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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc. |
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2nd Jun 2020, 10:22 pm | #1 |
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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? |
3rd Jun 2020, 11:03 am | #2 |
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Re: Tandberg 1500 series
I have fitted the end of an artist’s brush to the chassis to hopefully dampen the belts vibrations.
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3rd Jun 2020, 11:16 am | #3 |
Pentode
Join Date: May 2019
Location: Galway, Republic of Ireland.
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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 |
3rd Jun 2020, 12:19 pm | #4 |
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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. |
3rd Jun 2020, 12:48 pm | #5 |
Octode
Join Date: Jul 2006
Location: Perth, Western Australia
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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. |
3rd Jun 2020, 1:51 pm | #6 |
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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 |
3rd Jun 2020, 2:07 pm | #7 |
Octode
Join Date: Jul 2006
Location: Perth, Western Australia
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Re: Tandberg 1500 series
Ah, got you, as per normal Tandberg setup.
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4th Jun 2020, 4:48 am | #8 |
Octode
Join Date: Mar 2006
Location: Lund, Sweden
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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.
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4th Jun 2020, 7:32 am | #9 |
Heptode
Join Date: Oct 2007
Location: Birmingham, West Midlands, UK.
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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
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4th Jun 2020, 9:26 am | #10 |
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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.
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4th Jun 2020, 4:34 pm | #11 |
Heptode
Join Date: Oct 2007
Location: Birmingham, West Midlands, UK.
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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!
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4th Jun 2020, 7:17 pm | #12 |
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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. |
5th Jun 2020, 2:20 pm | #13 |
Hexode
Join Date: Mar 2008
Location: Margate, Kent, UK.
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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 |
5th Jun 2020, 6:39 pm | #14 |
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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.
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6th Jun 2020, 5:57 am | #15 | |
Octode
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Location: Lund, Sweden
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Re: Tandberg 1500 series
Quote:
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. |
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6th Jun 2020, 8:27 am | #16 |
Dekatron
Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
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Re: Tandberg 1500 series
In period, Hellyer noted that he sometimes had to change a Tandberg belt to alleviate a "singing" noise.
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