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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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Old 7th Sep 2020, 11:54 am   #1
Michael Maurice
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Default Tandberg TD20

I've been asked to look at a Tandberg TD20 which at some stage was modified for 110V 60Hz

The owner wants it converted back to 240V 50HZ.

I presume the motor pulley will need changing unless of course it has two steps, one for 50Hz one for 60Hz.

Does anyone know if that's the case or do I have to get a new pulley?
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Old 7th Sep 2020, 2:13 pm   #2
ms660
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Default Re: Tandberg TD20

So far as I can make out from looking at various pictures I would say that the capstan motor pulley needs to be changed, and if the original conversion was done properly the mains VDR along with all the motor capacitors and depending on the PROM IC colour code the three feed resistors for the supply and take up motors (two for the DC supplies to the supply and take up motors and the one for the AC supply to the take up motor when in playback/record mode)

Lawrence.

Last edited by ms660; 7th Sep 2020 at 2:30 pm. Reason: duplicate word removed
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Old 7th Sep 2020, 2:24 pm   #3
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Default Re: Tandberg TD20

Hi Maurice,
Assume it is the 20A ?
I believe it has a tapping on the transformer to select 115/230V

While this user guide says refer to qualified technician for voltage configuration, it does state in the specification at the end of the document both 115, 230V

http://sportsbil.com/tandberg/td-20a-om-english.pdf

The schematic shows the transformer has two primary windings in series, so I would assume this is the means for 115/230 configuration

http://sportsbil.com/tandberg/td-20a-se-circ-align.PDF

All three motors seem to be fed from the secondary of the transformer through speed regulators/switches etc
So seems to be just the changes to the transformer tapping

Best Regards
Chris
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Old 7th Sep 2020, 2:33 pm   #4
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Default Re: Tandberg TD20

There is a table of resistor/cap changes on the schematic (Table 2)
This shows different values for 115/230

Assume this motor is regulated by AC frequency so it will need a pulley change.

There is also a varistor to change on the AC input.

Best Regards
Chris
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Old 7th Sep 2020, 2:55 pm   #5
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Default Re: Tandberg TD20

Thanks everyone

I wonder where i can get a pulley from? I doubt the owner would have it.
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Old 7th Sep 2020, 10:37 pm   #6
unitelex
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Default Re: Tandberg TD20

If you can measure the motor shaft diameter and also the diameter of the portion where the belt runs then there must be somebody on the forum who has a lathe and some aluminium bar who could make one for you (with 20% increase on the diameter).

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Old 13th Sep 2020, 6:19 pm   #7
Paulus.d
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Default Re: Tandberg TD20

Would the pulley be the same on the series12 or 15?
Regards Paul
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Old 13th Sep 2020, 10:50 pm   #8
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Default Re: Tandberg TD20

No.

The owner has decided not to go ahead with the conversion.
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