My first task was setting up the control button and microphone for the Tranzit BLU.   The control button makes this a truly hands free system.  It is used to control the functions of the Tranzit BLU such as accepting calls, hanging up, skipping a track and so on.   This should be an any easy to reach, but unobtrusive spot.   I chose the underside of the steering column, just where it comes out near the underdash panels.   The microphone is used for hands free calling and I put it at the top of the drivers side A pillar – where there was an existing microphone from a long removed phone car kit.

To access this area, I had to remove the drivers side under dash panel.  These are very delicate now, so I had to take a lot of car.   I was then able to use electrical tape to bind together the wires for the button and microphone to push them through the back of the dash – firstly to the where the head unit would go, and then to the passengers side where the Tranzit BLU be.   This is a very fiddly job.

Because the car previously had a modern radio, all the speaker wires ended up behind the head unit.   For the Becker, they need to be in the passengers side foot well to join to the amplifier.   Normally, they would go through the fader unit, but I just joined them all up instead.    I wired them up in parallel as this is what the car appeared to do originally, albeit with a strange shared ground arrangement.

As far as I can tell, the original speakers were 5 Ohms.   Mine are 4 Ohms, so while not identical, quite close.  In parallel this should be 2 Ohms vs 2.5 Ohms, which I hope is ok.   The specifications for the Becker amplifier talk about it having 7W per channel with four speakers for 5W per channel with 2.  This also led me to believe parallel is the way to go.   The speaker wires and amplifier connection also needed to be pushed through the narrow spot behind the dash to the passengers side.  Anyone installing a Becker I would encourage you to do your own research here.

The hardest part of all of this pushing wires through narrow gaps was the antenna connection from the Tranzit BLU.   This goes from the passengers side to the head unit.  It has a 90 degree bend in the plug, which makes it very hard to push through small gaps.   Even using a guide wire to pull it through and a lot of tape to smooth it over, it took about 30 minutes of trying before I finally had it through and plugged into the Becker Mexico.

To install the Becker Mexico, the knobs front face is gently removed.   It is very easy to crack the faceplate.   There are two securing brackets that are normally used, but this part of my dash is quite cracked so I didn’t use them here.   Unlike the earlier cars it sits quite well.   While the face was off, I took the opportunity to clean it.

Before I properly installed the amplifier, I did another system test.   I found everything was working except for the control button for the Tranzit BLU.   I checked and it was connected properly.   The manual that came with the Tranzit BLU didn’t have any more help.   However, I found another version of the manual online which had an extended troubleshooting section.   This section covered using the dip switches on the unit to put it into ‘learning mode’ so it could ‘learn’ the value of the button.

The first time I tried this, it seemed to work, but pressing the button would disconnect Bluetooth.   I had managed to make it worse.   I was starting to worry I had damaged the button somehow pushing it through various dash gaps.   Trying the process again seemed to fix the issue and I now had a working control button.   The only slight annoyance is that each time I turn on the car or radio, I have to ‘engage’ the Tranzit BLU.   On the 560SEC and 300TE, I don’t.  I’ve emailed iSimple to find out how I change this.

Now it was time to install the guts of the system in the dash behind the glove box.   The original bracket for the amp was still there, and since I had the original amp, it snapped right in.   I used a couple of cable ties to hang the two relays off the bracket as well.   Looking at the photo, I see I forgot to bend back the tabs to hold in the speaker wires.  This needs to be done before I re-install the lower dash panel.

I put the lower dash panel back on the drivers side, but so far I have left it off the passengers side.   I want to drive the car a bit to make sure I am happy with everything first.   Those panels are so brittle, I am very careful how often I handle them.   I need to do a dry run for the June 2023 night drive, so I’ll probably take the 450SLC.

At least in the small test drive, I am really happy with the result.   Granted sound quality isn’t quite as good going through an FM transmitter, but its good enough and the Becker fits so well into the dash of the car.   So far the only thing I have noticed is that the ‘Stereo’ light on the Becker has stopped working for some reason.   It worked during testing, although at one point it stopped working and them seemed ok again.

The post 450SLC Becker Mexico Cassette install part 4 – Final installation appeared first on .

The challenge is that in the first 10-20 years these cars were around, they had all sorts of radios, phone kits, alarms and so on.  Most of the time the wiring for these systems is incredibly shoddy.   In many cases the companies offering these services either include them when buying the hardware, or charge a flat rage.  Either way it doesn’t allow for these things to be done properly.   It is a reason why it can be worth seeking out a car with its original radio still in place.

First was to trace all the wires going into the current radio.   The main ones I needed was the wires for each speaker, the switched power, constant power and antenna trigger.   There were some other wires that looked like they were the remains of some of the old phone kits.    The only one I couldn’t test properly is the antenna trigger, as the power antenna is not working properly.

