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Leon Crampin · 9th Oct 2017, 5:20 pm

Good result. The switches on these sets have lots of contacts, many wired in series. For example there could be 3 or 4 switches involved in connecting an AM section of the tuning gang to the coil it's trying to tune - so there are lots of possibilities for crackles and bad contacts.

These switches seem to respond well to being used after a dose of Servisol, so it's worth exercising the AM and particularly the SW switches a few times. The "gram" switch also benefits, although it has comparatively few contacts.

If the set sounds good on FM when mains powered, the quiescent current is probably not too far off. If you have limited measuring equipment, I could measure the total supply current on my set (quiescent current recently adjusted) when battery powered on FM at minimum volume, to give you a guide as to whether your set is miles out or not.

Leon.

9th Oct 2017, 5:20 pm	#29
Leon Crampin Octode Join Date: Nov 2005 Location: Surrey, UK. Posts: 1,874	Re: Grundig Concert Boy 1100 Good result. The switches on these sets have lots of contacts, many wired in series. For example there could be 3 or 4 switches involved in connecting an AM section of the tuning gang to the coil it's trying to tune - so there are lots of possibilities for crackles and bad contacts. These switches seem to respond well to being used after a dose of Servisol, so it's worth exercising the AM and particularly the SW switches a few times. The "gram" switch also benefits, although it has comparatively few contacts. If the set sounds good on FM when mains powered, the quiescent current is probably not too far off. If you have limited measuring equipment, I could measure the total supply current on my set (quiescent current recently adjusted) when battery powered on FM at minimum volume, to give you a guide as to whether your set is miles out or not. Leon.