SONY TC-K555ESA: Introduction

A Japanese (JDM) cassette deck. I think there was only one model above it: the TC-K555ESJ. But it is rare and expensive so I don't see myself having one of those pretty soon. But who knows? Anyway let's come back to the TC-K555ESA deck. This one has all the features you would dream of. To name a few: closed loop dual capstan, quartz locked linear torque brushless capstan motor, three heads (1 x S&F erase head, 2 x laser-amorphous record / playback heads), sapphire capstan bearings, ceramic cassette stabilizer, Dolby B, C, HX PRO, manual bias calibration, bias intensity selection, and other. Add a fully copper plated chassis and you're looking at a master recorder. At least this is what I consider mine to be. I don't have any deck better than this.

But even with all this high-tech inside, this machine is still prone to failures. Some bigger, some minor. Fortunately it is very repair-friendly. Boards are easy to get out and work on. TCM-200D10 mechanical block is a joy to operate and to fix -- bar the supply pinch roller alignment.

My deck was suffering a little bit so I decided to take a look at it.

Main issue though is that JDM gear is running on 100 V mains voltage and 60 Hz frequency. In Europe we're running on 230 V mains voltage and 50 Hz frequency. However we can use step-down power transformers. I am using a 220 V : 100 V step-down autotransformer and it works perfectly fine.

Disclaimer

The following articles are not to be treated as do-it-yourself tutorials on how to fix, restore, rebuild, or improve the unit in cause. This was not my initial intention. But you can consider this whole content as a general guideline, should you decide to launch into such an adventure.

The entire documentation is just a reflection of my work and I cannot be held responsible if you damage your unit, or even harm yourself in the process.

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SONY TC-K555ESA: Technical Data

This cassette deck has the following technical characteristics.

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SONY TC-K555ESA: Parts List

I have assembled a partial parts list for this cassette deck.

Descriptions and Parts Listings

The RECT(ifier) printed circuit board occupies the central compartment of the chassis and is located behind the mechanism block.

The SYSCON printed circuit board occupies the left compartment of the chassis.

The Playback printed circuit board is located in the upper right section of the chassis on top of the Record printed circuit board.

The Capstan printed circuit board is bolted to a steel plate that goes to the mechanism block on the back of the two flywheels. It implements the capstan motor driver circuit. There are two mandatory capacitor replacements on this board.

As always, let me throw a piece of advice. Do not hurry, take your time and do the job once. And do it well.

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SONY TC-K555ESA: Capstan Motor Board Restoration

Sony decks using the TCM-200Dxx mechanical block suffer from a dreadful capacitor leaking syndrome in various degrees on the linear torque direct-drive BSL capstan motor.

The issue doesn't really manifests itself until the leaking is severe and either the circuit tracks are severed or the the capacitors themselves short-circuit -- unlikely though. I have fixed at least three decks with the same problem.

However once the capacitors start leaking -- which they already did -- the electrolyte is attacking the solder compound. Removal of the capacitors will become close to impossible without the right tools. Let me tell you how I do it. I set the soldering station temperature at 290 degrees Celsius and I apply liquid flux on the surface mount terminals. Then I heat them up while applying some eutectic solder. It takes a little then I can easily remove the capacitors. Cleaning the pads however requires usage of more flux and eutectic solder. Then isopropyl alcohol to cleanup any traces of dirt left.

This is a precision job and if you don't have the right tools then disaster is guaranteed. You will most likely end up ripping the SMD parts off the copper traces. And this spells problems. A restoration is possible but the operation is very laborious. So I would avoid this procedure if I were in that situation.

Anyway let's continue.

This is the capstan motor printed circuit board. What I am looking at is the two SMD capacitors next to the supply capstan flywheel thruster shaft. They are rated 10 uF / 16 V.

Here are the old capacitors removed already.

And because technology evolved and we now have cheap MLCC high-capacity ceramic capacitors, I decided to give up on electrolytic capacitors in these positions. So I went with TDK MLCC miniature capacitors rated 10 uF / 16 V with X5R dielectric. So naturally very stable capacitors.

Clipping the leads to the right dimensions reveals that the SMD pads are perfect for soldering these SMT capacitors. Here they are mounted in happily waiting to do their job for decades to come.

But what are these two capacitors doing anyway? Let's examine the electrical schematics.

Both C905 and C911 are providing power supply rail filtering adjacent to the CX-20174 capstan motor control integrated circuit.

That's it for now.

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SONY TC-K555ESA: Better Capacitors

There are a few electrolytic capacitors in this deck that can be replaced with film counterparts for better reliability.

SYSCON Printed Circuit Board

On the SYSCON PCB there are three 1 uF / 50 V electrolytic capacitors around the supply rail regulators. They can be safely replaced with film capacitors of the same rating.

Replacements are in.

Old parts.

That's it for this circuit board.

Playback Printed Circuit Board

The playback printed circuit board is home to a few capacitors that can be improved for better reliability in time. I am talking about the electrolytic capacitors around the CX-20188 integrated circuits.