The install ultimately has more than just the Becker.   It includes USB charging ports so the ashtray doesn’t have to be hanging open while I drive.   It is also going to include the iSimple Tranzit BLU, the same as I used on the 560SEC and 300TE.

To ensure there was no power drain, I didn’t want the USB ports to be live all the time.   I also wanted to trigger the Tranzit BLU off the Becker, so the phone wouldn’t pair when it couldn’t actually work.    This resulted in using two relays.   The first one triggered off the switched power lead and powered up the Becker and the USB ports.   I didn’t want to power the Tranzit BLU off the Becker, so used another relay for this too.  It probably doesn’t draw much current, but I don’t know exactly.     The diagram below outlines the wiring I came up with for the Becker.

I could have run the USB ports off the switched power line for the radio, but the Becker only draws 2A, and the USB ports are rated at 3A.   I am not sure if this is each, or combined.   Possibly overkill, but using relays never hurt for an application like this.   In reality though, a better place to introduce relays in the car would be for the headlights, but that could be a future project.

To try and simplify things, I used a double terminal block for the ground wires and the constant power.  I grabbed it from the 420SEL parts car, so it should be a high quality unit.   I had a couple of spare relays on hand I could use.

The diagram makes it look like there are a lot of wires, but its fairly simple.   The main concept is that the trigger for the first relay is the ignition key, and the trigger for the second relay is turning on the Becker Mexico.

Before I fully installed all this in the car, I wanted to test it all.   Would be a major hassle if I installed it all, and nothing worked.    The passengers footwell worked quite well for this.    worked out well that I did, as I had to fix a couple of small things with how I wired up the relays.

I also had to wire in the speakers from four to two.   The Becker Amplifier is a 2x7W unit.   When it was new, it went through the factory fader switch.   I’m not going to put that back in, so I just wired all four speakers to work all the time.

Testing the Becker, it sounded pretty good with music playing via my phone.   There was a small amount of background noise that was more apparent at low volume.  I don’t think it would be audible with the engine running or with the wind noise while driving.

The post 450SLC Becker Mexico Cassette install part 3 – Wiring up the Becker appeared first on .

Last year I started to source the right radios for the cars I owned.   I originally planned to start with my 450SLC, but its taken me a bit longer to sort out the radio for the car.    Based on that, I started on my 560SEC and then moved to my 300TE.    I’ve been pretty happy with these installs, so now it was time to look at the 450SLC again.

The car was originally sold with a Becker Mexico Cassette.  I still have the original manual pack in the car.   The original radio was an ‘M’ series radio.     The separate amplifier was still there, but the Becker was long gone.    I’ve been trying to work out the Becker serial numbers, and while there is some conflicting information out there, I understand that means the radio was built late 1975 to early 1976.   This seems plausible for my car given it was complianced 5/77 and delivered 7/77.   The radios were installed in Australia, not Germany, so they would have been purchased in batches and installed in cars when needed.

It took me a while, but in the end I found a couple of appropriate radios.   Even better they were both ‘M’ series radios, so they should be almost identical to the one originally fitted to the car.   I built a test rig and was pleasantly surprised.   Both radios worked.   I was able to tune FM stations successfully.   I don’t own any cassettes so I could not test this.   However, the ‘wunderbar’ autotune feature did not.   This is a mechanical automatic tuning function and a differentiator from a high end Becker radio like the Mexico and a more mid level radio like the Europa.

Luckily a friend in the MBCNSW came to the rescue and was able to help me get the radios repaired.   My focus was to make sure AM/FM and the ‘wunderbar’ were all working properly.   I don’t own cassettes anymore so I wasn’t really concerned with the Cassette function.

When the radios came back, I was really happy with their operation.   The ‘wunderbar’ is such a great feature.

Next step was to test how I was going to get music and calls from my phone into the radio.   My default choice was the iSimple Tranzit BLU HF FM injector.   I’ve used this successfully on my 560SEC and 300TE.   As well as the FM injector option, it also has the possibility of an AUX in connection.

The Becker radios without cassette, such as the period Europa II or Grand Prix have an AUX in port.   This is supposed to be used by the external tape deck.   Obviously a Mexico Cassette doesn’t need an external tape deck.   There is another port on the back of the Mexico which I understand is used for the German traffic adaptor.   This is mono only, as the Traffic input would not require stereo.   I purchased a mono input adaptor (normally used for the earlier mono Europa and Grand Prix), and while I could get audio through it, I wasn’t very happy with the sound.  I think I’ll use the FM injector as before.

