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Old 3rd May 2021, 2:50 pm   #1
deltamonk
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Default Getting a charity shop radiogram working

Hi, my son has recently bought a Dynatron radiogram from a charity shop and we thought it might be fun to try to get it working (plug was cut off when found).

The model number has faded/fallen off but we can see 1511 on the sticker still, it looks like it may be a CG but we can't find anything about it online.

Plugging it in, the turntable spins but it doesn't look like the radio or tape deck have power. Fuses look fine and we can't see any obvious broken connections / missing wires etc.

We're wondering if there are any resources that might help us get this working. No real electronic knowledge but we're happy to learn! Getting everything powered up is probably stage 1 so any advice would be appreciated.
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Old 3rd May 2021, 2:54 pm   #2
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Default Re: Getting a charity shop radiogram working

As always pictures would help, but it sounds like it might be this model:-

https://www.service-data.com/section...1511pm-carlton
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Old 5th May 2021, 8:36 am   #3
deltamonk
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Default Re: Getting a charity shop radiogram working

That's brilliant, thanks!

Photos attached (just worked how to sorry). We can't see that either the radio or tape deck is actually connected to the power lead/switch so that doc will definitely help I think!

Much appreciated.
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Old 5th May 2021, 10:52 am   #4
Michael Maurice
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Default Re: Getting a charity shop radiogram working

The turntable is mains powered, to the left is the mains transformer, it is connected there.

The radio, the tape deck get their power from this transformer via the power supply which is part of the radio section. Do you have a test meter and do you know how to use it?
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Old 5th May 2021, 1:40 pm   #5
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Default Re: Getting a charity shop radiogram working

Ah, OK ... Thanks that explains a lot!

We had worked out the grey cable running round top-left was the power for the turntable but not about the transformer; presumably the black cable/bundle running back across the top of pic 2 is for the others in that case?

Quote:
Originally Posted by Michael Maurice View Post
Do you have a test meter and do you know how to use it?
No and no, but I will see if we can get hold of one.
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Old 6th May 2021, 4:54 pm   #6
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Default Re: Getting a charity shop radiogram working

This unit is similar to the Dynatron SRX20 and you will find on this site a schematic of the unit and notes on the repair of specific faults.

In "search this site" enter the model.

Should you be unfamiliar with circuit diagrams, the turntable is connected to windings on the transformer and so the thermal fuse will be OK.

There are 2 other fuses. They can be easily seen. FS601 which protects the +18volt HT supply and FS603 in series with the 6.3 volt dial lamps and protects the transformer should they fail and become a short circuit. The bulbs should be working.

Should FS601 be blown showing a black smudge in the glass envelope then there is a fault.

Should it be blown but no blackening, you might be lucky and all it needs is to be replaced.

When you have your test meter, you will be able to check the fuses.

Do note that repairing any radio or amplifier equipment requires a degree of skill learnt from years of experience and members local to you may help, so there is no shame in asking.

Chris
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Old 16th May 2021, 3:48 pm   #7
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Default Re: Getting a charity shop radiogram working

Thanks, sorry we have been focusing on his exams but just got a multimeter today.

Definitely 240v AC to the transformer but can't measure any DC voltage. Found three fuses we can see easily, none look blown.

Fuse on the side of the transformer has high impedance reading so that could be the problem, looks to be corroded.

Two fuses on the radio board are both measuring low so seem to be fine?

Will download the documents and have a look in more detail sometime soon and report back!
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Old 16th May 2021, 10:07 pm   #8
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Default Re: Getting a charity shop radiogram working

Does this unit have built in speakers or are they separate? Presume someone has painted the cabinet white.
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Old 17th May 2021, 6:06 pm   #9
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Default Re: Getting a charity shop radiogram working

Hmmm. Deltamonk, I read in your opening thread that the turntable worked but, according to my schematic should the transformer fuse be open circuit the turntable won't work as it it fed from the secondary of said transformer.

Just so further advice can be tailored to your experience of electronic circuits, do you see yourself as a novice or with some knowledge and most importantly, can you read a circuit diagram?

There will not be DC voltages on the mains transformer only AC. Also, just to be clear, a fuse can only read 0 ohms (short circuit)or open circuit, never infinity. This terminology is important should at any time you are advised to check other components and note the meter reading.

Nuvistor has a point, not the white paint of course, but the unit does have loudspeakers, doesn't it?

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Old 17th May 2021, 6:36 pm   #10
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Default Re: Getting a charity shop radiogram working

Quote:
Originally Posted by simpsons View Post
Also, just to be clear, a fuse can only read 0 ohms (short circuit)or open circuit, never infinity.
I'd beg to differ there - a blown fuse, so open-circuit, is infinite!

In fact, the resistance scales of many an analogue multimeter, at the high-resistance end, often have the little infinity symbol ∞ on the scale.
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Old 17th May 2021, 6:49 pm   #11
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Default Re: Getting a charity shop radiogram working

^^^^

What kalee20 said!

simpsons. If you want to discuss this further please do so in a new thread rather than take this one off topic.

Thanks.
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Old 17th May 2021, 6:58 pm   #12
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Default Re: Getting a charity shop radiogram working

I asked about the speakers because the front looks solid, some of these units had speakers that folded out from the side others had separate ones.
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Old 17th May 2021, 7:02 pm   #13
Edward Huggins
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Default Re: Getting a charity shop radiogram working

I think the LH and RH "doors" (they look like drawers) open to reveal the built in speakers.
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Old 17th May 2021, 7:30 pm   #14
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Default Re: Getting a charity shop radiogram working

Quote:
Originally Posted by Edward Huggins View Post
I think the LH and RH "doors" (they look like drawers) open to reveal the built in speakers.
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Old 26th May 2021, 3:50 pm   #15
deltamonk
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Default Re: Getting a charity shop radiogram working

Quote:
...according to my schematic should the transformer fuse be open circuit the turntable won't work as it it fed from the secondary of said transformer.
If I recall, it seems that both sets of wires are soldered onto the same pins on the transformer / each other, so that would explain that?

Quote:
Just so further advice can be tailored to your experience of electronic circuits, do you see yourself as a novice or with some knowledge and most importantly, can you read a circuit diagram?

There will not be DC voltages on the mains transformer only AC. Also, just to be clear, a fuse can only read 0 ohms (short circuit)or open circuit, never infinity. This terminology is important should at any time you are advised to check other components and note the meter reading.
Noted, thanks. Definitely novice level, we can't read circuit diagrams, or at least not "properly", but he has 15 weeks off school now so happy for him to learn

Only checked AC across the transformer / turntable but couldn't get a DC reading between any of the other likely looking pins. Most likely need to look up how to use the meter properly!

As a few people have asked: Yes there are speakers behind the doors in the "legs", they were painted shut presumably when the plug was cut off.

We have the documents (linked earlier) and going to start in earnest soon, learning to use the meter and read the diagrams I think is step 1...

Tom
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