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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 17th Sep 2019, 2:04 pm   #1
Chris55000
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Default Heathkit Stereo Tape Recorder STR-1

Hi!

I've started Scanning of the Full Assembly Manual & the files'll be posted here as soon as the various sections are ready to post!

Chris Williams
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Old 17th Sep 2019, 4:34 pm   #2
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Default Re: Heathkit Stereo Tape Recorder STR-1

Hi!

Manual Covers. . .

Chris Williams
Attached Files
File Type: pdf 1_Heathkit STR-1 Covers & Inserts.pdf (510.3 KB, 125 views)
File Type: pdf 2_Heathkit STR-1 Covers & Inserts.pdf (548.3 KB, 108 views)
File Type: pdf 3_Heathkit STR-1 Covers & Inserts.pdf (1,018.0 KB, 99 views)
File Type: pdf 6_Heathkit STR-1 Covers & Inserts.pdf (974.1 KB, 109 views)
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Old 17th Sep 2019, 5:01 pm   #3
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Default Re: Heathkit Stereo Tape Recorder STR-1

Can I just say in advance, thanks for doing the scanning. It will be great to have the circuits etc for when I restore mine.... in the distant future!

Cheers,

Peter
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Old 17th Sep 2019, 5:02 pm   #4
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Default Re: Heathkit Stereo Tape Recorder STR-1

Looking forward to seeing the rest of this.
Well done Chris!
Graham
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Old 18th Sep 2019, 11:09 am   #5
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Default Re: Heathkit Stereo Tape Recorder STR-1

Hi!

Introduction, parts list & soldering guide. . .

Chris Williams

PS!

Keep watching this space, more coming!
Attached Files
File Type: pdf Hearhkit STR-1 Intro - Parts List - Soldering.pdf (1.07 MB, 99 views)
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Old 18th Sep 2019, 1:38 pm   #6
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Default Re: Heathkit Stereo Tape Recorder STR-1

Hi!

PCB Assembly steps. . .

Chris Williams
Attached Files
File Type: pdf Heathkit STR-1 PCB Assembly.pdf (845.0 KB, 112 views)
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Old 18th Sep 2019, 2:42 pm   #7
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Default Re: Heathkit Stereo Tape Recorder STR-1

PS!

I'll scan the larger Pictorial Sheets at the end when I've done the basic pages!

Unusually, Heathkit don't appear to have issued any large sheet fold-out pictorials for this kit as none are referred to in the Manual instructions, but I'll make sure everything gets scanned & uploaded!

Chris Williams
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Old 19th Sep 2019, 11:05 am   #8
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Default Re: Heathkit Stereo Tape Recorder STR-1

Hi!

Block Diagram, Circuit Diagram, Layouts, Voltages and Fault-Finding Tables. . .

Please let me know if anything's difficult to read and I'll re-scan if needed!

Chris Williams
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Old 19th Sep 2019, 1:20 pm   #9
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Default Re: Heathkit Stereo Tape Recorder STR-1

Hi!

Press-Button Switch Wiring and Initial Chassis Assembly. . .

Chris Williams
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Old 19th Sep 2019, 4:06 pm   #10
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Default Re: Heathkit Stereo Tape Recorder STR-1

Hi!

Final Chassis Assembly/Wiring & Initial Tests. . .

NB!

A tiny corner of the Chassis Pictorial has overlapped onto P. 30 which means the Full Pictorial will have these tiny corners missing, but anyone who's good with Technical Drawing should be able to draw the missing corners in!

Chris Williams
Attached Files
File Type: pdf Heathkit STR-1 - Final Chassis Assembly & Testing.pdf (1,002.4 KB, 102 views)
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Old 20th Sep 2019, 1:30 pm   #11
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Default Re: Heathkit Stereo Tape Recorder STR-1

Hi!

Testing & Setting up with instruments. . .

Chris Williams
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File Type: pdf Heathkit STR-1 - Testing with Instruments.pdf (200.6 KB, 85 views)
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Old 21st Sep 2019, 7:25 am   #12
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Default Re: Heathkit Stereo Tape Recorder STR-1

Hi!

High Resolution 600 DPI Copies of Circuit & PCB Layout Diagrams for anyone who needs the best ones. . .

