Michell prisma circuit board
- Thread starter 22mart0
- Start date
- Joined
- Oct 15, 2014
- Messages
- 3,419
- Tagline
- ---not quite right
Can you take a pic of the back side of the board under that pot? What’s it read in ohms across the pot? You should be able to check to motor windings with the ohmmeter if you can find the right connections. If you separate the motor casings be careful as the pcb has the windings on it and the rotors are either side of the PCB. Very easy to damage.
- Joined
- Jan 14, 2011
- Messages
- 74,912
- Location
- Gillette, Wyo.
- Tagline
- Halfbiass...Electron Herder and Backass Woof
My AR-XB turntable uses a single ball under the platter shaft. The bottom of the shaft is concave shaped to fit and center the ball. The ball sits on a piece of Delrin plastic, all bathed in oil.
Once you determine what size ball, and if there is supposed to be Delrin or ? in the well, then search for the ball size.
Balls come in various grades and materials like steel, ceramic or ruby.
I'm still using the factory balls, one also sits under the tonearm pivot shaft. If I were to replace them I'd probably use a grade 25 steel ball as that's what I use when rebuilding bicycle hubs and crank bearings.
Once you determine what size ball, and if there is supposed to be Delrin or ? in the well, then search for the ball size.
Balls come in various grades and materials like steel, ceramic or ruby.
I'm still using the factory balls, one also sits under the tonearm pivot shaft. If I were to replace them I'd probably use a grade 25 steel ball as that's what I use when rebuilding bicycle hubs and crank bearings.
You need to know if the ball sits on a plastic disc or not.
Mine has a Delrin plastic disc at the bottom of the well that the ball sits on.
Without the plastic disc, my AR(Acoustic Research)-XB would quickly destroy the bottom of the well and the ball.
Normally the discs are hard to get out and replace as they've been there so long they're stuck. I used a modified dental pick to get mine out. I cut new ones out of a Delrin sheet with a hole punch, then filed the edge to fit.
Keep in mind I have no idea if your table is the same. But you did say it uses a ball, as does mine.
Mine has a Delrin plastic disc at the bottom of the well that the ball sits on.
Without the plastic disc, my AR(Acoustic Research)-XB would quickly destroy the bottom of the well and the ball.
Normally the discs are hard to get out and replace as they've been there so long they're stuck. I used a modified dental pick to get mine out. I cut new ones out of a Delrin sheet with a hole punch, then filed the edge to fit.
Keep in mind I have no idea if your table is the same. But you did say it uses a ball, as does mine.
On my AR, yes, I just drop the single ball bearing in on the Delrin disc that's at the bottom of the well. Add a little oil. Oil the platter shaft, and drop that in.
Giving it a spin, centers that ball in the cup or concave surface machined on the end of the shaft.
If yours uses a similar Delrin disc, or machined brass cup, or whatever, it's hopefully still in the bottom of the well, and you'll only need the ball, hopefully. The correct sized ball from a quality bike shop should work fine. I like using Grade 25 balls from a company called Wheels Manufacturing when overhauling my touring bikes.
https://wheelsmfg.com/catalogsearch/result/?q=Grade+25
Giving it a spin, centers that ball in the cup or concave surface machined on the end of the shaft.
If yours uses a similar Delrin disc, or machined brass cup, or whatever, it's hopefully still in the bottom of the well, and you'll only need the ball, hopefully. The correct sized ball from a quality bike shop should work fine. I like using Grade 25 balls from a company called Wheels Manufacturing when overhauling my touring bikes.
https://wheelsmfg.com/catalogsearch/result/?q=Grade+25
- Joined
- Oct 15, 2014
- Messages
- 3,419
- Tagline
- ---not quite right
Great to hear you got it working. Was it just the potentiometer? Motor quiet? Mine needed cleaning and new oil. I don’t recall there being a disc but it’s been a while. I had blueprints saved on my old phone that showed the detail of the spindle. Maybe they’re in my old thread somewhere? I just cut apart a few ball bearings till I found what I was after. 22mart0, let me know what you end up using if it’s a bike bearing, mine has no noise issues but might order a spare/something better. As far as oil I remember reading somewhere that someone from Michell spilled the beans about their Über expensive oil... it’s Mobil 5w30 rebottled and stupid money for a tiny bottle that says “Michell” on it. I used a few drops of SAE 30 as it was the first bottle I grabbed. You don’t need much either as George mentioned, a little on the shaft and a couple drops down the spindle well.
Andrew, are you working on a Great Lakes freighter? The seasons first freighter arrived at the port of Cleveland this week and was news worthy.
https://www.news5cleveland.com/news...-to-open-the-2023-great-lakes-shipping-season
https://www.news5cleveland.com/news...-to-open-the-2023-great-lakes-shipping-season
