On 10/10/2011 10:07 AM, Scott Dorsey wrote:
wrote:
I wish you lived a little closer, Chris. I have a Tek 546 scope
(50MHz) with the original cart, original manual, and a 1A1 and
a couple of 1A2 plugins. BTW the scope had developed HV problems
and would lose the trace within about a minute after turnon.
I understand that was a fairly simple problem to fix, however.
I also have original manuals for the plugins.

Most HV problems on those scopes can be solved by scrubbing the thing out
with soap and water and letting it dry thoroughly.

Occasionally you'll see HV rectifier problems and bad ceramic caps, but
leakage from built-up dirt is the number one problem.

Our local surplus dealer in Tidewater, VA just pulls the tubes out of
those things and dumpsters them; he says they aren't worth the money
to drag them out to hamfests and nobody wants them any more.

I actually have a 545 on my bench at work, although the cal guys hate me
and they keep trying to replace it with an Agilent DSO. It just runs
and runs, and it's easier to cal than they claim.
--scott

Thanks, Scott!

Great info. I had heard these were supposed to be fairly easy to fix
with that sort of problem. Your very specific suggestions are enough
to motivate me to take a second look at my beloved old boatanchor.
So I will as soon as I can get to it, and I'll stop back here and
let you know how it went.

73, David K3KY

Clutter wrote:

Great info. I had heard these were supposed to be fairly easy to fix
with that sort of problem. Your very specific suggestions are enough
to motivate me to take a second look at my beloved old boatanchor.
So I will as soon as I can get to it, and I'll stop back here and
let you know how it went.

The good news is that, unlike cheap Heathkits, they don't blow up their
power transformers often at all. Everything except the CRT and the power
transformer is readily replaced.
--scott


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

On Tue, 11 Oct 2011, Scott Dorsey wrote:

Clutter wrote:

Great info. I had heard these were supposed to be fairly easy to fix
with that sort of problem. Your very specific suggestions are enough
to motivate me to take a second look at my beloved old boatanchor.
So I will as soon as I can get to it, and I'll stop back here and
let you know how it went.

The good news is that, unlike cheap Heathkits, they don't blow up their
power transformers often at all. Everything except the CRT and the power
transformer is readily replaced.

I have a 545?, the one with plugins that was first sold about 1959,
someone found it as a hospital discard and gave it to me.

This was 20 years ago. After a bit of use, I notice the trace is not
straight, clearly a bad filter capacitor in the power supply. I actually
find it by using the scope to check itself, at one point the trace gets
even more non-straight, so that was the bad capacitor. It was a fairly
large value for a high voltage electrolytic, I expected problems. But
there at the local surplus store was the right capacitance and voltage.
And then the trace was back to normal.

Michael VE2BVW

On 10/11/2011 02:12 PM, Michael Black wrote:
On Tue, 11 Oct 2011, Scott Dorsey wrote:

Clutter wrote:

Great info. I had heard these were supposed to be fairly easy to fix
with that sort of problem. Your very specific suggestions are enough
to motivate me to take a second look at my beloved old boatanchor.
So I will as soon as I can get to it, and I'll stop back here and
let you know how it went.

The good news is that, unlike cheap Heathkits, they don't blow up their
power transformers often at all. Everything except the CRT and the power
transformer is readily replaced.

I have a 545?, the one with plugins that was first sold about 1959,
someone found it as a hospital discard and gave it to me.

This was 20 years ago. After a bit of use, I notice the trace is not
straight, clearly a bad filter capacitor in the power supply. I actually
find it by using the scope to check itself, at one point the trace gets
even more non-straight, so that was the bad capacitor. It was a fairly
large value for a high voltage electrolytic, I expected problems. But
there at the local surplus store was the right capacitance and voltage.
And then the trace was back to normal.

Michael VE2BVW

So, clearly this is a boatanchor I should keep
(546 and three plugins *and* cart)!

73, David K3KY