"THo" wrote in message
news:iKqQd.398480$8l.64298@pd7tw1no...
I was given an old oscilloscope, and I'm not sure if it's working
properly.
It's a tube-based one, Tektronic 515. There's only one probe with it, and
I
connected it to a radio, and it does respond, somewhat. But when there is
no signal of any kind, the image traced on the screen isn't a moving dot,
it's more like a band, and no matter how it's adjusted the band never
moves
more than halfway across the screen. I've attached a pic of the output
when
there is no input of any kind. How abnormal is this? Is there a way to
re-calibrate it or anything like that?

Tom


No.
This is not normal. It look like a sawtooth waveform from a sweep circuit.
Sorry, I am not familiar
with this model. Does it have any built-in scope calibrator? Many of their
even cheap scopes have
a built-in square wave generator. This allows you to set the waveform
amplitude and scope probe
frequency response (capacitance). I realize that this isn't much help. Why
don't you contact
Tektronics?

It helps a bit ...
maybe I should see if Tektronics is still around and try to get a manual.
The real problem is that it's so old --- vacuum tubes instead of integrated
circuits. Thx.
(I'm the OP)

"bj" wrote in message
rver.com...

"THo" wrote in message
news:iKqQd.398480$8l.64298@pd7tw1no...
I was given an old oscilloscope, and I'm not sure if it's working
properly.
It's a tube-based one, Tektronic 515. There's only one probe with it,
and
I
connected it to a radio, and it does respond, somewhat. But when there
is
no signal of any kind, the image traced on the screen isn't a moving dot,
it's more like a band, and no matter how it's adjusted the band never
moves
more than halfway across the screen. I've attached a pic of the output
when
there is no input of any kind. How abnormal is this? Is there a way to
re-calibrate it or anything like that?

Tom


No.
This is not normal. It look like a sawtooth waveform from a sweep
circuit.
Sorry, I am not familiar
with this model. Does it have any built-in scope calibrator? Many of
their
even cheap scopes have
a built-in square wave generator. This allows you to set the waveform
amplitude and scope probe
frequency response (capacitance). I realize that this isn't much help.
Why
don't you contact
Tektronics?

On Tue, 15 Feb 2005 17:57:34 +0000, THo wrote:

I was given an old oscilloscope, and I'm not sure if it's working properly.
It's a tube-based one, Tektronic 515. There's only one probe with it, and I
connected it to a radio, and it does respond, somewhat. But when there is
no signal of any kind, the image traced on the screen isn't a moving dot,
it's more like a band, and no matter how it's adjusted the band never moves
more than halfway across the screen. I've attached a pic of the output when
there is no input of any kind. How abnormal is this? Is there a way to
re-calibrate it or anything like that?


From the picture, this is a seriously ill oscilloscope. )-; alf of the
horizontal amplifier is shot, which you _might_ fix by just replacing a
tube, if you can find one. The vertical amplifier is incredibly noisy,
or set to exceedingly high gain and is picking up crap from the air.

There is a way to recalibrate it, and repair it, but a competent tech
could charge you more than you'd spend on another used unit.

Or, you could keep an eye out on ebay for another of the same model,
and make one working scope from the parts from both.

It is repairable, however, given perseverance, lots of reading, and
another scope. ;-)

Good Luck!
Rich

That's what I thought...
Thx

"Rich Grise" wrote in message
news
On Tue, 15 Feb 2005 17:57:34 +0000, THo wrote:

I was given an old oscilloscope, and I'm not sure if it's working
properly.
It's a tube-based one, Tektronic 515. There's only one probe with it,
and I
connected it to a radio, and it does respond, somewhat. But when there
is
no signal of any kind, the image traced on the screen isn't a moving dot,
it's more like a band, and no matter how it's adjusted the band never
moves
more than halfway across the screen. I've attached a pic of the output
when
there is no input of any kind. How abnormal is this? Is there a way to
re-calibrate it or anything like that?


From the picture, this is a seriously ill oscilloscope. )-; alf of the
horizontal amplifier is shot, which you _might_ fix by just replacing a
tube, if you can find one. The vertical amplifier is incredibly noisy,
or set to exceedingly high gain and is picking up crap from the air.

There is a way to recalibrate it, and repair it, but a competent tech
could charge you more than you'd spend on another used unit.

Or, you could keep an eye out on ebay for another of the same model,
and make one working scope from the parts from both.

It is repairable, however, given perseverance, lots of reading, and
another scope. ;-)

Good Luck!
Rich