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Old 12th Sep 2017, 8:34 pm   #1
poppydog
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Default Telefunken Partner Compact 101L

I have a very tidy Telefunken partner compact 101L radio/cassette in an unmolested state until now. The problem I have is its very quiet on all wavebands i.e. there is hardly any volume. If I plug some headphones into it its still very quiet and a little distorted, however, if I plug a din lead into it and play it through one of my grundigs, its fine, but if you try to play the grundig through the telefunken its still quiet. Where should I be looking?

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Poppydog
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Old 12th Sep 2017, 8:54 pm   #2
Tim
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Default Re: Telefunken Partner Compact 101L

The din output/input is usually between the input pre-amp stage and the power/audio amp. If you get signal out of the din socket ( you haven't said whether on radio, tape or both) but not out of the speaker( and feed in a known good signal and no output) then I would suspect the audio amp and /or switching to. This assumes the din lead is wired correctly.
See if you can feed a signal in across the volume control. You may need a 10u cap in series just in case of DC going back into your signal source.
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Old 12th Sep 2017, 9:17 pm   #3
poppydog
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Default Re: Telefunken Partner Compact 101L

Thanks for the reply, I should have been a bit clearer with this problem. I get sound out of the telefunken speaker however it is very quiet, I get this using the radio function only as I can't use the tape side as the belt is on its last legs. When the din lead is plugged in and I try to play my grundig through the telefunken its also very quiet through the telefunken speaker. I haven't got anything I can feed across the volume control.

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Poppydog
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Old 12th Sep 2017, 10:23 pm   #4
simpsons
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Default Re: Telefunken Partner Compact 101L

I would get the schematic for this model from the web but wonder if it is similar to the Japanease made Bajazzo CR7500 using a TBA810 sound output IC. Other Telefunken radio cassette models are of German design.

In any case, check out the sound output chip type as the sound is OK up to the volume control this would be my first port of call.. Look up the data sheet and see how close the DC levels are. Perhaps bridging the coupling electrolytic from the volume control slider just in case it has dried up before digging too deep.

The clue is that sound is available at the DIN socket. There is not much left to go wrong after that!!

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Old 13th Sep 2017, 8:26 pm   #5
poppydog
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Default Re: Telefunken Partner Compact 101L

Thanks for the replies.

Thankfully it has no IC chips (I cooked one over the weekend ), it has SI transistors throughout. As said, before I go delving too deep I thought I would look at the obvious. If I switch the radio on and put a wet finger on one end of volume pot I get a hum, if I keep my finger on it and move the pot up and down the hum goes up and down in volume as it should thus eliminating any fault with the speaker. The music however goes up and down but still very quiet. If I plug my headphones in and repeat the test the same thing happens through my phones, hum goes up and down in vol as it should and the music goes up and down, however the music is still very quiet. Does that also discount the output stage and the earphone socket? Hope you can understand what I mean. I've also managed to get a tape to play and its no different. I will look around the din socket to the output stage for dry joints etc. as it seems there is a problem between those two.

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Old 13th Sep 2017, 11:23 pm   #6
simpsons
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Default Re: Telefunken Partner Compact 101L

Hmm

I've just downloaded the schematic from www.radiomuseum and it shows an IC TBA570Q (IC 101) driving the audio output transistors. This IC is also used as am mixer and AM/FM IF amplification.

Pin 12 of the IC receives audio in from the volume control slider via C411 1uf; Pin 11 is audio out to T402/T403 audio output transistors. T401 sets the DC level via R416.

The DIN socket connection is from the top of the volume control and if the right volume level is there, then it shouldn't be too difficult to see why it isn't loud and clear out of the loudspeaker.

Chris nee Simpsons

Last edited by simpsons; 13th Sep 2017 at 11:25 pm. Reason: can't spell
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Old 14th Sep 2017, 12:38 am   #7
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Default Re: Telefunken Partner Compact 101L

Hello chris. TELEFUNKEN PARTNER COMPACT 101L is what I downloaded from radio museum a while back and it matches with what ive got here, unless my homemade wine is playing tricks on me. I see no ic chips only Japanese si transistors ( it is late mind ) regards poppydog
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Old 14th Sep 2017, 8:22 am   #8
simpsons
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Default Re: Telefunken Partner Compact 101L

Hello Poppydog

I think it must be the wine that's fuddled me!! DOH! "Insert brain here"

I can now see that there were 2 Telefunken models sharing similar model numbers but that is all. Dah dah Partner 101 and 101L. On closer examination the schematic I downloaded was for the 101, sorry for the wild goose chase.

I've exceeded my download on the radio museum site and so if you wish to upload your copy of the schematic, I like to think more light can be shed on the problem.


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Old 14th Sep 2017, 11:03 am   #9
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Default Re: Telefunken Partner Compact 101L

Quote:
Originally Posted by simpsons View Post

I've exceeded my download on the radio museum site and so if you wish to upload your copy of the schematic, I like to think more light can be shed on the problem.


Chris nee Simpsons

Not a good idea. RM is quite (rightly IMHO) protective of its IP.
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