开云体育

Steve Bringhurst wrote:

Thanx Stan for response;
My only present source for 8233/E55Ls is junker
3A1/3A6 P-Is (no extra charge for cath interface laden
& defective tubes), is there another reasonable priced
source? Last retail price I saw was about the same as
a whole surplus working modern scope, ca $85(?!).

I think you can find 8233's in the Antique Electronics catalog for around
$50, still not cheap. As you have noticed, you can buy a used 3A6 or 3A1 for
a LOT less than that and it contains TWO 8233's, but who can say how good
they are? I think all of mine have come from 3A1's and 3A6's. What else
uses them? Why are they so bloody expensive . . . are they used in some tube
audio stuff? That is the only thing I can think of that would run the price
up so high . . .

Haven't had enough experience with them yet to
recognize cath interface probs, assume it is
near-basline vert anomaly on display? Not good news
for a scarce and pricey tube.

There is a description of cathode interface and how to determine if you have
it on my web page at:

BTW, the internal structure of the dud looked good
under a loupe and direct sunlight, no burned or warped
grids, no discolored plate or lumpy/perforated cathode
visible thru the envelope, just the melted cath tabs
and clean & shiny getter. Strange indeed.

Thanx again. Best Rgds; Steve

OK, my pleasure.

Stan
w7ni@...

Hi,
I've got a R564B rack mount storage CRO with a blown transistor in
the power supply, not sure what other problems. I think the tube's OK.
I have the schematic for a 564 low voltage and high voltage power supply
but it's different in the R564B. The 564 had tube regulators and HV
supply, the R564B is all solid state.
Has anyone got a manual for a R564B that they could scan the schematics,
particularly the power supplies and email to me please. I have the
plugin manuals, in these scopes much of the circuitry is in the plugins
including the deflection amplifiers.
Thanks, Don Black.

Sorry that my email reply meant for Andrew in Sydney went out to the group.
I didn't check the reply address before I hit the send button (and I also
didn't correct the subject title). It's kinda late and I'm getting rummy I
guess.

As long as I'm here, my thanks to Dean Huster for the earlier suggestion
regarding a substitute for the air filter element for a 465B. A generic
Scotchbrite pad did indeed work well.

By the way, according to my neighbor who designed the TAS 465 horizontal amp,
the TAS 220 and 250 did originate from the Orient but the TAS 455/465/475/485
were Beaverton designed.

In another bit of trivia, the serial number for my TAS 465 starts with "BR"
as opposed to the expected "B0"; another neighbor suggests the "R" is
intentionally inserted into the SN when an instrument is refurbished. He
works in sales for a print server company, not Tek, but claims that it is a
legal requirement to put the "R" in. Indeed, my TAS has a Tek refurbished
sticker on it also. I thought I'd throw that one out there for comment as
I've not come across an official meaning for the "BR" yet. Does this make
sense to anyone?

Don

Hello Andrew,

Thank you for the reply from early May providing me with the TAS 465 service
manual part number.

I'm still trying to locate one (though it turns out my next door neighbor
designed the horizontal amplifier for it before he moved into marketing!!!
Can you believe a coincidence like that?!).

May I ask one more question? Can you tell me the exact wording of the title
of this manual?

Thanks again for your assistance and I hope things are going well in Sydney!

Don Cramer
KA7CEV
Beaverton, OR, USA

--- Stan or Patricia Griffiths <w7ni@...> wrote:

Steve B. wrote:

Thanx Phil, here goes;
I am trying to understand the failure mode of an

8233/E55L in a 3A6.

Both cathode tabs were melted and the 47^ screen

resistor is smoked.

With great trepidation, I replaced the defective

tube after checking

the asssociated 6DJ8s, xistors, and diodes. The

replacement held and

the screen resistor stayed cool. I suspected

possible filament-

cathode leakage/short in the otherwise fresh

looking dead tube. No

way to check for that now. I definitely don't want

to risk a

presently good 8233/E55L. Any ideas on the

probable failure mode?