Finally there was the the question of output.   The Becker radio outputs 2x7W at 4Ohms.   My working assumption was that with four modern speakers, it would be better to use a modern amplifier.   This is trivial with the Mexico Cassette, as it already uses a separate amplifier.  There are ready made adaptors on the market that accept the Becker amplifier plug and turn it into RCA outputs.   I tried one and it worked really well with a powered computer speaker on the Bench.    I have another one of the small Alpine amplifiers I used for the 560SEC install I can use here if needed.

Before installing any of this in the car, I have been doing extensive testing on the bench.  Much easier than once the radio is in the car.  During most of this testing I held the assumption I would use the external amplifier.  After hearing a Europa II Stereo without the amplifier in a friend’s W108, I’m not so sure.

In any case, the Becker Mexico Cassette is ready to install.   Now to speakers.

The post 450SLC Becker Mexico Cassette install part 1 – Preparing the radio appeared first on .

The Mexico Cassette was always standard on the 450 models, but optional on other cars in the early 70s.   At least by the introduction of the W123, it would become standard across the range.   While today it seems like a simple device, it was a very high end radio in its day.   Not only the integrated Cassette player, but the ‘wunderbar’ auto tune mechanism were not commonly found on cheaper radios.

The Becker Mexico Cassette is two piece radio with a 2x7W amplifier.  At least in Australia, it was superseded by the Becker Mexico Cassette 374 model.

Becker Mexico Cassette 370 Buttons

1. On-off switch, volume control
2. Pilot lamp
3. Tone control knob
4. Wave-band push buttons
5. Automatic push button
6. Sensitivity control
7. Manual tuning knob
8. Cartridge pit of radio
9. Fast winding of tape
10. Fast rewinding of tape
11. Ejector button

Radio Reception

Switch on radio:

The radio is switched on by turning the left-hand rotary knob (1) to the right.   Then the green operational pilot lamp (2) flashes up.  The desired sound volume is regulated by turning the same rotary knob (1) further to the right.

Tone:

By means of the left-land lever (3) the tone can be regulated according to personal requirements.

Station Tuning:

The station tuning can be done in two different ways.   The radio “Mexico-Cassette” offers the possibility to tune in a station either automatically by means of the station finder, or by hand.

Automatic Station Tuning:

After having switched on the radio, the desired wave band is chosen by depressing the corresponding push button (4).

The letters on the push buttons indicate M = medium wave, U = ultrashort wave.  When the automatic push button (5) is depressed, the dial pointer runs along the dial from left to right and stops when it reaches a station worth receiving.   Depress the automatic push button again, and the pointer will run to the next available station.   After the pointer has reached the end of the dial, it will jump back to the left, resuming station finding by moving along the dial.   The number of the stations to be tuned in automatically can be fixed by the sensitivity control (6), a three-state switch.  The different switch positions indicate:

1. Sensitive, i.e. pointer stops at many stations, also at faint-ones,
2. Medium, i.e. pointer stops at powerful and semi-powerful stations,
3. Insensitive, i.e. pointer stops at powerful stations only.

Manual station tuning:

After having determined the desired wave band by depressing a wave-band push button (4), the station can be turned in manually by turning the manual tuning knob (7).

Tape Reproduction

Playing of Cassettes:

Insert cassette, with full tape at right-hand side, into cartridge pit of radio and press until touch.   While cassette is inserted, change over from radio reception to tape operation takes place automatically.

Both volume and tone are regulated in the same way as for radio reception, by turning volume control knob (1) and tone control knob (3).

When tape reproduction is completed at one side of the cassette, the cassette is ejected from the cartridge pit the moment the end of the tape is reached.  At the same time the tuning unit automatically changes over to radio reception.   For playing the other side of the tape, the cassette is turned round and reinserted into the cartridge pit of the radio.

Ejection of cassette by hand operation:

If tape reproduction is to be interrupted before tape is finished, ejector button (11) must be pressed.   This will change over the tuning unit to radio reception whilst the cassette is ejected from the cartridge pit.

Fast winding and rewinding of tape:

By pressing the fast winding button (9) or the fast rewinding button (10) the tape is quickly wound or rewound, so to permit the selection of other music.   A short pressing of the antagonistic button stops the winding operation.

We recommend:

use on trade mark cassettes C60 and C90.   If it should be the case that once the tape entangles rewind the tape loop into the cassette by turning one of the two spools with a suitable object (pencil).

Care and maintenance:

Under normal conditions the radio unit requires no special maintenance.  From time to time the head should be cleaned with the aid of a cleaning cassette, because after any longer period of operation deposits are bound to settle there.   After approx. 1,000 operating hours the unit should be inspected by and expert and cleaned thoroughly.

Connection of supplementary apparatus:

The “Mexico-Cassette” car radio provides for the connection of an automatic antenna or a short wave adaptor as supplementary apparatus.

