Problem/question regarding my newely bought Sony D6C

Valentin rocks !

 

I'm afraid it is normal. It's caused by the head picking up the flywheel's rotating magnetic field.
User MagneticBlood has described this issue on the other forum (tapeheads) and offered a solution as well. However solution is quite complex and I don't recommend applying it.

 

Guys until pinch roller arrives (it wil ltakes two weeks or so unfortunately) I slightly and quite evenly sandpapered pinch roller cleaned then with isopropyl alcohol and corrected azymuth by ear. And it is much much better. and that muffly sound sometimes comes back but I noticed if I press cassette a little bit it fixes the muffling sound!!
So I thinks cassette misalignes itself somehow? In general sound is much better now. If on some cassettes it begans to lose quality I only press cassette little bit and the problem is gone.

 

Understood. But if it is magnetic then why switching to dolby B reduces that whine? and even more (practically gone when Dolby C is enabled? )

 

When all rubber parts will arrive eventually I will change all excelpt already changed belts. I need advice what and with what to lube mechanical parts with? What type of oil lubricant etc? I noticed when I disassembled my walkman that some kind of black lubricant is used on metal parts. I intend to clean all parts throughout and need you help guys to not ruine the walkman what oil to use and where exactly should I use oil. And what type of grease should I use and where? I want to properly re-lube/oil it without damaging or making it worse.
What about
Multi Purpose Synthetic Grease USDA Dielectric PTFE
https://www.amazon.com/dp/B00KU85W4G?psc=1&ref=ppx_yo2ov_dt_b_product_details
and
Liquid Bearings Synthetic Oil For Tape Decks
https://www.amazon.com/gp/product/B007GOVZLG/ref=ox_sc_act_title_3?smid=AMRJQZ8CFP4VH&psc=1

 

Where do you press on the cassette to fix it ? Please put a picture for reference.

I listened once again to your recording. First of all, the whine is present on all 3 positions of the Dolby, bring the volume up and you will see.
It's just more attenuated on the Dolby B and even more attenuated on C, but it is still there.
Dolby NR works by doing dynamic pre-emphasizing during recording (dynamic means it depends on the signal level) and dynamic de-emphasizing during playback.
So it is normal for the Dolby NR system to attenuate that whine to some degree. That's how the NR system works, so it does exactly what it's supposed to do.
For more information please read this article on wikipedia: https://en.wikipedia.org/wiki/Dolby_noise-reduction_system
I intend to do a more in-detail explanation of the Dolby systems and how a tape machine works in general, but don't know exactly when I will have the time to do it.

I recommend to lubricate rotating parts with watch oil, but the oil in your link will likely work as well. I also recommend cleaning the FF/REW lever and lubricate it with oil instead of grease.
You will find a link with FF/REW issue in my signature. Note this is something that is recommended to be done even if you don't have the problem right now. Pay attention to the small spring (remove it before removing the lever) !

The only place that I recommend using grease is the back of flywheel thrust adjustment screw and the pivot point of the motor (that lever that moves motor up and down).
As for the rest of metalic parts, you don't need to clean everything and re-lubricate. You would need to disassemble every single piece of the mechanism to really do so and there's a risk you do more harm than good.
So I recommend sticking to the rotating parts that you remove only, including the pinch roller pin and the capstan bearing (don't forget to clean the capstan of oil after that).

 

Somewhere in here sometimes on another end.


Regarding oil. So I should use that oil on all the rotating parts including pinch roller capstan and all cogs right? Cogs should be lubricated only center rotating part or should I slightly lubricate tooth aswell?
Thanks again Valentine! You are helping me alot!

 

Ok, in regard to pressing the tape as suspected that is an indication the pinch roller is the problem.
The tape itself will stay at an angle if you press on one side, so you will practically compensate for the misasligment the roller is creating.

In reagrd to oil, just the shafts should be oiled. The teeth of the gears should NOT be lubricated.
As for rotating parts, lubricate those that you will disassemble anyway to replace the rubber.
I would suggest leaving the table reels and the backtension gear (the one with a spring connected to supply reel) alone.
The table reels can be lubricated from above by putting some oil between the brass part and the reel itself then rotate.
Idea is I don't recommend disassemblying more than necessary.

