Date   

Re: 222 battery replacement

arthurok <arthurok@...>
 

what about using 4 gates cells in series?

----- Original Message -----
From: "DaveC" <davec2468@aim.com>
To: "TekScopes" <tekscopes@yahoogroups.com>
Sent: Friday, March 24, 2006 2:20 AM
Subject: [TekScopes] Re: 222 battery replacement


All of this is moot as far as 222x's are concerned as the PS-832 is too
large for the 222x battery compartments. (Darn - I've been looking for
an 8V SLA for a while!) The compartment is only about 1.1" deep and the
battery is 1.42" wide. It also appears to be a tad too long.
-=-=-=-
Not according to my measurements:
H: 3.0"
L: 5.39"
D: 1.43"
These measurements are max dimensions, from wall-to-wall.
The PS-832 is:
H: 2.7" (to the top of the connectors)
L: 5.49" (a snug fit, to be sure)
D: 1.42" (a really snug fit)
This all requires Dremeling the standoffs, those "walls" inside the compartment. You might have to separate the case halves and put the battery in the hold, and reseal it all. But I think it will fit.
But you can get more Ah's with the NiMH cells, so why not? If you've been having good luck, stick with it!
Enjoy,
Dave
Yahoo! Groups Links


Re: 7633 - repairable?

arthurok <arthurok@...>
 

i can do that dr. craig with my 465
i want something that is alot better then my old lab scopes

----- Original Message -----
From: "Craig Sawyers" <c.sawyers@tech-enterprise.com>
To: <TekScopes@yahoogroups.com>
Sent: Friday, March 24, 2006 2:25 AM
Subject: RE: [TekScopes] 7633 - repairable?


what do you think a good starter 7000 mainframe would
be thats
inexpensive and maintainable?
7603 + 7B53A and 2x7A18. That will get you (a) a linear supply, (b) 100MHz
with four traces and delayed/delaying dual TB (c) a really large screen
(1.22cm/div).

Going up from there, a 7704A + 7B85, 7B80 and 2x7A26 will do 200MHz and has
more sophisticated timebase capabilities. It has a switched mode supply,
that can be an interesting and time consuming exercise to fix if it goes
wrong.

Craig




Yahoo! Groups Links







Re: 7633 - repairable?

Craig Sawyers <c.sawyers@...>
 

what do you think a good starter 7000 mainframe would
be thats
inexpensive and maintainable?
7603 + 7B53A and 2x7A18. That will get you (a) a linear supply, (b) 100MHz
with four traces and delayed/delaying dual TB (c) a really large screen
(1.22cm/div).

Going up from there, a 7704A + 7B85, 7B80 and 2x7A26 will do 200MHz and has
more sophisticated timebase capabilities. It has a switched mode supply,
that can be an interesting and time consuming exercise to fix if it goes
wrong.

Craig


Re: 222 battery replacement

DaveC <davec2468@...>
 

All of this is moot as far as 222x's are concerned as the PS-832 is too
large for the 222x battery compartments. (Darn - I've been looking for
an 8V SLA for a while!) The compartment is only about 1.1" deep and the
battery is 1.42" wide. It also appears to be a tad too long.
-=-=-=-

Not according to my measurements:
H: 3.0"
L: 5.39"
D: 1.43"
These measurements are max dimensions, from wall-to-wall.

The PS-832 is:
H: 2.7" (to the top of the connectors)
L: 5.49" (a snug fit, to be sure)
D: 1.42" (a really snug fit)

This all requires Dremeling the standoffs, those "walls" inside the compartment. You might have to separate the case halves and put the battery in the hold, and reseal it all. But I think it will fit.

But you can get more Ah's with the NiMH cells, so why not? If you've been having good luck, stick with it!

Enjoy,
Dave


Re: 7633 - repairable?

arthurok <arthurok@...>
 

ive been thinking of getting into 7000 series
i have alot of letter an 1 series plug ins and notice that they
command a fairly high price on ebay
i even have a rack mountable 134 dual plug in power supply
if i sold off some of my spare plugins maybe i could get a
7000 mainframe and some plug ins
i really cant afford it but you know how that goes
what do you think a good starter 7000 mainframe would be thats inexpensive and maintainable?
the main reason i never got into 7000 is because i have
2 547 scopes and a 549 with a perfect tube plus alot of plugins

----- Original Message -----
From: "Craig Sawyers" <c.sawyers@tech-enterprise.com>
To: <TekScopes@yahoogroups.com>
Sent: Friday, March 24, 2006 1:46 AM
Subject: RE: [TekScopes] 7633 - repairable?


