UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Hameg HM307-3 Cleaning and Repair

WaveyDipole · 6th Jun 2019, 8:58 am

BTW, I have just tried that scenario on the simulator model to see what conditions it would generate. It showed an output of -790v and the collector voltage at T301 oscillated between +200 and +400v. Furthermore, there was a negative voltage at the non-inverted input of the 741 op amp, although not quite as low as that reported. However, the conditions do seem to approximately correspond to that reported.

If this is indeed the problem, then the output returns to -1kV once the capacitor is disconnected from the circuit which should suffice for test purposes. In the long term it would naturally need to be replaced.

6th Jun 2019, 8:58 am	#72
WaveyDipole Nonode Join Date: Mar 2013 Location: Leicester, UK Posts: 2,535	Re: Hameg HM307-3 Cleaning and Repair BTW, I have just tried that scenario on the simulator model to see what conditions it would generate. It showed an output of -790v and the collector voltage at T301 oscillated between +200 and +400v. Furthermore, there was a negative voltage at the non-inverted input of the 741 op amp, although not quite as low as that reported. However, the conditions do seem to approximately correspond to that reported. If this is indeed the problem, then the output returns to -1kV once the capacitor is disconnected from the circuit which should suffice for test purposes. In the long term it would naturally need to be replaced.