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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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18th Feb 2019, 9:48 am | #1 |
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Location: Truro, Cornwall, UK.
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Dynatron SRX20 Thermal Fuse
I am restoring a Dynatron SRX20 music centre. It appears to be dead. The 240V supply to the transformer is OK so I suspect it is the thermal fuse. Does anyone know the location and rating of this fuse?
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18th Feb 2019, 9:57 am | #2 |
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Re: Dynatron SRX20 Thermal Fuse
Hello and welcome to the forums.
The circuit diagram can be found in this thread:- https://www.vintage-radio.net/forum/...ad.php?t=52606 The thermal fuse is wired into the live side of the mains supply between the connector block and the transformer. Unfortunately I don't know its physical location or rating. If you can locate it, any marking on it may give a clue. If power is reaching the transformer, it's possible the fuse is embedded in the windings.
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18th Feb 2019, 10:15 am | #3 |
Dekatron
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Re: Dynatron SRX20 Thermal Fuse
Dynatron like Pye used the Philips type of embedded fuse in the transformer in some units. The fuse slides into a slot within the transformer windings and is easy to replace, if they are available.
They don’t usually just fail, there will be a reason, S/C rectifier?
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19th Feb 2019, 3:46 pm | #4 |
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Re: Dynatron SRX20 Thermal Fuse
I have found the fuse and replaced it. The tape deck now powers up, but the receiver is still dead - the lights don’t even come on - any ideas? There does seem to be some voltage at plug 101.
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19th Feb 2019, 3:56 pm | #5 |
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Re: Dynatron SRX20 Thermal Fuse
That's a pretty vague statement.
Your first move should be to use your meter to check that all DC power supply voltages are present and correct.
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20th Feb 2019, 3:53 pm | #6 |
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Re: Dynatron SRX20 Thermal Fuse
Thank you and sorry for the vagueness.
Am I correct that my meter should read: 25v across pins 1 and 6 (black/yellow) 36v across pins 2 and 3 (pink/pink) 6.3v across pins 4 and 5 (brown/brown) |
24th Feb 2019, 12:04 pm | #7 |
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Re: Dynatron SRX20 Thermal Fuse
Sorry, but I can't help you with that one apart from pins 4 and 5 (brown wires) which should have 6.3V AC across them. This voltage powers the lamps so, if the voltage is present and they're not lighting up you have a problem with F603 or the lamps themselves.
Check DC voltages at convenient points for example:- Chassis to C602 and C603 for the 18VDC supplies. Chassis to C604 for the 25VDC supply. Chassis to C262 for the 16VDC supply. Chassis to R262 for the 15.4VDC supply.
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27th Apr 2019, 7:50 pm | #8 |
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Re: Dynatron SRX20 Thermal Fuse
I guess the OP gave up on this?
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