Garrard RC88 Motor Hum. - UK Vintage Radio Repair and Restoration Discussion Forum

HoverJohn · 3rd Dec 2021, 11:00 am

I’m getting a noticeable motor or bearing hum as soon as the needle hits the in run to the tracks does anyone know any good tricks to reduce this. I’m guessing after 60 years the rubber disc on the garrard rc88 has hardened up a bit. Any good damper mat suggestions??
Sounds like a quiet mains motor hum.

Analogue man · 3rd Dec 2021, 6:15 pm

Quote:

Originally Posted by HoverJohn

I’m getting a noticeable motor or bearing hum as soon as the needle hits the in run to the tracks does anyone know any good tricks to reduce this. I’m guessing after 60 years the rubber disc on the garrard rc88 has hardened up a bit. Any good damper mat suggestions??
Sounds like a quiet mains motor hum.

It could also be the motor suspension which if it is rubber grommets they too have probably gone hard.

HoverJohn · 4th Dec 2021, 10:27 am

Ok I will check those out too.

Edward Huggins · 4th Dec 2021, 11:01 am

Can we assume that until the pick up meets the record's grooves, there is no intrusive noise emanating directly from the motor?

HoverJohn · 5th Dec 2021, 4:24 pm

Yes this is the rewound original mono variluctance unit with stereo compatible needle only the needle is touching (the picture has reflection on it so it’s not that clear.

Edward Huggins · 5th Dec 2021, 4:38 pm

That just does not look right. The tonearm looks too heavy and I can't see the stylus cantilever at all.

Heatercathodeshort · 5th Dec 2021, 4:42 pm

I'm probably talking rubbish here but does the RC88 have a mute switch during changing?
If it does the hum may not be apparent before the switch opens as the stylus meets the record.
My thoughts are hum picked up between the motor and and the pick-up coil. Due to the very low output of the variluctance pick up is it possible there is a wiring phase fault with the hum bucking coil, that is if it has one. Just ideas into the pot. John.

HoverJohn · 5th Dec 2021, 6:34 pm

Thanks for all the input I’ve got a bit more info while I wait for the gold stripe paint to dry on the radio tuner glass… the hum stops the second you lift the needle and starts again the moment it’s on the vinyl/shelac and the pickup is variluctance so the needle isn’t cantelever as the iron bit has to stay between the coil cores pic of needle below. It does sound the same frequency as the motor. Like it’s being physically transferred through the deck.

3rd Dec 2021, 11:00 am	#1
HoverJohn Pentode Join Date: Oct 2021 Location: Newbury, Berkshire, UK. Posts: 132	Garrard RC88 Motor Hum. I’m getting a noticeable motor or bearing hum as soon as the needle hits the in run to the tracks does anyone know any good tricks to reduce this. I’m guessing after 60 years the rubber disc on the garrard rc88 has hardened up a bit. Any good damper mat suggestions?? Sounds like a quiet mains motor hum.

4th Dec 2021, 10:27 am	#3
HoverJohn Pentode Join Date: Oct 2021 Location: Newbury, Berkshire, UK. Posts: 132	Re: Garrard RC88 Motor Hum. Ok I will check those out too.

4th Dec 2021, 11:01 am	#4
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,327	Re: Garrard RC88 Motor Hum. Can we assume that until the pick up meets the record's grooves, there is no intrusive noise emanating directly from the motor? __________________ Edward.

5th Dec 2021, 4:24 pm	#5
HoverJohn Pentode Join Date: Oct 2021 Location: Newbury, Berkshire, UK. Posts: 132	Re: Garrard RC88 Motor Hum. Yes this is the rewound original mono variluctance unit with stereo compatible needle only the needle is touching (the picture has reflection on it so it’s not that clear. Attached Thumbnails

5th Dec 2021, 4:38 pm	#6
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,327	Re: Garrard RC88 Motor Hum. That just does not look right. The tonearm looks too heavy and I can't see the stylus cantilever at all. __________________ Edward.

5th Dec 2021, 4:42 pm	#7
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Garrard RC88 Motor Hum. I'm probably talking rubbish here but does the RC88 have a mute switch during changing? If it does the hum may not be apparent before the switch opens as the stylus meets the record. My thoughts are hum picked up between the motor and and the pick-up coil. Due to the very low output of the variluctance pick up is it possible there is a wiring phase fault with the hum bucking coil, that is if it has one. Just ideas into the pot. John.

5th Dec 2021, 6:34 pm	#8
HoverJohn Pentode Join Date: Oct 2021 Location: Newbury, Berkshire, UK. Posts: 132	Re: Garrard RC88 Motor Hum. Thanks for all the input I’ve got a bit more info while I wait for the gold stripe paint to dry on the radio tuner glass… the hum stops the second you lift the needle and starts again the moment it’s on the vinyl/shelac and the pickup is variluctance so the needle isn’t cantelever as the iron bit has to stay between the coil cores pic of needle below. It does sound the same frequency as the motor. Like it’s being physically transferred through the deck. Attached Thumbnails