Hi, I have two of these HM 205-3 storage scopes.
Interestingly enough both have the same error.
In both cases the classical analog time base does not work. In digital storage mode they work fine.
The problem is as follows.
1) In analog mode (storage button not pressed) I don't see any trace. But there is a flickering in sync with the time base (repeatedly from bright to dark), so I can adjust the flickering from slow to fast. y position control seems to work, as it affects the flickering towards up / down the screen. Cannot judge if x-control has any affect on the flickering. (Image D and E.)
2) XY-Mode does not work either in the sense that there is no focused dot on the screen, just a dim diffuse light towards the right of the screen. Also here, the diffuse light moves accordingly when I rotate the y-position control. However it doesn't seem to be affected by x position control. (Similar to image E.)
3) component tester is able to produce a trace that can be shiftet in horizontal direction by rotating x-pos knob. (Image C.)
4) In digital storage mode, everything works as expected, also I can shift towards + or - x. (Image A and B.)
With the schematics at hand (
https://cdn.rohde-schwarz.com/hameg-archive/HM205-3_english.pdf), what i did so far was checking power supply voltages, +12V, -12, +5 V, +150 V, +130 V, on the "XY-04". They all seem ok, except 4,89 V instead of 5 Volt but that might be ok anyway.
Also, the 5 Volts for supplying the time base are present. I checked at the emitter of T3911.
With this background, I suspect that the error is located somewhere around the generation or, more probably, in the amplification of the analog time base. Where could I look next? Is that a common fault? After all, this affects two of two devices which I have here.
EDIT: While writing this, both of the scopes just magically recovered from half-broken to fully alive. I think there was a faulty contact at the X-Y-switch. After pressing/releasing it a couple of times, it's almost back to normal.
thanks
regards, rentier