Tek 545B O'scope Fuse and Power

[Noel Keith]

So, I recently got a Tektronics 545B oscilloscope. It's been sitting in a basement for god knows how long, and I thought it would be cool to see if it worked. well, it doesn't. It's missing it's fuse and fusecap, and it's power cable. I had read in a couple of places that the fuse only affected the high voltage stuff, like the CRT. I might be totally wrong about this, which is why I'm asking you guys Well, with that in mind, I found a newer power cable that seemed to fit the bill, so I tried using that. Nothing. I then tried using a voltage regulator. Still nothing. Now, I'm not sure if it's because of the mysterious missing fuse, or if something else has gone bad inside, or if it was the power cable (which I doubt). My next guess was that it was the missing fuse. Holy crap does this thing have a strange fuse. I've looked all over for something with a similar rating and size, but with no luck. I'm not as worried about the fusecap. I searched for a couple weeks online, but I eventually came to the conclusion that the thing would probably never work. Today though, I thought I'd give it a go again.
Back of the oscilloscope: http://i.imgur.com/uM64sfX.jpg
I opened it up to find TONS of gunk and dusk blanketing it's insides. I also found a pdf of its manual (which has slightly more info about the missing fuse). Now I think I got in over my head, because I'm too scared to touch anything. Before I go fiddling with 50 year old electrical components, I want to know if it works or not, what I can do to fix the fuse situation (even if only temporarily), and if I should check for anything else.

So, can anyone help me? I'd REALLY like to get this guy working again, but I need some help (obviously, hehe...)

 

[tm]

"Noel Keith" <noeltkeith@gmail.com> wrote in message
news:1215625b-bcc2-4bdb-8d44-09fd6bf306b3@googlegroups.com...
So, I recently got a Tektronics 545B oscilloscope. It's been sitting in a
basement for god knows how long, and I thought it would be cool to see if it
worked. well, it doesn't. It's missing it's fuse and fusecap, and it's power
cable. I had read in a couple of places that the fuse only affected the high
voltage stuff, like the CRT. I might be totally wrong about this, which is
why I'm asking you guys Well, with that in mind, I found a newer power
cable that seemed to fit the bill, so I tried using that. Nothing. I then
tried using a voltage regulator. Still nothing. Now, I'm not sure if it's
because of the mysterious missing fuse, or if something else has gone bad
inside, or if it was the power cable (which I doubt). My next guess was that
it was the missing fuse. Holy crap does this thing have a strange fuse. I've
looked all over for something with a similar rating and size, but with no
luck. I'm not as worried about the fusecap. I searched for a couple weeks
online, but I eventually came to the conclusion that the thing would
probably never work. Today though, I thought I'd give it a go again.
Back of the oscilloscope: http://i.imgur.com/uM64sfX.jpg
I opened it up to find TONS of gunk and dusk blanketing it's insides. I also
found a pdf of its manual (which has slightly more info about the missing
fuse). Now I think I got in over my head, because I'm too scared to touch
anything. Before I go fiddling with 50 year old electrical components, I
want to know if it works or not, what I can do to fix the fuse situation
(even if only temporarily), and if I should check for anything else.

So, can anyone help me? I'd REALLY like to get this guy working again, but I
need some help (obviously, hehe...)


_+_+_+_+_+_+_+_+_+_+_+_+_+_+

There is a Yahoo group dedicated to the old Tektronix scopes. Why don't you
join it and ask there?

http://tech.groups.yahoo.com/group/TekScopes/

Over 6000 members, sure to be someone that can lend you some guidance.

The usual way to clean these scopes out is with soap and hot water. That
subject is covered on the group.


regards,
tm

 

[Wild_Bill]

The last time I saw one of those was in the '80s and they were very old
then. The fuse is needed for any operation, and what good would a 'scope be
without the CRT powered, anyway?

For pursuing an interest in electronics, you would likely be far better off
with a 'scope of more recent vintage. You may find cheap/free equipment in
local Craigslist or Freecycle listings.

You may be in over your head suggested by the details you've posted. If you
chance applying power, be ready to interrupt the power quickly (switched
receptacle) and have another capable person present.

If this 'scope has been sitting around in a damp location, it may be too
dangerous to go thru the effort of applying power.
A proper ground wire should be attached to the case and a known good earth
ground before applying power. Depending on a used or old deteriorated power
cord could be a mistake.
If the 'scope is powered, it should not be left unattended and should
absolutely be disconnected from the AC power afterward.

