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Old 22nd Oct 2019, 10:47 am   #1
AndyWright
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Default Garrard AC20

I have a 1939 EKCO TRG502 radiogram which is fitted with a Garrard AC20 record player. This is a fixed speed 78rpm only, and requires the arm to be manually placed on to the record.

I've found that the record player runs too fast, and can't see any means of speed adjustment. Does anyone have any ideas?

Cheers

Andy
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Old 22nd Oct 2019, 12:11 pm   #2
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Default Re: Garrard AC20

I can't find any information or pictures of a Garrard AC20 record deck on the net. Could you post a few pictures of the motor?
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Old 23rd Oct 2019, 9:16 am   #3
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Default Re: Garrard AC20

I'll post a few pics later today, just discovered the camera battery is flat.
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Old 23rd Oct 2019, 3:24 pm   #4
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Default Re: Garrard AC20

Here are a few pics of the record player and motor.
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Old 23rd Oct 2019, 3:32 pm   #5
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Default Re: Garrard AC20

Can you remove the turntable and take a picture of the mechanism?
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Old 23rd Oct 2019, 3:53 pm   #6
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Default Re: Garrard AC20

Fast as opposed to slow running of a turntable is unusual.

That looks like a shaded pole motor to me and, if of the synchronous type, it will only run at one speed governed by the mains frequency.
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Old 24th Oct 2019, 10:09 am   #7
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Default Re: Garrard AC20

I've removed the turntable, but there's just a plastic cover, with three holes for applying oil. Maybe the next step is to remove the mechanism from the set?
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Old 24th Oct 2019, 10:12 am   #8
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Default Re: Garrard AC20

How is the drive transmitted from the motor to the turntable?
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Old 24th Oct 2019, 12:55 pm   #9
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Default Re: Garrard AC20

I haven't disassembled it yet, but it appears to be a bevel gearbox with the turntable sitting directly on the output shaft.
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Old 24th Oct 2019, 1:00 pm   #10
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Default Re: Garrard AC20

This may be a silly question, but how do you know that the turntable is rotating too fast?

Have you checked it with a strobe disc or are you relying on your ears?
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Old 25th Oct 2019, 12:18 pm   #11
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Default Re: Garrard AC20

I've used my ears whilst listening to different records, both instrumental and with vocalists and it definitely sounds too fast.

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Old 25th Oct 2019, 12:37 pm   #12
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Smile Re: Garrard AC20

Hi,
Just a thought. but was it designed to play 80rpm records? Possibly before 78rpm became the stardard?
Cheers, Pete.
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Old 25th Oct 2019, 12:43 pm   #13
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Default Re: Garrard AC20

By 1939, 78RPM was standard.

I suggest you check with a strobe which will be rather more accurate than your ears.

Most turntables of that era had some sort of governor which can be adjusted to set the correct speed, which is why a picture with the turntable removed would be helpful.
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Old 25th Oct 2019, 12:44 pm   #14
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Default Re: Garrard AC20

That may be the case, Pete, but a 78rpm record played at 80rpm is only 2.6% fast. Surely the speed tolerance of most record and tape decks is within + or - 2 to 3%.
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Old 25th Oct 2019, 4:16 pm   #15
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Default Re: Garrard AC20

I've managed to remove the motor and gearbox. Upon opening the gear box the input drive shaft from the motor has 2 brass weights attached, although they don't appear to do anything other than rotate with the shaft. The motor data plate says its an induction motor for 200 to 250V, 50 to 60Hz.
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Old 25th Oct 2019, 4:19 pm   #16
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Default Re: Garrard AC20

Brass weights are likely to be a governor to govern the speed - is it broken?
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Old 25th Oct 2019, 5:05 pm   #17
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Default Re: Garrard AC20

I had a look in the workshop and (as one does) managed to find a rather similar garrard motor. It's not an AC20, but looks to be of similar shape and size.

I've taken the attached pictures which show the governor with its rotating brass disc connected to the three centrifugal weights that move the disc back and forth according to speed. The two felt brake pads which bear on the disc are moved by a cam connected to the quarter-inch diameter control shaft that protrudes from the top plate and is normally connected to the speed control lever.

This kind of speed governor is pretty standard in 78 rpm gram motors. If yours doesn't have one, it either works on a different principle, or is incomplete. It certainly looks like a standard shaded pole motor that would need some kind of mechanical speed control. Otherwise it would run too fast..........

Martin
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Old 25th Oct 2019, 5:06 pm   #18
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Default Re: Garrard AC20

Both weights are fixed and cannot move in the conventional sense like they would on a centrifugal governor. They appear to have some kind of contact which rubs on the gearbox casting.

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Old 25th Oct 2019, 5:11 pm   #19
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Smile Re: Garrard AC20

Hi
Re; posts 13 & 14. I stand corrected. I've played my 80rpm records at 78rpm and I can't hear the difference.
Cheers, Pete.
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Old 27th Oct 2019, 4:21 pm   #20
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Default Re: Garrard AC20

I showed the motor to a couple of friends at the VMARS auction yesterday, and they agreed that the brass weights were some form of governor and gave tips on how to adjust it. I shall experiment over the next few days and report back.
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