PC oscilloscopes and real oscilloscopes

[Mike]

My 40 year old valve oscilloscope blew the mains fuse. I replaced the fuse but
now it just makes suspicious something-is-getting-hot-and-might-explode sort of
crackling noise (as if one of the electrolytic capacitors is getting ready to
make a quick exit). Given its age it's probably not worth spending the time
trying to figure out what's wrong.

I'm looking for a replacement with 2 channels and a 10MHz bandwidth. Looking at
Dick Smith and Jaycar it looks like $500 for a real scope or $300 for a single
channel (low resolution) LCD screen scope.

Does anyone have experience or recommendations for a PC scope, either a plugin
card or an external box that plugs into the parallel or USB port ?
Using the sound card isn't an option because of the low sample rate.

Mike

 

[John Smyth]

My 40 year old valve oscilloscope blew the mains fuse. I replaced the fuse but
now it just makes suspicious something-is-getting-hot-and-might-explode sort of
crackling noise (as if one of the electrolytic capacitors is getting ready to
make a quick exit). Given its age it's probably not worth spending the time
trying to figure out what's wrong.

I'm looking for a replacement with 2 channels and a 10MHz bandwidth. Looking at
Dick Smith and Jaycar it looks like $500 for a real scope or $300 for a single
channel (low resolution) LCD screen scope.

Does anyone have experience or recommendations for a PC scope, either a plugin
card or an external box that plugs into the parallel or USB port ?
Using the sound card isn't an option because of the low sample rate.

Mike

Did you have a look at what scopes you can get secondhand on ebay?
www.ebay.com.au
John Smyth

 

[David L. Jones]

My 40 year old valve oscilloscope blew the mains fuse. I replaced the fuse but
now it just makes suspicious something-is-getting-hot-and-might-explode sort of
crackling noise (as if one of the electrolytic capacitors is getting ready to
make a quick exit). Given its age it's probably not worth spending the time
trying to figure out what's wrong.

I'm looking for a replacement with 2 channels and a 10MHz bandwidth. Looking at
Dick Smith and Jaycar it looks like $500 for a real scope or $300 for a single
channel (low resolution) LCD screen scope.

Does anyone have experience or recommendations for a PC scope, either a plugin
card or an external box that plugs into the parallel or USB port ?
Using the sound card isn't an option because of the low sample rate.

Mike

Hi Mike,
Unless you need the digital storage or spectrum analysis capabilities
of a PC scope, stick with a proper analog scope. You will find analog
scopes still have the lead in ease of use, responsiveness, bandwidth
and dynamic range. You need a fairly expensive high end digital scope
to even start to come close.
Also avoid the cheap handheld LCD scopes unless you obsolutely need
the portability, they are just toys.
Don't buy a new scope from the like of DSE or Jaycar, they are very
poor value for money. Instead get yourself a second hand or
reconditioned scope. These can be had on eBay, Oatley or Macservice
(http://www.tmgestore.com.au/). For the same price as a new 20MHz
Jaycar/DSE no-name unit you can get yourself a nice 100MHz+ brand name
scope.

Dave

 

[Trevor Wilson]

My 40 year old valve oscilloscope blew the mains fuse. I replaced the fuse
but
now it just makes suspicious something-is-getting-hot-and-might-explode
sort of
crackling noise (as if one of the electrolytic capacitors is getting ready
to
make a quick exit). Given its age it's probably not worth spending the
time
trying to figure out what's wrong.

I'm looking for a replacement with 2 channels and a 10MHz bandwidth.
Looking at
Dick Smith and Jaycar it looks like $500 for a real scope or $300 for a
single
channel (low resolution) LCD screen scope.

Does anyone have experience or recommendations for a PC scope, either a
plugin
card or an external box that plugs into the parallel or USB port ?
Using the sound card isn't an option because of the low sample rate.

**Find a nice used Tektronix. They go forever and perform beautifully. My
favourite is the 465B.

 

[John Crighton]

My 40 year old valve oscilloscope blew the mains fuse. I replaced the fuse but
now it just makes suspicious something-is-getting-hot-and-might-explode sort of
crackling noise (as if one of the electrolytic capacitors is getting ready to
make a quick exit). Given its age it's probably not worth spending the time
trying to figure out what's wrong.