I was offered a 7633. It only displays a distorted 8,
independently of the
installed plugins and no readout. Is this a common failure mode? Is it
reparable without resorting to another 7633 for parts?
Sounds like a power supply problem.

The supply is simple - transformer, rectifiers, smoothing caps and then
linear regulators based around simple circuits (often using generic 2N3055
pass transistors). Eveything available, or easily substitutable.

Failure modes:

* Series pass transisors are socketted, and the solder connections to the
collectors' sockets at the board can crack (probably thermal flexing over
decades). If that happens, the driver transistor takes all the current and
blows, often taking out other transistors on the way.

* Power supply electrolytics can dry out and essentially go open circuit or
otherwise fail

* Bridge rectifiers have been know to go open

* Look out for glass encapsulated 9V zener diodes - these often go open
circuit

* There is a 43V zener in there too that can shift in value (recently
replaced one that was at 22V)

If a line is shorted, that particular supply crowbars. If that is the case
start by looking for shorts to ground.(tants).

But a figure of 8 on the screen sounds to me like a power supply reservoir
electrolytic problem.

Craig




Yahoo! Groups Links






Re: what is appropriate

Craig Sawyers <c.sawyers@...>
 

I am new to this list, so I am not quite sure what is
considered to be "off
topic". I have a DM501A
Although this is called the Tekscopes list, and this implies that it is for
oscilloscopes only, in practice any Tek instrument is discussed. So the
DM501 fits perfectly IMNSHO.

Craig


Re: Battery electrolyte leakage detectors? (acid/alkaline)

Ashton Brown <ashton@...>
 

Heathkit GD-1701 Flood Alarm - an inexpensive small box with 2 ICs: a LM1801N and a CD40106BCN -- connected to a length of wire and a small PCB er, 'rectangular Archimedes spiral'.

Works fine for its intended purpose: monitoring basements. A damp finger across the traces triggers it - 9V battery. Assuredly any old electrolyte would do even better; presumably a Fet-input op-amp + the oscillator/driver circuit for a small speaker ... one could monitor a shelf of battery-op devices, with the sensors in parallel.

Wouldn't be hard to crank out a bunch of spirals, smallest gauge 'zip-cord' type wire - and one box to watch them all! (One ring to ...)
Alas, no scanner here, though a possibility at neighbor's.
(I wonder if there's a WWW-cache of old Heath� � � schematics?)
Be lost sans my IG-4244 late-design Scope Calibrator with ~700 pSec Tr, decently refined as to artifacts. HP grade, if not quite.. as pretty as Tek.

HTH,
Ashton



onamathist wrote:

Hi folks. Does anyone know of a good sensing device to sniff out leaky
batteries, e.g. as one would find in a Tektronix 200-series portable
o'scope? (i.e. alkaline or acid electrolyte leakage)I'm thinking that
if I get one of these 'scopes sometime, I'd be really sad if it got
leaky on me and ruined itself (I also don't look forward to changing
the batteries, but some things just have to be done).

Thanks for any ideas!

Best,
Phil Stewart


Re: just got a 7514

Craig Sawyers <c.sawyers@...>
 

well everyone I have just arrived home with my new find a
7514 storage
scope
This is my first 7xxx series scope so this will be a
new learning experience for me so any thouhgts or advice on
this scope
would be very welcome thanks
Well, you've picked a real rarity to start off with! The 7514 was made for
only a very short time around 1970 when the 7000 series was first
introduced.

Apart from that, I have no direct experience of this unit - although with it
being rather rare (and because no-one knows what it is, cheap) I'd like to
own one!

Cheers

Craig


Re: 7633 - repairable?

Craig Sawyers <c.sawyers@...>
 

I was offered a 7633. It only displays a distorted 8,
independently of the
installed plugins and no readout. Is this a common failure mode? Is it
reparable without resorting to another 7633 for parts?
Sounds like a power supply problem.

The supply is simple - transformer, rectifiers, smoothing caps and then
linear regulators based around simple circuits (often using generic 2N3055
pass transistors). Eveything available, or easily substitutable.

