WM-EX60 dynamic bass boost tuning

Original capacitors measured: (1) 200µF, 2.1 Ohm ESR, (2) 220µF, 1.8 Ohm ESR. Either way it's out of specifications (20%).
For example, new organic polymer electrolytic capacitors had a capacitance of 308–310µF and an ESR of 0.15 Ohms.

I think it is clear that the original capacitors must be replaced. At least they weren't dead, which is a good sign for 30 year old capacitors.
In the next few days, we'll see what measurements with a digital caliper tell me about the free space under the board for installing new capacitors.

 

There is only 5.00 mm under the board, at best. Well, it's going to be tough. Of course, I will have to use a capacity smaller than the original one. Hopefully I can get these 270uF 5x11mm later.

 

John, I guess I should've posted the other side of the board last week, then you would've seen. You have better quality Headphone Amp caps than my EX60/70 board!! Going to check my ESR on this one. As I know one of my has a crackle that comes and goes.

 

These are both measure at around 280uF at ESR 0.65Ohms.. I will have to tear down the other one that makes a noise through the headphones on/Off. I will wait until you find a suitable Solution John.

Thanks for sharing your updates!

 

Duey,
Even if I wanted to, I can’t even come close to finding any similar capacitors from current global manufacturers. I have no idea who made the original 330uF 2V capacitors. There are no names on the capacitors themselves. Only temperature, capacity and voltage. For all current manufacturers, the minimum case size starts at 5mm dia (5.5mm with PET sleeve). I checked and it already has a bad fit. The corner of the board closer to the battery compartment is arched 1-2 mm upward beyond its natural position.

 

Yours are measured well. I don't think we can even find 270µF in a 5mm case right now. I ordered one (6.3ZLQ270MEFC5X11, CAP ALUM 270UF 20% 6.3V RADIAL) but the leadtime is 11 weeks.
I may have to force it in, not minding the slight bend in the corner of the board.

 

Yes, I read, All your hard work, hold up by two older Electrolytics!(Of a Odd Size) What a Shame John....

 

In the meantime, I'm waiting for spare parts for electronics, I have a question:
Are these cotton polishing wheels suitable for polishing the tape head?

If so, I have a Dremel tool with a wide RPM range (5,000-35,000).
What speed would you recommend?
What polishing paste is best for this?

 

Usually new small SMD capacitors can be used as substitute. Removed from their plastic base and legs folded out etc,. E-bay is also a source for older stock Nichicon and Elna in smaller sizes.

 

If you're talking about aluminum organic polymer (solid state) capacitors, then yes, they have more choice in package sizes of 5mm+.
Also, the capacitance is not high enough (<100 µF) in sizes 4-4.5 mm. For example, Panasonic 2SEPC330MZ (330µF, 2.5V, 5mm dia).


But I have read that their high leakage current characteristics (~500µA) compared to conventional aluminum electrolytic capacitors (~3µA) will cause distortion when used in an audio path.
They are ideal for power circuits (don't dry out, don't leak), but not as coupling capacitors in audio circuits.

Thank you! I'll look there too.

 

In regard to polishing the head, recommend using cotton swabs (those used to clean ears) cut in half since those typically have finer texture than polishing wheels.
As paste, use fine automotive paste of your choosing. For speed, I think 5000rpm is too high for this application. Would rather use a cordless drill than a dremel.

Interesting discussion about these capacitors.
On the photo posted by @Duey71 there's an R in a square logo, which is the manufacturer.
Seen that before and someone did mention here on the forum who was the manufactuer, but can't remember.

Think the only solution to keep the original capacitance of 330µF is to use SMD tantalum caps, like T491C337K004AT. These have a 0.9Ω ESR and a leakeage current of 13.2µA.
However this implies a bodge solution like glueing them upside down and add some wires to connect them. Not ideal, but it will work.

 

Thank you, Valentin!

 

I can't find a relevant researches on tantalum capacitors in audio paths. I know they are good in power circuits too. And the leakage current is much better than organic polymer caps. It would be good to find out the opinion of those who have heard them in audio circuits as decoupling capacitors in terms of their transparency or introduced distortion.

I see audio manufacturers generally choosing electrolytic capacitors as decoupling capacitors when they have the option of using tantalum or solid state capacitors, and have sometimes even used several of them on the same board in other circuits. Makes me think there were some reasons for this.

 

When I was recapping a Sony D-211 Discman several years ago I ordered a large selection of SMD capacitors, they were not solid state, just regular ones that can leak over time. I believe they were 0805 size, very small, from an e-bay store in Taiwan. E-bay stores have large sample books of SMD capacitors and resistors. A popular best seller 3 value assortment of 4v electrolytics is sold by Galaxyelectronics etc., etc.,. of course these could all be fake garbage components, but hey, it's not like we are repairing medical equipment or some communications radio on a plane lol.

 

In many portable devices there's only so much space for capacitors, hence why electrolytics may not be a suitable option despite having some advantages.
For example many MD portables and even later WM-EX walkmans use SMD tantalums as output coupling capacitors. See picture attached.
Also many new portable audio devices (DAPs, DACs/headphome amps, etc.) use SMD tantalums for output coupling.

As far as opinion goes, I have recapped quite a few walkmans (especially AIWAs) with SMD tantalums because electrolytics in the original footprint were hard to find.
Have been very satisfied with results, as far as listening goes. It may be interesting to do a comparison of aluminium electrolytic vs tantalum in the future, including measurements.

Given a 40dB SNR (no Dolby) and a THD of 1% (-40dB) are typical of cassette, the distorsion produced by caps has to be higher than this to be audible.
Found a recent study by Würth Elektronik: https://www.we-online.com/en/news-center/press/press-releases?d=anp125
Their study is focused solely on aluminium electrolytic capacitors, but the conclusions are interesting.

 

Thank you. This one has an ESR of 0.09Ω. There is another one - TPSY337K002R0040 from KYOCERA AVX. It has an ESR of 0.04Ω and a leakage current of 8.2µA.
Judging by the characteristics, they are Ok. Having some subjective opinions about the sound distortion caused by these types of capacitors, as well as installation aspects, I will leave them as a last resort.

I've seen a lot of compromises made by engineers and managers in Walkman-type players from all major manufacturers. Over the years, they have favored certain aspects over others.
For example, on the one hand - cost, dimensions, manufacturing complexity; on the other hand - performance, sound quality, lifespan.
They changed components based on these criteria, plus some advances by component manufacturers over the decades were also factors.

 

I was restoring the tape drive mechanism and lost one of the flywheel's nylon split washer. It jumped out from under all the protection of my hands and disappeared for life.

Shaft diameter is 1.2 mm. The second washer for the capstan measures approximately 0.8x2.5x0.25 mm.

Marian from fixyouraudio has a set of Walkman washers for sale and I asked his opinion on my case. Here is his answer:
"I tested these 0.8 mm washers on the capstans with 1.1 mm diameter. For 1.2 mm it might be too tight. I also have 1.1x2.5.0.2 split washers, these might fit better."

Does anyone know what size I should order?

 

Both sizes just to be safe

(PS: I would like to see your skills applied to other superior high end walkman which are more worthy )

 

Yes, I ordered both sizes.

Thank you, Duey71. Currently, high-end Walkmans in decent condition are disproportionately overpriced. And buying junk seems to create insoluble problems associated with the lack of spare parts to repair it.

 

I have a lot of high-end walkmans. What would be an appropriate price you would be interested in buying them from me for? And what models are you looking for? I have mostly Sony. decentman4you2007@gmail.com send me mail. Or I can just post a gazillion pictures in here LOL.