"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/
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