Date   

Re: Model 310 scope without Tektronix name

Miroslav Pokorni
 

You youngsters with eagle eyes.

You could not have read it on the screen, size of text is below PC screen
resolution, you must have seen one of those scope 'in flesh'.

Regards

Miroslav Pokorni

----- Original Message -----
From: "Rolynn PRECHTL K7DFW" <k7dfw@clatskanie.com>
To: <TekScopes@yahoogroups.com>
Sent: Saturday, January 17, 2004 9:37 AM
Subject: Re: [TekScopes] Model 310 scope without Tektronix name




This auction is for a Model 310 scope that Tektronix must have made for
IBM,
because there is no Tek's name on it, only IBM.

It has "Tektronix Inc" and "Portland, Oregon USA" just below the pilot
light.

K7DFW Tek Bvtn and Sunset 66-71

..._._


Re: Caig VS Tweek

John Miles <jmiles@...>
 

Last I heard, Sumiko still sells lots of "Tweek�" (Dave's name for the
sanely diluted product in a small bottle with nail-polish type brush.)

I have used this for >15 years re various intermittents, and I believe I
am not gullible - being also lab-trained in skepticism. Can probably
come up with some more data if any interested. As I said - D. is a
physics type, too - and he expected to be disappointed. It passed; one
caveat: it's hygroscopic (but not er 'deliquescent' = it won't attract
so much H20 vapor as to dissolve in it!) SO not for outdoor use!

This substance is also known as Stabilant-22. The only interesting test
results would be those resulting from a comparison of its
conductivity-enhancement effect to an equivalent quantity of DeOxit, WD40,
plain water, and various other potions, and then charting the deterioration
in conductivity (if any) over time. Nobody seems to have done that.

-- jm


Re: Model 310 scope without Tektronix name

ROLYNN PRECHTL K7DFW
 

This auction is for a Model 310 scope that Tektronix must have made for
IBM,
because there is no Tek's name on it, only IBM.

It has "Tektronix Inc" and "Portland, Oregon USA" just below the pilot
light.

K7DFW Tek Bvtn and Sunset 66-71

..._._


Feasibility of repair to 2225 oscilloscope.

David Briscoe <djsbriscoe@...>
 

Hello,
Firstly, I am new to this group.
I have a Tektronix 2225 scope that I would like to repair myself.
The beam has become completely unfocussed on the screen.
Instead of the display being a dot it is now a large diameter blob
moving across the screen.
I suspect the problem is damage sustained due to vibration.
Is there any way to ascertain for certain that the tube needs
replacement?
Are there any fault finding resources available (books, etc) that will
help me to find the fault on this scope?
I have the part number for the CRT (154-0907-00) and can obtain a copy
of the service manual.
I am also an electronics technician in a UK university so I have the
facilities for repair, but no experience with
Tektronix scopes (we use Hameg and they don't go wrong very often).
Can anyone advise me as to the best method of tracing the fault before I
start spending money?

Thanks.

Dave Briscoe
UK


email access going away temporarily

Gomez ADDams (Bill Lemieux)
 

I apologize if this message reaches anyone more than once, I am deliberately including a couple mailing lists I'm on so hopefully I won't be deleted when messages start bouncing in a couple of days.

My ISP (kaosol.net) is shutting down and will soon transfer all accounts to another company. Once I find out who it is, I may decide to keep them or I may decide to go elsewhere for my internet connectivity.

Judy's and my domains (owlhouse.org, qingtinqacupuncture.com) and private email addresses (gomez@owlhouse.org, jude@owlhouse.org) will remain the same no matter where we go, but it seems likely that we will be unable to access the accounts and that messages to those email addresses will bounce or just get dropped on the floor for some unknown but hopefully brief period.

regards,
- Bill "Gomez" Lemieux,
Denver, Colorado, USA, Sol-3

.......................................
When one fuse blows, it's bad luck.
If a second fuse blows, it's bad karma.


Re: Caig VS Tweek

Ashton Brown <ashton@...>
 

Guess I have to add my 3 kopeks re "Tweek". While I generally share the "snake oil" epithet re overuse of superlatives in the spray-can industry:

My physicist friend, a partner in Sumiko, Inc. (hi end audio, Berkeley - still going strong, I note) came across a substance - not at all well marketed by "inventor".. maybe a Mr. Wright / a Canadian. He tested the claims of "actual contact enhancement!" (via filling in the microscopic jaggies on all contacts). ie claim was that, *under pressure* this material conducted; Improved Contacts!!
It was most definitely not deemed a "cleaner". BUT.. if slopped onto insulator surface (unintentionally) No Problemo. Hence the "pressure" point.

