Revox A77 CH2 problem - UK Vintage Radio Repair and Restoration Discussion Forum

thecookie17 · 28th Jan 2018, 1:07 pm

Hi Guys, I recently got myself a Revox a77 mkIV for 200€. I have ordered some 10 1/2" reels to go with it but they have not arrived yet, although I have some old Philips tape I found at my grandfathers house, so I decided to try that. If I record something in stereo, Ch1 sounds fine to me, very good frequency response, however when I switch to stereo or Ch2 I notice a drop on high frequencies on that channel, and the audio becomes kind of muffled and a bit unstable. I have already tried cleaning the heads as best as I could with some cotton swabs and alcohol, and It did make an improvement over before, but it doesn't quite sound as good as channel I I think unfortunately.

Are you guys able to help me on this one?
Thanks in advance

Michael Maurice · 28th Jan 2018, 2:14 pm

Although you've cleaned the heads, you may still find a little dirt on them. Clean them again and wait for the alcohol to dry before using.

Also I would wait to try it with new tapes, those old Philips tapes were great for domestic recording but thats about it.

Ted Kendall · 28th Jan 2018, 2:22 pm

If the heads are clean and the tape is good, then the two most likely reasons are head wear or incorrect line-up. Revox heads are usually good up to a flat of 4mm on the head face - any more and the head is on borrowed time at best.

Lining up an A77 is fairly straightforward and much cheaper than replacing heads, so try this first - all the presets are accessible on the base of the machine. The best course if you don't know the procedure is to download the service manual. If you don't do things in the right order you won't do much harm but will end up mightily confused!

28th Jan 2018, 1:07 pm	#1
thecookie17 Retired Dormant Member Join Date: Jan 2018 Location: Hanau, Hesse, Germany Posts: 1	Revox A77 CH2 problem Hi Guys, I recently got myself a Revox a77 mkIV for 200€. I have ordered some 10 1/2" reels to go with it but they have not arrived yet, although I have some old Philips tape I found at my grandfathers house, so I decided to try that. If I record something in stereo, Ch1 sounds fine to me, very good frequency response, however when I switch to stereo or Ch2 I notice a drop on high frequencies on that channel, and the audio becomes kind of muffled and a bit unstable. I have already tried cleaning the heads as best as I could with some cotton swabs and alcohol, and It did make an improvement over before, but it doesn't quite sound as good as channel I I think unfortunately. Are you guys able to help me on this one? Thanks in advance

28th Jan 2018, 2:14 pm	#2
Michael Maurice Moderator Join Date: Feb 2006 Location: Wembley, Middlesex Posts: 7,224	Re: Revox A77 CH2 problem Although you've cleaned the heads, you may still find a little dirt on them. Clean them again and wait for the alcohol to dry before using. Also I would wait to try it with new tapes, those old Philips tapes were great for domestic recording but thats about it. __________________ Forum Moderator http://www.michaelmauricerepairs.co.uk/

28th Jan 2018, 2:22 pm	#3
Ted Kendall Dekatron Join Date: Jul 2008 Location: Kington, Herefordshire, UK. Posts: 3,671	Re: Revox A77 CH2 problem If the heads are clean and the tape is good, then the two most likely reasons are head wear or incorrect line-up. Revox heads are usually good up to a flat of 4mm on the head face - any more and the head is on borrowed time at best. Lining up an A77 is fairly straightforward and much cheaper than replacing heads, so try this first - all the presets are accessible on the base of the machine. The best course if you don't know the procedure is to download the service manual. If you don't do things in the right order you won't do much harm but will end up mightily confused!