Failure modes:

* Series pass transisors are socketted, and the solder connections to the
collectors' sockets at the board can crack (probably thermal flexing over
decades). If that happens, the driver transistor takes all the current and
blows, often taking out other transistors on the way.

* Power supply electrolytics can dry out and essentially go open circuit or
otherwise fail

* Bridge rectifiers have been know to go open

* Look out for glass encapsulated 9V zener diodes - these often go open
circuit

* There is a 43V zener in there too that can shift in value (recently
replaced one that was at 22V)

If a line is shorted, that particular supply crowbars. If that is the case
start by looking for shorts to ground.(tants).

But a figure of 8 on the screen sounds to me like a power supply reservoir
electrolytic problem.

Craig


tek 454 isolation switch

arthurok_2000 <arthurok@...>
 

my tek 454a manual shows no such isolation switch
maybe tek removed the feature for the public good
that switch on the back of the scope could accidently
be put in the floating position
the 3 wire adapter trick is at your own risk and positive
ul would never allow that "floating" switch
most older tek stuff isnt ul listed
trust me when im building or repairing something for use by
others im very carefull there is no fire or electrocution hazard
and i dont take risks at very high voltages at appreciable
currents "like a trasnmitter or linear amp "
stuff like that i troubleshoot cold and sometimes use a
variac to test at very low line voltage
accidents can happen i have a little tek 221 scope on the
way that i bought as is that someone damaged when testing a
tv without an isolation transformer
hopefully deane kidd will have whatever parts i need
he said the power supply was damaged and he found bad
parts in it i have a service manual on the way.
PLEASE GROUP DONT TAKE UNNECESSARY RISKS JUST BECAUSE SOME OF
US HAVE GOTTEN AWAY WITH DOING THINGS IN AN IMPROPPER MANNER
DOSENT MEAN THAT ITS GOOD PRACTICE REALIZING ITS WRONG AND
DANGEROUS IS NO EXCUSE TO TRY IT .
AN ISOLATION TRANSFORMER CAN EASILY BE MADE USING 2 BACK TO
BACK LARGE FILAMENT TRANSFORMERS OR MAYBE EVEN JUNK BATTERY
CHARGER TRANSFORMERS.
DOES THE GROUP APPROVE OF THAT METHOD???


Re: Floating scopes, isolation xformers.

arthurok <arthurok@...>
 

maybe there is a reason it wouldnt work using a standard dual trace plug in in differential mode?
a good diffrential plug in like a 1a5 has alot more common mode range then a 1a1 "i think im right"
im not into 7000 series yet
700 vac rms on the scope case is even worse then just
120 vac when doing a quick in the field check on a tv set
the newer tvs are all isolated so unless you are working on the hot side of a switching supply you dont need an isolation transformer

----- Original Message -----
From: "Ray Robinson" <robinson@shlrc.mq.edu.au>
To: <TekScopes@yahoogroups.com>
Cc: <robinson@srsuna.shlrc.mq.edu.au>
Sent: Friday, March 24, 2006 12:40 AM
Subject: RE: [TekScopes] Floating scopes, isolation xformers.


Hi Gang,

Years ago, I used to use an isolation transformer and removed the ground
pin to float a 7603 scope, to view the 30v p-p signal across the gates
on SCRs in 480v 200hp VFD drives.
I had no other way to view the 30v signals that were floating on top of
the 700v+ AC otherwise.
Gosh,
I don't do it that way.

I use a dual channel scope,
switch it to differential mode,
and invert one channel.

Regards
Ray



Yahoo! Groups Links






Re: Floating scopes, isolation xformers.

Ray Robinson <robinson@...>
 

Hi Gang,

Years ago, I used to use an isolation transformer and removed the ground
pin to float a 7603 scope, to view the 30v p-p signal across the gates
on SCRs in 480v 200hp VFD drives.
I had no other way to view the 30v signals that were floating on top of
the 700v+ AC otherwise.
Gosh,
I don't do it that way.

I use a dual channel scope,
switch it to differential mode,
and invert one channel.

