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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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6th Nov 2020, 7:58 pm | #1 |
Pentode
Join Date: Nov 2017
Location: London, UK.
Posts: 108
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Sony TC161-SD Motor Run Cap
Dear All,
I would be grateful for a bit of advice about a motor run cap on a Sony TC161SD cassette deck. The cap is a dual capacitance component (0,6uF and 0,4uF) switched by an internal 50/60Hz rocker switch. At the 50Hz setting the two capacitances are connected in parallel. My motor is running slow (about one tone in pitch) and I suspect the run cap, having read various helpful threads on this forum. The belts are new. My best guess (using a variety of meters) is that capacitance is between 20% and 30% high. ESR readings look OK. Is this enough to cause a very slight speed reduction and sluggish rw/ff function? Or should I look elsewhere? Thanks for any advice. |
7th Nov 2020, 12:38 am | #2 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,225
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Re: Sony TC161-SD Motor Run Cap
There's no harm in trying a new one, they cost very little, maybe a few pounds.
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7th Nov 2020, 12:47 am | #3 |
Heptode
Join Date: Mar 2003
Location: Waiheke Island, New Zealand
Posts: 503
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Re: Sony TC161-SD Motor Run Cap
I would look at the belts..
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7th Nov 2020, 1:06 am | #4 |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,604
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Re: Sony TC161-SD Motor Run Cap
Assuming you are only going to use it on 50Hz you could save a bit by just getting a 1uF Run capacitor and fitting it in the 50Hz position and remove the 2 old capacitors.
Cannot easily find a schematic but wondering if it has electronic speed control with adjustable capstan speed. David |
7th Nov 2020, 2:24 am | #5 |
Pentode
Join Date: Nov 2017
Location: London, UK.
Posts: 108
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Re: Sony TC161-SD Motor Run Cap
Thanks, all.
David, unfortunately there is no speed control. Speed is derived from 50/60Hz. So, would this do the trick? http://www.capacitorc.com/uploads/CBB61.pdf Described as a 450 VAC motor run cap and readily available. |
7th Nov 2020, 9:52 am | #6 |
Dekatron
Join Date: Jun 2013
Location: East Sussex, UK.
Posts: 3,327
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Re: Sony TC161-SD Motor Run Cap
You say the belts are new, but are they a bit tight. That can be a cause of running slow.
Might also be in need of lubrication on pulleys/motor etc. |
7th Nov 2020, 2:06 pm | #7 |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,604
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Re: Sony TC161-SD Motor Run Cap
I have used the CBB61 Motor Run capacitors, they are good.
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7th Nov 2020, 4:45 pm | #8 |
Pentode
Join Date: Nov 2017
Location: London, UK.
Posts: 108
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Re: Sony TC161-SD Motor Run Cap
Thanks,
I see that standard tolerance for motor caps seems to be ±5% which suggests that my presumed +20% to +30% readings might be a problem. Kemet do a 1uF C87 series motor run cap that is a perfect fit and I can do away with the internal frequency switch wiring and just run on 50Hz. Looks like it would outlast the Chinesium CBB61 by miles. The belts, as far as I can tell, are correctly tensioned, but I might try a few drops of sewing machine oil into the motor. |
20th Nov 2020, 8:10 pm | #9 |
Pentode
Join Date: Nov 2017
Location: London, UK.
Posts: 108
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Re: Sony TC161-SD Motor Run Cap
By replacing the motor run cap, I was able to improve the playback speed but it's still half a tone flat on commercially recorded tapes rather than a whole tone. Unfortunately, I have perfect pitch, so that won't do.
The aluminium Kemet version wouldn't fit, so I went with the CBB61 1uF device as recommended by David. Capacitance was well within 5% of its stated value. As the motor sits across the mains supply, there's no provision for speed adjustment. The belts are new and not overly tight, so I can only think that the motor/pulleys need lubrication. |
21st Nov 2020, 11:39 pm | #10 |
Octode
Join Date: Jul 2006
Location: Perth, Western Australia
Posts: 1,971
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Re: Sony TC161-SD Motor Run Cap
Given that you are sensitive to deviations from absolute pitch, you might be better served by a cassette player with the variable speed feature. The recordings themselves played back at exactly 1.875 inches per second are not guaranteed to play at exact concert pitch, or the pitch at which the music was performed.
Last edited by TIMTAPE; 22nd Nov 2020 at 12:05 am. |
22nd Nov 2020, 9:14 am | #11 |
Heptode
Join Date: Oct 2019
Location: Täby, Sweden
Posts: 709
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Re: Sony TC161-SD Motor Run Cap
Maybe it is worth measuring the time for a fixed length of tape to be processed, so the speed can be calculated? If it is not correct, maybe the factor it is out will be significant, highlighting the issue?
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22nd Nov 2020, 1:19 pm | #12 |
Octode
Join Date: Jul 2006
Location: Perth, Western Australia
Posts: 1,971
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Re: Sony TC161-SD Motor Run Cap
In this case it's not simply whether the Sony is running at the correct speed but the fact that the owner has "perfect pitch". Some musicians have excellent pitch memory. Recordings played off speed can annoy them.
When a cassette was recorded off speed/off pitch, it will be off when played at the correct speed but will sound correct when played at the same (incorrect) speed at which it was recorded. Many better quality reel to reel and cassette decks have a variable speed control on the front panel. |
22nd Nov 2020, 2:51 pm | #13 | |
Dekatron
Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
Posts: 3,675
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Re: Sony TC161-SD Motor Run Cap
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22nd Nov 2020, 5:13 pm | #14 |
Tetrode
Join Date: Nov 2020
Location: Edinburgh, Scotland, UK.
Posts: 89
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Re: Sony TC161-SD Motor Run Cap
I'd agree - worth checking if any brake bands are being released / held off correctly - springs can lose tension over time .
From memory , wasn't the 161 SD a dual capstan deck , with one capstan slightly bigger than the other to tension the tapes across the heads ? maybe I'm thinking of a different machine . I have a TC-209SD here which has been in storage for many years - the capstan is seized , so that although the motor turns valiantly , nothing happens - I need to strip down , clean , lube - when I get around to it ! |
22nd Nov 2020, 8:28 pm | #15 |
Pentode
Join Date: Nov 2017
Location: London, UK.
Posts: 108
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Re: Sony TC161-SD Motor Run Cap
Gents,
Thanks for taking the time to reply. One side of a TDK C90 tape took exactly 51 mins to get to the end of the reel, so even allowing for more than the nominal amount of tape, that's out of tolerance by some margin. I will dive back in and check the brake band and anything that may be slowing it down. Derek - it is a dual capstan deck with one capstan slightly larger than the other. I presume they're in the right configuration! |
22nd Nov 2020, 8:34 pm | #16 |
Octode
Join Date: Jul 2006
Location: Perth, Western Australia
Posts: 1,971
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Re: Sony TC161-SD Motor Run Cap
Yes dual capstan. I have one but from memory it has a fair bit of hum in the audio playback which seems to be a design issue. It was probably more prevalent in these early decks using an AC motor too close to the playback head. With mine I considered modding by adding mumetal shielding around the motor but as these motors tend to run fairly hot and need their own cooling fan the idea of restricting the cooling seemed risky. So there it sits in the cupboard...
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25th Nov 2020, 4:31 pm | #17 | |
Tetrode
Join Date: Nov 2020
Location: Edinburgh, Scotland, UK.
Posts: 89
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Re: Sony TC161-SD Motor Run Cap
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