Dave opened some (plastic bag) sealed new BNCs, double males + females; series connected a batch of ~50: measured net ohms on GR bridge.
Then 'treated' each with this [then unnamed material - a surfactant re chem. origin] and remeasured. While I can't lay hands on some scribbled #s -- there was a more than trivial improvement in conductivity. He made other tests re relay contacts, new and used (lo-current: stuff is never meant to be used re any hi-current contact).

Substance in conc. form was viscous, very expensive - and needed also, only a near monomolecular layer to do its thing. Dilution with (pure ie CP grade) isopropyl alcohol proved a good combo.

Last I heard, Sumiko still sells lots of "Tweek�" (Dave's name for the sanely diluted product in a small bottle with nail-polish type brush.)

I have used this for >15 years re various intermittents, and I believe I am not gullible - being also lab-trained in skepticism. Can probably come up with some more data if any interested. As I said - D. is a physics type, too - and he expected to be disappointed. It passed; one caveat: it's hygroscopic (but not er 'deliquescent' = it won't attract so much H20 vapor as to dissolve in it!) SO not for outdoor use!

Many hi-end audio shops have this stuff; been a while since I ordered direct. (Initially it was packaged in a tiny hypodermic-type syringe with a flex capillary molded-on, so you could apply the pure substance in awkward spots.) I've used both methods as complementary.

Finally, this still won't help w/ sealed pots until you unseal the sucker, obv. But I've fixed many a balky el cheapo relay, weak-spring-ed connector or p-b contact (a la keyboards) etc. over the years. Filthy things ought to be cleaned if you can. I heard of the Caig stuff as Was, originally: 'cramolin', when it first came out; I accepted D's hearsay that: it did not appear to exceed Tweek's capabilities.. though it may have included the original surfactant formula - unclear what the red stuff was about.. I did not follow up with seeking numbers or further info re Cramolin�-- I gather it's not in the latest offerings, anyway.

Bon appetit,


Ashton
..in search of the straight wire with gain, but not assiduously.


Miroslav Pokorni wrote:

I generally have not used DeOxit on front panel pots; only trimmers.
It seems to work OK, and for a long time on trimmers. I had a noisy
trimmer in the attenuator of a 2235 scope that I sprayed with DeOxit
a year ago. I just went out to the lab (fancy name for the garage) ;
I opened up the scope and varied the trimmer and it works fine.
My guess is that any kind of spray would work, it just washes off dirt and
with trimmers lubrication is not an issue, you hardly ever move them and if
solvent washes of lubricant there is nothing to hold dust to the pot. When I
needed to clean a pot, I used freeze spray (from CRC), and worked like charm
and there was no residue left.


For panel pots, I take them apart and clean them. Denis Cobley
recommended the Electrolube contact oil to the group back in May, but
since I bought a couple tubes, (From Echelon here in SoCal) I haven't
used it on any pots yet. Denis also recommended a gizmo that screws
onto the threads and injects the oil into the pot to get around
taking it apart. This won't work on many of the pots that Tek used,
as I find some of them have an O-ring seal around the shaft base.

It is a bitch to grow old and forgetfull. When you said gizmo, that reminded
me of what Denis recomended.

Actually, some of pots of lesser quality than ones used by Tektronix also
have O-ring on the shaft.


Re: Hah! SCORE!!

jvanderwall1941
 

--- In TekScopes@yahoogroups.com, "Bruce Lane" <kyrrin@b...> wrote:
snip
My next task is to locate appropriate main and delaying
timebases for it (7B15 and 7B10, if I'm not mistaken). I'll probably
do that when I hit the Bay Area later this year for my annual
scrounging trip. I've already got some 7A19's and 29's, so I'm good
for high-frequency vertical plug-ins.

Any advice or 'gotchas' regarding this model would be
appreciated. I already know to treat it delicately because of the
microchannel plate CRT -- how 'delicately' does that mean?

Thanks much.


-=-=-=-=-=-=-=-=-=-=-=-
Bruce Lane, Owner & Head Hardware Heavy,
Blue Feather Technologies -- http://www.bluefeathertech.com
kyrrin (at) bluefeathertech do/t c=o=m
"If Salvador Dali had owned a computer, would it have been equipped
with surreal ports?"