Regards
Ray


tv hd computer monitor sync seperator

arthurok_2000 <arthurok@...>
 

i was just looking at the data sheet for an intersil
isl59885 auto adjusting sync seperator for standard and
high definition tv
most older tek and hp scopes don't have built in sync seperators
at this moment i own only one scope that has that a tek 2225 and
that isnt delayed sweep
im thinking of making up a little box using that new intersil chip
that will lock onto standard 1 volt video levels and give me
horizontal and verticle sync outputs
this is much better then its predecessor chip in that it
automaticaly detects hdtv sync frequencies and isnt even affected by
macrovision sync pulses
i think i could put it in a little box and it would be a great
adjunct to working with video
i was thinking of how to put it inside
a 465 or 2336 but that would be a hastle
the tek 465/b option isnt exceptionly versitle
and after looking at the manual would be even a bigger hastle then
installing a dm44 option


Fw: Re: Floating scopes, isolation xformers.

arthurok <arthurok@...>
 

----- Original Message -----
From: "arthurok" <arthurok@ameritech.net>
To: "Chuck Harris" <cfharris@erols.com>
Sent: Thursday, March 23, 2006 11:39 PM
Subject: Re: [TekScopes] Re: Floating scopes, isolation xformers.


i never said it was a good idea
if you read the posts other people have done it to in a pinch
if the potential between earth and the scope case is
under lets say 30 volts rms or 48 volts peak
you arent taking much of a safety risk
i think thats the application ibm used the isolated
switch for on the 454 to make measurements where there was a
small voltage differential between test point ground and
scope line cord ground
lets say you had 6 volts rms between the test lead ground
and scopes earth ground under those conditions
you would get alot of current flowing through the probes
wire shield and maybe smoke it
you should always use an isolation transformer when working with a hot chassis device
unless i have to hook up a scope or a signal generator i dont
my meters are floating.
i wouldnt float the scope at a very high voltage because it might cause internal breakdown
ive never floated it higher then the 120 vac line and that was done with great care my scope is grounded right now
FLOATING THE SCOPE CASE ESPECIALLY AT A VOLTAGE THAT COULD BE LETHAL IS A BAD IDEA
I SEE THAT OTHERS HAVE DONE IT WITH GREAT CARE WHEN AN ISOLATION DEVICE WAS NOT AVAILIBLE. AS FAR AS IM CONCERNED HOT CHASSIS DEVICES ARE CRAP AND UL MAKES IT DIFFACULT TO GET ACCEPTANCE ON THEM
MOST MODERN TVS ARE FULLY ISOLATED NOW
EVEN THE CHEAP ONES .
y
----- Original Message -----
From: "Chuck Harris" <cfharris@erols.com>
To: "arthurok" <arthurok@ameritech.net>
Sent: Thursday, March 23, 2006 10:50 PM
Subject: Re: [TekScopes] Re: Floating scopes, isolation xformers.


No, it doesn't... Well, not so that it will help you much. The
scope probes connect directly to the metal on the scope's case, and
the scope's case connects to the big round pin on the power cord.

If you disable the round pin (bond wire), you will have your
scope "floating", but all the metal in its body, and the ground
clip on the scope probes will still be connected together. If
you happen not to be isolated yourself, bzzap! You'll be just
another bug in the old bug zapper.

It's your life, but please, stop trying to convince anyone that it
is a good idea.

-Chuck Harris

arthurok wrote:
the scope has an isolation transformer built into it
if you exceed the primary to secondary breakdown voltage of it you will damage it and the scope will nolonger be floating
----- Original Message -----
From: "msauve2" <mikes@flatsurface.com>
To: <TekScopes@yahoogroups.com>
Sent: Thursday, March 23, 2006 5:20 AM
Subject: [TekScopes] Re: Floating scopes, isolation xformers.


what is appropriate

Chris van Lint
 

I am new to this list, so I am not quite sure what is considered to be "off topic". I have a DM501A which I cannot callibrate in the AC RMS mode. Now this kinda plugs into the same gear you plug oscilloscopes (SC501,502,503 and 504). Question: Is it appropriate to discuss this in this forum and if not, can somebody point me in the right direction.

Chris


Re: Battery electrolyte leakage detectors? (acid/alkaline)

Chris van Lint
 

In principle any form of pH paper would change colour, providing it is not bone dry. The real problem is that by the time you notice that the paper colour has changed a considerably amount of damage has probably been done. There are continous electronic pH sensors available, but using them would be really gilding the lilly, as they are horendously expensive.

