'scope sweep problem

J

Jules

Guest
I've got a battered old Telequipment 10MHz 'scope that I use on the bench
here at home - it was working happily yesterday when when I powered it up
this morning I get no sweep across the tube at all.

I can use the beam finder to find both ch1 and ch2 beams, and
altering the X and Y position works - I just get no sweep across
the display.

Looks like the deflection circuitry is working, but the timebase has given
up completely?

For a while this morning when I hit the beam finder button I did get a
trace for each channel rather than a dot, and the trace even stayed for a
couple of seconds after the beam finder button was released. Now even
that's stopped working, and I just get a single dot on the screen for each
channel whether the beam finder is used or not.

Presumably the beam finder does something specific with the timebase and
that happened to still be working for a little while even though the
timebase circuitry during normal operation had given up?

Any ideas what to check for? The 'scope is a Telequipment D1101 - I doubt
anyone has schematics but presumably all 'scope timebases operate in a
similar way anyway.

cheers

Jules
 
Look for high ESR caps in the power supply and horiz sweep circuits. Start
in the timebase circuits. There may be other damaged components if the caps
went too far off value.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Jules" <julesrichardsonuk@remove.this.yahoo.co.uk> wrote in message
news:pan.2004.05.04.11.51.03.263370@remove.this.yahoo.co.uk...


I've got a battered old Telequipment 10MHz 'scope that I use on the bench
here at home - it was working happily yesterday when when I powered it up
this morning I get no sweep across the tube at all.

I can use the beam finder to find both ch1 and ch2 beams, and
altering the X and Y position works - I just get no sweep across
the display.

Looks like the deflection circuitry is working, but the timebase has given
up completely?

For a while this morning when I hit the beam finder button I did get a
trace for each channel rather than a dot, and the trace even stayed for a
couple of seconds after the beam finder button was released. Now even
that's stopped working, and I just get a single dot on the screen for each
channel whether the beam finder is used or not.

Presumably the beam finder does something specific with the timebase and
that happened to still be working for a little while even though the
timebase circuitry during normal operation had given up?

Any ideas what to check for? The 'scope is a Telequipment D1101 - I doubt
anyone has schematics but presumably all 'scope timebases operate in a
similar way anyway.

cheers

Jules
 
"Jules" <julesrichardsonuk@remove.this.yahoo.co.uk> wrote in message
news:pan.2004.05.04.11.51.03.263370@remove.this.yahoo.co.uk...
I've got a battered old Telequipment 10MHz 'scope that I use on the bench
here at home - it was working happily yesterday when when I powered it up
this morning I get no sweep across the tube at all.

I can use the beam finder to find both ch1 and ch2 beams, and
altering the X and Y position works - I just get no sweep across
the display.

Looks like the deflection circuitry is working, but the timebase has given
up completely?

For a while this morning when I hit the beam finder button I did get a
trace for each channel rather than a dot, and the trace even stayed for a
couple of seconds after the beam finder button was released. Now even
that's stopped working, and I just get a single dot on the screen for each
channel whether the beam finder is used or not.

Presumably the beam finder does something specific with the timebase and
that happened to still be working for a little while even though the
timebase circuitry during normal operation had given up?

Any ideas what to check for? The 'scope is a Telequipment D1101 - I doubt
anyone has schematics but presumably all 'scope timebases operate in a
similar way anyway.

cheers

Jules
Click to expand...
Can easily be just corrosion on switch
uS/div, int/ext switch etc
Schematic ets for D1011 available please em address on URL below


electronic hints and repair briefs including Telequipment scopes on

http://homepages.tcp.co.uk/~diverse
 
On Tue, 04 May 2004 12:51:03 +0100 Jules
<julesrichardsonuk@remove.this.yahoo.co.uk> wrote:

I've got a battered old Telequipment 10MHz 'scope that I use on the bench
here at home - it was working happily yesterday when when I powered it up
this morning I get no sweep across the tube at all.
Click to expand...
The first thing I would do would be to exercise all the switches that
are related to the sweep back and forth a few times. If you do this
with the scope warmed up, you may be able to spot one which is
intermittent.

If this works, just exercise that switch some more to rub the
oxidation off the contacts.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------
 
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