BTW, there is now a DC imbalance on both traces

that the controls

won't comp. Related?
The P/I came in a group w/a 564. It didn't fail

here. I have

entertained the possibility that fil voltage was

mistakenly applied

to the cathode pins in a tester, but this doesn't

explain the smoking

screen resistor observed with the defective tube

in place in the P/I.

Thanx in advance; Steve

Stan responds;

The reason I did not respond to this question (I
remember it now) is that I
have never seen or heard of this failure before. I
didn't think I had
anything useful to contribute, but I guess just
letting you know I have never
seen it in many years of observing would tell you
something . . . My guess
would be a random internal failure of the 8233 and I
would do what you did .
. . replace it and cross your fingers . . .

By the way, I believe the 8233 is subject to the
dreaded "cathode interface"
and I would keep 8233's with that symptom around
just for running such
tests. If you waste an 8233 with cathode interface,
you haven't wasted much,
IMO.

Thanx Stan for response;
My only present source for 8233/E55Ls is junker 3A1/3A6 P-Is (no
extra charge for cath interface laden & defective tubes), is there
another reasonable priced source? Last retail price I saw was about
the same as a whole surplus working modern scope, ca $85(?!).

Haven't had enough experience with them yet to recognize cath
interface probs, assume it is near-baseline vert anomaly on display?
Not good news for a scarce and pricey tube.
BTW, the internal structure of the dud looked good under a loupe and
direct sunlight, no burned or warped grids, no discolored plate or
lumpy/perforated cathode visible thru the envelope, just the melted
cath tabs and clean & shiny getter. Strange indeed.

Thanx again. Best Rgds; Steve

--- Stan or Patricia Griffiths <w7ni@...>
wrote:

Steve B. wrote:

Thanx Phil, here goes;
I am trying to understand the failure mode of an

8233/E55L in a 3A6.

Both cathode tabs were melted and the 47^ screen

resistor is smoked.

With great trepidation, I replaced the defective

tube after checking

the asssociated 6DJ8s, xistors, and diodes. The

replacement held and

the screen resistor stayed cool. I suspected

possible filament-

cathode leakage/short in the otherwise fresh

looking dead tube. No

way to check for that now. I definitely don't want

to risk a

presently good 8233/E55L. Any ideas on the

probable failure mode?

BTW, there is now a DC imbalance on both traces

that the controls

won't comp. Related?
The P/I came in a group w/a 564. It didn't fail

here. I have

entertained the possibility that fil voltage was

mistakenly applied

to the cathode pins in a tester, but this doesn't

explain the smoking

screen resistor observed with the defective tube

in place in the P/I.

Thanx in advance; Steve

Stan responds;

The reason I did not respond to this question (I
remember it now) is that I
have never seen or heard of this failure before. I
didn't think I had
anything useful to contribute, but I guess just
letting you know I have never
seen it in many years of observing would tell you
something . . . My guess
would be a random internal failure of the 8233 and I
would do what you did .
. . replace it and cross your fingers . . .

By the way, I believe the 8233 is subject to the
dreaded "cathode interface"
and I would keep 8233's with that symptom around
just for running such
tests. If you waste an 8233 with cathode interface,
you haven't wasted much,
IMO.

Thanx Stan for response;
My only present source for 8233/E55Ls is junker
3A1/3A6 P-Is (no extra charge for cath interface laden
& defective tubes), is there another reasonable priced
source? Last retail price I saw was about the same as
a whole surplus working modern scope, ca $85(?!).

Haven't had enough experience with them yet to
recognize cath interface probs, assume it is
near-basline vert anomaly on display? Not good news
for a scarce and pricey tube.
BTW, the internal structure of the dud looked good
under a loupe and direct sunlight, no burned or warped
grids, no discolored plate or lumpy/perforated cathode
visible thru the envelope, just the melted cath tabs
and clean & shiny getter. Strange indeed.

