I picked up a lovely 102 earlier this summer, and am just now getting around to looking under the motor board to clean and lubricate. As I was removing the screws, I managed to find one that was stuck, and the end of it is now damaged. Does anyone know the proper profile/pitch for this screw? I’m in need of a tap to chase the hole, and considering soldering or gluing a nut to the little rail that has the damaged threads, in order to make a simple yet effective repair.
I imagine it’s some sort of 55 degree thread angle that they used instead of the otherwise standard 60 degree threads we have in the states.
HMV 102 maintenance.
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- Victor II
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Re: HMV 102 maintenance.
The other issue I’ve got is a little bit of slop in the tone arm. Any tips on that? There’s a split ring on the underside that I assume will tighten the bearing.
How does one adjust this properly, and is there a recommended lubricant for the bearings? Sewing machine oil? If yes, how best to apply it?
How does one adjust this properly, and is there a recommended lubricant for the bearings? Sewing machine oil? If yes, how best to apply it?
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- Victor IV
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Re: HMV 102 maintenance.
The ring in the base can be tightened with a pair of thin-pointed pliers, but don't even think about removing it, or you will need three hands to get it all back together!
Barry
Barry
- Inigo
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Re: HMV 102 maintenance.
Yes, first put oil on this, and move back and forth to get it smooth. Better if you use solvent or gasoline to clean the old grease, and dry with an air gun. Then add thick oil or light grease, better if you can inject it beneath the ring to reach the ball bearings and race.
Then, if it's too hard, with a pair of needle nose pliers completely opened so they can catch the holes, rotate the ring ONLY A BIT counter clockwise. In reverse, if you find it too loose, and the tonearm has loose movement against nature, up/down etc, turn the ring clockwise. In any case, ONLY A BIT is usually necessary. A tiny bit of perpendicular play is unavoidable if you want a smooth tight adjustment.
As another colleague said, don't dismantle the ring or you'll find yourself with the tiny balls falling all around. It's very complex to assemble this again, so don't do that unless you have three hands, lots of patience and steady hands! I once dismantled the hmv194 tonearm bearing system and it took three hours to assemble again!
Then, if it's too hard, with a pair of needle nose pliers completely opened so they can catch the holes, rotate the ring ONLY A BIT counter clockwise. In reverse, if you find it too loose, and the tonearm has loose movement against nature, up/down etc, turn the ring clockwise. In any case, ONLY A BIT is usually necessary. A tiny bit of perpendicular play is unavoidable if you want a smooth tight adjustment.
As another colleague said, don't dismantle the ring or you'll find yourself with the tiny balls falling all around. It's very complex to assemble this again, so don't do that unless you have three hands, lots of patience and steady hands! I once dismantled the hmv194 tonearm bearing system and it took three hours to assemble again!
Inigo
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- Victor II
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Re: HMV 102 maintenance.
So it’s possible to remove the ring and add fresh grease without dumping the bearing balls everywhere?
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- Victor IV
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Re: HMV 102 maintenance.
NO! Don't remove the ring under any circumstances. Just turn it anti-clockwise a turn or two, to get some oil into the ball bearings, then do it up again until you have no sloppiness,
Barry
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- Victor II
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Re: HMV 102 maintenance.
Thanks for the word of caution. I will take heed and not remove
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- Victor II
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Re: HMV 102 maintenance.
I did some measuring on the damaged screw, and it seems to be about 48tpi (I’ve misplaced my fine thread pitch gauge so had to measure and count!)
Diameter is 2.74mm / 0.108”
The closest I can come to this is British association threads, number 6 - BA
Can anyone confirm this is correct? I’d like to get the proper tap, and make new threads in the hole that damaged the screw, and as I said earlier, possibly add a nut on the back to give a little more for the screw to hold onto.
I imagine someone has a parts machine with a good motor board screw out there that I can buy to eventually replace this one, since it is not a profile/length/shape that is likely to be available new.
Diameter is 2.74mm / 0.108”
The closest I can come to this is British association threads, number 6 - BA
Can anyone confirm this is correct? I’d like to get the proper tap, and make new threads in the hole that damaged the screw, and as I said earlier, possibly add a nut on the back to give a little more for the screw to hold onto.
I imagine someone has a parts machine with a good motor board screw out there that I can buy to eventually replace this one, since it is not a profile/length/shape that is likely to be available new.
- Marco Gilardetti
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Re: HMV 102 maintenance.
I believe the safest and quickest way to tell the thread of a screw is to find a matching nut.
Also, if the hole had strength enough to strip the thread of the screw in that way, I don't think an extra nut is necessary. Is the hole stripped at all? Possibly the screw was inserted at a wrong angle at the factory and the hole is still OK.
Also, if the hole had strength enough to strip the thread of the screw in that way, I don't think an extra nut is necessary. Is the hole stripped at all? Possibly the screw was inserted at a wrong angle at the factory and the hole is still OK.
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Re: HMV 102 maintenance.
anchorman wrote: ↑Sat Sep 03, 2022 2:26 pm I did some measuring on the damaged screw, and it seems to be about 48tpi (I’ve misplaced my fine thread pitch gauge so had to measure and count!)
Diameter is 2.74mm / 0.108”
The closest I can come to this is British association threads, number 6 - BA
Can anyone confirm this is correct? I’d like to get the proper tap, and make new threads in the hole that damaged the screw, and as I said earlier, possibly add a nut on the back to give a little more for the screw to hold onto.
I imagine someone has a parts machine with a good motor board screw out there that I can buy to eventually replace this one, since it is not a profile/length/shape that is likely to be available new.
All HMV threads I have ever measured have been UNC or UNF , I've always assumed this was due to the fact that the business started with importing American machines and the initial factories used these threads for repair and just continued for instance HMV 101 etc winding handle threads are ⅜ " UNC