UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players

Notices

Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

Reply
 
Thread Tools
Old 15th Sep 2021, 2:08 am   #1
Linnovice
Hexode
 
Join Date: Jun 2014
Location: Chelmsford, Essex, UK
Posts: 329
Default Humming Studer A807

Hi all. I own a Studer A807 MkII which is in very good working condition. It does have one very annoying problem though. In play or record it develops a very pronounced hum. It is not a steady sound, more an oscillating hum but I do not think its the capstan motor. If I lift the tape tension arm up slightly the hum disappears but as soon as I let it down the hum returns. (There is quite a lot of tension there.) If it try and adjust the height of the tension arm with the trimmer it makes no difference to the noise. I've checked all along the tape path for something rubbing or sticking but its all running perfectly and in ff and rw there is no noise.
Would anyone have any idea what could cause this? Since I've had the machine the noise has been there but new hearing aids is making it more obvious . Could it be a component in the tensioning, is there any adjustments on this board?
I have been told that these machines were made to last and usually were operated in machine rooms where any ancillory noises didn't matter. I can't believe that Studer would be that slap-dash in their approach though.
It is really irritating as the machine records and plays beautifully (apart from the hum that is ).
__________________
Small Scotch, New Aids and Happy Ears
Linnovice is offline   Reply With Quote
Old 15th Sep 2021, 8:31 am   #2
TIMTAPE
Octode
 
Join Date: Jul 2006
Location: Perth, Western Australia
Posts: 1,551
Default Re: Humming Studer A807

Is the hum coming from the physical deck or is it mixed in with the audio output?

As a tape plays, are the tension guides/arms sitting in the correct places as per the service manual? Yes the tensions will be adjustable but if they are significantly out it is for a reason. Just readjusting the tensions as per the manual may be all that's needed, but it may also only temporarily conceal symptoms rather deal with the root causes.
TIMTAPE is offline   Reply With Quote
Old 15th Sep 2021, 8:41 am   #3
DMcMahon
Dekatron
 
DMcMahon's Avatar
 
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 3,908
Default Re: Humming Studer A807

If a recording is done and played back on another machine is the hum heard on that machine, this may help to prove it is purely mechanically related.

David
DMcMahon is offline   Reply With Quote
Old 15th Sep 2021, 9:08 am   #4
Linnovice
Hexode
 
Join Date: Jun 2014
Location: Chelmsford, Essex, UK
Posts: 329
Default Re: Humming Studer A807

Morning Tim/David, thanks for replies.
It is definitely electro/mechanical. Recordings are good and play perfectly on other machines without any trace of hum.
I have adjusted the tension arm as per the manual and it is riding at the correct height according to operation. ie. Play/Record, FF/RW, Library Wind, Shuttle. All are correct.
As I said earlier. If I lift the arm (approx 10mm) the noise disappears. I don't think it has to do with position as I can't adjust it out with the trimmer. I think it is more due to tension but I do not think there is an adjustment for that.
Hopefully someone will know better
__________________
Small Scotch, New Aids and Happy Ears
Linnovice is offline   Reply With Quote
Old 15th Sep 2021, 11:12 am   #5
TIMTAPE
Octode
 
Join Date: Jul 2006
Location: Perth, Western Australia
Posts: 1,551
Default Re: Humming Studer A807

On my old Revox A700 if I adjust back tension to much higher than recommended, I do hear a growl. As the supply motor rotates, the growl warbles somewhat.

Does the manual state what the normal back tension should be in grams or does it just state where the guide should sit as a distance from a reference point on the fascia?

With the machine switched off and no tapes loaded, using a simple spring gauge attached to the roller and pulling upwards towards the supply platter, you should be able to measure the static tension on the (hidden) return spring at various points in its vertical travel. If the static tension is correct at the correct distance, that would normally ensure correct back tension as the back tension comes from the elongation of that internal spring.

Does the roller move smoothly with finger pressure up the slot, with increasing tension? No binding or restriction? Where in the slot does the roller guide sit when correctly adjusted as per manual? Is it roughly in the middle of the slot? A long shot. Is it possible someone has replaced this spring with one too strong?

Silly question, does the supply guide spin freely?

Last edited by TIMTAPE; 15th Sep 2021 at 11:33 am.
TIMTAPE is offline   Reply With Quote
Old 15th Sep 2021, 11:41 am   #6
Linnovice
Hexode
 
Join Date: Jun 2014
Location: Chelmsford, Essex, UK
Posts: 329
Default Re: Humming Studer A807

Yes, the supply guide does spin freely as well as sliding up and down within its slot. I've just checked the manual and it appears there are no adjustments as to grammage and pressure but, there are a couple of adjustment pots for setting different voltages. I will have look at those and report back.

Just off to get my truss out, this thing weighs a ton!!!
__________________
Small Scotch, New Aids and Happy Ears
Linnovice is offline   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 6:53 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.