UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Ferrograph S3 and S4 help with some issues please

jascha · 21st Nov 2018, 3:47 pm

Ps: I have so far checked the caps on the power supply/oscillator unit and all seem to be fine. The bias adjustment pot was totally jammed at half way and have freed it up but the only way I can get a full deep erase is to turn the bias adjustment fully clockwise which of course affects frequency response! Arghh! I swapped both the EL84 and EZ80 just as a curiosity (although they had passed the test already) but the result remained the same. It’s a low output from the oscillator perhaps? How can it be measured please and what should I expect to measure voltage wise?
Thanks again

21st Nov 2018, 3:47 pm	#5
jascha Hexode Join Date: Nov 2005 Location: Kent, UK. Posts: 332	Re: Ferrograph S3 and S4 help with some issues please Ps: I have so far checked the caps on the power supply/oscillator unit and all seem to be fine. The bias adjustment pot was totally jammed at half way and have freed it up but the only way I can get a full deep erase is to turn the bias adjustment fully clockwise which of course affects frequency response! Arghh! I swapped both the EL84 and EZ80 just as a curiosity (although they had passed the test already) but the result remained the same. It’s a low output from the oscillator perhaps? How can it be measured please and what should I expect to measure voltage wise? Thanks again