Marantz 6300 Speed Fluctuating

[BMG2017]

Hi Everyone,

Listening to some records this evening on my 6300. I’ve had it for about 2 years, it has worked great the whole time I’ve owned it. When I first got it, I dialed in the speed, it’s been perfect since then and I’ve never had to mess with the pitch controls. Just now, I noticed the music sounded slow, I got up and saw that the strobe was moving so I fiddled with the pitch until it sounded right. Its holding now that I readjusted the pitch, I am wondering if I should be concerned about it randomly slowing down?

Recently I moved some stuff around in my music room, the speakers are now located closer to the turntable than they previously were. This change up caused me to get some vibration interference at moderate-high volumes. I unfortunately can’t go back to my old layout, but I moved the speakers around and was still having issues.

I had a similar issue with one of my old turntables that had a mostly hollow plinth. I solved this issue by packing the inside of the plinth with modeling clay from Hobby Lobby. I couldn’t quite replicate this fix with the 6300 because its construction is very different. The turntable came with aftermarket feet, that are mostly hollow stainless steel cylinders, so I filled the inside of the feet with modeling clay. I also put a strip of clay around the underside of the platter. I was nervous about messing with the platter because I didn’t want to introduce wow and flutter.

After I put the turntable back together it sounded way better, bass was much tighter, and the feedback issue was resolved. I did this two weeks ago and I’ve listened to hours of records and the deck has held perfect speed until just now when I noticed it slow down.

I hope this modification wouldn’t have stressed the motor in any way, I tried to be conservative about how much weight I added to the platter. What do the experts think?

Thanks!

 

[MarantzRefrb]

When I restored my 6300, I had read about the fluctuating speeds being a potential problem, I took the advice of others here and preemptively replaced the stock pitch pots. I used Bourns 1K pots for the replacements, but it takes completely disassembling the tone arm to replace to the pots, wasn't an easy fix, but very worth it.

 

[BMG2017]

When I restored my 6300, I had read about the fluctuating speeds being a potential problem, I took the advice of others here and preemptively replaced the stock pitch pots. I used Bourns 1K pots for the replacements, but it takes completely disassembling the tone arm to replace to the pots, wasn't an easy fix, but very worth it.

I’ve been wondering if this unit was going to need restoration. I’m slightly intimidated by that because I’ve never worked on one. I’ve recapped receivers before.

Correct me if I am wrong, aren’t there several trim pots and a few electrolytics within the motor assembly? I’ve wondered if that motor was going to go bad one day, but I haven’t wanted to do anything to it because I don’t want to risk messing it up.

Recapping the power supply and replacing the switches and posts seems fairly straightforward, just a lot of disassembly.

 

[MarantzRefrb]

Here's the entire process of a recap, new switches and the two pitch pots for 33 and 45:
https://audiokarma.org/forums/threads/marantz-6300-restoration.920478/

I did not recap the direct drive motor, as I had heard the speed fluctuation is caused by the pitch pots, and that there is a possibility of causing harm to the motor when replacing those caps; that's a last resort operation, and something that can be done after everything else has been completed, if absolutely necessary. Mine is still working fine with the stock motor caps and rock-solid RPM after the pitch pot replacements.

The thing to watch out for is if you have version 1, or 2, of the 6300. Version 2 has plastic around the panel buttons, you can see in the link above, I have no plastic surrounding the panel buttons, so it's a version 1; there are a couple small differences in caps on the PCB between the two.

If you were going to replace the pitch pots, it might be worth recapping it entirely while you're in there, the Omron switches aren't necessary if all of your other functions are working correctly.

You will need to desolder the tonearm wires, from the Omron switch that controls the lift mechanism, in order to get the tonearm off the plate, and then remove the plate to replace those two pitch pots. If you take good pictures of the process, you'll know how it all went back together. I'd say if you've already restored receivers, you shouldn't have much trouble with this, not much in there to go wrong.

 

[BMG2017]

Here's the entire process of a recap, new switches and the two pitch pots for 33 and 45:
https://audiokarma.org/forums/threads/marantz-6300-restoration.920478/

I did not recap the direct drive motor, as I had heard the speed fluctuation is caused by the pitch pots, and that there is a possibility of causing harm to the motor when replacing those caps; that's a last resort operation, and something that can be done after everything else has been completed, if absolutely necessary. Mine is still working fine with the stock motor caps and rock-solid RPM after the pitch pot replacements.

The thing to watch out for is if you have version 1, or 2, of the 6300. Version 2 has plastic around the panel buttons, you can see in the link above, I have no plastic surrounding the panel buttons, so it's a version 1; there are a couple small differences in caps on the PCB between the two.

If you were going to replace the pitch pots, it might be worth recapping it entirely while you're in there, the Omron switches aren't necessary if all of your other functions are working correctly.

You will need to desolder the tonearm wires, from the Omron switch that controls the lift mechanism, in order to get the tonearm off the plate, and then remove the plate to replace those two pitch pots. If you take good pictures of the process, you'll know how it all went back together. I'd say if you've already restored receivers, you shouldn't have much trouble with this, not much in there to go wrong.

Thanks for the input, I appreciate it.