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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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12th Jun 2020, 2:05 am | #1 |
Hexode
Join Date: Mar 2018
Location: Bishop Auckland, County Durham, UK.
Posts: 373
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Defiant T15 repair
This early 1960s twin track tape recorder uses the BSR TD2 deck and suffered from the usual problems of parts seized up due to dried out grease. Once this had been attended to, playback of a pre-recorded tape appeared to be fine. However new recordings were distorted and the erase was poor. The audio output stage and erase/bias oscillator uses the pentode section of an ECL86 valve. Replacing the 50uF electrolytic capacitor that decouples the cathode (pin7) restored normal operation. Interestingly, the record level indicator features a DM70 rather than the more usual EM84. I've never seen one of these devices before, it worked quite well. I love these early 60s tape recorders.
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Regards Martin Last edited by martin.m; 12th Jun 2020 at 2:08 am. Reason: clarity |
12th Jun 2020, 4:51 am | #2 |
Octode
Join Date: Mar 2006
Location: Lund, Sweden
Posts: 1,631
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Re: Defiant T15 repair
Yes, there's something about the styling on machines from this era that is appealing to me too. I don't know if it's a pure nostalgic thing (I was born in the mid-60s, so by the time I became aware of my surroundings it was a bit after this era but on the other hand machines of that styling would have been what was commonplace for a decade or so since their introduction) or if there's something universally appealing about multi-tone grey.
For me, the period is the border between "old" (polished wooden cabinets with yellow or off-white trim) and "modern" (painted or vinyl covered in various tones of grey). Interesting that the machine has been fitted with a tape counter, that wasn't standard for TD2 decks was it? And an unusual type for that mounting position too - it was a common position on Philips machines, but they then had the digits above each other (so it would look symmetrical I suppose, a fairly strong design feature in those times). What's behind the apparent hatch to the right of the controls - a microphone? |
13th Jun 2020, 1:27 am | #3 |
Hexode
Join Date: Mar 2018
Location: Bishop Auckland, County Durham, UK.
Posts: 373
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Re: Defiant T15 repair
You are correct Ricard. The hatch is for storing the mains cable and microphone. The TD2 deck was used on many 1960s British made tape recorders, some have a tape counter and some don't. Fidelity used the deck in their Playmaster and Braemar machines but with their own plastic deck plate instead of the metal one. Most of these have a tape counter.
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Regards Martin |
13th Jun 2020, 10:07 pm | #4 | |
Octode
Join Date: Aug 2005
Location: Saltburn-East, Cleveland, UK.
Posts: 1,786
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Re: Defiant T15 repair
Quote:
Getting back to the Defiant machine, I have a T12 in my collection which has a similar control panel layout to the T15 however a much less good looking case and livery. What I did find odd is the way that the radio/gram input is arranged in circuit on these machines as it feeds directly into the volume control which allows the signal to be heard through the machines internal amplifier before record is selected. I suspect the input is arranged in this way to allow mixing with the microphone signal. Most other machines of this vintage have the radio/gram input connected via an attenuating network to the microphone input. Andrew |
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14th Jun 2020, 9:45 am | #5 |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,587
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Re: Defiant T15 repair
Attractive looking unit, looks to be in good nick. Had not realised that Defiant had done tape recorders, I remember that they had done some record players and possibly TVs ?
Somewhat unusual for this vintage of R2R machine to use the EZ80 full wave rectifier valve, many others using Selenium bridge rectifiers. Yes agree with Andrew that taking the radio/gram input directly into the volume control (via 47k resistor) is unusual. David |
15th Jun 2020, 3:48 pm | #6 |
Octode
Join Date: Mar 2006
Location: Lund, Sweden
Posts: 1,631
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Re: Defiant T15 repair
Feeding the radio/gram input this way would also make it possible to use the machine as an amplifier to play back records, which would be practical I would think (especially since in record mode the output valve is used for the oscillator).
Regarding the use of rectifier valves, I never been able to figure out why one is preferred over the other. Philips tended to use rectifier valves, whereas many other manufacturers opted for selenium. My guess is that valves were cheaper back in the day, but of course added to the heat buildup which is a disadvantage, especially in the relatively cramped internal environment of most tape recorders. (In the Defiant in this thread, the heat buildup is partly offset by the use of the DM70 valve in favor of a more common EM84, although I suspect that it too would become significantly less warm than an EZ80). |