The post Becker Mexico Cassette 370 Operation Instructions appeared first on .

The car was quite original except for the broken 90s cassette player. Being a 1979 model, it would have come with a Becker Mexico cassette with a black front panel and the large knobs. The S-Class and the 280CE all got the Mexico, whereas the lower specification models had to settle for the Europa cassette. The big difference is the Mexico cassette has an external amplifier and the ‘wunderbar’ auto tune feature.

A wrecker in Bendigo had one of these radios, which was promptly purchased. Even though the Beckers with the black front panel are not as desirable as the pinstripe models, they are actually harder to find. They were only fitted to cars for a couple of years in Australia.

Our task for the evening was to test and install the radio. I already had a test rig set up from my Becker radio testing. These radios are very simple to set up. There is a switched power feed, ground and left/right speakers. There is also a cable between the remote amplifier and the radio.

We were quickly able to establish that the radio worked! It was able to tune FM correctly, volume, treble/bass all working correctly. The stereo light would come on when a station is strong, as it is supposed to. Surprisingly, all the bulbs worked. On the downside, the ‘wunderbar’ auto tune feature was no longer working, we could not test the cassette function as I don’t own one, the actual stereo decal in front of the bulb was missing, and we couldn’t test AM as it never seems to work inside the warehouse.

That was enough to install the radio in the car for now. The ‘wunderbar’ is a nice to have feature, so it could be repaired at another time.

Next step was to have a look at the car, to see how badly the previous installer had hacked up the wiring. I was also wondering if the original amplifier was still there. A lot of times, installers would just cut the wire and leave the old amplifier in place.

Turns out the bracket for the amplifier on the passengers side of the car was still there, but all traces of it and its wiring were gone. The installer had been rather lazy and just wired the 90s radio into the original speaker wiring. They had even left the fader in place. Both left channels were spliced into the left channel for the car, and same with the right. It was all held to together with electrical tape, so it was pretty simple to entirely remove the old radio wiring. I then used an AA battery to check if I could get sound out of each channel. I got static from both front speakers, and the left rear. Its possible a connection has come undone at the back for the right rear. Fader still worked.

I had some proper Becker connectors from my parts car, so I was able to re-attach Becker connectors to these original speaker wires. A quick test before putting it in the car was that the sound was pretty good. Even with the power antenna down, FM reception was decent.

On install, the speaker wires were not quite long enough to allow the amplifier to go back in its bracket. That could be a future improvement to add some more speaker wire. By this time it was almost 11pm. For now the amplifier was able to slot in under the glovebox and out of site. I also couldn’t see a trigger wire for the antenna in the back. Another improvement would be to trace where that is and see if the power antenna is still working.

With only a couple of hours work, the car now has a working Becker Mexico Cassette, similar to the one that it left the factory with.

The post Reinstalling a Becker Mexico cassette in a 1979 450SE appeared first on .

The most significant difference between the Becker 374 and the similar looking Europa was the auto tune feature.   This is commonly known as the ‘Wunderbar’.   This version of the Mexico also features auto reverse, which the Europa did not get until later.    The Europa was found in W123 models of the same era.   My 1979 280SE is equipped with the Becker 374 Mexico.  The Mexico was also a two piece unit with a separate amplifier.

Becker 374 Mexico Buttons

1. On/Off Switch, Volume control
2. Tone control
3. Waveband push-buttons
4. Waveband display
5. Manual selector knob
6. Automatic push-button
7. Sensitivity switch
8. Stereo indicator lamp
9. Cassette slot
10. Track change-over
11. Track indicator
12. Fast forward
13. Fast reverse
14. Cassette ejection

Becker 374 Mexico Radio Instructions

Switch on/off

Turn the left knob (1) to the right.   The scale will illuminate.

Volume

To increase the volume, turn knob (1) further to the right.

Tone

The tone can be varied infinitely by the stub lever (2) on the left knob.   Lever up – high tone, lever down – deep tone.

Waveband setting

The desired waveband is set by pressing one of the waveband push-buttons (3).  The waveband display (4) illuminates simultaneously – M for medium wave and U for ultra-high frequency.

Station choice

Stations in the set waveband can be chosen by turning the manual selector knob (5).

Automatic station selector

Press the automatic button (8) briefly.   The pointer will traverse the scale from left to right, and will stop at a transmitting station.   At the end of the scale the pointer will jump back to search the scale again.

Sensitivity switcher (7)

The stub lever (7) on the right knob is used to determine the number of stations which are automatically tuned:

I = Pointer stops at many stations even those received only weakly
II = Pointer stops only at stations from which medium-strong signals are received.
III = Pointer stops only at stations giving strong signals.

