Stephen Coates' Homepage
Created: June 2014
Walkman Repair and Maintenance
On this page I document various repairs I've done to Sony Walkman cassette players, and some tips to keep them in good working order. This page isn't intended as a tutorial, but hopefully it will help you with repairing your own Walkman.
Since putting this page online in 2014, I have had quite a lot of people contact me to ask if I can repair their Walkmans for them. Although I do do repairs for people on occasion, I do not offer a professional repair service.
Click on a link or scroll down for more:
Sony WM-FX277 - On this model, I repaired the broken soldering on the headphone jack, fixed the intermittent buttons, and did a rather crude repair to the tape head's flat flex cable.
Sony Walkman WM-FX277
This is my Sony Walkman (a WM-FX277), which is about 12 years
old, and very well used.
Walkmans aren't in the greatest of environments. When in ones pocket, they will pick up dust and sweat, and may get damp. When running/cycling etc the mechanical parts will shake a lot. Tape heads can pick up dirt from the tape. Repeated insertions/removals of the headphone jack can result in intermittent connections.
The case of this model is held together by plastic clips. There
are no screws.
Remove the batteries, then remove the front plate which contains the text (Mega Bass, Preset etc). This should just pop off. Then the silver top should pry off if you use a thin screwdriver. It might be a bit tricky the first time you do it. You might end up breaking some clips if you aren't careful, but it'll still go back together fine; it just won't be held in place quite as well.
To remove the circuit board, undo the screw in the bottom left
hand corner, and unclip the board.
To remove the cassette mechanism, simply unclip it from the case and pull it out. Do be weary of the small flimsy wires, which can be quite easy to damage.
Headphone Jack Repair
When the headphone plug rotates, gets plugged in/pulled out,
yanked on etc, this places stress on the solder joints, and can
cause them to fracture, which will cause intermittent sound, or
no sound. This photo shows what a fractured solder joint looks
like. The joint on the right is fractured, and the joint on the
left is fine.
You could simply reflow them (melt the solder with a soldering iron, then let it solidify), or suck the old solder off, and put new solder on. I put new solder on all the joints, making it look nice and shiny, like in the photo below.
Fixing intermittent buttons
The buttons work by having two carbon tracks on the PCB. When
you press the button, a conductive material on the bottom of the
button presses against the two tracks, and connects them
With time and use, these tracks can get dirty. It could be that
they simply have dirt on them which needs washing off. Or it
could be that they are worn. I have found with this kind of
button, that every time you clean them, they wear down slightly.
If they are dirty or worn, they may not work at all, or they may
need extra force to get them to work.
A good fix for this can be to make the conductive buttons more conductive. You can do this by putting a bit of conductive ink on the buttons, as shown in the photo below. This is nickel conductive ink, but silver ink should be fine as well. If the buttons become too sensitive, you will have to scrape a bit of the ink off.
Buttons with conductive ink applied. They work much better now :).
Tape Head 'Flat-Flex' Cable Repair
The tape head is connected to the circuit by a small flat-flex cable. After I had taken the circuit board out a few times, this cable ripped. Flat-flex ribbon cables are really easy to break, so I guess this was inevitable. The ribbon had only four conductors, so I only needed four bits of wire to replace it.
I used some thin electronics ribbon cable (think IDE/Floppy drive cable) to replace the flat-flex.
The broken flat-flex, removed from the head.
Firstly the damaged flat-flex should be de-soldered and removed from the tape head, and from the circuit board.
Bear in mind the pinout of the head. On this model, the head has five pins. Two are connected together. Two are also very close together, but are not connected together. The following diagram shows the connections.
A piece of wire was prepared and soldered on to the head. The wire needs to be a bit flexible, as the head moves when you press Play. Note that in the following photograph, the fifth pin is not connected. I later extended the black wire so it connects to two pins (as in the diagram), rather than just one.
Once the head is neatly soldered (making sure the pinout is
correct, and that there are no shorts), you can solder the other
end of the wire to the PCB, and re-assemble the Walkman.
New wire (nearly) installed on the head.
New wire soldered onto the circuit board.
Cable replacement done!
Sony Walkman WM-FX551
I purchased this radio cassette Walkman via eBay a few years ago, and it has been my primary Walkman ever since. It has full logic controls, auto reverse, excellent battery life on one AA battery, and fits neatly in a pocket. Unfortunately, the radio stopped working all of a sudden. It appeared as though the onboard microcontroller had 'crashed'. I couldn't figure out what the exact problem was, but I narrowed it down to a particular board. I simply replaced this board with one from a donor Walkman.