Mike

What is the make and model is your faulty scope? Just interested to
know. Maybe it is not as bad as you think. Have you had a look inside?

Regards,
John Crighton
Hornsby

 

[John Crighton]

**Find a nice used Tektronix. They go forever and perform beautifully. My
favourite is the 465B.

Hi Trevor,
I have been hankering after one of those 465Bs for a a couple of
decades but I haven't been lucky enough to come across a good
cheap one for less than $400.
Just lately I must admit that my opinion of old BWDs has risen and
that of old Tektronix scopes has dropped slighty. Special Tek ICs
makes fixing old Tek stuff a lot harder. I have been told that there
are only a couple of hard to get special bits in the 465B so I am
still interested in finding one.
More of a want rather than a need.
Regards,
John Crighton
Hornsby

 

[Trevor Wilson]

Hi Trevor,
I have been hankering after one of those 465Bs for a a couple of
decades but I haven't been lucky enough to come across a good
cheap one for less than $400.

**$400.00 is still pretty decent value. After you've used one for awhile,
you begin to appreciate what quality is all about.

Just lately I must admit that my opinion of old BWDs has risen and
that of old Tektronix scopes has dropped slighty. Special Tek ICs
makes fixing old Tek stuff a lot harder. I have been told that there
are only a couple of hard to get special bits in the 465B so I am
still interested in finding one.
More of a want rather than a need.

**I know the feeling. I have three Tek 'scopes (454, 465b and 2430A
digital), one Philips PM3256 and a BWD 521. The BWD and the Philips require
regular cleaning of switches and pots. The Teks do not (the 454 and 465 get
used every day). The BWD has required some power supply rebuilding too.
Having said all that, the BWD is easy to work on, the Philips is a PITA. The
Teks don't ever need servicing, apart from calibration (and the odd Nuvistor
replacement in the 454). Well, except for the 2430A. It requires some work
and I don't have the balls to attempt it (yet).

BTW: If you do buy a Tek 'scope, get a Tek probe with it, if you can.
They're bloody excellent.

 

[John Crighton]

**I know the feeling. I have three Tek 'scopes (454, 465b and 2430A
digital), one Philips PM3256 and a BWD 521. The BWD and the Philips require
regular cleaning of switches and pots. The Teks do not (the 454 and 465 get
used every day). The BWD has required some power supply rebuilding too.
Having said all that, the BWD is easy to work on, the Philips is a PITA. The
Teks don't ever need servicing, apart from calibration (and the odd Nuvistor
replacement in the 454). Well, except for the 2430A. It requires some work
and I don't have the balls to attempt it (yet).

BTW: If you do buy a Tek 'scope, get a Tek probe with it, if you can.
They're bloody excellent.

I just bought an old 454 recently. It is working but has a few little
problems that I can live with for the moment.
When changing the input attenuator switch, the trace shifts up or
down. The shift control has to be readjusted to bring the trace back
to the same reference position. A slight pain.
This 454 uses nuvistors also. Where did you find your spare
nuvistor Trevor, locally or overseas?
I like the transistor sockets on this 454. Not all the boards have
transistor sockets, just some, but it is a nice thought for the
maintenance techs.

The BWD 820 model is nice to work on. Easy to get at everything.

I was removing a fan and some associated bits from a junked carcass
453 for another enthusiast and I was disappointed by the way the
wiring prevented assemblies from being moved more than slightly.
I was expecting assemblies to neatly flip out the way on their wiring.
Nope! They didn't.
The Rolls Royce quality that I was expecting from that famous
Tek myth wasn't here, accessibility wise, on this unit.

The other problem with my 454 is all time base ranges are slightly
out by the same amount. I can get over this by just moving the
red knob in the centre of the timebase switch slightly away from
the "cal" position. There is a pot inside that is supposed to adjust
the overall time base accuracy but it is not adjusting as expected.
The displayed waveform lengthens then shrinks as the pot is
turned in the same direction. The pot doesn't check open circuit
but I will look into that later. I have a habit of trying to make
things just a little bit better and then stuffing something.
$100 for a 150MHz CRO, I am happy with it.

