Hey all, I just finished going through a WM-DD3 according to the step-by-step instructions. Replaced the center gear, small gear, rubber idler tire and lubed/oil where recommended. Also replaced the output caps and the 2 tantalum caps for the FR improvements. I have an issue with the speed adjustment. Wfgui is showing about 2750Hz with the quartz oscillator. When desoldering the bridge, I can adjust the pot to get around the recommended 3090, but bridging the oscillator brings it down to ~2750. My test tape is from A.N.T and I've used it in the past for Nakamichi and other decks, it should be of good quality. Any suggestions on how to proceed?
My suggestion is to start by cleaning the capstan rubber ring with IPA as it typically gets contaminated with oil from fingers or from the mechanism during reassembly. Then remove the door and also thoroughly clean the pinch roller and capstan with IPA. If you have not done this it is very likely your test tape is contaminated with oil. Your test tape is 3000Hz or 3150Hz ? Note that the adjustment for 3090Hz is with a 3000Hz test tape. With a 3150Hz tape you will need to have 3240Hz with pad disconnected. As for the tape itself, unless it's contaminated on the back side with oil from the capstan, there's no reason to suspect the tape itself.
thanks Valentin. I did not clean the rubber ring but did thoroughly clean the head, capstan and pinch with a special formula S-721H beforehand. And yes, my tape is 3khz. My suspicion was more towards the electronics because the unit can maintain speed without the quartz.
I realised your suspicion was towards the electronics, but it's best to eliminate any potential mechanical issue before assuming anything electronic. I've seen this problem before and I can't remember of a single situation where the electronics was the culprit. What's the wow&flutter figure with PLL disconnected ? Please attach a screenshot of WFGUI readings.
That's your problem right there. W&F is way too high compared to what it should be and you have a mechanical problem. W&F with PLL disconnected should be around 0.14% WRMS maximum and it should drop to < 0.1% WRMS when PLL is connected. Depending on individual unit, there may not even be much of a difference betwen PLL connected and PLL disconnected (seen differences as low as 0.01%). Your focus should move on reducing that W&F figure to a value below 0.15% WRMS before making any adjustment on the PLL. The low speed with PLL connected indicates something is slipping or there's too much friction somewhere in the mechanism. Things that I recommend doing are as follows: - motor: check if it rotates completely freely and also lubricate its top bearing with oil; - motor position (left/right) and flywheel thrust play; check the link in my signature for details; - capstan rubber ring and motor spindle should be cleaned (I recommend using IPA) thoroughly; - capstan itself should be roughened with ferric chloride to eliminate any possibility it's polished (many times it's not visible to the naked eye) and tape is slipping over it;
I cleaned up a few parts and got W&F around 0.13% without PLL and then around 0.08% connected, with everything working properly. I put it back together and the speed is totally off, worse than before. So I'll have to take it apart again and will go through your tutorials this time
As a reference, the tape speed with PLL connected is typically between 2993Hz and 2997Hz. If it's less than 2990Hz that's a concern. This last screenshot you uploaded looks almost what it needs to be. The tape speed at 2988Hz is a bit low, but it's pretty close to what it should be. If you manage to obtain 2993Hz or so, while also having the 0.08% w&f, then you can call it good. Do note that the PLL adjustment does NOT affect the tape speed with PLL connected, but just the stability of the wow&flutter. Tape speed with PLL connected is determined just by the resonant frequency of the quartz crystal itself and will vary with individual units, hence why I gave the 2993-2997Hz interval and not a fixed value. If all the adjustments (motor position, flywheel thrust play) are done and motor is properly lurbicated, I would continue by doing 2 things: 1. Remove the motor and sand its spindle with a fine grit sandpaper (800, then 2000 grit), while the motor is running. Use 1.5V to power the motor. Sometimes there is roughness on the spindle and giving it a polish can help it have better grip to the rubber ring. 2. Roughen the capstan with ferric chloride. Have seen situations when a polished capstan caused lower tape speed than normal on DDs. Not very common, but can be possible.
