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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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4th Oct 2019, 1:41 pm | #1 |
Heptode
Join Date: Jun 2018
Location: Carmarthenshire, Wales, UK.
Posts: 564
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Akai 1720L solid state
The above machine on rewind of a 6"tape stops rewinding about an inch before end of tape it refuses to rewind the last inch or so I here a click like a relay going and it stops rewinding.But if I change the tape speed switch on the top it will rewind the tape all the way with no problem any ideas what it may be please
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4th Oct 2019, 3:17 pm | #2 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
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Re: Akai1720L solid state
When it stops rewinding, is the capstan still rotating? If it is then its mechanical, if it isn’t then the motor is stalling. Replace the motor run capacitor if it hasn’t been done already.
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4th Oct 2019, 3:29 pm | #3 |
Heptode
Join Date: Jun 2018
Location: Carmarthenshire, Wales, UK.
Posts: 564
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Re: Akai1720L solid state
No the capstan is rotating ok
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4th Oct 2019, 3:32 pm | #4 |
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Join Date: Feb 2006
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Re: Akai1720L solid state
More likely the idler wheel rubbers have gone hard an are slipping, there's more inertia at the faster speed to carry it through.
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4th Oct 2019, 3:36 pm | #5 |
Heptode
Join Date: Jun 2018
Location: Carmarthenshire, Wales, UK.
Posts: 564
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Re: Akai1720L solid state
I slakend the tape guide bearing and it seemed then to rewind ok whether it was a coincidence or not I don't know
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4th Oct 2019, 4:18 pm | #6 |
Heptode
Join Date: Jun 2018
Location: Carmarthenshire, Wales, UK.
Posts: 564
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Re: Akai1720L solid state
It rewinds ok as I said if I change tape speed to slow from fast
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4th Oct 2019, 8:35 pm | #7 |
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Join Date: Mar 2012
Location: Fife, Scotland, UK.
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Re: Akai 1720L solid state
I'm trying to remember.... I think the 1720/1721 changes the number of motor poles to change its speed, so there may be more torque available on the lower speed setting. The 4000 series keeps the same motor speed and adds a sleeve to the capstan itself.
David
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5th Oct 2019, 11:17 pm | #8 |
Banned
Join Date: Jun 2015
Location: Mareeba, North Queensland, Australia
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Re: Akai 1720L solid state
The 1700 series of recorders changed capacitors on the motors to change speeds as per my attached photo. Michael has the problem explained. Rubbers in Akai equipment always went hard and were renowned for slipping.
These motors also ran on 100 volts ( about) directly connected to mains on 110 volts, and connected to the 110 volt primary tap of the power transformer when connected to 240 volts. They also had two other very common faults: 1: there is a monkeymetal/zinc diecast cam that operates the moving parts when changing from play to fast forward and rewind that is famous for crumbling into small pieces 2: the record/playback slide switch frequently went open or partly open circuit. This caused low level recording, or low level playback and is a real $%^$& to diagnose!!. Joe |
6th Oct 2019, 11:40 am | #9 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Akai 1720L solid state
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6th Oct 2019, 11:56 am | #10 |
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Join Date: Feb 2006
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Re: Akai 1720L solid state
There are two motor run capacitors, the main one and another smaller one which is switched in for 50Hz operation. Capacitors are NOT changed for speed switching.
Speed change is effected by switching from 4 - 8 pole operation. |
7th Oct 2019, 2:37 am | #11 |
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Join Date: Jun 2015
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Re: Akai 1720L solid state
Apologies gentlemen!!
I do stand corrected. Joe |