NAD 5120 Turntable Refurbish

[J!m]

Well, the motor doesn't seem to turn, so that needs to be addressed. Acting like a bad switch and/or blown fuse. Dead simple design so I should have it figured out soon enough.

Tonearm is complete with the silicone damping vial. Auto lift mechanism was not lined up properly- fixed that pretty quickly. Spindle shaft seems good- needs oil but spins well. Bearing housing has low wear as it takes a while to drop into the well. Decent run-down time so that all seems good.

Arm is nowhere near as "floppy" as you might be led to believe. Cartridge is missing a cantilever so probably trash.

 

[Bob Boyer]

That tonearm definitely has me intrigued. Looks better there than in the other pix.

 

[J!m]

The counterweight is making up for the lack of technology in the rest of the arm. Serious engineering in that design.


This was just overhauled it looks like.



Put some deoxit on the contact for power. I’ll let it sit overnight and then start chasing down where the power is going. It’s acting like an open circuit…

 

[nakdoc]

That is a repurposed Philips turntable. Replace the tubular phase cap and the motor should turn again.

 

[J!m]

I think the maker made them for Philips as well. One other brand too- more popular in Europe.

I’ll figure out tomorrow if I’m getting power to the cap, and if so, then replace it. I didn’t think they failed open…

 

[J!m]

The big 680nf cap for the motor reads open. But the contact is also not showing continuity when closed, so I'll clean those now.

 

[J!m]

I want to avoid an order for one cap... can a similarly rated "safety cap" work to provide the offset for the motor? I can order a couple shipped for the cost of shipping from Mouser... (it is a .68uf / 680nf 160V rated originally) No matter what, I will over-rate the voltage...

 

[mr_rye89]

Yeah that arm looks like a cyberpunk Gray 108

 

[J!m]

Arm has a Shure cartridge (Encore Me75ED); found a new stylus for it for testing porpoises.

Now, would these capacitors be suitable for the motor?

2x 0.68uF 680nf 250V Polyester MKT Axial Capacitors for Marshall amp | eBay

Nice high voltage rating, smaller than what's there now physically. I am unsure if a motor run cap is in any way different from any other cap.

 

[vince666]

interesting tonearm system!

They used to include a suitable test record with that turntable, which is just great to measure resonant frequency of tonearm/cartridge combo.
I own that same kind of Test record which does also exist as a standalone test record where only side A is the exact same contents as side A of the NAD 5120 Test Record... after all, the resonant frequency measurement is just the side A.

 

[J!m]

I can't find that test record, but I have others.

And reading the manual etc. it seems it was "available" for testing and not included with the table here in the states.

The arm is very cool! The counterweight is tunable for resonant frequency and includes a silicone oil damping pot. It's a really interesting and complicated design for a deceptively simple looking tonearm. I need to add a bit more silicone to the pot, and clean everything, but it all seems to be in good condition.

Just need the motor cap so it'll spin- everything else looks good.

 

[vince666]

being that one tuneable, it's nice when you can adjust the resonant frequency just in the sweet spot with your cartridge of choice.
yes, there are also other test records which are good to measure resonance, i own a Shure Era V test record which can do that as well but in the end I often go with the one i did show you above.

 

[J!m]

I have one of the Shure records, and hi-fi news test record among others. Plus, Steven Stills 2 is my go-to for inner groove sibilance/anti-skate tuning.

 

[J!m]

I orderd a couple caps for the motor. The one on there, as NakDoc predictited, seems to be open. Hopefully that sorts it out.

I see I'm missing the center of the platter mat, which doubles as the 45 adapter when flipped over. Probably never find that, so I may model it and 3D print a replacement.

 

[vince666]

Plus, Steven Stills 2 is my go-to for inner groove sibilance/anti-skate tuning.

Ah, sure, we all have also some specific music records which are good for testing.
Here, as a tracking test (but it's not too bad to also set antiskating) , I use the 7 inches of this italian press of a famous early 80s song which was mastered/cut in a way that's definitely difficult to track... especially the attack of the "L" of "Let you down" on the chorus are just difficult to track and, also, the synth chords at the end of the song tend to be harsh... if a needle can track the whole song just perfectly without adding quite some extra VTF than you'd normally use, then it's a superb tracker!
I own two copies of this precious 7 inches single! LOL
It's also good to check if the needle starts to show early signs of wear.