Ask around to see if there may be any ham radio enthusiasts near you, who
might power up the 'scope for you. An elder person may be more familiar with
old, neglected tube equipment and more likely to have the correct type of
fuse holder cap.

The fuse holder cap is a bit obscure nowadays.. it has a tubular projection
with 2 wings? at the end.
With a fuse inserted into the cap, the fuse is then slid into the holder
until it is fully inserted, then the cap is turned clockwise about 90
degrees (maybe less but not more).
The fuse cap will then be latched into place.

Obviously, a lot of debris isn't good in an electrical appliance, but any
cleaning should be done cautiously and gently with no power applied and
better to do it outdoors (low pressure compressed air or duster can gas, for
example).

I'm not sure about that particular model, but check your literature to see
if there is an opening in a side panel where jumper bars go (banana plug
sockets 2 rows of 3 IIRC). There won't be any trace response without those
jumpers in the correct positions.
If applicable to this model, the said banana sockets are accessible with the
covers ON, nothing inside needs to be jumpered for normal operation.

--
Cheers,
WB
..............


"Noel Keith" <noeltkeith@gmail.com> wrote in message
news:1215625b-bcc2-4bdb-8d44-09fd6bf306b3@googlegroups.com...
So, I recently got a Tektronics 545B oscilloscope. It's been sitting in a
basement for god knows how long, and I thought it would be cool to see if it
worked. well, it doesn't. It's missing it's fuse and fusecap, and it's power
cable. I had read in a couple of places that the fuse only affected the high
voltage stuff, like the CRT. I might be totally wrong about this, which is
why I'm asking you guys Well, with that in mind, I found a newer power
cable that seemed to fit the bill, so I tried using that. Nothing. I then
tried using a voltage regulator. Still nothing. Now, I'm not sure if it's
because of the mysterious missing fuse, or if something else has gone bad
inside, or if it was the power cable (which I doubt). My next guess was that
it was the missing fuse. Holy crap does this thing have a strange fuse. I've
looked all over for something with a similar rating and size, but with no
luck. I'm not as worried about the fusecap. I searched for a couple weeks
online, but I eventually came to the conclusion that the thing would
probably never work. Today though, I thought I'd give it a go again.
Back of the oscilloscope: http://i.imgur.com/uM64sfX.jpg
I opened it up to find TONS of gunk and dusk blanketing it's insides. I also
found a pdf of its manual (which has slightly more info about the missing
fuse). Now I think I got in over my head, because I'm too scared to touch
anything. Before I go fiddling with 50 year old electrical components, I
want to know if it works or not, what I can do to fix the fuse situation
(even if only temporarily), and if I should check for anything else.

So, can anyone help me? I'd REALLY like to get this guy working again, but I
need some help (obviously, hehe...)

 

[Michael Black]

On Fri, 19 Apr 2013, Noel Keith wrote:

So, I recently got a Tektronics 545B oscilloscope. It's been sitting in
a basement for god knows how long, and I thought it would be cool to see
if it worked. well, it doesn't. It's missing it's fuse and fusecap, and
it's power cable. I had read in a couple of places that the fuse only
affected the high voltage stuff, like the CRT. I might be totally wrong
about this, which is why I'm asking you guys Well, with that in mind,
I found a newer power cable that seemed to fit the bill, so I tried
using that. Nothing. I then tried using a voltage regulator. Still
nothing. Now, I'm not sure if it's because of the mysterious missing
fuse, or if something else has gone bad inside, or if it was the power
cable (which I doubt). My next guess was that it was the missing fuse.
Holy crap does this thing have a strange fuse. I've looked all over for
something with a similar rating and size, but with no luck. I'm not as
worried about the fusecap.

Of course the fuse takes care of the whole thing, it's in the primary to
the power transformer. F601, it's a 6amp fast-blo 3AG fuse for 120vac
operation (3ampts if running off 240v). It's a standard glass fuse, you
should be able to get them anywhere. It goes into the fusecap, then you
screw (or is it turn?) the fusecap into the holder at the back of the
scope. I don't know where the fusecaps can be found these days, I
suddenly find I need one and can't find any among all the junk.

Nothing will happen unless that fuse is in place, and that includes the
fusecap.

