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RogerEvans · 4th Dec 2017, 10:13 am

Symon,

You may have guessed from my very generic comments that I had no idea the Hameg 208 was so sophisticated. Apologies for jumping in without finding more for myself.

Looking at the manual, the output of the timebase ramp generator is fed via D507 (on the timebase board if I read it correctly) to the diode switching matrix containing D701 - D710 which looks like it is on the horizontal amplifier board. Can you check that with the Hameg 208 in analogue mode you see the ramp voltage on both sides of D507 and that the peak to peak is essentially independent of sweep speed and the same on both sides of D507. Then repeat the measurement at the junction of R707 and R708. Is the peak to peak the same at all sweep speeds and is it roughly the same amplitude as measured at D507?

Regards,

Roger

4th Dec 2017, 10:13 am	#8
RogerEvans Hexode Join Date: Oct 2014 Location: Wiltshire, UK. Posts: 381	Re: Hameg HM208 Oscilloscope Timebase fault Symon, You may have guessed from my very generic comments that I had no idea the Hameg 208 was so sophisticated. Apologies for jumping in without finding more for myself. Looking at the manual, the output of the timebase ramp generator is fed via D507 (on the timebase board if I read it correctly) to the diode switching matrix containing D701 - D710 which looks like it is on the horizontal amplifier board. Can you check that with the Hameg 208 in analogue mode you see the ramp voltage on both sides of D507 and that the peak to peak is essentially independent of sweep speed and the same on both sides of D507. Then repeat the measurement at the junction of R707 and R708. Is the peak to peak the same at all sweep speeds and is it roughly the same amplitude as measured at D507? Regards, Roger