Telefunken Bajazzo 400

[Jimwall]

Hi ! Has anybody ever heard of Telefunken Bajazzo 400 radio tape anyhow this is not working on 220v ac I've checked diodes and fuses still dead!but if I put a 9v pp3 battery I get slight hiss from speaker and if headphones are plugged in barely hear FM !when switching Sw1 and Am you can head frequency changing but still hissing sound! Firstly is my Pp3 battery which is 8;5 v DC is it strong enough ? The volume a tone control work! Any guidance please! Images to follow

[Jimwall]

Images

[Tractionist]

Start by cleaning all switches ...............

[Jimwall]

Thanks for advice I did start measuring on the ac adaptor input socket and I did manage to get some sound for a few seconds! So on Sunday I resolvers the wires and no sound has come back on with a cable in. I am getting 220V AC on the account input 2pin socket but nothing across fuse or out from xformer? The xformer looked fine no heat marks the diodes n fuses are fine
The dc battery side the radio comes alive with hissing, but my pp3 battery goes from 9V to 3,6 V maybe not strong enough?also as this is a bagasse 400 I'm looking for a schematic or maintenance pdf!one thing is puzzling me is the ac socket has two wires that have 220V and another two wires that have around 8V dc these where the two wires when I touched them I got some sound but when resoldered them it remain dead

[Mr 1936]

Hi Jimwall

Some sets have a switch built into the AC input socket, so that when you push the AC cord plug in the switch opens and disconnects the internal battery. The wires with 8V on them may connect to this switch. You may need to clean the switch contacts, it should be a short circuit when the AC cord plug is removed (battery operation). The design will be such that there is good insulation between the 220V AC circuit and the 9V DC circuit.

The PP3 has the correct voltage (9V) but cannot supply the large current demanded by this type of set, especially when playing at high volume. I would expect the battery voltage to be at least 8 volts when the set is running.

[Jimwall]

Thanks 1936 I will go back to what I repaired and diagnose in reverse if sound came out the speaker then the fault has to be found I will update at the weekend ahead

[Jimwall]

This is the socket configuration as you can see the green and red wire as well as the two ac voltage wires go to the PCB.there is a metal connection that makes and breaks the green and red wire and works,also the connector switches over from ac to battery when connected and disconnected!so there are a few9 v batteries I could use the pp3 which is too small there is another bigger battery which the name I can't remember and its not popular here any suggestions

[Richardgr]

Few contenders here ..
List_of_PP_battery_sizes

It could be the PP9 you are thinking of.

[Jimwall]

Thanks now I did a little bit of fault finding and the transformer removed from the pcb seems to be shot. No output on the secondary output. There seems to be no thermal fuse on xformer
Resistance on primary seems ok secondary getting a short signal on multimeter
As mentioned earlier the 9v dc battery side turns the radio and tapedeck plays ok
So two questions arise can you get alternates for Pp9 batteries to work, or how do I know what amperage and voltage came out of the faulty transformer?

[Jimwall]

Here is the transfomer and a schematic inside the radio the schematic does not show the rating of the transformer

[Chris55000]

Hi!

The original transformer would have been a 220 V 50 Hz primary for German mains supplies and the secondary 7.0V at 250 mA for this type of set !

Allowing for the cassette motor current, plus the current taken by the Class B audio output stage at maximum acceptable volume levels, for this type of set, a 250 mA transformer is adequate because the maximum current is not being drawn from it continuously !

Allowing for 1.2 V diode drop across the bridge rectifier, the secondary rating needed is (9 + 1.2)/1.414 which is 7.2 V RMS, in practice the original would have been wound to give 7.5 V or 8.0 V r.m.s., which is the figure you should measure on the a.c. range of your multimeter.

If you get a reading across the primary (500 Ω to 1 kΩ for this small type of transformer), then failure to produce any output is eithe a wire broken from one of the secondary tags, or you've made a mistake trying to measure it with your multimeter –these small transformers are far more likely to go open–circuit on the primary side than the secondary side !

PP9 size batteries are still available from eBay and RS Components in your country and other online suppliers – I would try to get it working on the mains first as these batteries are extremely expensive !

Chris Williams

[Joe_Lorenz]

Well, ages ago I had a very similar set, a Bajazzo CR 4000. Me thinks it needed 6 batteries size D-cell or C-cell. Common faults were a spongy contact in the mains connector (has been discussed here), a wobbly switch (radio-cassette) and a loudness pot that had given up. In the end it went to the skip which I wouldn't do nowadays!

Regards, Joe

[Jimwall]

Thanks Chris and Joe will keep plugging away at this one

[AD360 Rob]

As an aside, a 9V PP9 battery will not be suitable for your radio cassette as they cannot supply the necessary current required for the tape motor to operate correctly. If battery operation is the only option then the original "C" cells are readily available

[Jimwall]

I have re measured and ohms reading red wire primary 563 ohms and the secondary 1ohm Green wire
No voltage output on secondary winding