Garrard RC121 mk2 Disassembly Issue

[PsychMan]

Well, I suspect this one might seem clearer tomorrow, but that might be wishful thinking.

After having stripped and reassembled the speed change mechanism in an RC121 MK2 deck, I cleaned and greased other areas and tested the results. One fault remained, the record size sensor needed a little persuasion to detect no record present and stop the cycle.

I found the linkage responsible and could feel it was gummed up. Unfortunately it was quite deep in the mechanism. I started stripping it down, taking pictures at each step like I do with most items, and noting down the bits in small plastic bags. I tried to pay attention to where things were...

Unfortunately I've re-assembled, and its clear some parts are not in sync with each other, and the size selector arm now doesn't move, and I have another sprung piece of linkage with a spring that never tightens.

I have pictures of each step of disassembly, but the tone arm moving does complicate things further. When I started I believe the deck had correctly stopped a cycle.

Are there any tips you could offer to help me out of this mess?! Or do I have to disassmeble and re-assemble trial and error till I get it right?

I can add some pictures if thats worth it, for now here is a before and after. Bottom plate missing in both of course

[PsychMan]

Before

[PsychMan]

After

[PsychMan]

I suppose I will have to just use some trial and error here. I have before balanced decks on the edges of 2 chairs, lay underneath and worked mechanisms by hand to observe.

Its a shame I don't have another RC121 MK2 I can observe to get everything back properly.

Does anyone know if these are similar enough underneath to the RC 210 or RC 121 4h? I have some machines with those decks

[Audio1950]

All I can tell you is that the sizing mechanism on the two RC121 versions are different. On the RC121 Mk2, the sizing arm hits edge of the record and stays in that position, whereas on the 121 4H, the arm hits the edge of the record and then returns to it's original position over the pick-up arm.

[PsychMan]

Thanks Barry, I appreciate hearing from our resident autochanger guru

I found a picture of a 210 , which seems completely different underneath. So looks like I will need to find another 121 MK2 if I cannot work this out from what I have.

Have you encountered similar problems yourself after stripping a deck?

[Edward Huggins]

Next to the Collaros, these very well engineered decks can be a challenge. Sorry for asking the obvious, but have you downloaded the Garrard manual with its exploded views to help you?

[PsychMan]

I have a service manual for RC121 MK2, but it doesnt have exploded diagrams unfortunately They may well help

I made some progress tonight, but still a fault remains. It cycles correctly now, but the needle set down position is significantly off, such that the adjustment is not able to correct it. Its also not always consistent either. On 12 '' inch records it starts too far in, and this may relate to the size selector being hit by the record as it drops. For other records its about an inch shy of where it wants to be.

[Audio1950]

There are three screws on the back end of the size selector. Don't ask me how to adjust them, I forgot that years ago, but they are the ones you twiddle with to get the size selector to detect the correct size. One of them is a locking screw which you have to loosen, that much I do remember.

[PsychMan]

Unfortunatelty no joy with the adjustment. On the selector arm there are indeed 3 screws. The middle is a smaller one listed as the "eccentric screw". To adjust, the other two are slackened, and the eccentric screw turned to make the adjustment.

I've tried a variety of adjustmenst and none will work. If I adjust so 12 inch and 10 inch set down positions are more less OK, then 7 inch records will not play as the selector arm is not recognising any record is there, adjusting back the other way gets me to where I was, and beyond that the arm doesnt move near enough for 12'' records to clear the rest!

The above tells me I have reassembled something underneath incorrectly and still something is out of sync. There is a bushing on the bottom part of the selector assembly with a screw, and while I have tried to adjust this, it appears the bushing is seized onto the post so I don't believe that has moved in the course of my work.

[Audio1950]

I've got an RC121 Mk2 in my Bush radiogram, so if there are any photos you need taking of various parts, I'll be happy to take them.

Barry

[PsychMan]

Ah, I believe we have the same radiogram Barry, SRG 86, great machine. Unfortunately mine has required a lot of work and I haven’t even started on the rough cabinet yet, chassis is done, now the changer.

It may be useful seeing some pictures of the innards when it has completed a cycle, underneath the metal plate, in particular the area around the tone arm where the speed selector assembly is, and another piece next to the cam with a spring which attaches to a part of the size selector. But anything you could do would help tremendously and I would certainly owe you a favour in return for going to such trouble

Thanks
Adam

[Michael Maurice]

Its the sort of thing I need to have in front of me to work out what's wrong, but if you want a second pair of eyes, please feel free to PM Me.

[PsychMan]

I think ive got to the crux of it. I've attached a picture focussing on the parts in question. There is a spring (circled) that attaches to the other circled piece (behind the cam wheel). The tension on this is not right, its too slack and based on what the manual says this is critical to size selection.

The straight part of the spring behind the cam has a bend in it, which suggests to me it is routed round the piece before leaving it. I cant seem to work out how to correctly route it. I think the bend must be there for a reason, but if I hook it round the bottom of the lever, the tension is too much.

If I could see how this spring is correctly routed I think that would quite possibly fix all this.

I see radiomuseum have the USA based sams manual for the RC121 MK2, and that does have exploded diagrams. Unfortunately I've hit my limit for today. Looking at my before pictures unfortunately doesnt show the routing of this spring.

[Nickthedentist]

Originally Posted by PsychMan

I have before balanced decks on the edges of 2 chairs, lay underneath and worked mechanisms by hand to observe.

Make yourself a test jig - trace the motorboard and cut out another from a bit of scrap MDF or ply, then attach four 6" legs made from offcuts of CLS or similar, and place the whole lot on an old mirror on your workbench. It makes the world of difference when you need to see what's happening underneath. BTDT!

[Audio1950]

I hope these pics will help, tried my best, but the camera is not top class!

The spring in question has no bends in either of the straight sections. One end is attached to the sizing arm, and the other end to the piece visible under the vertical oblong hole in picture 2. (you can just see the end of the spring). If you need further pics, let me know.

[PsychMan]

Thank you Barry! As you can see mine has a bend in it, I think it has got mangled in the mechanism when I initially put it back together wrong, I did have to make some changes to this to get it working again.

If anything though I would have expected the bend to increase tension in the spring rather than reduce but hopefully all will be come clear when I play around with it.

Does the bracket it attaches to (visible underneath the platter) move freely back and forth pulling the relevant spring or is it held in place at the stop position?

[Audio1950]

The bracket moves freely, but is held under tension by the spring at all times, even when the mechanism has switched off.

[PsychMan]

Interesting. Now I’ve straightened the spring and put it back in it seems like there is a little play in it. Maybe because one of the springs has been stretched out a bit, I’ll upload a video to demonstrate. I also notice it doesn’t stop at the end of the cycle unless helped, and was before I straightened the bent spring. I believe the spring tension is instrumental in this last little movement

[PsychMan]

https://youtu.be/9p456f-QYjw

This shows the movement of said bracket. I’ll produce some videos of operation during a cycle