Strange calibration problem..... VR Suction

[PMST]

Hi!

Today i decided my VR needed a clean and maintenance, i have done this several times in the past, taken the turntable off and top bar with lead screw off and given it an oil, this has never been a problem.

Today i have put it all back together and for some reason, the suction tube is getting higher and higher as its get to the centre of the record. I assumed this was because of the turntable somehow not being level against the overhead bar or VR frame, however i have checked relentlessly and the full body and metalwork of the VR is 100% level, the turntable is 100% level and i've taken measurements about 30 times. Side to side, front to back etc.

My set us is a VR with SP10, for the rubber mat i have a 5mm neoprene cut which is 100% true and flat. I've not had this problem before and can not seem to work it out.

Has any one else had this issue? The difference is fairly large, the suction tube is almost 3mm higher when at the centre of the turntable, than the outside. The only way to get it running smooth is to raise one side of the SP10 by a few mm, this corrects the problem, but it makes the turntable then slightly off from being level...... Which im assuming isnt a good thing....

Thanks!

[jonty2k]

Hi Matt,
I added a SL1200GR for added torque to my setup, the feet were different to the normal SL1200, I had new feet retainers made for the base and it took ages to set up the height correctly, hence the thread on the foot carrier, for adjustment, this I learned the long / hard way!! hope this helps.

[PMST]

The SP10 is a different shape to the 1200 so doesnt sit on the feet, it just sits on the base of the unit between them

[trailerparkjesus]

Is it cutting ok though? Is anything pushing the vacuum tube down on the back when it is moving towards the center?

[SueDenim]

Is it the whole head carriage raising up by almost 3mm as it moves across the turntable, or just the suction tube?
If just the suction tube, double check the screw at the back of it is tight.
Also try moving it across the turntable without the swarf jar tube attached as it might be placing pressure on the metal suction tube.

[PMST]

Even with the suction tube disconnected, it still does it so can't be a pressure issue from the tubing, just checked the screws and all tight. I'm looking into it now see if I can find anything else!

[PMST]

Ill try to check if the head is raising by checking if its still level with the platter once it reaches the center

[PMST]

The head is still level when lowered no matter where, so its an issue just with the suction section I think, if it was the whole unit and was off, then the head would surely raise putting it unloved when lowered?

[PMST]

I've taken some images, firstly of my levels, one on the main frame, one on the SP10 and one on the top bar

[PMST]

Next is pictures (please excuse the quality!) of the suction tune on the outside edge of the 12", and one at the centre of the record. You can see when it gets to the center, it is now touching the rubber around the bars on the cutter head, which effects the lead out groove, lifting the stylus out depending on how close to the center it is. I

I'm wondering, the rubber surrounding the bars on the cutter head that the suction tube is touching, would anything think that removing them would cause any issues?

[PMST]

The cutter head stays parallel with the record throughout, that is not a problem and cuts are fine, the issue is the suction tube just touching those rubber bits around the bars on the cutter head and just now and again, touching enough to lift the style out of the groove on the lock groove or thereabouts.

I can of course counteract this by not doing the lead out groove so far to the centre, but want to sort it anyway

[jonty2k]

Its definetely the level of the technics deck Matt, not the base plate or overhead, the left hand side must be lower than the right, the stylus / head will move according to the level of the vinyl the tube stays fixed.

[PMST]

Yeah I can raise it, it just means the level on the platter is really off when the tube runs smooth which I'm finding strange, but like you say surely it must be that?

[emidisc]

Just a couple of observations:-
In the photograph showing the spirit level on top of the overhead, there appears to be a gap on the right hand side ?
The clear tube on the support arm appears split?
Probably best to use a DTI (far more accurate) to check runout of baseplate to platter surface and repeat with overhead
Good Luck & Stay Safe to ALL Trolls
Peace
Emidisc

[PMST]

Both the clear tube on the support arms are split, i assume to place them on. But will check to make sure nothing is loose. In the photo its actual reflection, it does look like a gap! Just checked that and its sat flush and reading right.

Will look into DTI, thanks! I know how to measure platter run out, but how is best to measure the overhead?

[emidisc]

I would take a reading at either end of the top surface of overhead from the baseplate - they need to be parallel

[2bitcomputer]

Yeah, Mine is like this too - I think it's a design problem with the lead screw riding up higher as it goes along?
Also, I don't know if you've checked, but the weight of the head decreases.
For instance, if the weight is 14grams on the outside edge, when it gets to the label it is about 11grams.
Years ago I 'solved' the problem by raising the left side of the turntable.
I calibrate how far to raise the left side of the turntable by matching the grams on the outside edge to the grams at the label.
My turntable platter is NOT parallel to the lead screw/cross bar - I can see that with my eyeballs!
Seems to work tho...
Btw, I have done this with a 1200 and an SP10.

[PMST]

Yeah, Mine is like this too - I think it's a design problem with the lead screw riding up higher as it goes along?
Also, I don't know if you've checked, but the weight of the head decreases.
For instance, if the weight is 14grams on the outside edge, when it gets to the label it is about 11grams.
Years ago I 'solved' the problem by raising the left side of the turntable.
I calibrate how far to raise the left side of the turntable by matching the grams on the outside edge to the grams at the label.
My turntable platter is NOT parallel to the lead screw/cross bar - I can see that with my eyeballs!
Seems to work tho...
Btw, I have done this with a 1200 and an SP10.

This sounds like it, if I raise the side of the turntable by 1mm (roughly tried it using an old 1mm blank) and the suction tube runs smooth! will try weights in a bit, thanks!