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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

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Old 14th Jan 2021, 9:27 am   #41
ysgramor87
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Default Re: CCL Capacitor for Deccasound 600

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Originally Posted by Station X View Post
I know lots of advice has been given, but I suggest the first thing you do is check the continuity of the choke. If it's open circuit it could be a show stopper.
I'll do it first and update you. Same time I'll try to draw the circuit and measure each tags.

Thank you again.
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Old 14th Jan 2021, 9:41 am   #42
vinrads
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Default Re: CCL Capacitor for Deccasound 600

Hi it looked like the choke was o/c from the start , but I missed a load of threads, it would be unusual for a low tension choke to go o/c they are wound with quite thick wire. It looks like it is going to be sorted with a competent person, good luck with it . Mick.
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Old 14th Jan 2021, 12:09 pm   #43
Robint 47
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Default Re: CCL Capacitor for Deccasound 600

Well after following these threads it's like going back in time. I spent some very happy 20 odd years working in the Decca service dept at Bridgnorth working as technical support. In all those years I cannot recall one of these chokes going faulty in any way they were more or least used on all Decca audio products of a 6 Watt nature at that time. The transformers count those on one hand even the rectifier does not look original. So I still think the best advice is to strip back checking the mains Tx fitted is correct for the job and rewire back to spec. After a successful repair the end user will find he has got quite a nice sounding system even though it must be now some 40+ years old able to support a ceramic cartridge Decca used a Sonatone 9TA series which in its day was able to hold its head high . The speakers supplied by Decca were the L100 an 8ohm system which to my younger ears sounded quite good not having the colouration some units in plastic boxes have today Decca sold these items though as separates so the end user could choose an alternate deck and speakers hence the model no i.e. 6 meaning 6 Watt 0 series reference 4 of course there were 4 items and it did produce 6watts RMS per channel The amp had a mains output for a auxiliary source
Sorry if I have gone on a lot but it does bring back so many memories of things going right and wrong I still have a great many Decca manuals I retained when I left Decca the company selling out to Tatung . I will make some arrangement for them to be either copied or given to an organisation that will look after them some of them don't appear even on this site.
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Old 14th Jan 2021, 3:02 pm   #44
Michael Maurice
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Default Re: CCL Capacitor for Deccasound 600

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Originally Posted by Robint 47 View Post
In all those years I cannot recall one of these chokes going faulty in any way they were more or least used on all Decca audio products of a 6 Watt nature at that time.
I wonder if the output modules have failed, taking more current and taking out the choke. The transistors develop tin whiskers which may not have happened when you were servicing these at the time you were at Decca.

I can get a 20V 20VA transformer which should be sufficient to power the modules and the pre-amp. One could easily change the lamp to a 24V type.

You are unlikely to get a new choke, which means either having it rewound, fitting a resistor of say 47 ohms, or leaving it out altogether and increasing the reservoir capacitor.

You will probably find that back in the days when these were manufactured, the rectifiers couldn't handle large inrush currents, so the smoothing caps were limited in size. Today one could fit say an 8A rectifier and a 6800uF capacitor which would probably give the same or better ripple.

However this is only speculation until we can work out exactly what has failed and possibly why.
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Old 15th Jan 2021, 9:42 am   #45
ysgramor87
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Default Re: CCL Capacitor for Deccasound 600

I'll have a look over weekend, take some measurements and update you. If it's something complicated for me, I'll ask for help for sure.
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Old 15th Jan 2021, 6:47 pm   #46
ysgramor87
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Default Re: CCL Capacitor for Deccasound 600

Hi everybody,

Firstly,
I've found what's wrong with the circuit. Cable which comes to HT fuse was not soldered. I've soldered it and managed to get sound from one channel.

I have loud hum even when nothing is connected. (from transformer maybe?)
If I connect speaker to fine channel hum increases, if I connect other channel hum level is same.

But unfortunately, while I move it upside down to bring it normal position, I've lost the sound, there is just loud hum now. (I think I've touch volume knob while I moving it.

So it's better to look for professional solution. I'll send private messages.

Thanks for all your help, at least I'm learning something.

Fatih

When I moved it upside down to bring it to a normal position
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