Hello! My D6C has always suffered from a little flutter, but I recently realized how bad it is because just letting the tape lid close from its own weight is enough to cause a considerable flutter spike. I began by replacing the flywheel tire, which didn't seem to make any difference. When reassembling the motor assembly (following the service manual) I realized that just tapping on the case was enough to cause the same flutter spike, but that if I put a little bit of pressure with my finger on the side of the motor where the spring attaches, the problem was mostly gone. I guess it would make sense for the spring to lose its strength over the years, especially as this is an older unit, but I wanted to double check here before I attempt any repairs. Best regards!
Ok, after further investigation, I removed the motor assembly again and noticed the motor shaft has a significant amount of travel along the axis of rotation.
Does the outer shell of the motor rotate if you try to move it? I have one of my units do this at random and caused considerable wow and flutter and certain intervals... Remember to only power your WM-D6C from rechargeable batteries, not power supplies or AC adapters. Hope this helps.
@brunophilipe What wow&flutter figure do you get on WFGUI ? The play you mention in the shaft (up-down play) is something I have seen in some D6Cs, but despite this units still got the 0.04% WRMS at the end. That play can be reduced, but you need to take the brush holder out and press the rotor onto the shaft. There is a tutorial on how to open this motors, but I recommend not doing it unless necessary. I recommend doing the follwing: - sand the spindle of the motor with 800 grit sandpaper, then 2000 (while it is running) until the surface has a mirror-like finish. - clean the spindle and capstan ring with IPA - lubricate the motor top bearing - adjust the flywheel thrust play - adjust motor position so it is perpendicular to flywheel when running - adjust the servo electronics like in service manual (3090Hz with PLL disconnected) As for springs, they don't get weaker over time. That can only be a problem if someone elongated it beyond its elasticity point.
Thank you both! I performed some cleaning as Valentin suggested, and I think it improved it somewhat, but I'm afraid it didn't help much. Thankfully it plays perfectly if left to rest on a table, and so I'm not sure I wanna risk damaging it. I'll try scouting for a for-parts unit to take a motor from and maybe service that instead. Thank you again for your help as always!
Let us know what you find. And do all the steps I indicated, especially the sanding of the spindle, flywheel thrust play and servo adjustment. Cleaning alone will obviously not do anything, unless there is oil or grease on the parts. I recommended that more for good measure than anything else. Have never seen a bad motor on a D6C, only a handful that have obtained a bit higher w&f than the spec (0.05-0.06% WRMS) even after a full service, but even those are very good in practice and certainly not a reason to replace the motor. On DDs however I have seen motors that have high flutter due to the paper that's glued onto the rotor coming apart and in contact with the case/stator. If that is the case, motor can be diassembled, cleaned, that paper removed and relubricated. Have never seen these motors for sale actually, so fixing them is the best course of action if it is indeed faulty. One test that you can do on the motor is this: desolder it from the PCB and power it on a bench power supply at about 1.8V. Without any load current drawn should not exceed 20-30mA. If it's higher than that it indicates there is internal friction.
