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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 22nd Oct 2022, 9:08 pm   #21
paulsherwin
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

Proper meaty output transistors! Clearly a quality product, perhaps intended for use by teachers in classrooms.
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Old 22nd Oct 2022, 10:54 pm   #22
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

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Interesting that it was made for Tandberg Educational. They were mostly concerned with language lab stuff - it's difficult to see how a domestic radio cassette fits into that.
These players looked like radio-cassette units but were only cassette recorders. They were more suitable for classroom use because in the average shoebox mono tape player, the speaker faces upwards, so if you want proper distribution of the sound, you have to add an extension speaker. With a player like this the speaker faces forward, so is more useful.
Then you have essentials like a counter and cue & review for easy access to sections of a recording.

I mentioned Sanyo earlier as I have some Sanyo language lab cassette units which were promptly rebadged by Tandberg and also by ASC, two of the biggest language systems makers of Europe. I think they were just looking to put a product out there a lower price point than their in-house designs. Tandberg at this time (circa 1985) were still making their own mono standalone classroom recorders based on their language lab decks with dual capstan and real time counters. Very expensive.

I think I may have a spec sheet for the AT771, will look tomorrow.
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Old 23rd Oct 2022, 10:58 am   #23
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

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Proper meaty output transistors! Clearly a quality product, perhaps intended for use by teachers in classrooms.
They are TO-126 so not as large as a TO-220.

David
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Old 23rd Oct 2022, 11:13 am   #24
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

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Interesting that it was made for Tandberg Educational. They were mostly concerned with language lab stuff - it's difficult to see how a domestic radio cassette fits into that.
I suspect it was simply meant to complement their range of educational AV products. Simple-but-chunky radio cassettes always featured in the AV supply companies' catalogues, so there must have been a market for them. At my secondary school, similar machines were used in the classrooms by the language teachers to play snippets of the cassettes which went with the textbooks we had (the dreaded "Deutsch Heute" and "Tricolore"!)
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Old 23rd Oct 2022, 11:17 am   #25
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

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These players looked like radio-cassette units but were only cassette recorders. They were more suitable for classroom use because in the average shoebox mono tape player, the speaker faces upwards, so if you want proper distribution of the sound, you have to add an extension speaker. With a player like this the speaker faces forward, so is more useful.
Then you have essentials like a counter and cue & review for easy access to sections of a recording.
Well spotted, Ben, I hadn't even picked up on that!

Yes, the less lucky teachers at my school had tiny Sharp, shoebox-presentation machines, lashed up to an ancient (ex-16mm projector) speaker high up on the wall. The sound quality was good but they ran into clipping very easily as they probably only had 250mW amplifiers.
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Old 23rd Oct 2022, 11:20 am   #26
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

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Proper meaty output transistors! Clearly a quality product, perhaps intended for use by teachers in classrooms.
And it has a DIN speaker socket too. Most domestic equivalents just had the 3.5mm "earphone" socket.
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Old 23rd Oct 2022, 11:26 am   #27
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

I hadn't noticed it didn't have a radio.

Thinking about it, this model might have been more useful in schools with a basic AM/FM tuner added, but I suppose classes had stopped listening to schools broadcasts live off-air by the 80s. Maybe the designers also wanted to discourage theft!
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Old 23rd Oct 2022, 11:29 am   #28
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

Tandberg had a factory in the Lothians which failed around about 1980. A lot of stock got sold off and RME (Stockwell St, Glasgow) sold a lot of rather good top-loader piano key cassette mechanisms. They were by JVC and even had the JVC Sendust heads.

So Tandberg certainly had dealings with JVC over cassette mechs.

David
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Old 23rd Oct 2022, 12:23 pm   #29
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

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Quote:
Originally Posted by paulsherwin View Post
Proper meaty output transistors! Clearly a quality product, perhaps intended for use by teachers in classrooms.
And it has a DIN speaker socket too. Most domestic equivalents just had the 3.5mm "earphone" socket.
Yes must try it on external speaker to see how it compares to the very good sound from its internal speaker.

David
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Old 23rd Oct 2022, 12:31 pm   #30
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

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While in there, you may want to give the rubber spool table outer tyres and the idlers (one at back side, off the capstan; other on the spool table side) a once-over with fine sandpaper to remove the outer surface. Check also that the auto stop senor arm moves freely.

I have cleaned the rubber parts, which look to be good condition, at this stage I will not sandpaper them as everything looks to be working well.

Not yet worked out where the auto stop sensor arm is.

David
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Old 23rd Oct 2022, 12:42 pm   #31
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

Isn't it the white peg between the heads? When the tape becomes taut, it gets pushed in and de-latches the mechanism. Only works in record and play though AFAIK.
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Old 23rd Oct 2022, 2:28 pm   #32
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

The remaining 5 transistors are Japanese, all are 2SC820.

David
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Old 23rd Oct 2022, 2:44 pm   #33
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

Are you sure about that? It's an odd choice. I'd expect them to be one of the standard Japanese general purpose types - 2SC1815, something along those lines.
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Old 23rd Oct 2022, 2:59 pm   #34
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

A typo error, should have read 2SC828, they are the R variant with middle hFE gain range.

That is assuming that C828 = 2SC828, i.e. the 2S prefix is not shown on the transistor as often is the case.

A little surprised that all 5 are the same type.

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Old 23rd Oct 2022, 3:07 pm   #35
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

It's another general purpose type. You find them in all sorts of 80s Far Eastern stuff.
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Old 23rd Oct 2022, 5:07 pm   #36
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

The white peg mechanism between the heads does move freely and feels sprung loaded.

Not easy to see how it actually performs the auto stop function, should be clearer when powered and a tape operating.

David
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Old 23rd Oct 2022, 5:15 pm   #37
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

Here's an auto stop system that was sometimes used in cassette players (scroll down):

https://www.cse.iitk.ac.in/users/ami.../contents.html

System used in some JVC players here (scroll down):

http://www.ant-audio.co.uk/Tape_Reco...sette_Mech.pdf

Lawrence.

Last edited by ms660; 23rd Oct 2022 at 5:25 pm. Reason: Extra link added
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Old 23rd Oct 2022, 5:23 pm   #38
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

Thank you Lawrence, will have to compare this description with my hardware to see if I can understand it, reading it quickly it makes sense, just need to match the description to the hardware I see.

By pure co-incidence I briefly looked at the same link (the first link) a couple of days back for a different reason.

David
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Old 23rd Oct 2022, 5:25 pm   #39
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

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Thank you Lawrence, will have to compare this description with my hardware to see if I can understand it, reading it quickly it makes sense, just need to match the description to the hardware I see.

By pure co-incidence I briefly looked at the same link a couple of days back for a different reason.

David
Just added another link to that post for some JVC players.

Lawrence.
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Old 23rd Oct 2022, 5:29 pm   #40
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Default Re: Tandberg AT 771 Portable Mono Cassette Recorder

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System used in some JVC players here (scroll down):

http://www.ant-audio.co.uk/Tape_Reco...sette_Mech.pdf

Lawrence.
I think I have the hardware book the same as the link, got it through the Forum some time ago, will have to dig it out.

David
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