Thanx again. Best Rgds; Steve

__________________________________________________
Do You Yahoo!?
Spot the hottest trends in music, movies, and more.

Steve B. wrote:

Thanx Phil, here goes;
I am trying to understand the failure mode of an 8233/E55L in a 3A6.
Both cathode tabs were melted and the 47^ screen resistor is smoked.
With great trepidation, I replaced the defective tube after checking
the asssociated 6DJ8s, xistors, and diodes. The replacement held and
the screen resistor stayed cool. I suspected possible filament-
cathode leakage/short in the otherwise fresh looking dead tube. No
way to check for that now. I definitely don't want to risk a
presently good 8233/E55L. Any ideas on the probable failure mode?
BTW, there is now a DC imbalance on both traces that the controls
won't comp. Related?
The P/I came in a group w/a 564. It didn't fail here. I have
entertained the possibility that fil voltage was mistakenly applied
to the cathode pins in a tester, but this doesn't explain the smoking
screen resistor observed with the defective tube in place in the P/I.
Thanx in advance; Steve

The reason I did not respond to this question (I remember it now) is that I
have never seen or heard of this failure before. I didn't think I had
anything useful to contribute, but I guess just letting you know I have never
seen it in many years of observing would tell you something . . . My guess
would be a random internal failure of the 8233 and I would do what you did .
. . replace it and cross your fingers . . .

By the way, I believe the 8233 is subject to the dreaded "cathode interface"
and I would keep 8233's with that symptom around just for running such
tests. If you waste an 8233 with cathode interface, you haven't wasted much,
IMO.

Stan
w7ni@...

--- In TekScopes@y..., "Phil (VA3UX)" <phil@v...> wrote:

Relax Steve. A bit of humor, venting and off-topic chat is

something

fairly foreign to a group of mostly serious stodgy engineer/techies

(sorry

guys) that are interested in oscilloscopes. This sort of thing is

a true

abberation.

I do have quite a sense of humor, but on this topic it has been long
exhausted elsewhere, thanx to the persistently reoccuring pointed
derision therein of those who have gone to the trouble to do the
research by those who have not. Careful observation and verification
by the scientific method works as well here as elsewhere IF the test
conditions are likewise properly seen to. "Black magic" and "Snake
oil" will fail the test, as elsewhere. Opinion won't change the
actual result, either way, tho' granted it can bias the observation
either way. Unsupported misinformation is non-contributory to any
resolution of the facts and only adds to the confusion.

What was your first post about ? Perhaps nobody had an answer and

that's

why you didn't receive any replies. Run it by us again and we'll

get

things back on the rails.

Thanx Phil, here goes;
I am trying to understand the failure mode of an 8233/E55L in a 3A6.
Both cathode tabs were melted and the 47^ screen resistor is smoked.
With great trepidation, I replaced the defective tube after checking
the asssociated 6DJ8s, xistors, and diodes. The replacement held and
the screen resistor stayed cool. I suspected possible filament-
cathode leakage/short in the otherwise fresh looking dead tube. No
way to check for that now. I definitely don't want to risk a
presently good 8233/E55L. Any ideas on the probable failure mode?
BTW, there is now a DC imbalance on both traces that the controls
won't comp. Related?
The P/I came in a group w/a 564. It didn't fail here. I have
entertained the possibility that fil voltage was mistakenly applied
to the cathode pins in a tester, but this doesn't explain the smoking
screen resistor observed with the defective tube in place in the P/I.
Thanx in advance; Steve

Hi Fernando,
Check the power supplies in the D43. It sounds like
something common to both the deflection circuits and beam voltages. It seems
the horizontal circuits are working (assuming you're seeing straight
horizontal lines). It could also be a vertical amplifier problem, not passing
a signal but either having hum signal or oscillation causing the line to
thicken. Try different sweep speeds to see if it's some signal causing the
line to thicken.
The DM53A must have a problem in the trigger circuit. Have you tried an
external trigger to see if it's lack of internal trigger signal? It must be
getting lost somewhere there.
Don Black.

Red Tomato wrote:

Hi there,

This might be a bit offtopic since I'm bringing
Telequipment scopes to
discussion. But then again Telequipment was bought by
Tektronix in the late
60's I think, so I hope all is well :-)

As I said I own two Telequipment scopes (bought them
for 30 pounds), models
D43 and DM53A with the following problems:

a)D43: Although I have both beams on the crt and the
timebase seems to be
working ok, I have neither focus nor any signal at all
(ie just two thick
straight beams);

b)Lots of trigger misfires. The signal "wanders"
across the crt window. Trigger level looks ok though.
Timebase looks ok;

Can you guys advise me on what to do or where to
start? Both crt's look ok
(no burnt spots, etc) - I'm sure we're talking about
minor stuff here.