There's also a thermal cutout fuese in series to the primary of the power
transformer, but that isnt' even a factor until you get the proper fuse in
there witha fusecap.

I got one 20 years ago, though havent' had it on in about 10 years. It
was working fine when I got it, but I since someobody found it at a
hospital as it was about to be tossed out, I suspect it was still in
operation. It worked for a while, then the trace got bent. It's a
multiple section power supply I wasn't sure which section was the problem,
I found it by taking the probe and touching each of the sections across
their filter capacitor, until the waveform got worse. Changed that filter
capacitor, and all was fine. It is incredibly bulky, which is why I moved
it to the basement and thus it's a lot less useful, so it just sits there.


Michael


I searched for a couple weeks online, but I

eventually came to the conclusion that the thing would probably never
work. Today though, I thought I'd give it a go again. Back of the
oscilloscope: http://i.imgur.com/uM64sfX.jpg I opened it up to find TONS
of gunk and dusk blanketing it's insides. I also found a pdf of its
manual (which has slightly more info about the missing fuse). Now I
think I got in over my head, because I'm too scared to touch anything.
Before I go fiddling with 50 year old electrical components, I want to
know if it works or not, what I can do to fix the fuse situation (even
if only temporarily), and if I should check for anything else.

So, can anyone help me? I'd REALLY like to get this guy working again, but I need some help (obviously, hehe...)

 

[Phil Allison]

"Michael Black"

Of course the fuse takes care of the whole thing, it's in the primary to
the power transformer. F601, it's a 6amp fast-blo 3AG fuse for 120vac
operation (3ampts if running off 240v).

** As marked on the rear of the scope - the fuse needs to be a "slow blow"
type.


It's a standard glass fuse, you should be able to get them anywhere.


** Well, anywhere that has available a good range of fuses for electronic
equipment.

Slow blow fuses are commonly stamped or marked with a "T" before the amp
rating.

So look for a " T6.3A " fuse in 3AG size ( or 32 x 6.3 mm) - though such as
high value seems wrong for a tube scope.

If you use a standard "fast " fuse, it may well blow at switch on.



..... Phil

 

[Phil Allison]

"Noel Keith"

The thing is, I haven't been able to find a slow blow fuse with the right
Amp/Volt ratio.

** LOL - there no such thing.

The 3AG fuse you need will be probably be marked:

" T6.3A 125V " OR " T6.3 250V "

Sometimes the T is left off and the slow blow characteristic is identifiable
by having a coil spring or long spiral inside the glass.




..... Phil

 

[Dave M]

Michael Black wrote:

On Fri, 19 Apr 2013, Noel Keith wrote:

So, I recently got a Tektronics 545B oscilloscope. It's been sitting
in a basement for god knows how long, and I thought it would be cool to
see if it worked. well, it doesn't. It's missing it's fuse and fusecap,
and it's power cable. I had read in a couple of places that the fuse only
affected the high voltage stuff, like the CRT. I might be totally
wrong about this, which is why I'm asking you guys Well, with that in
mind, I found a newer power cable that seemed to fit the bill, so I tried
using that. Nothing. I then tried using a voltage regulator. Still
nothing. Now, I'm not sure if it's because of the mysterious missing
fuse, or if something else has gone bad inside, or if it was the
power cable (which I doubt). My next guess was that it was the missing
fuse. Holy crap does this thing have a strange fuse. I've looked all over
for something with a similar rating and size, but with no luck. I'm not
as worried about the fusecap.

Of course the fuse takes care of the whole thing, it's in the primary
to the power transformer. F601, it's a 6amp fast-blo 3AG fuse for
120vac operation (3ampts if running off 240v). It's a standard glass
fuse, you should be able to get them anywhere. It goes into the
fusecap, then you screw (or is it turn?) the fusecap into the holder
at the back of the scope. I don't know where the fusecaps can be
found these days, I suddenly find I need one and can't find any among
all the junk.
Nothing will happen unless that fuse is in place, and that includes
the fusecap.

There's also a thermal cutout fuese in series to the primary of the
power transformer, but that isnt' even a factor until you get the
proper fuse in there witha fusecap.

