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Uncle Bulgaria · 21st Apr 2019, 6:24 pm

The head has been lapped. No head gap is visible and the surface is a lot more even than it was. I've flattened the base of the head and adjusted the height of the motor spindles. Now to set the orientation.

At least one of the guides' brass tubes seems slightly smaller than the tape. Cut another?
To set the bias for recording, I presumably need a 'type' of tape. Is this best to be a new, current type or is there a 'generic' bias that will do for the varied secondhand tapes I have? Should I do it for 'Ferrotape'?
Hum appears to be less than the level the manual specifies (measuring VRMS across the 'speaker) but it still audible. A feature of the machine?
The bass control appears to do not very much. Could this be because the electrolytic capacitors C9/11/12/13 have gone off? I've replaced the others associated with the 'equalisation' module.

21st Apr 2019, 6:24 pm	#77
Uncle Bulgaria Nonode Join Date: May 2016 Location: Cornwall, UK. Posts: 2,338	Re: Ferrograph 4A: Restoration advice needed The head has been lapped. No head gap is visible and the surface is a lot more even than it was. I've flattened the base of the head and adjusted the height of the motor spindles. Now to set the orientation. At least one of the guides' brass tubes seems slightly smaller than the tape. Cut another? To set the bias for recording, I presumably need a 'type' of tape. Is this best to be a new, current type or is there a 'generic' bias that will do for the varied secondhand tapes I have? Should I do it for 'Ferrotape'? Hum appears to be less than the level the manual specifies (measuring VRMS across the 'speaker) but it still audible. A feature of the machine? The bass control appears to do not very much. Could this be because the electrolytic capacitors C9/11/12/13 have gone off? I've replaced the others associated with the 'equalisation' module.