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

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Old 21st Dec 2021, 9:18 pm   #1
Bailey.Vintage
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Default Faulty Decca RG98 Radiogram

Yesterday I bought a Decca RG98 Radiogram. It appears to be in good condition but could do with a few repairs which is why I'm posting here.

The radio works fine, just needs a good earth and it can pick up a few stations

My main concern is the turntable
This radiogram is specifically fitted with a Garrard R.C.111 turntable and it's model number is 515000

When I flick the selector switch to On the turntable spins, the record changer functions and the stylus arm rises but is locked in position and fails to move across to the record. After 5 seconds the arm lowers itself and the turntable stops spinning

When I brush the needle I get no audio whatsoever from the speakers but I know that the speakers are working because the radio is audible when turned on

I flipped over the turntable unit and I believe I may have found the main problem although I'm not 100%

I have linked the original manual and then my turntable
I believe there might be a missing wire on the empty terminal.

Would appreciate all the help
-Bailey
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Old 21st Dec 2021, 11:49 pm   #2
bill knox
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Default Re: Faulty Decca RG98 Radiogram

Hi

Regarding your Decca R/G, until the needle touches the record there will be no sound, Garrard have a switch under where the wires from the cartridge and R/G meet that shorts out the wiring until the needle is on the record.

You may have a faulty pickup cartridge, I have had terrible trouble getting a cartridge that gives anything out, the crystal attracts moisture and inside the cartridge goes green with Verdigris, I tried with one cartridge to open it up with a view to cleaning it and cocked it right up, I gave up on that one.

The RG98 was a good R/G but the RG103 was better and the RG105 I think it was, was even better but they all went to America, they had the Goodman's Axium 12 fitted, but the radio's were all the same just had different dials fitted.

Regards

Bill
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Old 22nd Dec 2021, 9:58 pm   #3
buggies
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Default Re: Faulty Decca RG98 Radiogram

I do not think there is a missing wire as the radiogram amplifier is only mono and the second wire looks like it would be for a stereo amplifier.
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Old 23rd Dec 2021, 9:18 am   #4
Edward Huggins
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Default Re: Faulty Decca RG98 Radiogram

When this Radiogram was made in 1955 there was no provision anywhere within the unit for Stereo adaption - it was all pre-Stereo. The original Mono only cartridge is highly likely to have completely failed.
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Old 24th Dec 2021, 6:21 pm   #5
PYE 405
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Default Re: Faulty Decca RG98 Radiogram

Hi Bailey, your photo shows an earthed screened cable with the inner two wires (positive/negative) for connection to the signal output from a mono cartridge.
Depending upon the type of cartridge fitted, the negative signal return can alternatively be made through the outer screen. Thus there is one connection unused in this instance.
As mentioned above, the switch could be muting the output due to mechanical issues with the arm not moving and lowering onto the record.
This is probably caused by hardened grease and the turntable will likely require partial strip-down with careful cleaning and re-greasing. This is a likely possibility for the arm not moving....
I must add that I do not know for certain if this model has a muting switch and it could simply be that the cartridge, as also mentioned, is producing no output.
As a matter of interest, when you load the record, are you placing it directly onto the turntable or on the upper part of the centre spindle and allowing the deck to drop the record automatically?
The only reason I ask is because many auto-changers will not play the record until one is detected by the swing arm. (Forgive me if you know how an auto-changer works and I am teaching Grandmother to suck eggs !)
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Last edited by PYE 405; 24th Dec 2021 at 6:42 pm.
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Old 24th Dec 2021, 7:11 pm   #6
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Default Re: Faulty Decca RG98 Radiogram

Another check that ought to be made is to establish that the amplifier is actually working when Gram is selected. The radio works, but it will be worthwhile looking to see where the black cable goes to as it leaves the turntable (on the left in the second photo). As a crude test, you should be able to produce hum/buzz from the speaker if ONLY the centre conductor is touched.
I must stress that you really should know what you are doing here as far as live mains powered vintage equipment is concerned. I am not being rude, but do you have knowledge of electronics such as this equipment? I would hate to make a suggestion for a test and you go and get electrocuted !!
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Old 18th Jan 2022, 5:42 pm   #7
Bailey.Vintage
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Default Re: Faulty Decca RG98 Radiogram

Thanks Andrew, I appreciate your advice. I must admit, I'm a little out of depth when it comes to vintage appliances although I do have somewhat of an understanding as I'm currently studying electrical engineering in college so I know what to and what not to touch etc. I'll do a quick check now on the record changer and if it proves inconclusive then I'll see about servicing the mechanical parts and ridding it of any grease

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