Category Archives: retro technology

Technology mainly from the field of entertainment electronics, audio and video technology. Repairs and equipment presentations

Calculator from 1975: PICO PA-80N

From 1975 this Japanese calculator comes. He was sold from 1975 to 1976 by the Eduscho – Tchibo coffee chain. The device is called “PICO” PA-80N. Exactly this model was also once in my father’s possession and I was already fascinated by the luminous seven-segment displays as a child. And that was the problem again. As far as I can remember, I was in elementary school age, when I first disassembled the device into its individual parts. That was not the problem, but it was not there. Over time, I disassembled the computer several times. At some point wires broke off and nothing worked. Reassembled, the Pico then disappeared into a box and was disposed of years later by my father. Why I took apart and assembled the small computer again and again, I can not say today anymore. Apparently it was the success of an eight-year-old, after assembly again to have a working device – just to last. 🙂 On an online flea market platform, I found just such a calculator and in addition to that in a TOP condition and almost gave it. So I had to have him …

Pico with the imitation leather case
To the dates:
The display has eight 7-segment digits based on LED technology. To be able to read the MikroLEDs they are embedded in a convex shaped plastic. This achieves a magnifying effect that makes the numbers readable.
Siebensegment – Anzeige mit 8 Digits

LEDs under the convex plastic encapsulant
The housing is made of aluminum and plastic and has the dimensions in about a cigarette box. 8.2 x 5.7 x 2.4 cm. In order to keep the calculator gently, there was a leatherette case to do so.
Mainboard des PICO

The calculator is powered by two Tripple A (AAA) batteries, so with 3V. Optionally, there was also an external power supply that could be purchased according to the then price list by almost 18DM. (unfortunately no price information for Austria)

Power adapter socket at the top
Technically, the small computer consists of a display board, a “motherboard” and a keyboard board. These boards are connected to each other with a multipolar bridge line. This should not be bent too often, because then quickly break off individual wires …
Opened circuit boards
The display board is driven by a Toshiba T1337 Displaydriver IC and the computer itself is a GI C593 (General Instruments) processor that handles the basic operations and percentage calculation. The processor works with a supply voltage of 15-17VDC and is able to drive Floureszentplays directly. In order to produce in the small Pico computer from the 3V of the AAA batteries also the 17VDC a small DC / DC converter on the Mainboard expires.
central processing unit
DC / DC converter circuit for the 17V of the CPU
datasheet from theC593 (source: 1977 Datacatalog GI Microelectronics)
In addition to the faux leather case, there was also a card with a user manual and a flyer. It was printed with warranty information and an advertising slogan:
“The Pico will become an indispensable arithmetic assistant for you. At school, at home, at work – wherever there is something to be expected, the Pico is at your fingertips. Just press keys, and you’ve already calculated the most complicated tasks. This is how arithmetic becomes a pleasure! “(Source: Internet)

Solar – Radiometer

The Radiometer – also called lightmill – is an instructive, physical demonstration object that was invented about 100 years ago by the English physicist Crookes. This small physical-technical arrangement clearly shows how light is converted into mechanical energy.



The working princip of the solar radiometer:

Impeller inside the part evacuated glass ball

If warm light, ie sunlight, light of light bulbs or spotlights, meets with light in the spectrum of which the infrared component is present (but not cold light from fluorescent lamps) on the wing cross resting on a needle, this will turn depending on the intensity of the light source , In a particular method, a partial vacuum is generated in the glass ball, so that the air resistance is not stronger than the rotational force of the impeller generated by the light energy. The blackened surfaces of the wing cross absorb more light energy than the bright surfaces. Due to the warming of the air molecules, a much higher pressure is created on the dark areas than on the bright areas. This causes the constant rotation of the wing cross. (Brownian Molecular Theory). Depending on the light intensity, up to 3000 revolutions per minute should be achieved. (Source: Manufacturer of the Radiometer)


DAT-Walkman Sony TCD-D3

Sony TCD-D3

At least one blog post per month to write I have set myself the goal, even if it is not always easy to implement this temporally. Anyone who has small children himself can perhaps imagine that. But in the evening and in between, I can collect material and edit it. -> it just takes everything much longer. This time I organized a Sony DAT recorder for retro audio. It is a Sony TCD-D3 from 1990-91, a so-called DAT Walkman.

