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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 14th Nov 2018, 6:56 pm   #1
NorfolkDaveUK
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Default B77 tape move sensor .

Ok I`m setting this machine up. I`m right at the blinking beginning ..lol ...and already its giving me grief .


TMS is 1.5 mm away from the back of the motor and it IS working in that its waiting for the motor to stop in FFW mode to then engage play , its just not waiting long enough ,. its engaging play about 1/2 maybe 3/4 of a second before the motor comes to a stop causing a loop and a failed play .

Anyone delt with this ? I`ve tried adjusting the TMS a million times . at the moment its 1.5mm away and square to the motor .

Thanks
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Old 14th Nov 2018, 8:06 pm   #2
NorfolkDaveUK
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Default Re: B77 tape move sensor .

i just cannot get this to play ball . everything on the board seems about right , the sensor is only getting 4.5v but thats shouldnt prevent it from working should it .

Last edited by NorfolkDaveUK; 14th Nov 2018 at 8:16 pm.
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Old 15th Nov 2018, 8:40 am   #3
NorfolkDaveUK
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Default Re: B77 tape move sensor .

well I`ve done everything i can think of too improve this to no avail . All i can assume is that the sensing is just crap . I`ve advised the person buying it and hes ok to never go from rew/ff straight to play . Its never a good idea anyway really . I dont know what else to do . I`ve changed all the transistors in the circuit incase they were noisy and interfering or something , no joy, moved the sensor in and out a gazillion times , no joy , checked the voltage and its 4.7v so that`s good enough . So there`s nothing more I can do but assume its not going to get any better and move on .
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Old 15th Nov 2018, 9:09 am   #4
Michael Maurice
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Default Re: B77 tape move sensor .

It's not a crap sensing system at all, when it's working it is very very good.

I've had this fault myself and cured it! Replace C5, 47uF on the tape drive board.
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Old 15th Nov 2018, 9:25 am   #5
NorfolkDaveUK
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Default Re: B77 tape move sensor .

i`ve re-capped the whole board bud , its made no difference , i will re-place the replacement and check the soldering , and see if i can find anything .

thanks Michael .
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Old 15th Nov 2018, 9:29 am   #6
NorfolkDaveUK
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Default Re: B77 tape move sensor .

UGH....it was me ...I put a 4.7 on c12 and c5, should be a 47 ....lol ...on we go ...

edit : Yup that fixed it ....THANK YOU Michael as always !

Last edited by NorfolkDaveUK; 15th Nov 2018 at 9:54 am.
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Old 15th Nov 2018, 12:00 pm   #7
TIMTAPE
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Default Re: B77 tape move sensor .

Perhaps a good example of a downside of automatically recapping everything in sight. Unless we recap with absolute accuracy, we risk introducing new faults.
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Old 15th Nov 2018, 2:28 pm   #8
NorfolkDaveUK
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Default Re: B77 tape move sensor .

Quote:
Originally Posted by TIMTAPE View Post
Perhaps a good example of a downside of automatically recapping everything in sight. Unless we recap with absolute accuracy, we risk introducing new faults.
Thank you Dr Tim
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Old 15th Nov 2018, 2:43 pm   #9
Ted Kendall
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Default Re: B77 tape move sensor .

An ESR checker can save a lot of needless re-capping.
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Old 15th Nov 2018, 2:55 pm   #10
NorfolkDaveUK
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Default Re: B77 tape move sensor .

Lol . They are 45 - 55 years old , they cost pence , just replace them . I`ve done 5 units this week . 2 x A77`s , 1 x B77 , 1 x TEAC A-3340-s (this one was epic , 113 caps over 10 boards ) , and one Sony TC - 377 . All of them sound a heck of a lot better afterwards and now wont fail for years so how can it be needless ? Each to their own if you don`t want to re-cap then don`t re-cap . I messed up on 2 caps and must have fit a good few hundred this week . I can live with that .
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