GW Instek GOS-620 schematic?

[Sylvi]

Hi

I have a GW Instek GOS-620 20MHz analogue oscilloscope that is six months out of warranty and I would like to get the schematic for it. Does anyone have one or know where to find one?

Instek has discontinued this unit from what I understand, replacing it with its bigger brother which has a built in multimeter and component tester or other stuff.

My scope has a problem in the vertical positioning for both channels. If there is a small sine wave (2-divisions peak-to-peak) in the lower half of the display and I sweep it upward using the vertical position control, the wave gets smaller until it is a flat line about three-quarters of the way up. If the sine wave is a bit larger, it will be okay at the bottom of the screen but as it is swept upward the top half distorts then clips.

I suspect the problem will come down to a bad solder connection in the vertical offset circuit.

I ordered a new DSO which might be here in a week or two, after which I can open up the Instek and work on it with impunity.

[Zero999]

I can't help you with the schematic I'm afraid.

Where did you buy it from and how long ago? It's possible you're still entitled to something under the consumer protection laws, in your area, even if the warranty period has expired.

[MT]

https://elektrotanya.com/gw-instek_gos-620_gos-630.pdf/download.html