Sony D-35 Discman (1990) Capacitor replace and internals pics

The most recent phase of my recurring Discman "mania" started in the Winter of 2020-2021. After months of devouring old discussion threads and absorbing intriguing Kaosun comments... it all began again on May 17 2021. That is when a Sony D-35 arrived in the mail. Then, on May 31, I snagged another D-35 on ebay which had all the correct indicators for success. Finally I was going to get into the good models and get to hear what they sound like...

D35 (D-350 everywhere outside of North America) was the flagship top model of 1990. The D-35 / D-350 only has a single weak UPD6376 DAC so it is quite limited. Nonetheless I like the sound, especially from the line out, which is noticeably better in clarity and separation than the headphone out, in my opinion. (Assuming the listener is playing a disc of highly layered and detailed ambient electronica... then it becomes almost easy to tell )

The first D-35 worked fine with just slight skipping on occasion on the first few tracks of a CD. Very light use on the motor. Cosmetically great condition and with the external AA gondola, case, AC adapter etc,.

The second D-35 was bare bones, with no accessories, only a brief description to go on along with some decent pictures. Arrived about a month later and powered up and played fine when on its side. Pure luck! And it was in great condition. Someone had used gold spray paint nearby and it had drifted onto the player, adding a delicate dusting of fine gold particles over the front and keys. It removed fine with Windex, about 50 Q-tips, plus an hour to so of effort. Cool effect that got me wondering if I should have left the paint alone? With the $1.50 Mabuchi RF-410CA replacement motors in hand I started off on the 2nd D35...

Instead of using a 3D printed motor / placer spacer tool, as some suggest, I simply used a feeler gauge of paper cards. By familiarizing myself with the exact sensation of how the paper pushed under the platter felt I was able to reproduce the placement on the new motor without any problems whatsoever.

The headphone out audio coupling capacitors on the D-35 are the notorious mismatched 220uf 4v Nichicon and 220uf 6.3v Elna. Space is very limited but I was able to fit Nichicon 220uf FW series audio capacitors the second time around. First off I had Nichicon KA 220uf and after about a year came back and changed them plus the remaining 330uf in the power supply area.

Overall I felt there was a definite difference and good improvement to be heard over the old original capacitors. So much so that I wanted to replace all 12 capacitors, which I did, with Elna audio caps that would fit. It is my strong opinion that the audio fidelity and separation did improve yet again when all the ancillary capacitors were also changed. If it was all placebo, then it was a lot of fun, so I would do it again. And again and again. Like I do now on any and all Discman or audio devices that come my way.

The final 330uf was a challenge due to no easily obtainable modern small 330uf. But it can be done with the standard 5mm diameter and 11mm long Elna when fit carefully.

One other thing to add is that, for me, the countless hours of detail cleaning are the most fun. Getting Teflon grease into the hinge arm and other squeaky areas. Polishing scratches out of the display screen. All this gives time to appreciate the quality and workmanship of the device. I really came to love the D35 as one of the most beautiful Discman players.








Take lots of pictures prior to de-soldering wires


The old motor is on the left. New Mabuchi RF-410CA on the right with
the soft steel shield sleeve. Leave on or remove?
The only difference with the new motor is the shaft length. The new motor has too short
a shaft - but it works. Make sure to soak the bronze sleeve bearing with
synthetic oil for a day or two prior to installing. The new motors are dry.
And will run noisy when connected to an AA battery for testing. Quiet after oiling.
This is failure mode of the original motor some say. I agree. Junk toy motors not even
oiled properly from the factory.
















Dust and dirt drop down inside the keys. Full disassembly is required
for complete cleaning.

 

Nice work. I have a few of these Mabuchi motors as spares if I ever need them for my D-350 and the shaft length is longer than the factory motors. Good tip on oiling those bearings before fitting a replacement motor.

 

Mabuchi RF-410CH is the original motor used by D35 / 350 and D303. Mabuchi RF-410CA is the similar one that's all over e-bay for about a $1.50. Shorter shaft makes CD platter placement less resilient and could be easier to be disloged off axis in future. Kaosun said on his site forum that he got the last supply of the original Mabuchi RF-410CH motors from Toshiba. How many motors that was is left to the readers imagination...

I even tried taking the old motor apart to swap the rotor / windings / shaft into the body of the new motor. So as to use the new bronze bearings. Almost worked. The tolerances are too close on the new motor magnets. They scuff the rotor. I bet one could use a machine tool to ablate the magnet material away. It was very soft and crumbled.

The Mabuchi RF-410CA from e-bay is usually described by some sellers as NOS from a warehouse. They are probably old and definitely have dry bearings. They run scratchy and loud from an AA battery. As soon as they are oiled it goes quiet. They also have a small pinhole oil port leading to the bronze on the back / base bearing. Yes really. Not even the old original motors have that. I fed oil into the pinhole and let soak a few days. It was actually absorbed.

 

Just to update this, there’s a better motor to use that’s found in a Philips assembly called the CDM-12.3 (went in a Marantz machine), can be found on various site such as Ali.

 

That's correct, nearly 2 years ago I ordered 2 of the Philips CDM-12.3 from e-bay (not Ali because they did not accept Paypal if I remember correctly) but had to return as it had different motor in it. How and why it had changed motor I can only speculate I did not feel like trying again - but should have - as there are no doubt the correct Mabuchi motors lurking out there in another New Old Stock device.

 

Ok I’ve ordered two off Ali so I’ll let you know if they’re correct motor. And post the seller here.

 

Ahhh so my D350 repair failed… I ended up cracking the top of the spindle platter, the black plastic part.. whilst removing the top metal hat it took the plastic with it.

I glued it and got the correct height but yeah seems the motor is touch and go… not always spinning up. I think I need to source a new spindle head…

Any cheaper models carry the same spindle platter with the pointy metal hat? Besides the 303 and 35/350

 

When removing the platters ones has to use two wedges simultaneously, one on each side, to squeeze up slowly and carefully pop the platter off. Spacing has to be correct too - I just used a feeler gauge of paper card stock. Stack the cards, test, adjust, test etc., until it's just right. Then save as the reference gauge when installing the new platter etc.,

I don't see why the "top metal hat" has to be touched at all.

For finding a new one... yeah... the motor shaft is small on the D35 / 303. A cheap old D-9, for example, would not work due to larger motor shaft.

 

Yesss... i will be extremely careful when i attempt the D303 i have, don't want to mess that one up too lol... I'm getting the 3D printed spacer done, if i get two made, i wonder if there's any harm using that as a way to pry up the platter, if its stiff enough?

New one, Yahhh that's the kicker, maybe i'll get lucky and find one sub $100. Shame no one 3D prints the platters.

 

I ended up using the platter from the CDM 12.3 replacement motor, with some trimming of the hat and removing the top door stabiliser the unit plays perfectly just need to replace a few headphone caps .