Stereo Indicator lamp (8)

The stereo indicator lamp (8) illuminates when a chosen station is transmitting stereo signals.    Note! Perfect stereo reception is possible only in areas with sufficiently powerful transmitters.   The unit is thus fitted with a continuous mono/stereo change-over, i.e. when the received signal weakens, the equipment switches automatically to mono reception.   The stereo indicator lamp continues to light up however and extinguishes only when the station can no longer be received satisfactorily.

Becker 374 Mexico Cassette functions

With the Reverse cassette section of the MEXICO CASSETTE VOLLSTEREO the cassettes need no longer be turned over at the end of the tape – i.e. on reaching the end of the first side the unit switches automatically to the second track.

Tape Playing

Insert the cassette into the cassette slot (9) and push in up to the stop.   Switching from radio to tape is automatic.

Track indicator (11)

The track indicator shows which track is being played now.

Track change-over

By pressing the track change-over button briefly the opposite track can be played.   At the end of the tape the change-over is automatic (continuous operation).

Fast forward (12) and fast reverse (13)

By pressing the forward (12) or reverse (13) buttons the tape is advanced or rewound quickly to choose other pieces of music.   A brief press on the opposite button stops this winding process.

Cassette ejection

The operation of the ejection button (14) ejects the cassette from the cassette slot, and the unit switches automatically to radio reception.

We recommend:

Only use branded cassettes C60 and C90.   Chromiumdioxide and Ferrochromium cassettes can be played without damaging the tape unit.

Through vehicle vibrations the tape roll in cassettes can shake loose.   It is thus advisable to store cassettes in commercially available cassette boxes with tape spool locks, where they are also protected from dust.   If despite this the spool has loosened or a loop has developed in the tape, rewind the tape by turning one of the spools with the point of a pencil.   To prevent distortion of cassettes, protect them from direct sunlight or excessive heat.

Care and maintenance:

By cassettes the quality of reproduction gradually diminishes as deposits on the playing head are unavoidable.   The playing head should thus be cleaned from time to time by using a cleaning cassette (available at your specialists).  Be sure to pay close attention to the instructions included with the cleaning cassette!  After about 1,000 hours of operation the equipment should be serviced by a service expert.

Connection of accessories

Possibilities here are automatic antenna, short-wave adaptor, traffic waveband adaptor, and EIC adaptor (interference suppression).

Fade-over control

When additional loudspeakers are installed at the rear of the vehicle the sound distribution can be varied between front and rear speakers by the fade over control.

Antenna trimmer:

After installation the antenna trimmer must be adjusted for optimum medium wave reception.   Therefore select a weak station in the medium waveband at about 1500kHz.  Insert a suitable screwdriver in the opening in the front panel below the manual selector knob and by turning lightly adjust the antenna trimmer to the maximum volume.

Becker 374 Mexico Technical Data

Radio Section:

Semi-conductors:   33 transistors, 38 diodes, 5 ICs
AM-circuits: 3x RF (variable), 7x IF
FM-circuits: 3x RF (variable), 12x IF
Wave ranges:  (AM) M 510-1630kHz, (FM) U 87.5-108MHz (stereo)
Station choice:  Automatic selector, Manual selector
Stereo-decoder:  PLL-switch decoder with continuous mono/stereo change-over
Intermediate frequency:  AM 460kHz, FM 10.7Mhz
Fading control: effective for 2 stages
Limitation:  2 diodes
FM: Automatic frequency control (AFC)
Tone control: Continuous with intermediate lever
Output voltage: 2x5W with 2 loudspeakers, 2x7W with 4 loudspeakers
Loudspeaker Impedance:  5 Ohm
Possible connections:  Automatic antenna, EIC-adaptor, SW-adaptor
Operating voltage:  12V minus to mass
Current consumption:  0.36-1.3A depending on modulation
Fuse:  5 AT
Dimensions:  Radio 185 x 52 x 167 mm, NF-part 147 x 42 x 55 mm

Cassette section:

Tone carrier:  Compact cassette C60, C90
Tape speed:  4.76 cm/sec.
Operating method:  Stereo reproduction, automatic reverse with track indicator.
Motor:  Electronically regulated direct-current motor
Cassette ejection: by pushing the ejector button, automatically when power supply is interrupted
Track change over:  By pressing the track change over button automatically at tape end
Change-over radio/cassette: Automatically when cassette is inserted and ejected.   Automatically at radio information if VK-5 is connected.

The post Becker 374 Operation Instructions appeared first on .

In most countries, the CD Player was an optional extra even on the 560 models, but Mercedes-Benz Australia priced them so high they needed justification for the difference between the 420 and the 560.   This was harder than in other markets as Australian 420SELs come with a very high level of standard equipment.

