Electronics > Repair

Oscilloscope horizontal issues

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MadeForThat:
Hi all, just came across a telequipment d66 scope, and powered it up with the finest spade connectors I could muster. It seems the vertical axis functions as it should, but the horizontal beam position jumps back and forth across the screen. Imagine a beam jumping from the 3 to the 9 positions on a clock, with no real rhythm or explanation. When attempting to use in xy mode the axis does react, so I don't think the amplifier circuit is fully dead, but I wonder if this jumping indicates a malfunctioning component within it. I also cannot seem to get it to sweep, so I assume the issues are related. Without a sweep I do not know if the trigger is functioning either. Any input would be greatly appreciated as my understanding of analog electronics are "not good" at best haha. Would like to start changing that :)

MadeForThat:
Can't post a video unfortunately, but it jumps between these 2 points randomly. A potentially helpful detail is that the axis adjustments still work to relocate the "points" and the horizontal offset between the 2 stay the same.

Xena E:
What effect does changing the horizontal timbase have?

rhb:
My money is on a cracked solder joint.  Seriously, you can  locate the area of failure by tracing the horizontal circuit and watching the vertical deflection.  Rather a PITA without a  schematic, but doable.  Use the front panel connections to locate the sweep generator.

Good luck,
Reg

George Edmonds:
Hi

May I first say in the strongest possible terms that this is NOT a suitable repair project for someone who has little or no experience with CRT oscilloscopes.   It dates from the early 1970’s where  utility supply derived very lethal high and EHT voltage supplies were common,

There are a number of very lethal, poorly shielded power supplies in use so unless you have been trained to work on such high voltage power supplies DO NOT WORK ON IT.

There is a poor copy of the service manual on line that is easily found with Google.

In the past I have had a great deal of experience with the repair of Telequipment  oscilloscopes, one of the most common problems is with the fixed resistors going high in value or open circuit.

Keep safe

G Edmonds

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