Chris Williams
Attached Files
File Type: zip Heathkit STR-1 Circuit Diagram High Res.zip (1.51 MB, 129 views)
File Type: zip Heathkit STR-1 PCB & Voltages High Res.zip (1.55 MB, 116 views)
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Old 21st Sep 2019, 8:23 am   #13
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Default Re: Heathkit Stereo Tape Recorder STR-1

Thanks for doing this Chris!

I don't own the STR-1, but as a long term Heathkit collector it's interesting to study its design. I wonder if the electronics were a purely British design or whether it's an adaption of something from the US.
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Old 21st Sep 2019, 12:50 pm   #14
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Default Re: Heathkit Stereo Tape Recorder STR-1

Hi!

I think the design is (very roughly!) based on the Mullard 3W Tape Amplifier with extra refinements added by Heathkit for three–speed playback compensation.

Another major difference was that the Mullard circuits used the erase–head itself as the bias–oscillator coil, in a Colpitts type circuit, which necessitated a relatively low impedance R/P head, as the bias voltage from across the bias oscillator circuit isn't adequate for the normal type of head without using an additional step–up transformer!

If you wish to study the Mullard Circuits, download the January and February 1971 issues of "Practical Wireless" from the American Radio History site and look at the "PW Stereo Tape Recorder" project!

There's still more Heathkit Manual & the larger pictorials from it to come, by the way!

Chris Williams
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Old 21st Sep 2019, 9:02 pm   #15
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Default Re: Heathkit Stereo Tape Recorder STR-1

Quote:
Originally Posted by wd40addict View Post
I wonder if the electronics were a purely British design or whether it's an adaption of something from the US.
The very British TD10 deck would make this seem like a purely British design (and even more so considering the relationship to the Mullard 3W amp design) so possibly it was never sold in the USA at all?
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Old 21st Sep 2019, 9:14 pm   #16
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Default Re: Heathkit Stereo Tape Recorder STR-1

Hi!

The Assembly Manual itself gives the uniquely British design of this machine away in itself, as apart from the manual text, whose typeface I'm still trying to find the name of (it's NOT any form of Courier!), the drawing lettering itself is entirely British in design as well – in fact all five of the different styles of British Drawing Lettering are mixed up in the circuit–diagram here and there!

There were American Heathkit R to R machines made, and I believe it was possible to get some of the kits specially imported (at great expense!) at one time, the decks were entirely an American product and the amplifier totally different in design!

Chris Williams
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Old 21st Sep 2019, 10:03 pm   #17
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Default Re: Heathkit Stereo Tape Recorder STR-1

Thanks for this information Chris , Very useful.
Will study it in detail when and if I get a chance..
Only other Heathkit bit of kit I have is a Short wave receiver...
Peter W Reelguy.
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Old 23rd Sep 2019, 11:50 pm   #18
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Default Re: Heathkit Stereo Tape Recorder STR-1

Hi!

On a more technical note than the Assembly Manual, the STR–1 I bought has two faults, one mechanical and one electronic!

The mechanical one is I can't move the joystick into rewind and fast–forward is very sluggish, so I bit the bullet and bought the exploded view manual so I could investigate it, the most likely cause being ancient goo, so it looks like printing out all the diagrams and do a bit of James May on it!

The electronics fault is very, very low volume from the L.H. channel on both replay & record, with no indication on the record–level meter – I found the record monitoring volume virtually the same as the playback volume, so that and the non–responding meter almost certainly points to an o/c electrolytic in the first three L.H. channel stages!

(Of course there could be an o/p amplifier failure, but as this is only three transistors with a silicon transistor driver, chances are that will be working!

On a design note, Heathkit used a 6000μ 40V reservoir/smoothing capacitor, much more than the 2000–3500μ that was the usual value in most transistorised mains–powered amplifiers of that era – I don't think the Wharfedale amp my friend bought (a piano–key switch version of the Leak Delta 30) uses any more than 3300μ!

Chris Williams

PS!

I'm not sure whose heads it's got, but I'll be using one of those little Chinese LCR testers if I have to check them as they use a.c. energisation of the test component, but quite honestly I'm not suspecting head failure!
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