I have a Marantz 6100 and I just put a new belt on it, and I think it's running slow. I didn't have anything better to do so I timed 200 revolutions with a stopwatch and divided and got 32.7.

First of all, I know there is a correct way to measure these things involving strobe lights, but I don't know what kind of equipment is required.

Second, how can you adjust the speed on these things?

Third of all, what kind of speed tolerance is acceptable? +-.5rpm? None?

To check the speed of your table you need 2 things:

1) a strobe disc
http://www.extremephono.com/free_turntable_strobe_disk.htm

2) a neon lamp

Put your print out on the table and put the neon above the disc, start the table.

If the dots stay steady, your speed is ok.

If not, maybe your belt is not from a correct size or you have an issue withe the motor.

Tony

Isn't there some way to adjust the motor speed? I assumed there would be an adjustment pot somewhere.

Based on your description, it seems that would sync using the frequency of the mains current, right? Is mains current exactly 60hz enough for us? That surprises me; I would assume mains current would be a pretty rough frequency, just as it's a pretty rough voltage.

There isn't any adjustment of speed on the 6100. Is your bearing clean? Kind of a strange spindle bearing arangement as I recall. Not the easiest to take apart, clean and re-lube but I was able to get in there with some minor disassembly. Maybe the motor could use some oil/lubing too. Make sure belt and the platter surface the belt rides on are clean.

32.7 might not be all that slow given you timed it manually and maybe got a little dizzy and mis-counted? The strobe discs are an easy way to check speed. You really only need any flourescent light bulb to check it.

I use an old flourescent fish tank light that I picked up at GW for a couple of bucks :thmbsp:

I'm surprised that mains current's frequency is something to be relied on; like voltage, I assumed it was 'nominal'.

The platter spins free smooth as silk, I don't think I'm going to mess with it. I suppose the motor could need a little TLC, though.