It also required a new belt. The existing belt was worn out and would slip, causing the tape mechanism to not work correctly (The mechanism would try to start, but would only work intermittently).
Walkman belts are a bit awkward. They tend to come in standard diameters, but the replacements you can buy from typical suppliers such a CPC are too thick. Walkmans require a very thin belt. Fortunately I was able to order a replacement from eBay user Mihokm. He has a dedicated store where you can buy belts by the Walkman model number. He ships from Slovakia, but the belts arrived very quickly and were sold at an affordable price.
Link to Mihokm's eBay Store: http://stores.ebay.co.uk/Walkman-Belts
The following video shows how I dismantled the Walkman and how I repaired it. This Walkman is nice and easy to repair compared with the cheaper models such as the FX277. It is held together by machine screws and the circuit boards are connected together with proper connectors. Clearly this model was designed for servicing!
Sony Walkman WM-10
This Walkman was sent in for repair by a customer in America. It was very problematic.
The WM-10 is an early model from the 1980s, and was Sony's attempt at making a Walkman "small". Other models of the time were too big to fit in a typical pocket. This one is barely bigger than the cassette itself and "shrinks" when you remove the cassette.
Problem 1: The Belt
Being old, the belt had degraded and turned to goo. This goo had got all over the place. It had to be cleaned off the pulleys (where the new belt would go). It had also got into a small leaf switch which turns the Walkman on when you press the play button. The switch had to be desoldered and cleaned in alcohol, and the rest of the 'belt goo' had to be cleaned off with alcohol and cotton-tips.
The top circuit board showing the decomposed belt.
I obtained a replacement belt from Mihokm on eBay
The leaf switches after they had been cleaned and re-soldered.
Problem 2: Power Supply
To keep the size small, the WM10 required only one AA cell, thus providing 1.5V. The audio amplifier ICs can happily run at 1.5V, but the motor requires 3V. In other, larger Walkmans, the 3V is obtained by having two AA cells in series, but this is not possible in the WM10. So, Sony decided to include a separate circuit board which serves as a DC to DC converter - converting the 1.5V from the battery to the 3V required for the motor.
This particular Walkman wouldn't turn on. Testing revealed the problem to be with this DC-DC converter board. It was not outputting 3V like it should. I tested some of the transistors and Q803 turned out to be dead. I just replaced it with a generic surface mount transistor with similar specs, and the board then worked fine.
The PCB can be removed by desoldering it from the main PCB.
The DC-DC converter board on its own for testing.
As per the 'Troubleshooting Manual', the DC-DC converter board can be tested on its own by hooking up a 1.5V cell, and connecting a resistor across two pins as shown.
A note about the Headphone jack:
In the WM10, the headphone jack contains a switch, which turns the unit's power OFF when the headphones are UNPLUGGED. If the unit appears to not power up, make sure you have something plugged into the headphone jack to turn it on! This caught me out numerous times :).
Problem 3: No Sound Output / Faulty Audio Amplifier IC
After getting the unit to power up, there was no audio coming through to the headphone jack. I spent ages tracing the audio path throughout the Walkman using my oscilloscope, and testing various components. Eventually I concluded that the main audio amp IC was faulty. This is a Sony branded CX20089 IC and is designated IC303.
I couldn't get an exact replacement for this chip. However, there are several almost-identical chips available. In this case I was able to get an LA4533 off eBay. This IC has the same pinout as the CX20089, but it turned out to be a smaller package, so I had to "bodge" the chip in with some creative soldering.
These chips have a 'muting' function. This is used to prevent a loud 'pop' when the machine is first turned on. When you push down on the play button, the button presses one leaf switch which turns the unit on. It then presses another switch which triggers a small timer circuit which enables the 'mute' function for about one second. The transistor in the timer circuit (Q302) is originally a PNP transistor. However, the muting function in the new chip (LA4533) works the other way round to the CX20089! This can be fixed by swapping Q302 for a NPN transistor (any generic one should do).
This repair with the new chip ultimately worked OK. The only issue was the volume control. The LA4533 seems to have higher gain than the CX20089, and now the volume control is much more sensitive. This will be fine though as long as you are careful.
The layout of the chips on the board.
The new chip bodge soldered in. Make sure all the pins are making a good connection!
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