Bruce--Glad to see miracles can still happen. The 7104 was my bench
scope from whenever we got it until I retired in 1995, probably 15
years. I and one other engineer used it continually over this time
without burning the phosphor or suffering any problem whatever with
the mainframe or the 7A29s. We always used a 7B92A sweep which was
nearly as fast as the pair you mentioned and very linear over the
whole ten divisions (but we discarded the first division on
principle). Note that the original 7B92 was spectacularly nonlinear
over the first *two* divisions at fast sweeps, and was simply
useless. For anything faster we used samplers, and an XY recorder for
permanent records.

The only time I actually worried about burning a phosphor was when we
got one of the smaller scopes with a MCP which was fine, except that
Tek had lost its mind and used a microprocessor to scan the front
panel controls and adust the scope accordingly. The scan was very
slow and the result was that it was all too easy to turn up the
intensity a little and find out you had turned it up a lot! Even so,
it never harmed the CRT.

Regards,

Jonathan Vanderwall


Model 310 scope without Tektronix name

Miroslav Pokorni
 

This auction is for a Model 310 scope that Tektronix must have made for IBM,
because there is no Tek's name on it, only IBM.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2588169693&category=4677

Regards

Miroslav Pokorni


Re: Any way to clean...?

Miroslav Pokorni
 

I generally have not used DeOxit on front panel pots; only trimmers.
It seems to work OK, and for a long time on trimmers. I had a noisy
trimmer in the attenuator of a 2235 scope that I sprayed with DeOxit
a year ago. I just went out to the lab (fancy name for the garage) ;
I opened up the scope and varied the trimmer and it works fine.
My guess is that any kind of spray would work, it just washes off dirt and
with trimmers lubrication is not an issue, you hardly ever move them and if
solvent washes of lubricant there is nothing to hold dust to the pot. When I
needed to clean a pot, I used freeze spray (from CRC), and worked like charm
and there was no residue left.


For panel pots, I take them apart and clean them. Denis Cobley
recommended the Electrolube contact oil to the group back in May, but
since I bought a couple tubes, (From Echelon here in SoCal) I haven't
used it on any pots yet. Denis also recommended a gizmo that screws
onto the threads and injects the oil into the pot to get around
taking it apart. This won't work on many of the pots that Tek used,
as I find some of them have an O-ring seal around the shaft base.

It is a bitch to grow old and forgetfull. When you said gizmo, that reminded
me of what Denis recomended.

Actually, some of pots of lesser quality than ones used by Tektronix also
have O-ring on the shaft.


Re: Caig (Any way to clean...?)

Miroslav Pokorni
 

At the best, I can say that site is interesting.

The letter purporting to present Cramolin's side of story is not even
coherent. Can not blame it on language skill, it was sent from Pennsylvania
and that is a business letter.

The Caig's side of story is written very smoothly, but it is paroles only,
no substance. Mind you, letter is just relating a story of relations between
those two companies, but at the web site it was presented as an argument on
effectiveness of product. Reminds me of conversations with Caig's Technical
Support when I was looking for a product to fix contact problems on DIMMs,
essentially a cheap edge connector, quality restricted by price of product.
Over several conversations with a lady in technical support I got her to
contradict herself, because she would say what she thought that customer
wanted to hear. Only constant thing was that I should buy in volume.
Eventually, ProGold turned ineffective, the only help was vigorous rubbing
with Kimwipes (lint free paper wipers) soaked in isopropyl alcohol.

Regards

Miroslav Pokorni

----- Original Message -----

From: "Greyhawk" <greyhawkeng@hotmail.com>
To: <TekScopes@yahoogroups.com>; "Fred Olsen" <fwolsen@execpc.com>
Sent: Friday, January 16, 2004 7:22 PM
Subject: Re: [TekScopes] Re: Caig (Any way to clean...?)


There Is An Interesting Article Here About Caig Labs And
Cramolin Red Here:

http://www.pitt.edu/~szekeres/caigcram.htm

Greyhawk

----- Original Message -----
From: Fred Olsen
To: TekScopes@yahoogroups.com
Sent: Friday, January 16, 2004 21:18
Subject: [TekScopes] Re: Caig (Any way to clean...?)