Both scopes seem to be built like a tank - the quality
of wiring is superb -
and there's life in them - it would be a shame to
scrap them just like that.

Thanks in advance for all your
comments/suggestions/tips

Best Regards

Fernando Fonseca
Portsmouth, UK.
----------------------------------------
John Lennon's dead. Phil Collins alive?!
----------------------------------------




____________________________________________________________
Do You Yahoo!?
Get your free @yahoo.co.uk address at
or your free @yahoo.ie address at

Interesting range of opinions thus far.. and *yes* there's a
relationship to scopes in all of this, IMhO. At least re test
equipment operation, there are physics-laws + state of the
'mensuration art' which together define what you may expect to "see"
-- and how much of that CRT picture you "believe". (But even there!
re risetime artifacts, delay-line aberrations and such: it is never a
*perfect* representation: just "close".)

As a Marantz, Crown, etc. mini-dealer in the '60s - early '70s, I
imagine I've heard most of the philosophical arguments too: the
physics (not so precise as an engineer-mentation wants to suppose) --
not so fuzzy as an artist might want to argue. (sigh) To me the
final arbiter ever was:

The AR (Acoustic Research) "Live VS Recorded" concerts in these times
of great audio strides. Here the "listenien room" WAS the same exact
site as the live performers inhabited. It was classical music; never
mind one's taste: all the difficult instruments of the orchestra had
to be re-produced! Musicians would play then secretly [cackle]
switch to "pretend mode" as the speakers + electronics took the next
passage.

Bottom line: where no one (?) or a very few in audience could come
close to IDing the transitions *correctly* -- THAT is "good
enough". Period.

Now about that chirping 485 I have to do the ESR- capacitor-dance
over; it's a PITA to work on compared to a trusy 545B.. I don't have
anymore :[ (There: scope related, for the CPAs and other Content
Cops? clucking in the techno-correct peanut gallery.)


Ashton - - a mime is a terrible thing to waste -

Hello,


I'd agree with both Stan and Dean. If you want to meet the specs spelled
out in
the manual, then you should go by the manual. But I and many others the
ballpark estimate is good enough. For the record I use a oscillator in a
can from a scrap computer to check that the timebase is more or less where
it should
be. And if you need to be bang on use a counter.


Windsor Chan





_______________________________________________________
Get 100% FREE email for life from Excite Canada
Visit

Hello,


Perhaps a change in subject is would be good right now.

I caught up on the topics because I recently signed up.
Anyway did you check the horizontal plates for jitter ?

Because I had a problem just like yours with thick trace going up and down
but laser sharp going across. See the thread: RM31a jitter adventure :)


Windsor Chan





_______________________________________________________
Get 100% FREE email for life from Excite Canada
Visit

"guitar amps sound different with different sets of tubes from different manufacturers. Damned if I know why, but they do. Sometimes radically different. I almost feel that I have a split personality by making that statement, but it's true. It seems that audio/guitar amplifiers are just "tone controls", the tone being the result of the sum of the parts."

As a hobby I have a small (very small) recording studio and I would agree with you even after my earlier post on the hype in Audio. My reason is based on the idea that the guitar/amp constitutes a total instrument and what comes out of the "buzz box" is how the artist wants it to sound. You will note that guitars are always miked rather than patched directly into the mixer you want to capture all that crud the open backed, poorly coupled speaker is producing. Also take a look at the circuits in any guitar amp they tend to be nonlinear, poorly coupled with starved power supplies and I contend that if you used a "audiophile" preamp and amp you would not get the tone you would want, it most likely would sound like a acoustic guitar. basically what we are talking about is the difference between a Strad and a Yamaha violin both sound correct but they sound different and one is not necessarily better than the other just different.

Jim

After looking at my 535A this a.m., you are correct. There are tube lineups just as you say in my scope AND CA plugin. However, I don't recall seeing many 6AK5, 6AU6, or 12AU7 tubes from the European manufacturers.

