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Old 8th January 2014, 10:57 AM   #1
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Default Scope Fault. Can You Help?

Just go my Scope back from my brother and it has not journeyed well.
The Horizontal scan is reduced in width and also non linear. Y What part of the circuit should I investigate first? I do have the service manual and schematic.I will supply a photo later.

Last edited by chienmort; 8th January 2014 at 11:13 AM.
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Old 8th January 2014, 11:36 AM   #2
impuls is offline impuls  Yugoslavia
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Clean pins of the tube.
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Old 8th January 2014, 12:01 PM   #3
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Originally Posted by impuls View Post
Clean pins of the tube.
Thank you I will try that first.
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Old 8th January 2014, 12:08 PM   #4
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Originally Posted by chienmort View Post
Thank you I will try that first.
Hmm ...

reduced scan and non-linear means the horizontal amplifier is suffering, no longer a saw-tooth from the sweep generator.

Very first thing is to check all power supplies are in spec. If the vertical deflection is also reduced (using cal square wave) then it is a general psu fault.

This assumes it is a 'scope with a CRT!
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Old 8th January 2014, 12:32 PM   #5
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Yes old school scope with CRT. Vertical deflection seem OK. looks like the sawtooth. Now i just need to find a scope to view it on
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Old 13th January 2014, 03:10 AM   #6
1audio is online now 1audio  United States
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From the description either 1/2 of the deflection amp is dead or hopefully the wire to the CRT has come adrift. The amps are usually differential but the deflection gets distorted if one side is not right. Will the position controls move the trace across the screen?
Demian Martin
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Old 14th January 2014, 03:53 AM   #7
RNMarsh is offline RNMarsh  United States
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Check for fuses first - any in the horizonal amp + or - drive?

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Old 23rd January 2014, 02:29 PM   #8
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it's not something like a control setting in the wrong position some scopes allow you to narrow the horizontal width.
what make and model scope are we talking about?
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Old 4th March 2014, 10:24 PM   #9
jblmar is offline jblmar  United States
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If you haven't resolved the problem, try pushing in all connectors on the chassis. It's possible a connector got loose in transit.
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Old 6th March 2014, 02:09 AM   #10
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I have had trouble with transistor sockets in scopes in the past.
They can cause all sorts of trouble.
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