DAT (Digital Audio Tape) is an audio magnetic tape recorded digitally. The recording format and the sound quality are essentially similar to those of the audio CD. The recording takes place on small cassettes, which were also used in the storage area in the EDP (DDS tapes). The DAT format was intended as the successor of the audio cassette, could not prevail in the broad market. It is also discussed here that the music industry did not want to see the format in the consumer world, as it was possible with the system to produce digital, lossless copies.

The technical structure of the cassette drive corresponds to that of a video recorder. The tape is pulled out of the cassette with loading arms and passed around a rotating head (DAT-R). The recording is done in helical scan. The copy, which I acquired this time as “defective”, was with the defect: Cassette shaft does not open, described. After dismantling, I noticed that I was not the first to look at the inside of the device after the factory. Someone was already messing around. All (tantalum) capacitors were soldered, the lead wires to the battery pole contacts were “pinched off” and the wires were missing. The Flexiprint, which connects the front panel to the mainboard, had a broken track when looked at closely.

fixed trace

The broken wire could be repaired by carefully scraping off the insulation and brazing a stranded wire. The capacitors I have all newly soldered and of course checked before. Here I noticed that some were not soldered properly and had a cold loosening at a pole or were not connected to the pad. The battery contacts were also provided with new wires. On the mainboard there is also a DC / DC converter, which makes the supply voltages for the logic and the audio components from the 9V input voltage. (5V +/- 7V). This converter is housed in a completely soldered tinplate box. Of course, nobody was inside and checked the Elkos inside. That was done quite quickly and the small box was overtaken. Now I was able to provisionally reassemble the boards and drive and put them into operation. As data carrier I used a DDS (storage) cassette. So tension on it and “Eject” pressed and lo and behold, the cassette compartment opens immediately. From my Handyaudioplayer as a music source, I made a trial recording. And what can I say, a wonderful sound quality!

The next issue to fix is ​​more of a visual nature. These are the side casings, which are coated with a rubber coating and this begins to seem to change chemically and becomes sticky. So I washed this gum carefully with isopropanol and tried not to replace the white printed lettering with. That worked quite well. With acrylic clearcoat I then painted the parts.

painted side casings

After curing the clearcoat I was able to assemble everything again and start the final test. The following pictures show the inside of the TCD-D3.

Specifications of the TCD-D3

  • Type: Digital Audio Tape Dec
  • Audiotracks : 2-channel stereo
  • Tape speed: 4.075, 8.15 mm/s
  • recording time: 240 minutes
  • headsystem: 2000rpm, rotary
  • D/A converter: 16 bit linear
  • A/D converter: 16 bit linear
  • Samplefrequency: 32-48kHz
  • Frequency Response: 20Hz to 22kHz
  • Signal to Noise Ratio: 90dB
  • Dynamic Range: 90dB
  • Total Harmonic Distortion: 0.0008%
  • Analoginput: 80mV (line), 0.25mV (mic)
  • Analogoutput: 0.5V (line)
  • Dimensions: 85.2 x 40 x 120.1mm
  • Weight: 0.42kg


Panasonic AG-6400 VHS-Portable

Panasonic AG6400

A new member of the collection of old multimedia devices is the Panasonic AG-6400. The AG-6400 is a (semi) professional video recorder from the 80s. The device records on VHS magnetic tapes and also reproduces this standard. It is portable and was the recorder for the video cameras of that time. It draws its energy from 12V NP1 batteries and can provide approx. 27W for the camera connected to it. That was about the power requirement of a 3-tube camera.

This device, too, had gotten some traces of time that largely restricted its function. Simply said – it was broken. This defect manifested itself in a stuck capstan shaft . At first I thought the shaft was ‘seized’ due to corrosion, but the reason was completely different. Interestingly, a ball bearing had been pressed out of its press fit, so that the flywheel attached to the shaft touched the bobbin of the capstan motor. The magnets in the flywheel held it in place. This error could be easily and quickly remedied by pushing back the ball bearing and then fixing it.

the videorecorder without housuing
pcb folded out to service position
view to the mechanics (drumhead)

After the mechanical fault was repaired and a first function test, a fault in the 5V power supply was still to be found on the power board. This was expressed by a failure to start all drives. Here, an IC fuse was defective in the switching converter. This was triggered by a defective Schottky diode in the buck converter circuit. This bug was also quickly solved. And after checking and adjusting the operating voltages according to the setpoints in the service manual, the drive did its job again. I was even amazed at the excellent image quality that the device could reproduce. Due to its compact dimensions, I can even use the AG6400 to digitize old VHS tapes in the future.