My 1987 560SEL is still equipped with a working Becker 868.   At least I know the radio works well.   I threw away all my old CDs about a year before I purchased the car.    I had never really examined the manual before, but wanted to compare with the Becker 1402 I was looking at earlier in the week.    I’ve never really needed to examine the manual as the radio function is actually simpler than the cassette player.

I’ve never been able to find much information about the Becker 868.  It seems to be a derivative of the Becker 860, which is sometimes for sale in Europe.  In later years (around 1990 or so), the 868 was replaced by the 874.   It looks very similar, but has an unlabelled button to the right of the ON button.  It also seems in other markets the 876 was the most common player.   I can only assume there were minor regional differences like the cassette players.

Becker 868 Buttons

1. ON/Off
2. Digital Display
3. Volume Control
4. Tone Control, bass
5. Tone Control, treble
6. Indication for tone control
7. Wave band – and station recall button
8. Indication for pressed station recall button
9. Automatic bar
10. Function control button
11. Manual tuning (decreasing station frequency)
12. Manual tuning (increasing station frequency)
13. Wave band indicator
14. Stereo indicator
15. CD-slot
16. Selection key (forward)
17. Selection key (backward)
18. R/CD-key
19. Eject button
20. Light diodes

Becker 868 radio functions

On/Off

To switch on the radio, push button (1).  The radio will ‘remember’ the last station tuned and the last volume and tone setting before the radio was turned off.   The station frequency is displayed (2).   By turning the ignition key from position 1 or 2 to position 0, the radio is turned off.   By pressing the key (1), the radio is turned on again.   To switch off, push button (1) again.

Volume

Pressing button (3) downwards will decrease the volume, pressing button (3) upwards will increase the volume.

Tone

By pressing the button (4) the bass is boosted or reduced, by pressing the button (5) the treble is boosted or reduced.   Pressing buttons (4) and (5) at the same time gives an intermediate setting.  The indicator (6) show, how bass and treble are set.

Wave band selection

Select desired wave band by pressing one of the wave band buttons (7).  The indicator (13) shows the set wave band.

Wave band

U = ultra-short wave (FM) – 87.5 MHz – 108 MHz
M = medium wave (AM) – 510 kHz – 1620 kHz

Station tuning

Stations can be selected either by automatic search, numerical frequency input, manual tuning or the preset buttons.   For good FM-reception we recommend to tune in the most powerful, local station.   Enclosed you find a cassette explaining physically caused radio interference, their causes and possible helps.

Automatic search

Press automatic-bar (9) downwards (= decreasing station frequency), or upwards (= increasing station frequency).   The radio has a three-stage sensitivity switch.   It searches for the powerful stations during the first sweep, for the less powerful during the second sweep and for the weak ones during the third.    When starting the automatic search you can select the desired sensitivity state directly by pressing the automatic-bar (9) twice (= less powerful stations) or three times (= weak stations).   If the automatic-bar is pressed again within approx. 8 seconds after a station has been tuned in, the station search will continue along the same sweep as before.

Numerical frequency input

You can select stations in all wave bands by entering the station frequency.   Frequencies beyond the frequency ranges are not accepted.   In the FM-band the input of the station frequency is limited to one digit after the decimal point.   The first digit after the decimal point must be keyed in!   Example FM-station 95.0 MHz:  Select FM-band by pressing one of the U-buttons (7), press function control button (10).  The display (2) disappears, the station is mute.  Press buttons (7) in the sequence 9, 5, 0.   The station frequency will then be displayed and the station be heard.

Manual tuning

Press the button (12) (increasing station frequency) or press the button (11) (decreasing station frequency).

Station recall buttons

All wave band buttons (7) are at the same time station recall buttons.   You can store 6 FM-, and 4 AM-stations.   Example:  The FM-station 95.5 MHz should be stored at one of the U-buttons:  Set wave band by pressing one of the U-buttons (7).  Select FM-station 95.5 Mhz by numerical frequency input, automatic search or manual tuning.   Press the desired U-button (7) and hold down until the frequency of the station to be stored re-appears in the display.

Now the last set station becomes audible and its frequency is displayed.   Then the radio is mute and the display disappears.   After that the new set station becomes audible and its frequency is displayed.   Now the station is stored at this button and becomes audible whenever the same button is pressed and as long as the car is in the the transmitter range of the station.  When storing another station at the same button, the station stored before is cleared.   When recalling a stored station, the indicator (8) shows the number of the pressed station recall button.

Stereo reception

The indicator STEREO shows that a chosen FM -station is transmitting stereo signals.   Good quality stereo reception, however is possible only in areas of high field intensity.   Your radio is fitted with a continuously operating stereo decoder which automatically switches the radio from stereo to mono reception, if the signal becomes weaker.  The stereo indicator remains lit.   If the signals of the tuned in station become too weak, the stereo indicator lamp (14) goes out.

