Tag Archives: audioplayer

Sony Walkman WM-DD11

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The portable cassette player from the manufacturer SONY with the type designation WM-DD11 is the content of this article. Colloquially known as “Walkman”, I received this part for my collection. Of course with the comment “defective” – ​​so again a little challenge and at the same time the hope that no mechanical, no longer available parts are affected. My request before the purchase whether there was any damage to the circuit board was also answered in the negative. The device is so far in order, the tape of an inserted cassette is moving – there is just no sound from the headphones. So ideal conditions for a restoration.

But unfortunately you cannot trust every statement and you cannot look “under the hood” beforehand and convince yourself whether the actual condition of a device corresponds to the description. When I held the part in my hands, the first impression was also very convincing. There were no noticeable scratches and dents. The area of ​​the battery compartment that was visible from the outside was also clean. So batteries inserted, also an audio cassette and then pressed on play. Lo and behold, the tape transport runs as described. Even as described, the part does not make any sound. So perfect starting conditions for my mini repair / restoration project.

But before I start dismantling, I did a little research on the history of SONY’s DD Walkman series. The first model in the DD series was sold in 1982. The designation “DD” stands for “Disc Drive”, which means that the “Disk”, i.e. the flywheel disk, is also part of the capstan drive system (motor). The belt for the other drives (tape reels) is placed directly around the disk. There are / were two price brackets of the DD models – the DD series with one-digit numbering (DD-1, DD-2, etc.) and those with two-digit numbering (DD-11, …). The devices with the single-digit number belong to the “high-end rail”. The device restored here comes from the “cheap line”. The DD-11 is not so high-quality and is also more simply constructed, but defective devices are available for very little money and are also fairly easy to repair. (The DD-11, for example, does not have a center wheel, an often defective part of the high-end series that is broken due to weak material. What then usually remains are defects in the electronics or on the mechanical side – an aged belt The belt is the same as that already installed in the legendary TPS-L2 Walkman and has the component serial number: SN 3-499-042-99 (this source or number has not been verified) You can also find the belt if you go to “TPS -L2 belt “searches on various online portals.But now enough information on the general part. I experienced a sobering and grounding of my restoration euphoria immediately after unscrewing and opening the case. Unfortunately, the circuit board is not at all undamaged. Once again someone did not remove the 1.5Volt cells and left them in the device for a very, very long time.

The batteries that leaked, as it is, have left clear marks on the circuit board. This means that extensive cleaning of the circuit board is necessary before the search for corroded conductor tracks can begin.

After cleaning and removing the battery electrolyte residues, I was able to make out a few defective conductor tracks. Fortunately, these are pretty easy to fix. In most cases it is sufficient to remove the solder resist in the defective area and to tin the exposed copper tracks. Depending on the width of the track, the defective part of the track is then reconnected with individual strands or wires.

Now the time has come to carry out a first functional test after a provisional assembly. And as described, the capstan drive works, the tape is transported – but there is no noise whatsoever from the connected speakers. Now is the time to look at the number one source of failure – the old electrolytic capacitors. Eleven of these are installed on the board.

When I removed the first electrolytic capacitor for a capacity test, the well-known fishy smell rose again. As expected, the capacitance of the capacitor was also well below the nominal value. So I made a spontaneous decision to remove all eleven electrolytic capacitors in order to swap space. (In modern language it is called “recap”: D)

The following values ​​must be renewed:
– 5 Stück 220 µF / 4V
– 1 Stück 100µF / 4V
– 3 Stück  47µF / 4V
– 1 Stück 10µF / 16V
– 1 Stück 4.7µF / 25V

 

I like to replace the SMD electrolytic capacitors with SMD multilayer capacitors, as these are now also available in very small designs in high capacities with suitable dielectric strength.

After the renewal, the board looks nice again. A repeated provisional commissioning shows that the effort was worth it. The music on the inserted tape sounds in the expected quality. The next step is to calibrate or adjust the belt speed. A reference tape is required for this. Years ago I recorded one with a very good tape recorder. The recording consists of a 1kHz and a 5kHz sine tone. This band is now used as a reference in the DD11. To do this, the output of the DD11 is connected to a frequency counter or oscilloscope and adjusted with the trimmer potentiometer during playback until the 1000 Hz or 5000 Hz can be seen exactly on the oscilloscope.

The Walkman can now be reassembled. All screws are properly tightened again and finally the function tested again and the beautiful piece can be put in the showcase …

Cassette player/recorder SONY TC150B

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Sony TC-150 cassette recorder

The Sony TC-150 is the newest, old member of the collection. Once again purchased as a defect device, this baby found a place in the workshop. After a quick inspection, it was immediately clear that the ravages of time were gnawing and, as is often the case, the drive belts became brittle or decomposed. Otherwise, the device is in perfect condition, hardly any scratches and damage to the case. The battery compartment was also clean. There are four belts of different lengths in the device.

belts to replace

Suitable replacement belts can be obtained, for example, from a large electronics store that is represented in Austria by six megastores. You will quickly find what you are looking for under the name “drive belt range” and “1.1mm edge length”. Replacing the straps is less quick. Here you should take at least half an hour and carefully take the drive apart.

The main circuit board must be removed in order to access the pulleys or to be able to unscrew them further. However, this is only possible if some lines are unsoldered. Only then you can fold up the board. Once that’s done, you can unscrew the retaining plates above the pulleys. They form the backing of the flywheels (capstan shaft). On this occasion, it is advisable to check the capstan shaft for dirt (due to belt wear) and damage, or it should be cleaned. The pressure roller must not be neglected either. In this model, both were in great condition. The pinch roller was neither glazed and brittle, nor contaminated with tape wear or shrinked. So I could put on the new straps. The main belt from the engine is put on with a rotation of 90 °. Here you should note the installation position of the old belt, if it still exists, or at least do a short test run after fitting the new belt.

If everything turns again (and especially in the right direction) then the assembly can be done. Solder the wires again, screw the circuit board and the repair is done. To have this man a test cassette, here are some parameters, such as tape speed or the tracking of the tape head, which are given and adjusted if necessary.

the TC150 after belt replacement
the VU-meter for recording level control to as battery meter

 

Technical data of the SONY TC-150:

Vendor:                                    Sony
Type:                                         TC-150 (Europa) bzw. BT-50 USA
year of production:           ca. 1977 – 1982 (according to various sources)
Modell kind:                          portable  Cassette Corder
Hauptprinzip:                      NF-Audio
                                                     Magnetbandaufzeichung/Wiedergabe
tape speed:      4.8cm/s
heads:                                      1 recording-/playback head
                                                     1 earase head (Permanentmagnet)
semiconductors:                8 tranistors, 5 diodes, 2IC´s, 1 FET
Power          :                           Outputpower: max 360mW
                                                     Powerconsumption : max 9W
Supplyvoltage:                   battery 4×1.5V AA, or accupack BP28
                                                     12V Caradapter bzw. 6V 4W wallplug
operationtime:                    2.5h at continous recording
Speaker:                                 dynamic 5cm Lautsprecher
Abmessungen:                    174 x 29.5 x 113 mm (BxHxT)
weight:                                    ca. 769g