Notice how dirty the board in my unit is. The former owner used some kind of grease spray on it for some reason. I will clean it thoroughly using a spartan method. First, I will apply ammonia based window cleaner on the entire board. Then let it work out for about five minutes or so. Then clean it with the shower and 40 degrees Celsius hot water. After that, the board goes to the kitchen oven for 10 minutes at 50 degrees. Sounds crazy but I have washed up a lot of boards like that. They all came clean and in good working condition.

Notice how clean the printed circuit board appears now. Original capacitors are designated C119, C123, C219, and C213 and are rated 1 uF / 50 V. Replacements are of type Panasonic ECQ series stacked film, rated the same as the old ones.

Old capacitors.

The other capacitors are all right for now. They don't require replacements. Neither these required. But I stated clear my reasons above.

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SONY TC-K555ESA: Servicing the Mechanical Block

In the past somebody attempted to replace the supply pinch roller on this machine and failed to do so. Furthermore he even managed to destroy the tape path alignment. Fortunately the heads screws were not touched. It is a well known problem of the TCM-200D class mechanics that a worn out supply side pinch roller would cause tape skewing. So let's change these rollers. Or better let's change every rubber part in this deck. There is the cam belt and the capstan belt. While the latter is easy to replace, the former requires a little bit of outside of the box thinking.

This is the mechanical block on my tiny workbench.

View from above.

And a close picture with the tape path. Pretty unique and weird erase head with transparent sidewall so that you can see the coil windings.

Disassembly is now in progress. Notice the worn capstan belt. I turned it on the other side a couple of years ago for a bit more grip.

While here I decided to replace the electrolytic capacitors on the two small PCBs affixed to the mechanical block. I started with the quartz frequency reference circuit. Only a couple of parts here to change. I used Nichicon PWM series replacements.

All electrolytic capacitors are replaced.

...PICTURE FOLLOWS SOON...

The take-up side pinch roller is very easy to replace. It pops out easily if you put back-force between the roller and the roller arm. Use a soft plastic tool for this operation. The supply side pinch roller however is a little bit difficult to get out. Removal of the pinch roller arm assembly is pretty easy. Warning: doing so breaks the tape path alignment. But this is the expected result.

Then getting the roller out of its axle requires an improvised rig. I used a bicycle brake cable stopper as spacer, the take-up pinch roller axle as pushing rod, and a vise to apply even and controlled pressure on the pushing rod. If you align everything perfectly in line, the operation is done smoothly. Be very careful though, don't push the rod all the way in, or the supply side axle will get out of the roller assembly. And it is hard to push it back in place. I applied even pressure in a very controlled manner and observed when the axle cleared completely the pinch roller. Thus, the roller gets out easily and the axle stays engaged in the left guidance hole, ready to be pushed back through the hub of the new pinch roller. This is all possible because the pushing rod (i.e. the take-up side pinch roller axle) is a tiny bit smaller in diameter and can be easily retracted by hand from the fixture hole of the pinch roller arm assembly.

In the picture below, the old roller has already been removed and I'm preparing to install the new one. You can also see the pushing rod.

I put a drop of oil inside the pinch roller hub and pushed the axle in reverse order using the same rig.

New roller is installed. Old roller is out.

Then I mounted the pinch roller arm assembly back in its place on the mechanical block. Here are both rollers happily replaced.

Now regarding the belts. I have removed the capstan flywheels, the take-up side also being the induction motor. Care needs to be taken since there are some washers on both sides of the capstan axles, relative to their respective bearing.

Then I removed the front plastic decorative plate to gain access to four screws that separate the capstan bearings carrier from the main mechanical block steel plate. I also loosened the circuit board on the back side of the steel plate and I was thus able to access the cam belt. I used a fine tool to get it out of there and then I inserted the new belt.

Surprise, surprise. Somebody was here before. And he didn't find a suitable replacement belt thus he tied a knot in a similar belt and transformed its dimension into something that worked. Ugly as hell. Here are the old belts versus the new ones.

I mounted everything back in place in reverse order.

I then oiled the capstan bearings with Isoflex PDP 65 oil which I had left from servicing Revox and Studer machines. Then inserted the capstans with care not to scratch them. The washer are also in place. I added the capstan belt and secured everything back in place with the steel plate which is also home to the quartz frequency reference circuit.

I cleaned everything with IPA and the mechanical block is ready to go back in the deck.

Now it is ready for alignment. I did the initial alignment with mirror cassette. Then I used a test cassette with various signals and a dual analog millivoltmeter connected on the outputs of the deck. I thought the alignment would've been harder but in fact it was quite easy to do it.

At the end I secured the alignment nut with some nail polish.

And a picture with the flash activated so that you can see the new pinch rollers in their final position.

So far so good. The mechanical block is very stable. I have tested ferric, chrome, and metal tapes. All run smooth without tape skewing. Now let's record some music!

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Please note that all the work presented herein this site is non-commercial. This is my hobby and I am doing this in my spare time. Through this page I freely share my knowledge with you. But if you like my work, please consider helping me buy a transistor or a capacitor for my projects.

Thank you!

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