I got one 20 years ago, though havent' had it on in about 10 years. It was
working fine when I got it, but I since someobody found it at a
hospital as it was about to be tossed out, I suspect it was still in
operation. It worked for a while, then the trace got bent. It's a
multiple section power supply I wasn't sure which section was the
problem, I found it by taking the probe and touching each of the
sections across their filter capacitor, until the waveform got worse.
Changed that filter capacitor, and all was fine. It is incredibly
bulky, which is why I moved it to the basement and thus it's a lot
less useful, so it just sits there.

Michael


I searched for a couple weeks online, but I
eventually came to the conclusion that the thing would probably never
work. Today though, I thought I'd give it a go again. Back of the
oscilloscope: http://i.imgur.com/uM64sfX.jpg I opened it up to find
TONS of gunk and dusk blanketing it's insides. I also found a pdf of its
manual (which has slightly more info about the missing fuse). Now I
think I got in over my head, because I'm too scared to touch
anything. Before I go fiddling with 50 year old electrical components, I
want
to know if it works or not, what I can do to fix the fuse situation
(even if only temporarily), and if I should check for anything else.

So, can anyone help me? I'd REALLY like to get this guy working
again, but I need some help (obviously, hehe...)

I think that you really are over your head with this old scope if you can't
deduce that a missing fuse is probably the reason that it doesn't light up.
This scope isn't for the faint of heart to work on. Since it's been idle
for who knows how long, then it's almost ceretain that most, if not all, of
the power supply filter capacitors need to be replaced, along with many more
electrolytics in other circuits.
Most of the power supply sources in it are regulated, and sometines even an
experienced technician can find them hard to get right. Ripple and noise on
the voltage sources are critical to proper operation of every circuit in the
scope.
As for the dirt, I understand that the Tektronix service dept used to
actually wash scopes that had been traded in for newer better scopes down
with detergent and a low pressure garden hose. Then the scopes were air
dried for several days (in a warm, dry place). Then, repair and calibration
were performed.

The scope can almost certainly be restored to working condition, but that
usually takes someone with proper knowledge, experience and test equipment.
You need another scope and a good DMM just to get the power supplies running
properly,

--
Dave M

 

[Phil Allison]

"Dave M"

As for the dirt, I understand that the Tektronix service dept used to
actually wash scopes that had been traded in for newer better scopes down
with detergent and a low pressure garden hose. Then the scopes were air
dried for several days (in a warm, dry place). Then, repair and
calibration were performed.

** I take it the scope has a fan inside - right ?

Many times I have had to give large power amps a " bath " for the same
reason.

Plus, on one occasion, because the customer's storage shed for his hire
business had been flooded with muddy storm water.


..... Phil

 

[Noel Keith]

To make a correction, when I got the scope I DID have the fuse. It had fallen out somwhere when I took it home though. I had no luck finding it. The thing is, I haven't been able to find a slow blow fuse with the right Amp/Volt ratio. Currently I just want to see if I can get the power light to turn on. As long as I know it's getting power, I can work from there. It's been in a pretty dry area (but dirty-ish), so I would be suprised if something was damaged in there. The guy I got it from said it worked when he got it, but that was several years ago...

I also sorta lied about me having to electronics experience, actually. I'm an electronic musician and I've been experimenting with making my own synths. In fact the reason I'm fixing this up is to hook it up to my synths and see the waveforms, just as a way to show it off (and also to keep the house warm in the winter hehehe). Now that I'm looking at it, it seems to be in pretty good condition! Hmmm... I don't suppose there would be any way to subtitute anything else for the fuse? That is, without blowing it up.

 

[Michael Black]

On Sat, 20 Apr 2013, Phil Allison wrote:

"Michael Black"

Of course the fuse takes care of the whole thing, it's in the primary to
the power transformer. F601, it's a 6amp fast-blo 3AG fuse for 120vac
operation (3ampts if running off 240v).

** As marked on the rear of the scope - the fuse needs to be a "slow blow"
type.


It's a standard glass fuse, you should be able to get them anywhere.

I couldn't be bothered going down to the basement to check, the manual was

handy. The parts list says fast-blo. The odd thing about the manual is I
see no photo of the back panel.

** Well, anywhere that has available a good range of fuses for electronic
equipment.

Slow blow fuses are commonly stamped or marked with a "T" before the amp
rating.

So look for a " T6.3A " fuse in 3AG size ( or 32 x 6.3 mm) - though such as
high value seems wrong for a tube scope.

If you use a standard "fast " fuse, it may well blow at switch on.