P.S.: the front motor shaft should also be lubricated. Pull the spindle a bit out (it has about 0.5mm of movement) and put some oil in. Then clean the spindle.
When re-assemblying you should align the motor to be perpendicular to the flywheel. This is described in the service manual and there's a tutorial as well in my signature.

 

Just to check if I understood service manual correctly so C607 in schematics is electrolytic surface mounted aluminum capacitor. Size should be in diameter no more then 5.5mm and height 5-6 mm. and C317 is an through electrolitic capacitor with maximum diameter of 8mm and maximum heighth of 12mm. (So they would fit in there.

 

Yes, C607 is the 47μF SMD one. In terms of size, there is space for a taller one, but the diameter should be the same as original.
You can even fit a through hole one with legs bent at 90 degrees if you cannot find a SMD one, but of course ideally you should put one that's the same as original.

C317 is a 220μF through hole one rated at 25V. The rule of thumb is pretty much any 220μF@25V will have the same dimension as original or even smaller (it is not uncommon that newer ones are a bit smaller).
Same goes for the SMD one: a SMD 47μF@16V will very likely be what you need. You can also use a 10V rated one, as there is more than enough margin from the 6V it's operating at.
Alternatively, a SMD tantalum can also be used if an electrolytic is hard to find. Do not however that on SMD tantalums the line is the positive side, opposite to electrolytics, where the line is the negative.

You can replace both C317 and C316 since they are the same.

 

Thank you again Valentin! Yes I am intending to change both 316 317.

 

I received all rubber parts for my D6C changed all rubbers including pinch roller. Cleaned lubricated all parts that you told me to. Assembled the walkman and there is no sound at all from it It phisically works (tape runs but db meter doesnot light up and no music comes from headphones, just the little hum that I was tolking in forum earlier during silence between tracks) I cleaned volume contacts and line out line in mic and headphone jack using contacts cleaner. I am checking the wires but cannot see any brocken ones. When I try to play while disassembled (without shield itnerferance is hearable in headphones. No music whatsoever plays Help! What to check?

 

Update Dissasembled and reassembled and it it works now I don't know whats up with it.. Checked every wire none appears to be brocken. Hm

 

I think the variable treble I was having problem with is gone. And It was a pinch roller for sure. I really cannot change the SMD cap. It is in such a place Will try to find pro who will do that. BTW I ordered replacement cap and missed in size and it is a bit smaller. Will it be an issue? Specs are exactly the same 16V and 47 uf
I am holding replacement with tweezers in a photo

 

The capacitor can be smaller if it has the same voltage rating or a voltage rating that's higher than the operating voltage.
Bigger is an issue here as it won't fit, smaller is good as it will be easier to solder it.

 

I hope you're getting your problem straightened out.

Can anyone recommend a good all-around test tape? I have two WM-6C walkmans, one is the earlier pointy amorphous head, and the other is the rounded head amorphous.

Maybe there is a test tape that will work in my full-size deck also? Thanks.

 

I'm not aware of an all-around test tape, most are dedicated to one or a couple of similar tasks: Dolby levels, azimuth, wow&flutter, crosstalk, etc.

I recommend buying a set like this if you want or need to have all (or most) of them: https://www.ebay.com/itm/313120402902
They will work on any device be it walkman, portable recorder/player, boombox or deck.

The Dolby level one has the correct 200nWb/m ANSI levels on it, but you will need to convert the values specified in the service manuals to the ANSI standard, as many playback level adjustment procedures are specified for the 160nWb/m DIN standard.

 

@Valentin thank you.

 

Guys I have got a test tape from ebay. Measured speed of my sony d6c on nak100 software uaing 3khz tone recorded on that test tape and it is 2987hz not 3000hz. Should I correct the speed?

 

You can't adjust the speed since the D6C is a quartz lock unit and speed is determined by the crystal frequency.
Only speed that can be adjusted is with speed tune on (quartz is disconnected) or by disconnecting the PLL pad yourself. But W&F will be higher.

Depending on the actual speed of the deck that recorded this test tape, that 2987Hz might be fine or a bit low.
With a test tape I recorded myself on a quartz lock direct drive deck, I typically obtain between 2992Hz and 2996Hz on quartz lock walkmans.

It's normal that these units have the speed a bit lower than those without quartz.
Without a reference I can't tell if the speed is right or not. If it plays pre-recorded tapes at a speed that doesn't sound low, I would consider it fine.