Elaborate wiring between the boards



In the data sheets and advertising for the AG-6400, the manufacturer has advertised some features and functions as follows:

High quality image reproduction

The tape speed corresponds to the VHS standard with a video track width of 49µm. Several technologies for clear and detailed image reproduction are combined in the device.

HI-FI Sound
A four-channel system consisting of two ‘normal’ audio channels with Dolby noise reduction and two ‘HD-Sound’ channels allow you to enjoy high quality recordings. A 3.5mm headphone jack and two 6.3mm microphone jacks for separate feeding of both channels, including separate control with VU meters, complete the range of audio options.

VU-meter and audio level controls

Time Code record and playback
For control in linear editing systems, the recorder enables the recording of external EBU timecode signals on channel 2 of the longitudinal track.

External camersocket

A connection for an external camera with a maximum power consumption of up to 27W is also available. Cameras with 3-tube Vidicon system can be connected here.

A diagram with the connection options is shown in the following picture:

Anschlußschema de AG6400 (Bild: Herstellermanual)

Technische Daten:

Manufacturer National/Panasonic  Central Osaka Japan
Year ca. 1988
System VHS Portable Videorecorder
Powersupply DC 10.5 to 16V
Powerconsumtion 14Watt, (with camera ca. 41W)
Videosystem Fourhead  rotationsystem (helical scanning)
Luminanz FM azimuth recording
Farbsignal subcarrier phaseshift Recording
Video SNR 43dB
Audiosystem Normal und HD-Audio
Normalaudio 1  fixed audiohead
HD-Audio 2  rotating heads , 1 earasehead
Stereoton Normalstereo (2Kanäle über Längsspur )
  HD-Stereo (2Kanäle über Schrägspur)
TV-System CCIR (625 Zeilen, 50Halbbilder) PAL Colour
tape speed 23.39mm/s
rewind time(180min tape) 4.5min
size 222x90x270mm
weight 3.0kg (without battery)

Sony Video8 Walkman GV-8E

Sony GV-8E

Occasionally I browse flea market websites for vintage and retro devices from the 70s, 80s and 90s. If an absolute bargain is in sight, then I strike and sacrifice a few euros. This time I found a whole box of Sony portable media players. The whole thing just cost me the equivalent of a pack of Cafe. However, the state of the devices in terms of function is also unknown. A particularly beautiful piece (yes – that’s always in the eye of the beholder) from this box is the Videowalkman GV-8E from Sony. This is a portable, analog video player / recorder that has a VHF / UHF television tuner and an LCD monitor integrated in one device. While that may not be anything exciting today, the GV8E was a very nice and expensive piece of technology when it was launched in 1988. So the portable lands on my table and gets its 6V DC supply from the power supply. The disillusionment comes as quickly as the initial euphoria. The device shows no function despite the power supply being upright. It does not react to any key press, no LED lights up. (Somehow I was expecting this or something similar)

But the ambition is too great not to look inside the device and to look for the problem. I quickly started disassembling and roughly dividing the device into its components. The service documents can be found online, which are very helpful here.

GV8E in parts

After examining the block diagram of the entire system, the start of the troubleshooting was the DC / DC converter board. This board, covered by a shield plate, produces all the voltages required for the supply of the individual components from the 6V input voltage. A measurement on the test pins on the board showed that some voltages were missing. So there must be a problem here.

solder side of the DC/DC converter board
partside of the DC/DC converter boards

After removing the shield plate and inspecting the components, I noticed a defective 1.6A fuse (F103). This fuse protects the primary circuit of the switching converter. It can be seen from the plan that transistor Q114 was low-resistance and thus caused the fuse to trip.

extract from the circuit diagram of the DC / DC converter

The transistor is a 2SB1121 bipolar PNP transistor. Of course I didn’t have that in my collection. So thinned the component boxes for a suitable replacement …

replacement for the 2SB1121 is the PBSS5250Z

Then I found a PBSS5250Z, which has a slightly larger housing, but should do its job in the circuit.

defective Q114 desodered

Due to the larger design and the limited space available, I could only solder the replacement transistor upright.