I believe, as you say, that Tek picked the best manufacturer of each particular tube type, covering both performance, longevity, noise, and infant mortality. They did not just blindly sign contracts with one manufacturer like many in the radio business or TV's did (well, like RCA *wouldn't* use RCA tubes in their sets?)

What is truly amazing is the longevity of the scopes, including the tubes within. Tens of thousands of hours and they still work like new.

Chris
TekScopes@... wrote:

I'm not really sure what you mean by "small signal positions" . . . do you mean the first stage of a sensitive amplifier? ???For letter series tube amplifiers, the first stage was often a cathode follower, probably a 6AK5 (5654), Tung-Sol or RCA, or maybe a stage with gain containing a 6AU6 or 12AU6, Sylvania, RCA, GE, or Westinghouse. ???In some cases, it was a 7586 nuvistor, RCA or Hitachi. ???Virtually none of these tubes were Amperex, Telefunken, or Mullard.

After a couple of years working in the test department at Tek in 1960-62, I can say from personal experience that Tek had the very best luck with Amperex 6DJ8's over any other brand used in 530/540 scopes. ???They tried GE, Sylvania, and some CBS if I remember right. ???The differences were not subtle. ???Tek bought untested tubes because they were cheaper and every brand they tried had ten times as many bad new tubes right out of the carton than Amperex. ???It simply
took too much technician time to weed out the bad tubes that were new right out of the box, so Tek tended to stick with Amperex. ???I am talking about failures like open filaments, cracked glass, dead shorts between elements, and stuff like that. ???I don't recall much performance difference between brands of 6DJ8's once you got past the gross infant failures. ???No new stuff I worked on used many 12AX7's . . . I think there was one in each scope power supply and I
don't recall what brands were used or any significant failure rate of those, any brand. ???Same for 12AT7's and 12AU7's.

Stan
w7ni@...

__________________________________________________________________
Get your own FREE, personal Netscape Webmail account today at

Right on. Same for the Japanese paying mega bucks for the old Western Electric theatre amps. Audio is rife with "the emperor's new clothes" syndrome, and the brain plays a lot of tricks on us.

Chris

TekScopes@... wrote:

"The ear is a funny thing" very true but we do not hear with our ears we hear with our brains and are therefore subject to all the follies of the mind IE we tell ourselves what we want believe and we end up believing it, and I am not talking about Audio.

To me the question has always been that it may sound different but is it necessarily better? ???Audio is very subjective and having worked in the audio industry in the 60's and 70's (SAE, JBL, Altec) and I can tell you that most of it is hype and the rest is peer pressure. I for one am not a fan of asymmetrical distortion and I find tubes to be "fuzzy" sounding you may call it warm if you wish.

That said and done a couple of years ago I off loaded a Mac 275 for $7500 that I had paid $395 for in 1969. . . ???anit tubes great! ???

Jim

__________________________________________________________________
Get your own FREE, personal Netscape Webmail account today at

europachris@... wrote:

Has anyone ever wondered why Tek used Telefunken, Amperex, and Mullard tubes in their scopes and not RCA, GE, Westinghouse, or Sylvania, at least in the small signal positions? I would guess that they knew these were higher quality, more reliable, quieter, more linear, and more consistent. Those same parameters make a difference at 10kHz as they do at 5MHz.

Chris
TekScopes@... wrote:

I'm not really sure what you mean by "small signal positions" . . . do you mean the first stage of a sensitive amplifier? For letter series tube amplifiers, the first stage was often a cathode follower, probably a 6AK5 (5654), Tung-Sol or RCA, or maybe a stage with gain containing a 6AU6 or 12AU6, Sylvania, RCA, GE, or Westinghouse. In some cases, it was a 7586 nuvistor, RCA or Hitachi. Virtually none of these tubes were Amperex, Telefunken, or Mullard.

