years.

Craig
Thanks Craig. Should I be concerned with that many hours on it? I see no blooming or burning on the display.
Re: Tek 214 running without batteries

 

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On 03/05/2013 07:50 PM, Steve wrote:
?

--- In TekScopes@..., "Dennis Tillman" wrote:
>
> Hi Scott,
>
> The manual for the 212 (similar as far as the battery power supply goes)
> says
> "The batteries act as a large filter capacitor for
> the input rectifier in the AC line mode of operation."
>
> If the batteries are dead they don't have the ability to act as a filter
> capacitor - their internal resistance will have gone way up, and they won't
> be absorbing (and smoothing) the current from the rectifier when the voltage
> rises above the battery voltage.
>
> I have run my 214 with dead batteries, no problem. Presumably the dead
> batteries were not doing anything for the reasons stated above. On the other
> hand I am going to wait to hear from anyone else before I try running mine
> without batteries. I'm not entirely convinced by my own arguments that
> trying this will not harm my precious little gem of a scope.
>
> Dennis

Dennis,

Actually, the batteries perform more a zener diode effect in the 211-214 (the power supply in the 221 is totally different). Operating with them removed will overstress components in the primary of the switching power supply. I would not recommend it.

In some cases, the failure mode of a NiCd cell is that it simply won't hold a charge. In this case, the scope will continue to work fine on line power with the dead battery still installed. Other failure modes are a short, caused by a nickel "whisker" growing between the plates in the cell. In this mode, the scope won't work as the voltage will be too low.

It is possible to blow a whisker out of a NiCd cell and revive it. A curve tracer is a good tool for this, as you can monitor charging current after you blow the short out. Use a large electrolytic cap, several tens of thousands of microfarads. Charge to a low voltage, such as 3 volts or so with the curve tracer. Using heavy gauge wire between the cap and the cell, quickly connect the cell with the matching polarity. You will get a large inrush of current and hopefully the whisker will blow, leaving a functioning cell. Charge it as normal – 12 hours at 1/10 the current of the amp hour rating.

I have had mixed results with this method. Sometimes I regained years of life in the cell. Other times it works for one charge cycle, then shorts again. The mechanism that causes nickel whiskers to grow generally produces thousands of them. The tallest one shorts the plates first. When you blow it, the next tallest one will continue to grow until it shorts. That maybe the next day, or years later!

- Steve

And I've even improved my luck by heating the cell first,
to about 200 f.
Re: 134 current amplifier replacement PSU

Mark Wendt
 

On 03/06/2013 07:32 AM, Craig Sawyers wrote:
Those don't look to bad. How do you store the bags so that they're
easily
accessible, and so you know what you have in them?

Mark
Well, you don't know what is in the official Tek bags either - you just root
through them looking through the side of the bag until you find the one you
want.

But the ones in the Rapid Electronics bags I just have vertical between two
sets of books. I know that it is older generation probes I have in those,
so that is where I look if I want a x100, for example.

Craig
I guess I'd have that problem if I had official Tek bags. ;-)

At the moment, I've got cardboard boxes I roll up my probes and cables in, and stuff 'em in a drawer. Same for BNC cables, connectors, attenuators, terminators and such. Or draped over the back of the chair...

I guess what I'm looking for is some kind of easily indexable, easily stored, storage system.

Mark
Re: Free Tek 7000 scopes and plug in units

 

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Hi Tony,
??? I might be interested - I am in Clacton, not too far away...

What is the state of the 7704s? I have some working plugins for my other scope, so could maybe get something working fairly quick..?

What do you want for them?

Best Regards

David Thomas


On 06/03/2013 11:16, Tony wrote:

?

Hello all,
I am moving and have to dispose of the following as a complete lot:

2x 7704A
3x 7A26
4x 7B53A
1x 7B92A
4x 7A13
1x 7A18

These are in various states of repair, though most have faults.
I paid ?150 for the lot from a local company that folded a few years ago.
I would rather sell them or give then away than send them to scrap.
I located close to Stanstead Airport.

Any takers?

Tony Sedivy






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Re: 134 current amplifier replacement PSU

Craig Sawyers
 

开云体育

I use them for GR terminations, adaptors and air lines too.? And they are good for larger fasteners and fixings too that won’t fit in my parts drawers.

?

Craog

?

From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Pa4tim
Sent: 06 March 2013 12:26
To: TekScopes@...
Subject: Re: [TekScopes] 134 current amplifier replacement PSU

?




Hey, that is a nice idea to, you can see what is in it, can write specs on it with a permanent marker and they cost next to nothing.?

I think I will look for those, Just toss then in a few small drawers. I tried those drawers for the cables but everything gets in a knot, those bags prefent this. Nice, see or i can get them in an office shop over here.

Nice for all those adapter cables I not use often, some not mucht used probes, thermocouples ect, and then I can use the rack for the banana leads and coaxcables I use the most.

Fred PA4TIM


Op 6 mrt. 2013 om 12:56 heeft "Craig Sawyers" <c.sawyers@...> het volgende geschreven:

?

> ROFL! Yeah, my probe, cable and wiring collection has grown to the point
> where it's getting unmanageable too. Stuffing them in the scope cart
drawer
> worked when I got back into the swing of things, but I really need to
start
> figuring out a better storage system. I like the idea of the VHS boxes.
Too
> bad I tossed out all my VHS stuff many moons ago when I reconfigured my
> video system to DVD, now BlueRay.

For probes that don't have official Tek zip bags, I use these
. Note that
in the description it says " Useful for general purpose storage of test
leads, cables, probes, accessories"

The same thing must exist in the US.

Craig
Re: 134 current amplifier replacement PSU

Craig Sawyers
 

Those don't look to bad. How do you store the bags so that they're
easily
accessible, and so you know what you have in them?

Mark
Well, you don't know what is in the official Tek bags either - you just root
through them looking through the side of the bag until you find the one you
want.

But the ones in the Rapid Electronics bags I just have vertical between two
sets of books. I know that it is older generation probes I have in those,
so that is where I look if I want a x100, for example.

Craig
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