Q114 renewed

Now a new fuse is still missing in the board. After installing and checking the other components in the affected circuits, the next function test was started. All boards electrically connected again and 6V connected to the battery terminals – and look – the Powersupply board starts up and the voltages are there. Now the GV8E can be switched on again with the power button, the LED also lights up and a quiet noise can be heard from the loudspeaker. However, none of the drive motors are running and the LCD monitor remains dark. The LED lights up briefly when the “Ejekt” button is pressed, but the motor responsible for ejecting the cassette compartment does not start. That means -> continue searching for errors. First of all I will take a look at the LCD monitor. It is quickly removed and dismantled. All the less pleasing is the condition of the board. Here the “decaying” electrolytic capacitors raged with their “body fluids”. (Of course this means the electrolytes)

Leaked electrolytic capacitors

The liquid electrolytes of the electrolytic capacitors have leaked over the years and have attacked the conductor tracks and also the solder joints. Sometimes it is so bad that small components, such as SMD transistors and resistors, fall off the board as soon as they are touched. At the latest now it is absolutely necessary to have the circuit diagram of the device at hand. Otherwise it will be difficult afterwards to correctly refill the missing parts. But first the old electrolytic capacitors had to be removed.

this is what the circuit board under the electrolytic capacitors looks like

With PCB cleaner I was able to remove the remains of the electrolytes and only then could I see the damage to the circuit board. Corroded areas had to be sanded with a glass brush and burned components had to be replaced. After cleaning again, the new capacitors (this time ceramic multilayer capacitors instead of the electrolytic capacitors) have found their place.

pcb with new parts

After this procedure the time had come. The next function test started. After reconnecting all plug connections and the power supply, there were further signs of life. The backlight (CCFL) started again and in the upper left corner it was “00:00” to see the flashing clock of the on-screen display … Unfortunately, that was all. The OSD display was very blurry and the rest of the picture was white. The brightness controls did not respond. So the board had to be examined “big”.

The board of the LCD monitor still had many broken conductor tracks, which had to be laboriously repaired with individual strands and enamelled copper wire. There were also some SMD components (resistors and transistors) so corroded at their connections that only an exchange helped. The result looks a bit wild, but another function test was finally positive.

fixed displayboard

After I reassembled the monitor, I went to the drive. Here, too, I first checked or renewed all SMD electrolytic capacitors, as ALL of them had really leaked out. Fortunately, the circuit boards here were not so severely etched and can be easily cleaned. Then the function test came. And unfortunately there were still problems here. There was no cassette ejection and no reaction from any of the drives. After studying the service manual and measuring many supply voltages, I was able to identify a processor as a source of errors. It is a SONY CXP80116.

Sony CXP80116

This chip controls all drives, leds, queries sensors, etc. It is also responsible for ejecting the cassette compartment. It controls a driver IC (bridge) via pins 20 and 21, which in turn supplies the charging motor. And exactly the two outputs remained at 0V. When the “Eject” button was pressed, only a few millivolts were measured instead of the 5V. So at first there was a suspicion that the driver IC has an error and is pulling down the outputs of the controller. So the outputs from the controller to the motor driver were separated and 5V directly connected to the motor driver input – and lo and behold, the loading motor was activated. So the problem is with the 80116. After some back and forth I was able to find one of these and exchanged it. Another test pleased me, because the cassette could be loaded again and the head drum started.

And the next problem already appeared. One of the two loading arms only drove half off and then got stuck. That means I also have to disassemble the mechanics of the drive. Said and done. Fortunately, it was only a small bolt that holds a drive lever. This had loosened and slipped out. So the problem was quickly resolved. Now I was finally able to do a function test again. And this time everything worked. The cassette was loaded, the head disk started, the tape was threaded and finally it could be played. After I had tested all functions, the GV-8E can be reassembled. Now he can go to the showcase as a “museum piece”;)


working again


Technical data of the GV-8E:

  • Video recording System: Rotierendes Zweikopf-Helical-Scan-FM System
  • Audio recording System: Rotierender Kopf, FM System
  • Videonorm: CCIR, PAL color
  • Kassettenformat: 8mm Videokassette
  • Bandgeschwindigkeit: SP: 2.0051 cm/s LP:1.0058cm/s
  • LCD Bildschirm: 6.2×4.6cm (3inch Diagonale)
  • Bildschirmtyp: TN LCD/TFT active Matrix mit 92.160 Bildpunkte
  • TV-Tuner: VHF Kanal 2-12, UHF Kanal 21-69
  • Anschlüsse: RF-Antenne, Video Input/ Output Chinch, Audio Input/Output Chinch (mono), Headphone 3.5mm Klinke
  • Energieversorgung 6V (Akku oder Netzadapter)
  • Leistungsaufnahme: 7.1W
  • Abmessungen: 129x67x213mm
  • Gewicht: 1.15kg ohne Akku
Typenschild des GV -8E


Cassette player/recorder SONY TC150B

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
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




Mini-TV Broksonic

Broksonic CIRT-2097T

This beautiful, small, new piece of technology from the eighties has been added to my collection. It is a small tube radio receiver with radio part called CIRT-2097T from the manufacturer Broksonic (according to Internet research it is an US company). The device I received with the attribute “defective” quite cheap on a flea market platform. So I thought, the risk can be taken and risk a repair attempt. What great things can not be broken – if it’s not just the picture tube.

inside the Broksonic

After a short functional test with the plug-in power supply, it soon became clear that nothing was working. No picture – no sound, no nothing. Since the device also has a battery compartment, I next wanted to try to feed the power via the battery terminals to see if there may already be a problem. And there it was already – the problem. The battery cover was almost impossible to get off, it held as glued. After some back and forth, I got the lid but then non-destructive and it revealed the cause of “jamming” or better “gluing”. There were still batteries in the battery compartment (probably for 20 or more years). They were in a bad condition, totally corroded and leaked. In part, the outer coat of the cell was corroded and no longer available. Oh dear – I thought, hopefully the leaked dielectric did not move inside the unit and did damage there. There was nothing left for me to do but to disassemble and check everything. And then the evil manifested itself:

from leaked battery cells distroyed pcb

About a quarter of the TV board had come in contact with the battery fluid. And the stuff has done a great job, etched away almost all the traces and leads from components.

So I first tried with PCB cleaner to remove all the crystals and the rest of the battery juice to get a closer look at the damage. A few random measurements with the ohmmeter quickly showed that many traces were severed. So it did not help, the tracks had to be uncovered. Only then would a reasonable repair possible.

Rough cleaning with the brass wire brush

With a rotating brass wire brush, I then began to remove the etched areas, remove the remains of the solder resist and expose the copper traces.

Fine work with glass brush

After the rough preliminary work had the glass brush ran. Only with that it was possible to remove all paint and corrosion residues and finally expose the traces. A tedious job …

the exposed and repaired copper tracks

… but finally it was possible to uncover and repair all damaged areas. Some resistors and capacitors also had to be renewed because their leads were also in poor condition.

After the repair, a bump test could then be carried out – lo and behold, there was no further error and the device was working properly again. So I was able to protect the repaired area of ​​the board with solder varnish from renewed corrosion and reassemble the device.





Finally, here is an overview of the technical data:

vendor:                            Broksonic (US-Firma New York)
type:                                  CIRT-2097T
year of production:   ca. 1982
model:                               TV+FM Empfänger portable
receiverprinciple:       Superhet
screensize:                     2 Zoll SW Bildröhre
bands:                               AM, FM, SW (Radio), VHFI,VHFIII,UHF (TV)
                                              AM: 535-1605kHz
                                               VHF Kanal 2-13(US), 2-12 (E)
                                               UHF Kanal 14-83(US),21-69(E)
supply:                               battery or accu, AC with adaper
supplyvoltage:              accu 6V, battery 6×1.5V AA
speaker:                           dynamic 16 Ohms speaker
outputpower:              150mW
dimensions:                  150x53x202 mm (BxHxT)
weight:                             ca 1.1kg

Philips “Sonate” Philetta Euro280

Philips Philetta Euro 280 “Sonate”

In the years 1968 to 1970, the radio receiver was built with the inscription “Philetta Euro 280” by Philips. It is a small multi-band receiver with transistor equipment. The type designation 12RB280 / 30 with the inscription “Sonata” seems to be another version of this model. In any case, I have dug up the version “Sonata” – once again from the depths of the Kellergefilde – and after superficial cleaning connected to the mains. Immediately after switching on, the scale illumination lights up and a loud 50 Hz hum can be heard from the loudspeaker. Increasing the volume level adds some noise. So switched to the FM band and searched for a station – and lo and behold, it works. Only the buzzing disturbs. Otherwise, the device works without any major problems. To find the cause of the humming, you begin with the troubleshooting as usual in the power supply.

entfernte Rückwand

The rear panel is quickly removed and the power supply unit, consisting of a, mounted on a support plate transformer including rectifier and filter capacitors removed. Now, without using the oscilloscope and the multimeter, you can immediately see where the ravages of time have left their mark. The two electrolytic capacitors do not look quite healthy anymore.

