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RCA RP-218 changer

Posted: Fri Mar 07, 2025 3:11 pm
by hermitcrab
been playing the 1963 RCA hutch lately because the sound is so clean... yesterday I picked up a few used albums and played them on the RCA... Something didn't sound right , so I tried the RPM app on my phone... the changer is playing about 35 rpm.. this is new to me , never noticed it before . what would cause the changer to speed up?... the platter is clean , no excessive build up anywhere, it is playing a couple rpm too fast on all speeds ... do I need to shave the idler? I am hesitant to do such a drastic move, as how do I know if the line voltage was higher then usual? I have about 6 different meters , digital and analogue and none of them read the mains voltage the same...always a volt or two difference

Re: RCA RP-218 changer

Posted: Fri Mar 07, 2025 4:33 pm
by stbasil
Maybe the idler is hitting the motor spindle between speeds? Just a thought....

Re: RCA RP-218 changer

Posted: Fri Mar 07, 2025 5:18 pm
by Motorola minion
I have a 1963 as well, but haven't gotten around to it. The flat-pack cartridge with "airplane" stylus is likely not good.
This speed question plainly gives me an excuse to pull my changer at last ;)
The mat is stiff, so I need to get my snap ring pliers to pull the platter and see what is what :roll:
Ill get a power cord to power just the phono, check speed if its not locked up.
Stay tuned.

Re: RCA RP-218 changer

Posted: Fri Mar 07, 2025 6:06 pm
by electra225
Motor mounts sagged, causing suggestion #1?

Re: RCA RP-218 changer

Posted: Fri Mar 07, 2025 9:20 pm
by hermitcrab
electra225 wrote: ↑Fri Mar 07, 2025 6:06 pm Motor mounts sagged, causing suggestion #1?
I wish, those got changed out with new ones last year when I went through the changer

Re: RCA RP-218 changer

Posted: Fri Mar 07, 2025 9:24 pm
by hermitcrab
Motorola minion wrote: ↑Fri Mar 07, 2025 5:18 pm I have a 1963 as well, but haven't gotten around to it. The flat-pack cartridge with "airplane" stylus is likely not good.
This speed question plainly gives me an excuse to pull my changer at last ;)
The mat is stiff, so I need to get my snap ring pliers to pull the platter and see what is what :roll:
Ill get a power cord to power just the phono, check speed if its not locked up.
Stay tuned.
Not sure what cart mine has , but it has the dual needle setup where you push it one way for 33 and the other for 78... and it is failing , sometimes one channel will not play , I think due to the saddle being old.

Re: RCA RP-218 changer

Posted: Fri Mar 07, 2025 11:14 pm
by Motorola minion
RP-215/216 have pulley height adjustable by a threaded shaft with 3/8" nut but I don't see one on mine :shock: :?

Maybe what you see below is the same and, if so, it may be adjustable only by adding thin spacer washers under the pulley.

Ill pull it out later to check but I think motor mount grommets are gone, there is a lot of play and no cushion holding up motor to mitigate vibration transmission onto motor board.
SO...motor shaft has dropped a bit as pulley rides too high on 33 step. Ill attempt to run and see if speed is even close
RP-218 motor pulley.JPG

Re: RCA RP-218 changer

Posted: Sat Mar 08, 2025 2:05 am
by TC Chris
hermitcrab wrote: ↑Fri Mar 07, 2025 3:11 pm it is playing a couple rpm too fast on all speeds ... do I need to shave the idler? I am hesitant to do such a drastic move,
Just a quick note on the idler-diameter thing. The diameter of the idler wheel has no effect at all on speed. The diameter of the motor' turret, yes. The diameter of the platter, yes. But no on the idler. It just translates whatever motion it gets from the motor to the platter. It's a little bit counterintuitive.

Shaving an idler can correct LOW speed if it's caused by a glazed surface and slippage, but generally you'll hear low of speed variation--"wow." And it's not related to diameter, just to surface friction or lack of it.

Chris Campbell

Re: RCA RP-218 changer

Posted: Sat Mar 08, 2025 3:29 pm
by Conelrad
The buildup of idler detritus on the motor shaft can increase speed, as it will change the ratio. Give it good cleaning and see what happens.

Some broadcast TT's had a slightly larger motor shaft on the 45RPM setting, to get just a bit more music between ads.

That drove some listeners with perfect pitch crazy. :o

DG

Re: RCA RP-218 changer

Posted: Sun Mar 09, 2025 2:05 am
by Doug
Only thought I have if the the motor mounts are bad
With the platter on the idler may ride up or down or even tilt.
Which motor mounts are mention above.

Re: RCA RP-218 changer

Posted: Sun Mar 09, 2025 8:17 pm
by Hi-Fi-Mogul
Conelrad wrote: ↑Sat Mar 08, 2025 3:29 pm The buildup of idler detritus on the motor shaft can increase speed, as it will change the ratio. Give it good cleaning and see what happens.
DG
I vote for this also. I have been amazed sometimes at
how much rubber was annealed onto the stepped
speed rotor.

Re: RCA RP-218 changer

Posted: Tue Mar 11, 2025 7:37 pm
by Motorola minion
Looks as if I need to take that suggestion, second from top is the 33.3 rpm turret, which looks pretty crusty.
RP-218 motor pulley 1.JPG