Miroslav Pokorni wrote:
> My experience with those 'miracle lubricants' has been that they are
snake
> oil and that includes Caig Lab. I tried their DeoxIT with very
indifferent
> results,

Since the original question regarded pots I would remind all that DeoxIT
is intended for connector, switch, and relay contacts. Caig's
recommended product for carbon and conductive plastic pots is CaiLube
MCL.

While I too have had mixed results with Caig's current products, they do
work fairly well in their intended applications. Overhyped and
overpriced though, and products from Chemtronics and others work darn
near as well.

It seems though that 'everyone' has forgotten about the original
product, Cramolin, from the original Caig Labs in New York. Cramolin
'red' was a thin liquid cleaner/preservative, Cramolin Special (green)
was just a preservative for new or clean contacts, and Cramolin Paste
was for high voltage / high current use. There was also a Paste-G which
was graphite-filled. I think that they had a mineral oil base.

The stuff had an odd smell, and the 'red' turned colors when it attacked
oxides, but it really worked quite well. Or works, I should say, as I
still have some and have used it regularly for 35+ years. It is
intended to be applied in a very thin film, near molecular, and so a
little goes a long way.

As I recall it, not well, the products were produced by the original
Caig under license or some other sort of proprietary agreement and are
no longer available from the present company. A search of their site
will turn up references to them as discontinued products. A source for
something like the original compounds still exists in Germany. The
whole product line is named Cramolin, from ITW Chemische Produkte GmbH.
http://www.cramolin.de/

Fred
--
<><
--
Outgoing checked by Norton AV




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Re: Any way to clean...?

Jeff W <vwthingy@...>
 

Miroslav Pokorni wrote:
Your experience with Electrolube would be of great interest, I
daresay, for
group as a whole. In particular, over long term, say six months or
longer.

My experience with those 'miracle lubricants' has been that they
are snake
oil and that includes Caig Lab.
I generally have not used DeOxit on front panel pots; only trimmers.
It seems to work OK, and for a long time on trimmers. I had a noisy
trimmer in the attenuator of a 2235 scope that I sprayed with DeOxit
a year ago. I just went out to the lab (fancy name for the garage) ;
I opened up the scope and varied the trimmer and it works fine.

For panel pots, I take them apart and clean them. Denis Cobley
recommended the Electrolube contact oil to the group back in May, but
since I bought a couple tubes, (From Echelon here in SoCal) I haven't
used it on any pots yet. Denis also recommended a gizmo that screws
onto the threads and injects the oil into the pot to get around
taking it apart. This won't work on many of the pots that Tek used,
as I find some of them have an O-ring seal around the shaft base.

Next time I take apart a pot I'll report back the findings.....

Jeff


Re: Caig (Any way to clean...?)

Miroslav Pokorni
 

----- Original Message -----
From: "Fred Olsen" <fwolsen@execpc.com>
To: <TekScopes@yahoogroups.com>
Sent: Friday, January 16, 2004 6:18 PM
Subject: [TekScopes] Re: Caig (Any way to clean...?)
Since the original question regarded pots I would remind all that DeoxIT
is intended for connector, switch, and relay contacts. Caig's
recommended product for carbon and conductive plastic pots is CaiLube MCL.
I am quite glad to report that so far I have not been forced to fix any pots
on instruments, so do not have a first hand experience with CailLube. On
radios I use copious amounts of white gas or alcohol, so that amounts to
washing off accumulated dirt together with lubricants. But, I am not an
antique restorer, I just do utility thing.


It seems though that 'everyone' has forgotten about the original
product, Cramolin, from the original Caig Labs in New York. Cramolin
'red' was a thin liquid cleaner/preservative, Cramolin Special (green)
was just a preservative for new or clean contacts, and Cramolin Paste
was for high voltage / high current use. There was also a Paste-G which
was graphite-filled. I think that they had a mineral oil base.
I did hear about original Cramolin, and from what I remember, someone said
that Caig Lab started life as distributor of Cramolin. However, I never knew
that Caig Lab was in New York, before they bought sunglasses and moved to
California.

A source for
something like the original compounds still exists in Germany. The
whole product line is named Cramolin, from ITW Chemische Produkte GmbH.
http://www.cramolin.de/
Thank you for giving link to Cramolin site, it would be interesting to check
it out.