Chris

----- Original Message -----
From: arthurok
To: jfor@quik.com ; onamathist ; TekScopes@yahoogroups.com
Sent: Friday, March 24, 2006 1:08 PM
Subject: Re: [TekScopes] Battery electrolyte leakage detectors? (acid/alkaline)


maybe some sort of sensitive litmus paper that would detect
vapors
----- Original Message -----
From: "J. Forster" <jfor@quik.com>
To: "onamathist" <pstewart@gwi.net>; <TekScopes@yahoogroups.com>
Sent: Thursday, March 23, 2006 8:04 PM
Subject: Re: [TekScopes] Battery electrolyte leakage detectors?
(acid/alkaline)


> The best method is the calibrated eyeball, applied a few times a year.
> IMO, any
> battery operated equipment needs to have it's battery looked at fairly
> often.
>
> In the past, most of this high end gear was used in companies with regular
> cal
> cycles. That cal cycle would have spotted things like the fuzz on NiCds,
> the
> early signs of a failure, and things like that would have been fixed
> before
> being returned to service. That just does not happen when the instrument
> is in
> private hands. (Among other things, a new NiCd pack may well exceed the
> value or
> price of the instrument.)
>
> In fact, I've gotten a lot of perfectly good Tek (and other) gear because
> the
> 'owner' of the gear (the group it was assigned to within a company for
> cost
> accounting purposes) was not willing to pay the calibration charges any
> longer.
> The calibration department puts it in the pound for a while, and if it was
> not
> rescued in a few months, it was sold for surplus. In a large business,
> such a
> procedure does make some sense, especially if you are working on
> government
> contracts, but perfectly good equipment gets discarded as a result. Hence
> $600
> toilet seats and high taxes.
>
> In my experience, it's the neglected batteries that leak. I'm likely as
> guilty
> as anyone else for not taking periodic care of batteries, but it's part of
> the
> reason I'm not a real fan of battery powered equipment. The stuff just
> goes bad
> sitting on a shelf.
>
> FWIW,
> -John
>
> onamathist wrote:
>
>> Hi folks.
>> Does anyone know of a good sensing device to sniff out leaky
>> batteries, [snip]
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>



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More thanks to Denis Cobley, was 2430A repair

Didier Juges <didier@...>
 

Another satisfied customer :-)

Denis helped me through fixing my 2430A, which is now passing all self tests. In the process, and through the abundance of information received from Denis on this and other Tek scopes, I feel considerably more confortable trying to fix the next big one, a 2445B with a dead Horiz amplifier.

The short version of the 2430A was a bad Trigger hybrid, which I replaced by scavenging a 2430 I had which had no tube. After the replacement, I still had a Trig fault, which went away after running a Self Cal.

Thank you again Denis.

Didier KO4BB


Re: Replacement knobs

arthurok <arthurok@...>
 

.050 and 1/16" covers most tek knobs

----- Original Message -----
From: "asm_2750" <asm2750@gmail.com>
To: <TekScopes@yahoogroups.com>
Sent: Thursday, March 23, 2006 9:25 PM
Subject: [TekScopes] Replacement knobs


When I got my 7603 aparently the intensity pot got a little minor
damage, noting a little epoxy couldnt fix. The pot still works you
just have to turn it in a weird fashion. The plastic part of the knob
however, due to it being old I guess disengrated when I touched it.
Some of my other tek knobs show alot of age but work well. So I was
wondering is it possible to get replacement knobs with out having to
buy non functional equipment? Then I'll need to find a set of small
allen wrenches so I can get to that pot and epoxy the plate back on
I'm sure the local homecenter has them. Yahoo! Groups Links


just got a 7514

Nyleen Bailey
 

well everyone I have just arrived home with my new find a 7514 storage
scope but no plugins, anyways its dirty from sitting but looks very
well kept under the grime, I have already looked on bama for a manual
but didnt see one listed so if anyone has one or could copy one that
would be great This is my first 7xxx series scope so this will be a
new learning experience for me so any thouhgts or advice on this scope
would be very welcome thanks

Steve


Replacement knobs

asm_2750
 

When I got my 7603 aparently the intensity pot got a little minor
damage, noting a little epoxy couldnt fix. The pot still works you
just have to turn it in a weird fashion. The plastic part of the knob
however, due to it being old I guess disengrated when I touched it.
Some of my other tek knobs show alot of age but work well. So I was
wondering is it possible to get replacement knobs with out having to
buy non functional equipment? Then I'll need to find a set of small
allen wrenches so I can get to that pot and epoxy the plate back on
I'm sure the local homecenter has them.

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