A quick measurement of the voltages brings certainty. The DC voltages have a decent ripple, which causes the “hum”. So the function of the electrolytic capacitors to smooth the DC voltage is no longer, or poorly, given. A measurement of the capacities confirmed that. So I renewed the capacitors.

Power supply with renewed capacitors

Immediately after switching on, even before I had the probe at the measuring points, a noise was heard without “humming”. The oscilloscope image now showed a clean DC voltage – almost no ripple. The receiver worked again very clean, without disturbing background noise. That was apparently the only mistake.

Technical information:

The main principle of the receiver is a superhet (according to the superposition principle) with an IF of 460/10700 kHz. The waveband of the receiver:

frequency scale
  • long wave
  • medium wave 1 (520-1400kHz)
  • medium wave 2 (1400-1600kHz)
  • shortwave
  • UKW

The output stage has a power of 3W, which is converted into sound energy in a dynamic loudspeaker with permanent magnetic excitation. The case is made of plastic and has the dimensions 43×17.5×10.5cm with a weight of 2.4kg. The receiver is supplied with 220V / 50Hz mains voltage.



Walkman City Bummler from the 80s

IMG_3810From the early 1980s comes the “City Bummler” a mobile, portable cassette player – in short a Walkman. At that time, I received it as a Christmas present during my middle school years. The special feature of this device was a built-in microphone and two headphone ports. So you could listen to music in pairs and if you wanted to say something without having to remove the headphones (or to reduce the volume), so you had to press only  an orange colored button and the intercom was active. The device was sold as a low-priced “replica” version of the first Walkman from Sony, the TPS-L2 which came on July 1, 1979 on the market. The citybummler was distributed by UNIVERSUM via the source mailer.

City Bummler with a self made coverplate after the original got broken

The device was delivered in a box with headphones, cassette pocket and carrying case with strap. For operation, three AA size 1.5V batteries were needed. The volume control is carried out with two separate sliders, so that each channel can be controlled separately. Unfortunately, the city loafer has not passed the last 35 years quite unscathed. Over time, the cassette cover was broken off, which I then replaced in my youth with a homemade tinplate lid. At some point I did not like the case color and I painted the device green. (or I just had green paint at hand). At least the “loafer” still exists and it works too.

IMG_3814I was then on the Web in search of a well-preserved, in the original state city loafer. However, the offer is extremely low and the few offers on online auction houses are not interesting because of the immense shipping costs.

Fellow FE-1

But a compromise and at the same time a new piece in the collection is the FELLOW FE-1 Walkman. I got the most cheap and fully functional on a second-hand stock market.

left: Fellow FE-1, right: City-Bummler
both devices in comparison

The Fellow is also a clone of the Sony TPS-L2. It differs essentially in the arrangement of the keys of the drive.






IMG_3811IMG_3809IMG_3808IMG_3821 IMG_3812 IMG_3814 IMG_3819


analogue multimeter – Unigor 3n

Unigor 3n
Unigor 3n

From the years from 1964 comes the analogue multimeter Unigor 3n from Norma, respectively Goerz-Metrawatt. It was characterized by the large measuring range of 52 measuring ranges, all of which can be selected with just one selector switch. The measuring mode and polarity reversal is realized with a push-button switch. All measurements (except the 10A range) are possible on just one terminal pair.

The measuring mechanism is a “clamping band measuring unit” with a very good vibration resistance and low self-consumption.

The internal resistance for voltage measurements is a maximum of 4MOhm in the highest measuring range (see photo technical data). The voltage drop in current measurements is given as 12mV in the 120uA range and 120mV in the 30A range. The measuring accuracy is 1% for DC and 1.5% for AC measuring ranges.

Like the Unigor 6e, the 3n model is also equipped with various safety features.

The power supply of the multimeter takes over a 1.5V mono cell.


Technische Daten
technical specification