Replacing Preset Potentiometers in a Revox A77 - UK Vintage Radio Repair and Restoration Discussion Forum

Humber888 · 1st Apr 2016, 3:24 pm

I may have missed a previous thread, but are the Piher PT15 series of enclosed carbon presets a good replacement for the originals in Revox A77s? I know about the tendency of the originals to suffer wiper breakage but wondered whether the newer Pihers are better constructed. They seem to be about the only modern presets I can find that have the same lead spacing as the originals. I notice that Piher also do a cermet range (PTC15 series), but these seem to be difficult to buy in small quantities.

Many thanks.

Mike

SteveCG · 1st Apr 2016, 3:33 pm

Mike,

When I replaced some presets in an A77 I used whatever I had that would reasonably fit. If you have found some presets that have the same lead spacing then 'congratulations' to you!

I think my only word of advice is to make sure that the adjustment slot on those presets that are on the plug-in cards is visible through the hole in the detachable aluminium (Al) cover. I found that the Al cover needed to be in place for the final tweaking.

1st Apr 2016, 3:24 pm	#1
Humber888 Heptode Join Date: Jul 2012 Location: Bromley, London, UK. Posts: 702	Replacing Preset Potentiometers in a Revox A77 I may have missed a previous thread, but are the Piher PT15 series of enclosed carbon presets a good replacement for the originals in Revox A77s? I know about the tendency of the originals to suffer wiper breakage but wondered whether the newer Pihers are better constructed. They seem to be about the only modern presets I can find that have the same lead spacing as the originals. I notice that Piher also do a cermet range (PTC15 series), but these seem to be difficult to buy in small quantities. Many thanks. Mike

1st Apr 2016, 3:33 pm	#2
SteveCG Nonode Join Date: Jun 2009 Location: Herefordshire, UK. Posts: 2,495	Re: Replacing Preset Potentiometers in a Revox A77 Mike, When I replaced some presets in an A77 I used whatever I had that would reasonably fit. If you have found some presets that have the same lead spacing then 'congratulations' to you! I think my only word of advice is to make sure that the adjustment slot on those presets that are on the plug-in cards is visible through the hole in the detachable aluminium (Al) cover. I found that the Al cover needed to be in place for the final tweaking.