HAMEG HM 103 Oscilloscope problem - only get a single dot - no horizontal line

[RaspberryPieman]

Hi,
I have a HAMEG HM 103 Oscilloscope, which has been working fine for years.

However, when I turn it on, now, I only get a single dot - no horizontal line.
I can move the dot up and down using the Y-POS knob and from side to side using the X-POS knob.
But if I try to view the normal square-wave by probing the 'cal' post, I now just get the non-moving dot.

I have tried pushing in and out all the push-buttons and rotating all the knobs, to check for bad connections.

I have downloaded the manual, but it does not have anything like this problem in its trouble-shooting guide.

Does anyone have any suggestions on how to diagnose or fix this problem ?

Regards,
Martyn

[jsantoro]

Make sure it is not in XY mode. Look for a Horiz Ext button or maybe even on the timebase knob

[alsetalokin4017]

I would think that the calibrator would produce a vertical line rather than a single dot, if the timebase is simply nonfunctional or turned off as in x-y mode.

I'd try cycling the Hor. Ext. button a few times. Maybe spray some Deoxit on the contacts first.

[nctnico]

Don't use contact sprays because these will dissolve metals in the long term. If the buttons don't work I'd start by taking the scope apart and reseating all connectors (unplug and then plug in again).

[alsetalokin4017]

Don't use Deoxit because it dissolves metals? Whaaaaat?

My 50 year old Tek scope begs to differ.

[nctnico]

It is simple for contact sprays to work they must dissolve metals. What makes it worst is that the wiring will wick it everywhere else too. equipment + contact spray = FUBAR . I've seen it one times too many already.