Another contender for those contact lubricants is Nye Oils. They seem to be
supplying specialty lubricants, for watches, fine mechanisams etc., so
contact lubricants are within things that can be expected from them, but Nye
does not make any wild claims about restorative abilities of their ware.

Regards

Miroslav Pokorni


Re: Scope humour

Rex W. Athey <mister_twister@...>
 

That reminds me of why tubes and transistors love to play baseball. They like to watch those electrons go from 1st base to home plate.

Rex


Re: Caig (Any way to clean...?)

Greyhawk <greyhawkeng@...>
 

There Is An Interesting Article Here About Caig Labs And
Cramolin Red Here:

http://www.pitt.edu/~szekeres/caigcram.htm

Greyhawk

----- Original Message -----
From: Fred Olsen
To: TekScopes@yahoogroups.com
Sent: Friday, January 16, 2004 21:18
Subject: [TekScopes] Re: Caig (Any way to clean...?)


Miroslav Pokorni wrote:
> My experience with those 'miracle lubricants' has been that they are snake
> oil and that includes Caig Lab. I tried their DeoxIT with very indifferent
> results,

Since the original question regarded pots I would remind all that DeoxIT
is intended for connector, switch, and relay contacts. Caig's
recommended product for carbon and conductive plastic pots is CaiLube MCL.

While I too have had mixed results with Caig's current products, they do
work fairly well in their intended applications. Overhyped and
overpriced though, and products from Chemtronics and others work darn
near as well.

It seems though that 'everyone' has forgotten about the original
product, Cramolin, from the original Caig Labs in New York. Cramolin
'red' was a thin liquid cleaner/preservative, Cramolin Special (green)
was just a preservative for new or clean contacts, and Cramolin Paste
was for high voltage / high current use. There was also a Paste-G which
was graphite-filled. I think that they had a mineral oil base.

The stuff had an odd smell, and the 'red' turned colors when it attacked
oxides, but it really worked quite well. Or works, I should say, as I
still have some and have used it regularly for 35+ years. It is
intended to be applied in a very thin film, near molecular, and so a
little goes a long way.

As I recall it, not well, the products were produced by the original
Caig under license or some other sort of proprietary agreement and are
no longer available from the present company. A search of their site
will turn up references to them as discontinued products. A source for
something like the original compounds still exists in Germany. The
whole product line is named Cramolin, from ITW Chemische Produkte GmbH.
http://www.cramolin.de/

Fred
--
<><
--
Outgoing checked by Norton AV




------------------------------------------------------------------------------
Yahoo! Groups Links

a.. To visit your group on the web, go to:
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What kind of cap is that ?

plasmatec2000
 

Hi,

I got a lot of caps that are labeled Tektronix

http://www.beautyphoto.de/tektronix.jpg

and I wish to know what material is the foil.

The foil is transparent with light green cast.
Not possible to stretch,
makes harsh sound when touching,
plastic foil and aluminum foil are separat,
is this cheap MKT ?


Re: 7104 Service Manual wanted

nr1dx@...
 

Bruce

The other email address you just sent "returned fatal errors"

Dave


From: "Bruce Lane" <kyrrin@bluefeathertech.com>
Date: 2004/01/16 Fri PM 09:31:31 GMT
To: tekscopes@yahoogroups.com
Subject: [TekScopes] 7104 Service Manual wanted

Hi, gang,

OK... I've checked my usual sources. Cheapest price I've seen so far for a service manual (original Tek hardcopy) for the 7104 was $135.00.

That really seems kind of high. I know there's at least a couple of listmembers who sell manuals -- that being the case, I'd like to hear from you if you can beat that price.

The serial number involved is B021884.

Thanks much.
-=-=-=-=-=-=-=-=-=-=-=-
Bruce Lane, Owner & Head Hardware Heavy,
Blue Feather Technologies -- http://www.bluefeathertech.com
kyrrin (at) bluefeathertech do/t c=o=m
"If Salvador Dali had owned a computer, would it have been equipped with surreal ports?"




Yahoo! Groups Links

To visit your group on the web, go to:
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Re: GR, not Tek!

Miroslav Pokorni
 

A very interesting site, Craig.

I find it amazing that Teradyne put such an effort in preserving GR's
history. Even more so, when it is common after acquisition of a company to
obliterate any sign of existence of acquired company, kind of 'plow the salt
into the fields'.

