Garrard RC70B spring - UK Vintage Radio Repair and Restoration Discussion Forum

PaulR · 19th Jun 2016, 7:39 pm

I have been trying for ages to get one of these decks to play reasonably well. It has boiled down to trying different sorts of rubber in the pickup. Some are too stiff and some not stiff enough. Anyway, a piece of bicycle inner tube seems about right, but only with the counterbalance spring removed to make the head much heavier than intended. With the spring in place the sound becomes distorted and the needle jumps. This suggests that the rubber is too thick/stiff, but I have tried every sort known to man and I cannot get it to track properly.

The way the spring fits seems pretty obvious, but it occurs to me that it may not be correct. Before I consign it to the loft again could someone who has this or a similar deck please post a photograph of how the spring is intended to fit. These were fitted to quite high end radiograms and I am sure they must have worked reasonably well when new.

Thanks

Paul

Techman · 19th Jun 2016, 10:45 pm

I think the spring looks a bit like a clothes peg spring on these decks from what I can remember. I seem to remember finding slithers of wood wedged under these springs to increase the tension and lessen the weight of the pickup head.

My advice would be to check the ACTUAL tracking weight of the pickup and go from there, but to be honest, it sounds like you still haven't got the rubber damping parts correct. Having just said that, the fact that you say that the needle is actually jumping does indicate that the tracking is perhaps too light.

PaulR · 20th Jun 2016, 8:23 pm

Yes, that's the spring it has. Without the spring it tracks at 84g and with it 32g. I can get it to track reasonably well with the spring in place using a piece of rubber band as the top damper but then I get odd high frequency effects. I can improve these by holding the needle screw as it is playing which leads me to think the rubber isn't giving enough damping, but as soon as I use thicker rubber then it won't track properly and jumps in the grooves.

The only other thing I can think of is that the rubber tube I used for the pivot is rather thin. It is held firmly in the pole pieces but it may not be providing enough damping. I am reluctant to play around with this too much as I have already broken and re-soldered the wires to the coil and in any case I haven't any different tube to try.

I think it may have to go back into the loft before I do something nasty to it in my frustration!!!

19th Jun 2016, 7:39 pm	#1
PaulR Dekatron Join Date: Oct 2003 Location: Southport Lancashire, UK. Posts: 3,233	Garrard RC70B spring I have been trying for ages to get one of these decks to play reasonably well. It has boiled down to trying different sorts of rubber in the pickup. Some are too stiff and some not stiff enough. Anyway, a piece of bicycle inner tube seems about right, but only with the counterbalance spring removed to make the head much heavier than intended. With the spring in place the sound becomes distorted and the needle jumps. This suggests that the rubber is too thick/stiff, but I have tried every sort known to man and I cannot get it to track properly. The way the spring fits seems pretty obvious, but it occurs to me that it may not be correct. Before I consign it to the loft again could someone who has this or a similar deck please post a photograph of how the spring is intended to fit. These were fitted to quite high end radiograms and I am sure they must have worked reasonably well when new. Thanks Paul

19th Jun 2016, 10:45 pm	#2
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Re: Garrard RC70B spring I think the spring looks a bit like a clothes peg spring on these decks from what I can remember. I seem to remember finding slithers of wood wedged under these springs to increase the tension and lessen the weight of the pickup head. My advice would be to check the ACTUAL tracking weight of the pickup and go from there, but to be honest, it sounds like you still haven't got the rubber damping parts correct. Having just said that, the fact that you say that the needle is actually jumping does indicate that the tracking is perhaps too light.

20th Jun 2016, 8:23 pm	#3
PaulR Dekatron Join Date: Oct 2003 Location: Southport Lancashire, UK. Posts: 3,233	Re: Garrard RC70B spring Yes, that's the spring it has. Without the spring it tracks at 84g and with it 32g. I can get it to track reasonably well with the spring in place using a piece of rubber band as the top damper but then I get odd high frequency effects. I can improve these by holding the needle screw as it is playing which leads me to think the rubber isn't giving enough damping, but as soon as I use thicker rubber then it won't track properly and jumps in the grooves. The only other thing I can think of is that the rubber tube I used for the pivot is rather thin. It is held firmly in the pole pieces but it may not be providing enough damping. I am reluctant to play around with this too much as I have already broken and re-soldered the wires to the coil and in any case I haven't any different tube to try. I think it may have to go back into the loft before I do something nasty to it in my frustration!!!