GW Instek GOS-620 schematic needed

[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.

[tautech]

http://www.produktinfo.conrad.com/datenblaetter/125000-149999/129640-sp-02-en-30_MHz_Oszilloskop_630.pdf

[Sylvi]

THANK YOU !!!!