Becker 868 Compact disc reproduction

Notes on compact discs

• Hand the disc by its edge, and keep the disc clean, do not touch the rainbow coloured surface.
• Do not stick paper or tape on the labeled surface
• Do not expose the disc to direct sunlight or heat sources such as hot air ducts, or leave the car parked in direct sunlight where there can be a considerable rise in the temperature.
• Before player, clean the disc with an optional cleaning cloth, radially from the inside to the outside.
• Do not use solvents such as benzine, thinner, commercially available cleaners or anti-static spray intended for analog discs.
• After player, store the disc in its case.

Disc play

Before inserting a compact disc, switch on the unit by pushing the ON/OFF key (1).  Insert the disc into the disc slot (15) with the label surface facing up.  The disc is automatically loaded into the unit and play starts at the beginning of the first selection.   The indication shows the operating mode CD, track number, and the tone control setting.

When the last selection has been played, the unit switches automatically to radio reception.   As long as a compact disc is in the slot the two light diodes (2) at the right and left side of the CD-slot illuminate.

R/CD-key

With the R/CD-key (18) you can switch to radio reception during CD-reproduction.  By pressing the R/CD-key again, play starts from the last reached point.

Selection keys for-/backward

By pushing the selection key (17) once, you can repeat the selection being played.   By pushing the key (17) several times, you can repeat several selections or the whole disc.   By pushing the selection key (16), the momentarily played selection is faded out, the reproduction starts at the beginning of the next selection.   By pushing the key (16) several times, you can skip ahead until the beginning of the last selection.   The indicator shows the selection that is played at the moment.

Eject button

Shortly press the eject button (19) to remove the disc and to switch to radio reception.   If the disc is ejected  and left for more than 15 seconds, the disc is automatically inserted into the unit again to avoid damage and dirt.

Precautions

• If the disc is automatically ejected, remove the disc and load it again.
• If you car was parked in direct sunlight and there has been a considerable rise in temperature inside the car, allow the unit to cool off before operating.   If the temperature exceeds 60C or more, the protection functions and the player cannot be operated.
• On a rainy day or in a very damp area, moisture may condense on the lenses inside the unit.  Should this occur, the CD-player will not operate.  In this case, remove the disc and wait until the moisture evaporates.

Becker 868 physical connections

1. Chassis (-)
2. Switched (+)
3. Illumination
4. Permanent (+)
5. Connection socket for automatic antenna (+12V)
6. Loudspeaker sockets
7. Antenna socket
8. Fuse 5 AT
9. Connection socket for speed dependent volume control
10. –
11. Connection receiver – CD-player
12. AF connection
13. Direct voltage converter

Attention!

Before installation remove the red transport screw at the back and keep it in the marked out thread for later transports (see fig.). To guarantee sure operation the unit should not be installed more than 20 degrees titled.

Upper diagram:  Radio secured with transport screw.
Lower diagram: Screw in thread for later transport.

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The first car in line is my 1977 Mercedes-Benz 450SLC.    When I purchased the car in 2003, it had a 90’s era cassette player installed.   I had just returned from America and had the Pioneer MP3 CD player from my 1986 300E available, so I had it installed in its place.   For a radio that is over 20 years old, the Pioneer has done well.   In the last year or so, it has started to play up a bit.  It also lacks hands free function, an important feature with the strict mobile phone use laws in NSW.     One option would be to replace it with a modern head unit that has this capability, like the one in my 560SEC.     The modern radios especially look out of place in this car, so now was the time to replace it with a proper Becker radio.

My 450SLC would have been sold new with a Becker Mexico Cassette.    I actually found the original amplifier behind the dash, not hooked up.    There are more varieties than you might think of this this Becker radio.   I looked at a lot of cars for sale, and consulted with a MBCNSW member who has a very original 1977 450SE.

Through this, I was able to try and piece together some of the differences.   I’m still looking for more information on this topic to really understand, but the visual differences seemed to be as follows:

• The very early radios have a small balance wheel under the volume knob.  I understand these radios were available around 1971-1972.    The AM/FM buttons are labelled M and U.   The model insignia says Becker Mexico Cassette at the top, with Mexico in script, and the Becker and Cassette being lower case.    There is no stereo light on the radio, but the tape flap says stereo.   There are no markings for the secondary functions for the knobs.    The rewind/fast forward buttons have a single arrow pointing inwards.  I do not believe this radio was supplied on Australian delivered cars, but is seen on imports.   I’m also told there is a slightly later version of this radio with the stereo light, but not the other changes of the mid production model.