Which makes sense, and I just copied what was in the manual. I turn mine

on, and the lights dim. If it was fast, you're right, that kind of inrush
would blow the fuse before the thing had a chance to take off.

Michael

 

[Phil Allison]

"Michael Black"

Phil Allison wrote:
"Michael Black"

Of course the fuse takes care of the whole thing, it's in the primary to
the power transformer. F601, it's a 6amp fast-blo 3AG fuse for 120vac
operation (3ampts if running off 240v).

** As marked on the rear of the scope - the fuse needs to be a "slow
blow"
type.


It's a standard glass fuse, you should be able to get them anywhere.

I couldn't be bothered going down to the basement to check, the manual was
handy. The parts list says fast-blo. The odd thing about the manual is I
see no photo of the back panel.

** So the thick plottens .......

Seems there is disagreement between the manual and the labelling on the
back.

A "T 6.3" amp fuse is too big for a tube scope - but an "F 6.3" amp fuse
would be about right, given the inrush surge of the circa 200VA supply
transformer.



..... Phil

 

[Bill Gill]

On 4/19/2013 4:03 PM, Noel Keith wrote:

So, I recently got a Tektronics 545B oscilloscope. It's been sitting in a basement for god knows how long, and I thought it would be cool to see if it worked. well, it doesn't. It's missing it's fuse and fusecap, and it's power cable. I had read in a couple of places that the fuse only affected the high voltage stuff, like the CRT. I might be totally wrong about this, which is why I'm asking you guys Well, with that in mind, I found a newer power cable that seemed to fit the bill, so I tried using that. Nothing. I then tried using a voltage regulator. Still nothing. Now, I'm not sure if it's because of the mysterious missing fuse, or if something else has gone bad inside, or if it was the power cable (which I doubt). My next guess was that it was the missing fuse. Holy crap does this thing have a strange fuse. I've looked all over for something with a similar rating and size, but with no luck. I'm not as worried about the fusecap. I searched for a couple weeks online, but I eve
ntually came to the conclusion that the thing would probably never work. Today though, I thought I'd give it a go again.
Back of the oscilloscope: http://i.imgur.com/uM64sfX.jpg
I opened it up to find TONS of gunk and dusk blanketing it's insides. I also found a pdf of its manual (which has slightly more info about the missing fuse). Now I think I got in over my head, because I'm too scared to touch anything. Before I go fiddling with 50 year old electrical components, I want to know if it works or not, what I can do to fix the fuse situation (even if only temporarily), and if I should check for anything else.

So, can anyone help me? I'd REALLY like to get this guy working again, but I need some help (obviously, hehe...)

When I was a calibration tech for Collins Radio in Richardson, TX we had

a wash cabinet for washing out dirty electronics equipment. It had a
turntable in it and a spray head to rinse it off. We just sprayed
things with soap solution and rinsed them off, then put them in an
oven set at around 120 degrees over night. Paper covered electrolytics
needed to be wrapped to keep the paper from getting wet.

The scope will probably need to have the filters replaced. If it has
an old fashioned selenium rectifier that will undoubtedly need to be
replaced. Early models had the seleniums, unless I am remembering
the 545A. And there is a fair chance a bunch of tubes will be weak.
This is particularly important for the power supply regulator
tube(s). I don't remember if it had 1 or 2 series regulators. If
you have the manual you can tell easy enough.

Bill

 

[Noel Keith]

Alright, so I was able to find 2 types of fuses that I THINK should work. Only thing is that they're ceramic, and not glass, but it shouldn't matter. 6.3A 250V Slow Blow, and 6.3A 125V Slow Blow. They were cheap so I bought 5 of each, just in case I needed a backup for whatever reason. I'm also looking for a F6.3A fuse now too. I did manage to get some life in to it though.. A buddy of mine who works on these things came over and brought a spare fuse from another Tek scope of his and said he wanted to see if it worked. Well, it blew instantly. But...hey! At least I got it to do something, right?...right? Also, the fan turned on for that brief moment of life and was slowly spinning.

 

[Phil Allison]

"Bill Gill".

When I was a calibration tech for Collins Radio in Richardson, TX we had
a wash cabinet for washing out dirty electronics equipment. It had a
turntable in it and a spray head to rinse it off. We just sprayed
things with soap solution and rinsed them off,

** Is there some kind of rule that makes Americans refer to all liquid
detergents as "soap " ??

Dish washing liquid ( for hand washing) has no alkali, rinses off
completely, is non-conductive, non corrosive to bare metals and hence safe
for use with electronics.