After a couple of years working in the test department at Tek in 1960-62, I can say from personal experience that Tek had the very best luck with Amperex 6DJ8's over any other brand used in 530/540 scopes. They tried GE, Sylvania, and some CBS if I remember right. The differences were not subtle. Tek bought untested tubes because they were cheaper and every brand they tried had ten times as many bad new tubes right out of the carton than Amperex. It simply
took too much technician time to weed out the bad tubes that were new right out of the box, so Tek tended to stick with Amperex. I am talking about failures like open filaments, cracked glass, dead shorts between elements, and stuff like that. I don't recall much performance difference between brands of 6DJ8's once you got past the gross infant failures. No new stuff I worked on used many 12AX7's . . . I think there was one in each scope power supply and I
don't recall what brands were used or any significant failure rate of those, any brand. Same for 12AT7's and 12AU7's.

Stan
w7ni@...

At 10:52 PM 6/15/2001 +0000, you wrote:

Methinks the tops of my boots are needing a few more inches to clear
the effluent which is building.

Ain't no way the human sense of hearing has the bandwidth or the
dynamic range that even modest test equipment has.

It isn't human dynamic range or bandwidth that creates this demand for
certain devices/brands Dean; it's a tone; a certain character of sound
quality. There is no technical definition for this "tone/sound thing" and
I doubt that we can measure it without first knowing what it is.

Phil

There is not a
doubt in my mind that I could write up a page of pure fiction
(including some references to Atlantis and perturbences in the orbit
of Io) and be able to sell my own homemade capacitors (I think that
Saran wrap and aluminum foil will do nicely) and homemade speaker
wire (I think that braiding some Solder Wick with spark plug wire may
do the trick) and sell these items for fantastic amounts of money to
Golden-Eared audio enthusiasts. Easily. It wouldn't be honest, but
sometimes when I read all the ads, it appears that this crowd doesn't
want honesty.

Audio is so darned subjective that no one person can say what's
right. More of my opinion (and that's exactly what it is) should be
showing up in the October 2001 installment of "Q & A"
in "Poptronics". I'll gladly put my 12AX7's on the block. Lessee,
here's the ad copy:

"Specially burned in for smooth audio quality without the sharp edges
one experiences with all new tubes. The lettering on the glass has
been removed to improve the transparency of the sound. Tubes with
specially-rounded exhaust nipples available upon special order."

Dean



To unsubscribe from this group, send an email to:
TekScopes-unsubscribe@...



Your use of Yahoo! Groups is subject to

Well hang on guys. I'm with you to a point. My original response was mainly ridiculing the hype and component pricing that is the consequence of that hype, within the audio community. I am not an audiophile but I am a guitar player (sort of) and I can tell you that despite my technical nature and inherent skeptisicm of statements not accompanied by data, guitar amps sound different with different sets of tubes from different manufacturers. Damned if I know why, but they do. Sometimes radically different. I almost feel that I have a split personality by making that statement, but it's true. It seems that audio/guitar amplifiers are just "tone controls", the tone being the result of the sum of the parts. Whatever the attributes are in high grade 12AX7's that make them sound better than lesser brands in audio applications, they apparently are of no consequence to the operation of the vintage scope circuits we are all interested in and we therefore aren't even aware of them.

Phil

At 04:18 AM 6/16/2001 +0000, you wrote:

--

I would respectfully suggest we return to our respective fields of
expertise and experience and the central topic of this forum,
Tek 'scopes and related items. Enough misinformation has already
flowed in other technical forums to to run off members over the
whipping of this VERY dead horse therein. I came here to learn what I
don't know, and not to be vicariously ridiculed for what I have
already learned through my own experience elsewhere.

Odd, this is only my second posting and I have yet to get a response
to my first on-topic request for information at mssg #278. This is
the Tek group, right?

Relax Steve. A bit of humor, venting and off-topic chat is something fairly foreign to a group of mostly serious stodgy engineer/techies (sorry guys) that are interested in oscilloscopes. This sort of thing is a true abberation.

What was your first post about ? Perhaps nobody had an answer and that's why you didn't receive any replies. Run it by us again and we'll get things back on the rails.

Phil

Somewhat exasperated; Steve Bringhurst


To unsubscribe from this group, send an email to:
TekScopes-unsubscribe@...



Your use of Yahoo! Groups is subject to