Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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yoda439
 
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Default Tek 465M as/usm Oscilloscope Problem

Hello all,I have built a octopus/huntron tester for checking component.The
problem is after about 15 minutes I loose my x-horz trace.It starts to
flicker and then turns into dot only.When I wiggle the volts div. knob on
the upper left of the scope it trys to come back.The vert.trace works
fine.When the scope is first turned on it works fine until it warms up.I
want some expert advice before attempting repair thanks.I am self taught
in this hobby but having a blast.

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Jim Yanik
 
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"yoda439" wrote in
lkaboutelectronicequipm
ent.com:

Hello all,I have built a octopus/huntron tester for checking
component.The problem is after about 15 minutes I loose my x-horz
trace.It starts to flicker and then turns into dot only.When I wiggle
the volts div. knob on the upper left of the scope it trys to come
back.The vert.trace works fine.When the scope is first turned on it
works fine until it warms up.I want some expert advice before
attempting repair thanks.I am self taught in this hobby but having a
blast.



does the vertical channel (V/div switch;Ch.1?) used in X-Y mode work OK in
normal scope mode? Maybe an intermittent Ch.1 atten switch.
--
Jim Yanik
jyanik
at
kua.net
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yoda439
 
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It does the same thing in normal scope mode after about 15 minutes.Thanks

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Jim Yanik
 
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"yoda439" wrote in
lkaboutelectronicequipmen
t.com:

It does the same thing in normal scope mode after about 15 minutes.Thanks



Then it's probably an intermittent attenuator.
Clean with 90% isopropyl alcohol.(not tuner cleaner/lube spray.)

--
Jim Yanik
jyanik
at
kua.net
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yoda439
 
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I will try that thanks.This was my first scope and I really like it and
have learned alot.I also have the Tek 305 W/DMM built in that I also
enjoy.I also built the ESR capacitor scope tester with the 5.6R and 2k7
resistors as it showed in schematic and puts about 10mV across the
probes.I am running 100KHZ with sine through it as suggested.One person
suggested using 1K and not 2k7 with square wave instead.I calibrate it
with 1R,3R and 10R as suggested.I will post when the scope is fixed for
other readers.What do you think? Thanks



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tekman
 
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yoda439 wrote:
I will try that thanks.This was my first scope and I really like it

and
have learned alot.I also have the Tek 305 W/DMM built in that I also
enjoy.I also built the ESR capacitor scope tester with the 5.6R and

2k7
resistors as it showed in schematic and puts about 10mV across the
probes.I am running 100KHZ with sine through it as suggested.One

person
suggested using 1K and not 2k7 with square wave instead.I calibrate

it
with 1R,3R and 10R as suggested.I will post when the scope is fixed

for
other readers.What do you think? Thanks


The ESR tester is nice, but for my everyday work I miss one featu it
lacks power (SMPS repair and most often fault find on low impedance
side - rectifiers, caps, etc.).

So I upgraded it it with variable frequency: I choose
400Hz/1kHz/4kHz/10kHz/40kHz/100kHz switchable bec. this was the most
useful for my application - others may choose different ones. I would
not recommendto go higehr than 100 kHz due to phase shift effects,
makes the frontend circuitry for the scope in X/Y mode harder to
design.

Output Power I've increased to deliver up to 1 A RMS. Tracker/ESR
tester works now nicely from 20 mOhm to 20 kOhm. This combines ESR and
Octopus(Huntron tracker) mode for me in one single box.

hth,
Andreas

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yoda439
 
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Well,I fixed the 465M and it works great.I took the cover off and had to
pull the metal shield that covers the CRT.I then removed the Volts/Div
cover and the contacts appeared to be ok.These are very delicate and could
be damaged very easy.I finally wiggeld the small cal.box and this seemed
to be the fix that steadied out the Horz.trace.It pulled right out and had
6 very fine pins on it.I cleaned the pins with alcohol and put it back in
and this did the trick.Thanks for all your help.

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