UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio 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 2nd Jun 2020, 10:22 pm   #1
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 6,105
Default Tandberg 1500 series

I recently restored two of these tape recorders. Both came back because after some time, both were exhibiting a vibrating noise, like a bearing.

In fact it wasn't a bearing, the noise was coming from the drive belt which was wildly vibrating.

I've no idea what is causing it or why its only when the machines have been running for some time.

Taking a leaf out of Philips book, I noticed they have little brushes which the belts run through, I have devised a similar arrangement and if successful will post some pictures tomorrow.

In the meantime has anyone had this problem before? What causes it and is there any other cure?
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline   Reply With Quote
Old 3rd Jun 2020, 11:03 am   #2
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 6,105
Default Re: Tandberg 1500 series

I have fitted the end of an artistís brush to the chassis to hopefully dampen the belts vibrations.
Attached Thumbnails
Click image for larger version

Name:	09FDCF4D-9C62-4908-A6D3-7E90EC6A9002.jpg
Views:	43
Size:	38.0 KB
ID:	207521   Click image for larger version

Name:	915652F4-AAA3-4DAC-9240-2FCF64D22755.jpg
Views:	61
Size:	92.3 KB
ID:	207522  
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline   Reply With Quote
Old 3rd Jun 2020, 11:16 am   #3
hillmanie
Pentode
 
Join Date: May 2019
Location: Galway, Republic of Ireland.
Posts: 201
Default Re: Tandberg 1500 series

Is it possible to identify the source of the vibration? Is it likely to be in the belt itself? Perhaps replacing the belt with a shorter, tighter one might help?
TT
hillmanie is offline   Reply With Quote
Old 3rd Jun 2020, 12:19 pm   #4
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 6,105
Default Re: Tandberg 1500 series

I dont think it's the belt itself as it has the correct crossection and the correct tension.

Fitting a shorter belt would but excessive stress on the table bearings.
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline   Reply With Quote
Old 3rd Jun 2020, 12:48 pm   #5
TIMTAPE
Octode
 
Join Date: Jul 2006
Location: Perth, Western Australia
Posts: 1,296
Default Re: Tandberg 1500 series

Michael, in the photo is that the motor pulley to the right? It looks like the belt is running on a smaller diameter as if for 60 Hz or am I missing something?

If so maybe the slightly lower tension would have an effect.
TIMTAPE is offline   Reply With Quote
Old 3rd Jun 2020, 1:51 pm   #6
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 6,105
Default Re: Tandberg 1500 series

Yes that is the motor pulley and yes there are two steps the belt crosses over to the left of this pulley and rides in the lower step in one direction, the upper step in the other.

Please see the picture below
Attached Thumbnails
Click image for larger version

Name:	tandberg belt.jpg
Views:	43
Size:	103.9 KB
ID:	207542  
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline   Reply With Quote
Old 3rd Jun 2020, 2:07 pm   #7
TIMTAPE
Octode
 
Join Date: Jul 2006
Location: Perth, Western Australia
Posts: 1,296
Default Re: Tandberg 1500 series

Ah, got you, as per normal Tandberg setup.
TIMTAPE is offline   Reply With Quote
Old 4th Jun 2020, 4:48 am   #8
ricard
Octode
 
ricard's Avatar
 
Join Date: Mar 2006
Location: Lund, Sweden
Posts: 1,459
Default Re: Tandberg 1500 series

I'm wondering if the plastic pulleys underneath the real holders could be slightly warped, causing the belt to shift up and down ever so slightly, the resonant effect of the tightened belt then amplifying whatever motion there is.
ricard is offline   Reply With Quote
Old 4th Jun 2020, 7:32 am   #9
saxmaniac
Heptode
 
Join Date: Oct 2007
Location: Birmingham, West Midlands, UK.
Posts: 521
Default Re: Tandberg 1500 series

Probably teaching my granny to suck eggs but are the fast wind clutch felts touching the reel tables due to mis adjustment of the operating levers. If there's not the 1mm gap as spec in the manual you can get slight dragging causing vibration
saxmaniac is offline   Reply With Quote
Old 4th Jun 2020, 9:26 am   #10
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 6,105
Default Re: Tandberg 1500 series

The machines both of them were back with their owner. It would be one hell of a coincidence if the same clutch pulleys on both machines were warped and or the decks were misaligned in the same way. Of course not impossible.
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline   Reply With Quote
Old 4th Jun 2020, 4:34 pm   #11
saxmaniac
Heptode
 
Join Date: Oct 2007
Location: Birmingham, West Midlands, UK.
Posts: 521
Default Re: Tandberg 1500 series

Unless it's the curse of non original spare belts, mine chirps for 15 mins or so until it all warms up. Not loudly enough to be a problem but probably just some grotty old knicker elastic used in the belt manufacture!
saxmaniac is offline   Reply With Quote
Old 4th Jun 2020, 7:17 pm   #12
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 6,105
Default Re: Tandberg 1500 series

That could well be the problem. I bought it from a German seller on EBay, next time
I’ll try Lasse.
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline   Reply With Quote
Old 5th Jun 2020, 2:20 pm   #13
Paulus.d
Hexode
 
Join Date: Mar 2008
Location: Margate, Kent, UK.
Posts: 334
Default Re: Tandberg 1500 series

I know it sounds silly but \i think I've had this and all I did was reverse the crossover the of the belt ..... which one goes over the other .....
The vibration being the belt rubbing on itself
Paul
Paulus.d is offline   Reply With Quote
Old 5th Jun 2020, 6:39 pm   #14
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 6,105
Default Re: Tandberg 1500 series

The machine is designed so that belts do not touch where they cross over. I have reversed the crossover but it made no difference.
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline   Reply With Quote
Old 6th Jun 2020, 5:57 am   #15
ricard
Octode
 
ricard's Avatar
 
Join Date: Mar 2006
Location: Lund, Sweden
Posts: 1,459
Default Re: Tandberg 1500 series

Quote:
Originally Posted by Michael Maurice View Post
It would be one hell of a coincidence if the same clutch pulleys on both machines were warped and or the decks were misaligned in the same way. Of course not impossible.
I would rather say that after this time, it would be the rule rather than the exception that the plastic pulleys have warped in some way, even if it is seldom detrimental to the proper operation of the macihne. Whenever I've dismantled a clutch assembly, it has struck me that there are usually fine cracks near the hub of the pulley, and there is often some warping. I think the plastic used is not completely stable over time. I suppose the good thing is that the cracks tend to alleviate some of the stress built up in the plastic which will help avoid it breaking completely.

And then the second part of the puzzle would be that the movement induced by the warped pulleys injects energy into the belt, which is slightly stretched and hence has a natural resonant frequency, ergo, the belt will tend to vibrate at its resonant frequency no matter exactly what the excitation frequency might be.

Tandberg have a specified how the belts should cross over in the service manual, I've found that sometimes that makes a difference, but mostly not.

On some of the older machines at least, there's a little loop of piano wire I think bolted to the speed changing assembly, which goes either side of the belt, seemingly avoiding it coming off the motor pulley should it vibrate too much. So I'm wondering if this was a problem seen even in the factory.
ricard is offline   Reply With Quote
Old 6th Jun 2020, 8:27 am   #16
Ted Kendall
Nonode
 
Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
Posts: 2,237
Default Re: Tandberg 1500 series

In period, Hellyer noted that he sometimes had to change a Tandberg belt to alleviate a "singing" noise.
Ted Kendall is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 1:38 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 - 2020, vBulletin Solutions, Inc.
Copyright ©2002 - 2020, Paul Stenning.