[James Sweet]

wrote in message
...
Greetings,

I have a ('77 ?) Tektronix 485 scope (serial starts with a 'B' or an
'8', number is 167020) that I received 4 years ago. At the time it
worked, although I was (still am somewhat) pretty "green" regarding
electronics as I am more of a hobbyist than a professional as I love
to learn and "tinker". In the past, I have serviced tube amplifiers
for friends. Right now I have a 3M (Mincom) M56 professional
multitrack tape recorder I am currently in the process of aligning. I
guess you could say I am an "analog dinosaur" of sorts... LOL.

When I initially got the 485, the unit powered up and I could do some
basic sweeps, but I have not really used it since I initially got it
(mainly due to getting married, having kids and buying a new house -
funny how those things take up gobs of your life ;-). When I went to
turn it on about a year ago, I noticed a clicking or chirping with no
beam. Apparently as I understand it based on some quick research on
the 'net, this is not an uncommon symptom on these 'scopes having a
power supply trying to start but failing due to current overload of
some sort (capacitors?).

So, I did a search on Tektronix repair and came up with a person that
thinks they will be able to fix it.

However, for the price of the repair (and maybe a little more), I am
wondering if I wouldn't be better served with something like a 2465/A/
B?

Here's some reasons why maybe I think I should go with the 2465:

1) Compared to the 485, it's a newer 'scope with perhaps less hours
than my 485 (don't know how much use my 485 has had; it appears to be
in average or slightly better condition)
2) Less "mechanical" parts in the 2465 (e.g., pots, etc. from my
understanding) to fail
3) Lots think this is the epitome of the analog oscilloscope

Reasons why I should maybe stay with my 485:

1) Better proprietary IC availability (?, don't beat me up; I thought
this was what I read...)
2) Easier to service/repair than the 2465
3) More robust for the beginner

Obviously if I am thinking like this, I have no idea what I should
ultimately do. What does everyone think? ducking


The 485 is a really excellent scope, and the problem you describe should be
fairly easy to repair. There's no sense in upgrading, as a beginner you
probably won't use a large portion of the features the 485 provides even.

[Sam Goldwasser[_2_]]

"James Sweet" writes:

wrote in message
...
Greetings,

I have a ('77 ?) Tektronix 485 scope (serial starts with a 'B' or an
'8', number is 167020) that I received 4 years ago. At the time it
worked, although I was (still am somewhat) pretty "green" regarding
electronics as I am more of a hobbyist than a professional as I love
to learn and "tinker". In the past, I have serviced tube amplifiers
for friends. Right now I have a 3M (Mincom) M56 professional
multitrack tape recorder I am currently in the process of aligning. I
guess you could say I am an "analog dinosaur" of sorts... LOL.

When I initially got the 485, the unit powered up and I could do some
basic sweeps, but I have not really used it since I initially got it
(mainly due to getting married, having kids and buying a new house -
funny how those things take up gobs of your life ;-). When I went to
turn it on about a year ago, I noticed a clicking or chirping with no
beam. Apparently as I understand it based on some quick research on
the 'net, this is not an uncommon symptom on these 'scopes having a
power supply trying to start but failing due to current overload of
some sort (capacitors?).

So, I did a search on Tektronix repair and came up with a person that
thinks they will be able to fix it.

However, for the price of the repair (and maybe a little more), I am
wondering if I wouldn't be better served with something like a 2465/A/
B?

Here's some reasons why maybe I think I should go with the 2465:

1) Compared to the 485, it's a newer 'scope with perhaps less hours
than my 485 (don't know how much use my 485 has had; it appears to be
in average or slightly better condition)
2) Less "mechanical" parts in the 2465 (e.g., pots, etc. from my
understanding) to fail
3) Lots think this is the epitome of the analog oscilloscope

Reasons why I should maybe stay with my 485:

1) Better proprietary IC availability (?, don't beat me up; I thought
this was what I read...)
2) Easier to service/repair than the 2465
3) More robust for the beginner

Obviously if I am thinking like this, I have no idea what I should
ultimately do. What does everyone think? ducking

The 485 is a really excellent scope, and the problem you describe should be
fairly easy to repair. There's no sense in upgrading, as a beginner you
probably won't use a large portion of the features the 485 provides even.

I agree 100 percent.

My first guess would be one or more of those imfamous tantalum gumdrop
caps have decided to turn into short circuits. These are on the power
supply PCB on the bottom. Save yoursefl some grief and replace them all
(maybe 2 dozen). I have just been putting in aluminum electrolytics.
Not sure how much difference it makes.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

[Scott Dorsey]

James Sweet wrote:

The 485 is a really excellent scope, and the problem you describe should be
fairly easy to repair. There's no sense in upgrading, as a beginner you
probably won't use a large portion of the features the 485 provides even.

