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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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25th Apr 2017, 6:35 pm | #1 |
Hexode
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Identification Transistor Dynatron Record Player (Carnival)
Can any one identify this Transistor Dynatron Record Player
it has a Garrard AT6 Turntable as im after a wiring diagram for it the volume on this player is very low and this component looks to be in poor shape (picture uploaded)
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25th Apr 2017, 6:41 pm | #2 |
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Re: Identification Transistor Dynatron Record Player
The component in poor shape looks like a thermistor probably used to compensate the output transistors bias with change of temperature.
Could be a VA1077 from the remaining colours. Not well up on record players perhaps a Cordova GR14? Cheers Mike T
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25th Apr 2017, 6:42 pm | #3 |
Hexode
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Re: Identification Transistor Dynatron Record Player
Dynatron Carnival 1963/64
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25th Apr 2017, 7:03 pm | #4 |
Hexode
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Re: Identification Transistor Dynatron Record Player
Thanks for the replys
Ive found a data sheet for the Dynatron Carnival but it does not tell me any values for the Thermistor, just wondering how would i test it and if needed what would i replace it with?
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25th Apr 2017, 7:08 pm | #5 |
Dekatron
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Re: Identification Transistor Dynatron Record Player
Almost certainly a VA1077, data in this link:
http://www.electrojumble.org/DATA/Mu...rom_VA1053.pdf Lawrence. |
25th Apr 2017, 7:30 pm | #6 |
Dekatron
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Re: Identification Transistor Dynatron Record Player
You can download the wiring (circuit) diagram from this site. See the top RHS of this screen.
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25th Apr 2017, 8:51 pm | #7 |
Hexode
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Re: Identification Transistor Dynatron Record Player
I now have the wiring diagram thanks.
I'm just wondering what would be a suitable replacement. Could i use a 33ohm resistor as a temporary replacement?
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25th Apr 2017, 11:52 pm | #8 |
Dekatron
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Re: Identification Transistor Dynatron Record Player
Although that 'component' looks to be in poor shape, do you actually know that it is causing your low volume?
Have you checked the output from the cartridge? Have you fed a signal into the amplifier input to test whether the low volume is due to the amplifier and not the cartridge? What about doing the 'buzz' test on the cartridge connectors with the volume turned full on - what were the results? |
26th Apr 2017, 12:05 am | #9 |
Hexode
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Re: Identification Transistor Dynatron Record Player
Yes i have used my old trusted mp3 player connected to the amp input and i can only just hear it play when the amp is on full volume
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26th Apr 2017, 12:11 am | #10 |
Dekatron
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Re: Identification Transistor Dynatron Record Player
Ah, that's ok then.
You've got the data on the thermistor and know what resistance it should be at around room temperature so you can test it. If faulty then I would probably experiment with a resistor. |
26th Apr 2017, 8:22 am | #11 |
Dekatron
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Re: Identification Transistor Dynatron Record Player
You have proved the amp is faulty, have you done any testing to try and find which stage is causing the fault? It may well be the thermistor but some standard fault finding techniques may prove the fault elsewhere .
Frank |
2nd May 2017, 11:03 am | #12 |
Hexode
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Re: Identification Transistor Dynatron Record Player
Just replaced the Thermistor with a 33ohm resistor and it's now working.
My next question is it safe to leave the resistor in place or should I get a new Thermistor if so what type should I replace it with?
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2nd May 2017, 11:09 am | #13 |
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Re: Identification Transistor Dynatron Record Player
Ideally that 33 ohm resistor should be replaced with a VA1053, VA 1077 or equivalent thermistor (are these still available, btw?), as these vary in resistance with temperature, as you no doubt know. Their purpose is to stabilse the output stage under changing temperatures. A glance at the data sheets in that link will show that the resistance of an NTC thermistor falls with increasing temperature, in the case of the VA1077, from approx 33 ohms @ 25 deg. C to under 1 ohm @ 100deg. C., and rises again as the device cools down.
Last edited by 'LIVEWIRE?'; 2nd May 2017 at 11:18 am. |
2nd May 2017, 2:29 pm | #14 |
Hexode
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Re: Identification Transistor Dynatron Record Player (Carnival)
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9th May 2017, 8:07 pm | #15 |
Hexode
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Re: Identification Transistor Dynatron Record Player (Carnival)
I fitted the EPCOS 33Ω 3100mW NTC Thermistor from RS and its now working properly
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