Blaupunkt (car radio) positive earth conversion

[david squires]

Hi,
I would really appreciate some advice on converting a Blaupunkt Frankfurt car radio (7631642000) to positive earth. The radio has a label on the top cover describing the conversion by "changing the soldered connections on the board" - but the rest of the label is missing.
I'm hoping to fit the radio to my 1964 Sunbeam Alpine.

Thankyou
David Squires

[chris wright]

Is your Frankfurt a valve/transistor or all transistor model and what year is it.
A 64 model would be a U serial prefix and probably an all transistor, but a 62/63 (T) could be either. If it's a hybrid, I don't have the answer to your question yet but I may when the schematic arrives from Germany in a day or two.

64 Alpine's are great cars!

My hybrid Blaupunkt is now in my 64 Razor Edge Karmann Ghia and I've constructed the MP3 cable with attenuator following the advice in these forums. I've tested it on a Walkman as I'm hoping for an MP3 for Christmas.
It works fine.
Rgds chris

['LIVEWIRE?']

Originally Posted by david squires

Hi,
I would really appreciate some advice on converting a Blaupunkt Frankfurt car radio (7631642000) to positive earth. The radio has a label on the top cover describing the conversion by "changing the soldered connections on the board" - but the rest of the label is missing.
I'm hoping to fit the radio to my 1964 Sunbeam Alpine.

Thankyou
David Squires

David,
Not sure what year your radio is, but, from memory the connections concerned are on the amplifier PCB in all transistor models. As Chris says the year oof manufacture is identified by the letter preceding the serial no., up to 'Y'(1968). I have in my workshop(abt 3/4 mile from here) a Kon 'V' (1965) and will check how the polarity change is done on that, should be the same as on a Frankfurt of the same age. Most BP sets of that era were also dual voltage(6/12v) as well.

[chris wright]

Hi,
I received the documentation for the T code (62/3) Frankfurt valve and transistor radio this morning. If this is like your model then this is how to change it's polarity.

The amplifier box has a ribbed metal plate in the top surface which pivots expose the fuse and a square plastic plug with an arrow on it. There is a + and a minus marked to the rear of that plastic plug. Pull the plastic plug out and revolve it so the arrow points towards the + (which is diagonally towards the rear of the fuse). Just to be clear, the rear is the surface with the transistors and cooling ribs.

Note that you ONLY need to change the polarity on the amplifier. To change the voltage from 6-12, there are other plugs under sliding plates which need moving on BOTH the Radio and the Amp sections.

There is yet another sliding plate on the side of the radio which allows access to the aerial trimmer.
Rgds chris

[Biggles]

If you are still having problems with fitting the radio, I'm local to your area and may be able to lend a hand. Send me a PM if you need help.

Biggles.

['LIVEWIRE?']

Originally Posted by 'LIVEWIRE?'

David,
Not sure what year your radio is, but, from memory the connections concerned are on the amplifier PCB in all transistor models. As Chris says the year oof manufacture is identified by the letter preceding the serial no., up to 'Y'(1968). I have in my workshop(abt 3/4 mile from here) a Kon 'V' (1965) and will check how the polarity change is done on that, should be the same as on a Frankfurt of the same age. Most BP sets of that era were also dual voltage(6/12v) as well.

8.06PM 1/12/06

The Koln 'V' radio(all transistor, by the way) has reverible plastic plugs to change the polarity and voltage. I guess yours must be an earlier model if you have to change soldered connections

[david squires]

Thank you everyone for your extremely quick replies,
the Blaupunkt Frankfurt car radio has ID number E2922217, I understand that the 'E' identifies the year. The radio has the amplifier integral to the main case, and not seperate as I have seen on other Blaupunkt radios. On the rear face of the case, next to the power cable is a 6 pin plug socket with a mating clear plastic plug incorporating two jumper pins. There are no markings on the socket or plug identifying voltage or polarity configuration though.
The incomplete instruction label on the case suggests that the positive earth configuration is made by changing soldered connections on the board. The missing instruction appears to be a diagram illustrating the position of the connections on the board.
Once again, your advice would be most appreciated, and thanks Chris for the Alpine encouragement
best regards
Dave Squires

[chris wright]

Hi David,
This is a bit of a Mystery. E is 61/62 but at that time as i unserstand it, all Frankfurts were hybrid (valve in the main box and transistor power pack and amp.

Earlier models didn't start with E and your description of the plastic covered input socket with a jumper in it is very definitely like the later all transistor versions. Here is a useful web site for checking models (but I don't see anything that actually matches the description on here).
http://members.aol.com/porshalaka/De...nktRadios.html
Let us know more and if possible a picture or a link to a picture would help.
Rgds Chris

['LIVEWIRE?']

Originally Posted by david squires

Thank you everyone for your extremely quick replies,
the Blaupunkt Frankfurt car radio has ID number E2922217, I understand that the 'E' identifies the year. The radio has the amplifier integral to the main case, and not seperate as I have seen on other Blaupunkt radios. On the rear face of the case, next to the power cable is a 6 pin plug socket with a mating clear plastic plug incorporating two jumper pins. There are no markings on the socket or plug identifying voltage or polarity configuration though.
The incomplete instruction label on the case suggests that the positive earth configuration is made by changing soldered connections on the board. The missing instruction appears to be a diagram illustrating the position of the connections on the board.
Once again, your advice would be most appreciated, and thanks Chris for the Alpine encouragement
best regards
Dave Squires

What Physical si is your radio? If it measures about 7"(178mm)x5"(127mm)x1.8"(46mm) it is almost certainly early to mid 1970s. The only thing that puzzles me(and I worked from late 71 to 1995 as Radio Repair engineer for a Blaupunkt Dealer) is that, so far as I remember all the smaller, single unit radios were 12v Negative Earth Only. The amplifier was a4 or 5 Transistor unit mounted in the LH side, as viewed from the front, the output devices being AD161 &162. The 7 631 xxx xxx part no., suggests to me that the model dates from 1971.(There is possibly also a 3 figure stamped on no. (e.g. FD245) this is Manufacturing Date 1972, week 45. The 6pin socket is for the connection of a car tape recorder or player, but could be adapted to take Ipods, etc, though the output would only be mono. The connections to this socket have been noted on other threads recently, the two pins bridged by the shorting link being Radio AFout (pin 1) and AF i/p to amplifier(pin2) On these radios the power connection is to a 1/4" 'Lucar' terminal above the DIN Socket.