Agreed, and I bet a nickel the issue is that there is too much dust and
dirt providing leakage paths in the high voltage section. Have the tech
give it a good cleaning and you will probably be fine.

I'm still using a Tek tube scope at work and it's always been flawless
although the calibration guys hate me.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[West]

"James Sweet" wrote in message
news:no13j.19418$XT.16175@trnddc01...

wrote in message
...
Greetings,

I have a ('77 ?) Tektronix 485 scope (serial starts with a 'B' or an
'8', number is 167020) that I received 4 years ago. At the time it
worked, although I was (still am somewhat) pretty "green" regarding
electronics as I am more of a hobbyist than a professional as I love
to learn and "tinker". In the past, I have serviced tube amplifiers
for friends. Right now I have a 3M (Mincom) M56 professional
multitrack tape recorder I am currently in the process of aligning. I
guess you could say I am an "analog dinosaur" of sorts... LOL.

When I initially got the 485, the unit powered up and I could do some
basic sweeps, but I have not really used it since I initially got it
(mainly due to getting married, having kids and buying a new house -
funny how those things take up gobs of your life ;-). When I went to
turn it on about a year ago, I noticed a clicking or chirping with no
beam. Apparently as I understand it based on some quick research on
the 'net, this is not an uncommon symptom on these 'scopes having a
power supply trying to start but failing due to current overload of
some sort (capacitors?).

So, I did a search on Tektronix repair and came up with a person that
thinks they will be able to fix it.

However, for the price of the repair (and maybe a little more), I am
wondering if I wouldn't be better served with something like a 2465/A/
B?

Here's some reasons why maybe I think I should go with the 2465:

1) Compared to the 485, it's a newer 'scope with perhaps less hours
than my 485 (don't know how much use my 485 has had; it appears to be
in average or slightly better condition)
2) Less "mechanical" parts in the 2465 (e.g., pots, etc. from my
understanding) to fail
3) Lots think this is the epitome of the analog oscilloscope

Reasons why I should maybe stay with my 485:

1) Better proprietary IC availability (?, don't beat me up; I thought
this was what I read...)
2) Easier to service/repair than the 2465
3) More robust for the beginner

Obviously if I am thinking like this, I have no idea what I should
ultimately do. What does everyone think? ducking


The 485 is a really excellent scope, and the problem you describe should
be
fairly easy to repair. There's no sense in upgrading, as a beginner you
probably won't use a large portion of the features the 485 provides even.

Hi James. I had a 485 many years ago to use for field work ( not that easy
schlepping it around the country). I think it had a 250 MHz bandwidth. It's
really packed so be careful when attempting repairs. Starting with checking
the low voltage power supplies is a good idea. Also be careful if sending it
out prepaid for service. Check the service place thoroughly for references
and for viable guarantees. The 485 is a professional scope that way exceeds
the hobbyists requirements. So if you can repair it reasonably, you will own
a classic gem.

Cordially,
west

[Mike Rivers]

On Nov 27, 6:04 pm, "James Sweet" wrote:

The 485 is a really excellent scope, and the problem you describe should be
fairly easy to repair. There's no sense in upgrading, as a beginner you
probably won't use a large portion of the features the 485 provides even.

Yeah, but he's going to need a decent scope in order to repair the
485.

[Doug McDonald]

Sam Goldwasser wrote:


Reasons why I should maybe stay with my 485:

1) Better proprietary IC availability (?, don't beat me up; I thought
this was what I read...)
2) Easier to service/repair than the 2465
3) More robust for the beginner

Obviously if I am thinking like this, I have no idea what I should
ultimately do. What does everyone think? ducking


I'm an expert on these things. The 485 is the best portable
analog scope ever made. It is arguably the best analog scope ever made,
though the 7904 series competes well on the bench. Do anything you
can to keep one working. There is no substitute for a 485/7904,
and I've used them all, including $50,000 digital ones. For repairing
analog electronic oddities, digital frequently simply
doesn't work.

A 485 is 350 MHz scope.

The 2465 is a very poor substitute, though a good scope.

Doug McDonald

[James Sweet]

"Bret Ludwig" wrote in message
...
I no longer recommend owning or using Tektronix analog scopes,
period. Yes, they were very well built, but none of them are 100%
supported and they all lose the same parts. The hybrid issue is a big
one, but CRTs, attenuators, and high voltage parts on all solid state
Teks are getting unavailable even through the back channels.

If some company decided to FULLY SUPPORT certain Tek models,
guaranteeing availability of every part from new production-or at
least every part that is getting scarce-I'd say yes.

Ironically you can still get every possible part for many tube Teks,
but the size, weight, power draw and heat make them nonstarters. That
is why the parts are available.

Buy a new scope.