If you are into Tekscopes Trevor or if anyone else is interested,
I have a couple of boat anchor size valve types that I would like
to give away to a good home for free. Model 533A and model 549.
Both not working but there was signs of a trace on both scopes.
Here is a picture of similar scopes.
http://www.cse.uta.edu/TheMuseum@CSE/images/533 scope frmed.jpg
http://www.google.com.au/search?q=c...corriveau/500/549.html+oscilloscope+549&hl=en
The ones I have are a bit shabby not nice like the pictures.

You mentioned Philips scopes Trevor. Maybe you know this
model from my description. I just can't remember the model
number. Twenty years ago at one place I was working there
was a little two tone grey Philips cro with a grey hard plastic
pouch like container at the back of the CRO for storage
of the operators manual and probes. Pouch suggests something
soft , this thin container was hard plastic but I don't know
what else to call it. The CRO was 15 Mhz bandwidth.
I have been looking for this model PM??? for use as a battery
operated CRO. Back then, I modified one of these CROs to
run off 24 Volts DC.
The power supply was just transformer, bridge and cap to one
main regulator, approximately 24V DC input. So it was easy
to use a couple of small batteries for a few hours running
where 240V was not available on outside jobs or for using
it for testing circuits where the CRO could float. Not earthed.
It was very handy for that.
I just missed out on buying one years ago for $30 and haven't
seen another since. I can't recall the model number. Maybe
you know of it Trevor.

Regards,
John Crighton
Hornsby

 

[Mike]

What is the make and model is your faulty scope? Just interested to
know. Maybe it is not as bad as you think. Have you had a look inside?

It's a Telequipment D43.

There's no obvious burn marks or bulging caps.
I'm concerned that something may go bang if I try to find the source of the
sound while it's switched on. Bits of capacitor flying around the room is
something I'd rather avoid.


Mike

 

[John Crighton]

It's a Telequipment D43.

There's no obvious burn marks or bulging caps.
I'm concerned that something may go bang if I try to find the source of the
sound while it's switched on. Bits of capacitor flying around the room is
something I'd rather avoid.


Mike

Hello Mike,
here at the aus.electronics factory the boys are not going
to let you off with that weak excuse for not fixing your CRO

Cripes! you are more likely to get hurt slipping on a floor at the
supermarket, getting run off the road by a driver who is drunk,
dopey on medication, high on drugs or just plain stupid/senile
or hasn't been to sleep for 24 hours or more. You go out on
the road and and mingle with dangerous bastards like that and
now you are backing off from helping a nice little CRO that is
crying out for your help. Aw c'mon Mike :-(

Here is a place to down load the circuit diagrams.
http://www.thevalvepage.com/servdata/testeq/telequip.htm
The fourth item down the page is your D43.

We are all here to help you.

Regards,
John Crighton
Hornsby

 

[Trevor Wilson]

It's a Telequipment D43.

There's no obvious burn marks or bulging caps.
I'm concerned that something may go bang if I try to find the source of the
sound while it's switched on. Bits of capacitor flying around the room is
something I'd rather avoid.

**I don't think you need be worried about that. Your description sounds very
much like a buggered power tranny. Expect lots of smoke and a smell which
will take weeks to dissipate.

 

[Mike]

**I don't think you need be worried about that. Your description sounds very
much like a buggered power tranny. Expect lots of smoke and a smell which
will take weeks to dissipate.

Switched on, after about 20 seconds a thin trail of smoke started
rising from the mains transformer. As you say, the smell is quite
distinct and does linger. Makes you wonder what they put into those
old resin encapsulated transformers.

Mike

(posting via Google as iinet's news server is broken again!)

 

[John Crighton]

Switched on, after about 20 seconds a thin trail of smoke started
rising from the mains transformer. As you say, the smell is quite
distinct and does linger. Makes you wonder what they put into those
old resin encapsulated transformers.

Mike

Hello Mike,
try disconnecting all the secondary windings and see if the
transformer still overheats/smokes. There is still a chance
that you might not have a dud transformer. Try it and see.
Regards,
John Crighton
Hornsby