Just Replacement Of Hall Sensor Belt Solved Running Problems In BIC Cassette Deck T-1
This set had visited me in February, 2016 with multiple problems. I did overhauling of mechanism, changed all its belts and also did a dry solder patch up of the board. Unfortunately, I do not remember to have covered these with any snaps or written an article, when I searched for its records. The set revisited in September, 2022 with the complaint that it gets off while playing.
After opening and cleaning the inside, when I checked the deck while running a cassette, I noticed that the belt of hall sensor detection was running erratically.
Those of you who are new to hall sensor and its function, may please visit this link to know all about it: Hall Sensor Working Principle – Your Electrical Guide
In this Deck, the circuit is like this:
The DC output from the DN6839 Hall Sensor keeps Q2 and Q1 functional holding down the solenoid plunger, engaging the play mechanism pushed down. If the rotating magnetic wheel stops, the output of Hall Sensor at pin 3 drops stopping biasing of Q2 resulting in its shutting down, which in turn shuts down Q1. Both transistors are NPN type. You can see that a manual switch for pause is also connected at the collector of Q2 similarly.
So the belt plays an important part, as it is connected to the play wheel (take-up wheel) and runs parallel to it. The belt has to be in correct tension to run the magnetic wheel. (If any of you are interested to get the service manual of this set, kindly visit: BIC Model T-1 Two-Speed Cassette Deck Manual | HiFi Engine. [You need to sign in or register and then sign in to download the above manual. It is totally free!]) So, I selected a correct size belt and replaced it. Then the set worked very well without intermittent shutting off.
I played two tapes both A and B sides for checking. Work accomplished quickly and soon enough to add satisfaction to the collection bag.
This article was prepared for you by Parasuraman Subramanian from India. He is 72 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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You may check on his previous article on Left Channel Output Found Charred In QUED A240CD Amplifier
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14 Comments
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Mark
February 11, 2023 at 2:14 pm
Hey Parasuraman,
An excellent repair as usual.
Parasuraman S
February 11, 2023 at 8:55 pm
Many thanks, dear!
Albert van Bemmelen
February 11, 2023 at 3:10 pm
A compliment to your professional engineering technique in that you managed to again fix this old cassette deck after it had worked perfectly over about 6 years! And thanks for the link to the service manual download, which also may come in handy in case a similar cassette deck needs to be examined.
Albert van Bemmelen
February 11, 2023 at 3:19 pm
Apparently registration on that website is sadly no longer possible for new 'members'.
Parasuraman S
February 12, 2023 at 6:55 am
Oh! I did not know that! Thanks for the info!
AdamS
February 13, 2023 at 5:38 pm
Albert, I understand this site, and its sister site Vinyl Engine (which focuses solely on turntables) have been repeatedly targeted by hackers and spammers, plus people setting up multiple accounts to try and bypass the download limit of five manuals per day.
Registration for both sites is temporarily suspended while the owner puts better security in place, so keep trying!
Parasuraman S
February 14, 2023 at 9:33 am
Oh! So, that is it! Many thanks for the info!
Parasuraman S
February 11, 2023 at 8:56 pm
Many thanks for your analytical encouraging comments!
Babu M S
February 11, 2023 at 5:06 pm
Very good repair work sir.Thanking you for sharing.
Parasuraman S
February 12, 2023 at 6:55 am
Many thanks dear Babu!
Waleed Rishmawi
February 11, 2023 at 8:30 pm
thanks for sharing your repair success and also the service manual. these mauals are hard to come by now a days. I really enjoyed your explanation of the sensor and the circuit with it. have a blessed ay
Parasuraman S
February 12, 2023 at 6:56 am
Many thanks for your continued support and encouragement!
Yogesh Panchal
February 15, 2023 at 3:40 pm
Good Job Sir,
Thanks! For sharing detail of Hall Sensor.
Parasuraman S
February 15, 2023 at 8:57 pm
Many thanks for your comments!