New scopes are expensive, used Teks in good working order are relatively
cheap and still offer excellent performance. There's millions of them out
there and parts units can still be found. If you're a business with budget
to burn then yes, buy a fancy new scope, but if you're a hobbyist on a
budget, you can't beat an old Tek.

[Doug McDonald]

James Sweet wrote:


New scopes are expensive, used Teks in good working order are relatively
cheap and still offer excellent performance. There's millions of them out
there and parts units can still be found. If you're a business with budget
to burn then yes, buy a fancy new scope, but if you're a hobbyist on a
budget, you can't beat an old Tek.



There is only one problem: there are no "new scopes" that will
substitute for a 485/7904 for some purposes of work on analog signals.
Period. They don't exist.

We don't know what the use of the original poster is supposed to
be. The "have to have analog" ones generally involve visual
detection of rare events in analog signals. The dead time of
fast digital scopes can cause hopelessly great "down time fraction"
for this.

For most purposes digital scopes are fine.

Doug McDonald

[Michael A. Terrell]

Bret Ludwig wrote:

I no longer recommend owning or using Tektronix analog scopes,
period. Yes, they were very well built, but none of them are 100%
supported and they all lose the same parts. The hybrid issue is a big
one, but CRTs, attenuators, and high voltage parts on all solid state
Teks are getting unavailable even through the back channels.

If some company decided to FULLY SUPPORT certain Tek models,
guaranteeing availability of every part from new production-or at
least every part that is getting scarce-I'd say yes.

Ironically you can still get every possible part for many tube Teks,
but the size, weight, power draw and heat make them nonstarters. That
is why the parts are available.

Buy a new scope.


I agree 100%!!!!!!!! Buy a brand new chinese scope with no support,
and throw it away when it dies. Repeat till you're tired of using crap,
then buy a used US made scope.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

[David DiGiacomo]

In article ,
Doug McDonald wrote:
There is only one problem: there are no "new scopes" that will
substitute for a 485/7904 for some purposes of work on analog signals.
Period. They don't exist.

Iwatsu still makes high performance analog scopes. They used to be resold
by LeCroy, but now I think you have to get them from Japan.

[Mike Rivers]

On Nov 29, 12:06 am, Bret Ludwig wrote:

I no longer recommend owning or using Tektronix analog scopes,
period. Yes, they were very well built, but none of them are 100%
supported and they all lose the same parts. The hybrid issue is a big
one, but CRTs, attenuators, and high voltage parts on all solid state
Teks are getting unavailable even through the back channels.

Thing is that with a few rare exceptions (applications, not scopes) a
used but working Tek 485 can be used anywhere a new digital scope
costing ten or more times as much would be used. And when something
irreplaceable fails, you do what people who are accustomed to keeping
old gear going do - you look for another one (probably cheaper than
the one you own now), use that one, and keep your old one for spare
parts. Or vice versal. You have to be resourceful to save money and
still have good test equipment.

The assumption is that you don't need to get it certified/calibrated
on a regular basis. That can be very expensive, but it will be about
as expensive for a more modern scope. It's getting it in and out the
door of the calibration lab that costs money.

[James Sweet]

wrote in message
...
On Nov 29, 6:40 am, Doug McDonald
wrote:

We don't know what the use of the original poster is supposed to
be.

See my original post:

"In the past, I have serviced tube amplifiers for friends. Right now I
have a 3M (Mincom) M56 professional
multitrack tape recorder I am currently in the process of aligning."

Probably going forward, much of the same.

Well using a 485 for that sort of work is sort of like using a McLaren F1 to
go buy groceries. It'll do the job just fine, but there remains a huge
amount of untapped capabilities.

That said, it'll do as fine a job as as anything else you can find, and as
old as it is, the price should be reasonable.

[JosephKK]

Michael A. Terrell posted to
sci.electronics.equipment:

Bret Ludwig wrote:

I no longer recommend owning or using Tektronix analog scopes,
period. Yes, they were very well built, but none of them are 100%
supported and they all lose the same parts. The hybrid issue is a
big one, but CRTs, attenuators, and high voltage parts on all solid
state Teks are getting unavailable even through the back channels.

If some company decided to FULLY SUPPORT certain Tek models,
guaranteeing availability of every part from new production-or at
least every part that is getting scarce-I'd say yes.

Ironically you can still get every possible part for many tube
Teks,
but the size, weight, power draw and heat make them nonstarters.
That is why the parts are available.

Buy a new scope.


I agree 100%!!!!!!!! Buy a brand new chinese scope with no
support,
and throw it away when it dies. Repeat till you're tired of using
crap, then buy a used US made scope.



What US made scopes? Both Tek and HP moved their manufacturing to
Taiwan, Malaysia and China over a decade ago.