• The mid production radios do not have the balance wheel.   There seems to be versions that have AM/FM on the buttons and some say M/U.   The model insignia still says Becker Mexico Cassette, but the Becker and Cassette are now in upper case.    Secondary functions are shown for the two knobs, left being bass/treble and the right being tuning sensitivity.   RW and FF buttons are double arrow facing outwards.    I still haven’t worked out if there are distinct varieties here.   I’ve seen both AM/FM and M/U buttons in the same (M) serial number range, so the variations may have been based on market too.

• The late production radios are similar to the mid production units, except the model insignia says Becker Mexico in all caps, with the cassette door now saying Cassette.    I’ve only seen this model with AM/FM buttons.   From what I have seen this was available from 1978 onward.    For Australia, that means 1978 only, as for 1979 we got the black Becker with the big knobs.

My 450SLC is a 1977, so it should have the mid production version.    I would have been happy with any of them, as the difference is quite small, but I have been able to find an early and a mid production, both of which need repairing.  Hopefully at least one of them is repairable.    I don’t own any cassettes, so I am just going to get the radio working.

It is possible to have these radios modified so the cassette function is replaced with a Bluetooth module.   I may do that, but I prefer to keep things original so I have come up with a different solution.   I’ve found an FM injector that not only allows mobile phone music playing, but also hands free.   In the past, I was not a fan of playing the music through a phone, as I had a work phone that was managed by my employer.   Therefore, I couldn’t load my music on the phone.   My current employer does not have this arrangement which gives a bit more flexibility.

I also plan to use this FM injector on my 560SEL, as I have not been that happy with the normal FM transmitter I have in that car.   I get a lot of interference, and I still need to drive around with the ashtray hanging open.

While my primary focus has been finding a solution for my 450SLC, I was also interested in doing the same for my 560SEC.   It has an Alpine MP3 CD player I quite like.    But it doesn’t look as good in the car as a Becker does.   On checking the data card, the car came with a Grand Prix Cassette (option code 251).  Unlike in Australia, the CD player was not standard on 560 models in the UK.   My goal was to source the right radio, even if I didn’t install it right away.   These radios are getting more and more desirable, and harder to find.   Better to get one now, and have repairs done while parts are still available.

The original Becker radio would have almost certainly been a model 754 or minor variation.   This was available in 1986 and 1987.    The 754 is not the best radio to re-install because it uses an internal lithium battery to keep the radio unlocked.  If this battery gets too old, the radio locks and it must be unlocked by a Becker service centre.    A much better option is a 1402 or 1480.   The 1402 was standard in Australia for the 126 (outside the 560) from 1988 to at least 1990, and has a code to unlock.    This means no battery to mess with.    The 1480 was used in the USA for 1990 and also simply requires a code to unlock.   It has a very similar face, but with a silver strip running along the front, and the Mercedes-Benz logo on the tape door.

It’s probably better to avoid the 780 and 1432.    The 780 integrates with the factory alarm, and was fitted to cars sold with the alarm system.    If not removed with the alarm properly disarmed, the radio is locked and again requires a Becker service centre to unlock.    It looks like it can be installed without the alarm system connected, but its one more risk of an issue.   The 1432 was a two piece unit, with the second piece in the boot, same as the CD player.   Most of the time you see them for sale its just the head unit, which is useless without the other piece.

I was able to find a 1402, which was working when removed from the sellers car.   It was missing the plugs, which I got from USA eBay.    I was also later able to get some more from the Las Vegas junkyard.    Since I am going to send the Mexico cassette off for repair, I wanted to test the 1402 as well.

In order to make a test kit, I grabbed the original speakers from the 420SEL parts car.   The Becker was long gone, but the speakers were still original, and even better had their original connectors.   Making it even easier, there is a connector very close to the speaker, so I had them out in minutes and they plug directly into the 1402.   I then used an old car battery I have lying around for testing, and some test wires to make a temporary harness.

In short order I was able to get the Becker 1402 to fire right up.   The wire for illumination worked correctly too.    It was even able to pick up a station playing country music without an antenna.   I’m not a fan of country music, but I was very pleased to hear it coming through the speakers.

Next I hooked up the FM injector.   In no time, I had music from my phone playing through the Becker radio.   Despite the original speakers from the 420SEL, it sounded ok, if a little tinny.    Will sound much better with good speakers.     It’s also been good to validate the FM transmitter.   I’ll likely be installing it in my 560SEL too.    It’s called an iSimple Tranzit BLU HF.   Not sure if its a temporary lack of stock, or it’s going out of production, but I grabbed a few while I could.   They were about a third of the retail price, so not a bad deal.

Due to the simplicity, I may even install the FM injector into the SEL before I do the full Becker Radio installs in the other cars.

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