No more display output on the Hameg hm1005


28 August 2023
Is Part Of
Image showing the front panel of the Hameg HM1005 oscilloscope. This 90s series oscilloscope uses physical buttons and a CRT screen for its interface.Hameg HM 1005
No more display output on the Hameg hm1005
Unfortunately, the output has disappeared from the Hameg hm1005. This is most likely caused by the previous repair to the final vertical amplifier. The problem seems to manifest slightly differently as the under and over scan indicators do not seems to suggest the trace is off screen. Hopefully none of the transistors are damaged as the vertical amplifier is carefully balanced using complementary pairs of transistors for all its half a dozen stages.

We should investigate the cause at some point. Starting with blanking circuits and afterwards following the signal paths from were both inputs are combined into the amplifier.

It should be noted that there is also no horizontal output or deflection so perhaps the HV power supply has issues.