Regards

Miroslav Pokorni

----- Original Message -----
From: "Craig Sawyers" <c.sawyers@tech-enterprise.com>
To: "TekScopes" <TekScopes@yahoogroups.com>
Sent: Thursday, January 15, 2004 4:21 PM
Subject: [TekScopes] GR, not Tek!


Hi all

Anyone interested in the history of GR, I found a downloadable 1916
catalogue here
http://www.teradyne.com/corp/grhs/pdf/catalog-bulletins/Catalog_A_1916.pdf
.
In fact this is just a section in the General Radio Historical Society on
http://www.teradyne.com/corp/grhs/ - it seems to have lots of fascinating
stuff there if you like the early history of electronics.

Enjoy!

Craig


Re: Any way to clean...?

Miroslav Pokorni
 

Your experience with Electrolube would be of great interest, I daresay, for
group as a whole. In particular, over long term, say six months or longer.

My experience with those 'miracle lubricants' has been that they are snake
oil and that includes Caig Lab. I tried their DeoxIT with very indifferent
results, improvement lasted a week or so and it was back to where I started.
Then, I tried Caig's 'R5 Power Booster', with similar results. You must have
heard of Caig's 'battery challenge', apply R5 to an old flash light and
'watch it come back to life'. I applied it to a new flash light that would
go dim after a while and when you pull batteries out and re-insert them, the
light works fine for a week or so. I tried R5, pulled batteries out, cleaned
all surfaces (batteries and contacts) with R5, few times each, re-assembled
the flash light and in a week I was where I started. After few tries with
R5, I substituted water for R5, with same results. Than I did not use any
'cleaner', just rubbed batteries and contacts with dry cloth and again light
lasted a week or so, so buying DeoxIT or R5 was a waste of money and effort.

I recognize that rubbing surfaces (pots, connectors, switches etc.) need a
lubricant to reduce wear and smooth operation, but those promised miracles
just appear to be snake oils.

Regards

Miroslav Pokorni

----- Original Message -----
From: "Jeff W" <vwthingy@cox.net>
To: <TekScopes@yahoogroups.com>
Sent: Thursday, January 15, 2004 9:58 PM
Subject: [TekScopes] Re: Any way to clean...?


Bruce wrote:
Does anyone know of a way to clean the (apparently sealed)
pots on the front panel of a 7000 series?

I have found that the cycling them results in a very temporary fix.
I have become pretty good with taking apart these pots, cleaning
them, and putting them back together. In the past, I used to just
collect the excess grease and recycle it, but I recently picked up a
couple tubes of Electrolube contact oil to try out.

Jeff


Re: Replacing CC resistors

Miroslav Pokorni
 

And low inductance should not be forgotten. Those dastardly carbon
compositions are quite irreplaceable as (50 Ohm) terminating resistors.

In these days, ceramic composition is offered as replacement for carbon,
with low inductance, high surge etc., but no one is talking about long term
stability. Examples are Ohmite's 'OX', 'OY' and 'Little Demon' series.

Construction of those ceramic composition resistors appears to be same as
that for carbon composition, so the same problems might crop up past 1000
hours standard test for resistors. A true hermetic seal would certainly
improve long term stability, but that is a difficult proposition. It appears
that only thing that would do that trick is a layer of glass or glassified
ceramic around resistive element and phenolyc encapsulant to provide
mechanical protection for that fragile sealing material, but that would
drive price of resistor sky high.

Regards

Miroslav Pokorni

----- Original Message -----
From: "Michael Dunn" <mdunn@cantares.on.ca>
To: <TekScopes@yahoogroups.com>
Sent: Friday, January 16, 2004 2:26 PM
Subject: [TekScopes] Replacing CC resistors


Yes, old carbon comp resistors *can* drift. Just a thought: if
you're replacing CCs with film resistors, keep in mind one of CC's
attributes - their high surge capacity. Analyze or measure the
circuit (most likely during turn-on), and overrate the replacement's
power if necessary.

Michael



TEK 485 Question

w1ksz <w1ksz@...>
 

I think I found the cause of the trace shifting on my 485. One end
of the Position Pot (R1300) goes to +13v. The voltage drops slowly
to 11.5v as the scope "warms up". Now I just have to locate where
the +13v comes from. The power supply schematic doesn't show it, and
the reference to the A Time Base Generator schematic doesn't help.
Does anyone know where it comes from ?

Thanks, Dick, W1KSZ

181821 - 181840 of 188071