OTOH, products sold for washing clothes and for use in dish washing
machines generally contain alkalis, the water solution is conductive,
corrodes bare metal and is hard to fully rinse off.

Dish washing liquid is the only one that is proven safe to use.

Liquid hand wash ( soap free & pH balanced ) is probably OK too.

Use any others at your peril.



..... Phil

 

[Phil Allison]

<jurb6006@gmail.com>

I prefer to use mild solvents actually, like alcohol/acetone.

** Acetone sure is NOT mild !!!

This is mainly for PCBs though,

** Neither is any good for removing oils, grime or drink spills that contain
sugars or fats from PCBs.

when it comes to cabinetry and shit I dunno, dish soap seems really good.

** Dishwashing liquid is ideal for cleaning PCBs of nearly anything -
except non water soluble flux.



.... Phil

 

[Jeff Liebermann]

On Sun, 21 Apr 2013 14:31:42 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

Liquid hand wash ( soap free & pH balanced ) is probably OK too.

I have my doubts about anything that has pH Balanced on the label. The
term is completely meaningless and is mostly a marketing buzzword.
What is the pH of the soap being balanced against? What benefit does
this alleged balancing act have for the user? Too many unanswered
questions.
<http://www.oprah.com/style/What-Does-pH-Balanced-Mean>
The best example is pH balanced shampoo. What it does is suds only
over a very narrow range of pH. I don't recall the numbers, but it
specifically avoids the typically pH=5.5 of skin so that it does *NOT*
suds when first applied. Only after dilution with water, or a 2nd
application does the pH of the mix increase to roughly a neutral pH=7,
where it will produce suds. The obvious result is that users use
twice as much shampoo as they would with one that would suds at any pH
value. I suspect that hand and dishwashing soap may be similar, but I
haven't bothered to check.

Incidentally, the shampoo business gets extra credit for making the
bottle caps the same color as the shampoo, so that the user can't
easily see how much shampoo they are "measuring" into the cap. Also,
by increasing the surface tension, and designing the dispenser orifice
so that the first drop comes out as a huge blob of shampoo, which also
promoted un-necessary consumption.

As for cleaning a dirty TEK 545, I would use an air hose to evict the
dirt and spiders. Then some 409 and a tooth brush on the really grimy
spots. Leave the rest alone as I assume that all the electrolytics
are bad and that it will need disassembly to replace those anyway.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Trevor Wilson]

On 4/20/2013 10:54 PM, Phil Allison wrote:

"Michael Black"
Phil Allison wrote:
"Michael Black"

Of course the fuse takes care of the whole thing, it's in the primary to
the power transformer. F601, it's a 6amp fast-blo 3AG fuse for 120vac
operation (3ampts if running off 240v).

** As marked on the rear of the scope - the fuse needs to be a "slow
blow"
type.


It's a standard glass fuse, you should be able to get them anywhere.

I couldn't be bothered going down to the basement to check, the manual was
handy. The parts list says fast-blo. The odd thing about the manual is I
see no photo of the back panel.


** So the thick plottens .......

Seems there is disagreement between the manual and the labelling on the
back.

A "T 6.3" amp fuse is too big for a tube scope - but an "F 6.3" amp fuse
would be about right, given the inrush surge of the circa 200VA supply
transformer.

**Don't be too certain. My second CRO was an Hitachi copy of the Tek
545A. It was a massive, heavy, noisy, hot bugger. So close, was the
copy, that the Tektronix service manual was perfectly suitable for
fault-finding and operational needs. FWIW, the only major difference
between the Hitachi and the Tek was Hitachi's use of 2% tolerance
resistors throughout the entire CRO (except for high precision areas).
Tek used 10% or 20% tolerance resistors throughout. The thing used a
full RLC delay line with 20 or so valves. The vertical amplifier valve
filaments operated in a series string of (as I best recall) 120 Volts
DC. Regulation for various circuits (including heaters) was via 3 X 6080
dual triodes. The thing ate them. It had a 200mm fan in the back and
consumed 500 Watts under normal operation. Great in the workshop during
Winter. Not so good during Summer. My subsequent CRO was all solid state.

A 6.3AT fuse, for 117VAC is within possibility. I've got a manual for it
somewhere. BAMA probably have it for free download if you're interested.

