Hameg 203-6

[Aleksandar_CKU]

On the Hameg 203-6 oscilloscope I have the identical problem pictured here.

Video: [url]https://streamable.com/7mmwqt]https://streamable.com/7mmwqt] [url]https://streamable.com/7mmwqt [/url]

Picture:

I don't have the ability to measure high voltage, and it will be quite difficult to disassemble the device and reassemble it. Can anyone tell me where and what I should look at? I can roughly say that I heard something click. It's as if something has become unsoldered or one of the ceramic capacitors is broken.

I found an identical problem on the forum, only it concerns the second series of Hameg oscilloscopes: https://www.eevblog.com/forum/testgear/please-help-me-to-fix-hm605-oscilloscope-no-trace/ [/url]

Please help!

[Zenith]

I had a similar problem with a 203-6 which turned out to be caused by the unblanking pulse not being set properly. It just needed adjustment. There's a procedure in one of the 203 series manuals which says to use another scope with a 10X probe connected to a -1900V line via a 10nF 2kV capacitor and then adjust a pot to get the correct waveform. I chickened out of the scope part and just adjusted the pot until the trace came right, then went wrong again, and positioned it in the middle of the range where it worked.

Of course, it may be a faulty component rather than needing adjustment, but it looks like an unblanking problem.

[Aleksandar_CKU]

I found what the problem was. One of the BF199 transistors screamed - T501!

[Zenith]

I'm pleased to hear you got it to work. With scopes you can rapidly get to the point where you need another scope to fix them. It doesn't have to be a very good scope.

You might also change the 1000µF smoothing caps in the power supply. You can reach them without removing the PCB. They are notorious. If they haven't failed yet, they soon will.