Tektronix TDS3032 Goes Faulty!

[Brian Hoskins]

My Tektronix 3032 DSO has developed a rather annoying fault. Channel 2 works fine and shows no fault symptoms at all, but Channel 1 has developed a fault on certain voltage ranges. If I try to view a waveform on Channel 1 it will display the waveform, but if certain voltage ranges are selected the waveform dissapears off screen and "clipping" comes up in the information box, suggesting that the scope thinks it's seeing a signal which is too large for the voltage range currently selected. This fault condition happens whether a probe is connected or not.

The scope passes it's self-test but if I ask it to do a full diagnosis, everything passes except for Aquisition. I've tested the aquisition part of the scope and it is working - I'm able to sample, save and print waveforms without problem. I'm assuming that Aquisition returns a fail due to the fault on channel 1 of my scope, and infact I'm assuming that the two are directly related as they've both reared their ugly heads at the same time.

I took my scope to a local insutrument repair company and they were unable to find the fault. I've taken a look myself thinking that perhaps there was an o/c protection resistor or something causing part of channel1's range to malfunction, but I was unable to find anything obvious. I contacted Tektronix earlier today and they said they can repair the equipment but it's a one-off charge of £600. I assume that they don't do any fault-finding as such. Instead they probably repalce the motherboard and throw the old one away. Apparently the £600 includes a full certificate of calibration.

I've packaged the scope up ready for sending off, but I just wondered whether anyone else has experienced similar problems before? If you have, and you managed to find the fault with your unit, I'd very much appreciate your feedback - perhaps I can check the same with mine before I shell out such an enormous sum of money for it's repair.

Thanks in advance (although I'm not expecting much feedback on this one)

Brian

[minnie]

Stereo problem? Are you using volume controls?

[Brian Hoskins]

Umm no it's not a HIFI. It's my oscilloscope - http://www.tucker.com/java/jsp/doorway_partnoTEKTDS3032_invid26330.htm

Thanks anyway

Brian