--
Trevor Wilson www.rageaudio.com.au

 

[Trevor Wilson]

On 4/20/2013 7:03 AM, Noel Keith wrote:

So, I recently got a Tektronics 545B oscilloscope. It's been sitting in a basement for god knows how long, and I thought it would be cool to see if it worked. well, it doesn't. It's missing it's fuse and fusecap, and it's power cable. I had read in a couple of places that the fuse only affected the high voltage stuff, like the CRT. I might be totally wrong about this, which is why I'm asking you guys Well, with that in mind, I found a newer power cable that seemed to fit the bill, so I tried using that. Nothing. I then tried using a voltage regulator. Still nothing. Now, I'm not sure if it's because of the mysterious missing fuse, or if something else has gone bad inside, or if it was the power cable (which I doubt). My next guess was that it was the missing fuse. Holy crap does this thing have a strange fuse. I've looked all over for something with a similar rating and size, but with no luck. I'm not as worried about the fusecap. I searched for a couple weeks online, but I eve
ntually came to the conclusion that the thing would probably never work. Today though, I thought I'd give it a go again.
Back of the oscilloscope: http://i.imgur.com/uM64sfX.jpg
I opened it up to find TONS of gunk and dusk blanketing it's insides. I also found a pdf of its manual (which has slightly more info about the missing fuse). Now I think I got in over my head, because I'm too scared to touch anything. Before I go fiddling with 50 year old electrical components, I want to know if it works or not, what I can do to fix the fuse situation (even if only temporarily), and if I should check for anything else.

So, can anyone help me? I'd REALLY like to get this guy working again, but I need some help (obviously, hehe...)

**I had one of these more than 30 years ago. It was hot, noisy, heavy
and an average performer. Do yourself a favour - buy a newer CRO. Even
something as old as a Tek 565b will be a revelation. You'll even be able
to move it about, without a forklift.

--
Trevor Wilson www.rageaudio.com.au

 

[Phil Allison]

"Jeff Liebermann"
"Phil Allison"

Liquid hand wash ( soap free & pH balanced ) is probably OK too.

I have my doubts about anything that has pH Balanced on the label.

** Yawnnnnnnnnnnnnnnnnnnnnn................

The
term is completely meaningless and is mostly a marketing buzzword.
What is the pH of the soap being balanced against? What benefit does
this alleged balancing act have for the user? Too many unanswered
questions.

** It broadly refers to it being non alkalai - ie SOAP FREE !!!!!!!!

That is, it will not irritate the skin on ones hands like ordinary soaps do
and washing liquid is infamous for.

Been using them for 20 years myself.

Work very nicely at cleaning my electric shaver too.



.... Phil

 

[Phil Allison]

"Trevor Wilson"
Phil Allison wrote:

** So the thick plottens .......

Seems there is disagreement between the manual and the labelling on the
back.

A "T 6.3" amp fuse is too big for a tube scope - but an "F 6.3" amp
fuse
would be about right, given the inrush surge of the circa 200VA supply
transformer.

**Don't be too certain. My second CRO was an Hitachi copy of the Tek 545A.
It was a massive, heavy, noisy, hot bugger. So close, was the copy, that
the Tektronix service manual was perfectly suitable for fault-finding and
operational needs. FWIW, the only major difference between the Hitachi and
the Tek was Hitachi's use of 2% tolerance resistors throughout the entire
CRO (except for high precision areas). Tek used 10% or 20% tolerance
resistors throughout. The thing used a full RLC delay line with 20 or so
valves. The vertical amplifier valve filaments operated in a series string
of (as I best recall) 120 Volts DC. Regulation for various circuits
(including heaters) was via 3 X 6080 dual triodes. The thing ate them. It
had a 200mm fan in the back and consumed 500 Watts under normal operation.
Great in the workshop during Winter. Not so good during Summer. My
subsequent CRO was all solid state.

A 6.3AT fuse, for 117VAC is within possibility. I've got a manual for it
somewhere.

** Here is a pretty good pic of the insides of a 545B.

http://www.barrytech.com/tektronix/vintage/tek545bright.jpg

The AC tranny looks like it *might* be 500VA - but I expect Tek would use a
conservatively rated unit with a low temp rise.

If the OP would care to measure the primary resistance - I can say for sure.



.... Phil