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  1. #1
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    Tandberg TR-200 problem 1 kanal

    Dear all, sorry for my writing in English, but I could not get any help on other forums and here I can see some specialists in Tandberg electronics.

    My problem is: I have a TR-200 and I get the sound coming only from the left channel (A and B). I have checked the 4 big electrolytes, other smaller ones also seem to be OK. Output transistors (2N5496) and driver transistors (MPSU06/56) are also OK, I have checked only some resistors and they seem OK. I don't see any traces of burnt components, dry solder joints, bad connection etc.

    I have cleaned and measured the balance potentiometer with my meter and it seems to be ok - when I turn the knob in the left position I get no sound from L channel, visa versa with the R channel.

    I have swapped the cable from the preamp R channel to the L channel and I still get the sound from the R channel only. So, the problem is with the output stage, not with the preamp, correct? Is there any particular component I should check?

    Thank you all and Happy New Year!

  2. #2
    Hifi-entusiast
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    Hi, it could still be old/bad soldering or other contact problems. Have you tested the mono switch and headphone output? You could find the schematic here: Norsk HifiForum • Se emne - Tandberg TR 200 and compare channel voltages.
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  3. #3
    Medlem
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    Sitat Sitat fra Norway1000 Se Innlegg
    Hi, it could still be old/bad soldering or other contact problems. Have you tested the mono switch and headphone output? You could find the schematic here: Norsk HifiForum • Se emne - Tandberg TR 200 and compare channel voltages.
    I have soldered out and checked the mono switch, it seems ok. Although, when I push it on/off, I have no change in sound. When I plug in the headphones, I get sound in both channels (seems mono), but when I turn the balance knob completely to the L position, I have sound only in the right channel. I have sound in both channels, when I turn the balance knob just a little bit from the L position. When turned completely in R position, still sound in both channels (seems mono).
    Thanks for the schematics, I have it.

  4. #4
    Hifi-entusiast
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    If you have sound in both channels using a stereo headphone, both power amplifiers are working properly. If there is sound only in one loudspeaker there must be a fault in the wiring and or the speaker selector switch. This is assuming both speakers are working properly. The fault in the balance pot and or the mono switch may be unrelated to your other problems. Quite frequently there are several faults at once in these receivers as they are quite poorly built initially.

  5. #5
    Medlem
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    If you have sound in both channels using a stereo headphone, both power amplifiers are working properly. If there is sound only in one loudspeaker there must be a fault in the wiring and or the speaker selector switch. This is assuming both speakers are working properly. The fault in the balance pot and or the mono switch may be unrelated to your other problems. Quite frequently there are several faults at once in these receivers as they are quite poorly built initially.
    Thank you.
    Yes, I'm sure both speakers are working properly. I think the speaker selector is ok too, because when I plug the speaker in A or B RIGHT, there is sound, but no sound when plugged in A or B LEFT with speaker selector being switched respectively (no matter A, B or A+B).
    By the way, I had LEFT channel working initially when I got the receiver, but after a while, it failed and now after a year or so I decided to take care of it...

  6. #6
    Æresmedlem Pink_Panther's Avatar
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    Try to clean the mono/stereo switch.
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  7. #7
    Moderator Kjell_Kranzberg's Avatar
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    Is the pre/tone-amp in working order?

  8. #8
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    I have changed the driver transistor Q605 - MPSU05 (with meter it was OK though), and now I have the left fuse 33V burning immediately.

  9. #9
    Moderator Kjell_Kranzberg's Avatar
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    And now you have shortcut in Q 605...
    and probably in at least one power transistor.
    Check the drivers ande the two powertransistors again.
    Check all emitter-resistors connected to the drivertransistors and the powertransistors.
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  10. #10
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    Sitat Sitat fra Kjell_Kranzberg Se Innlegg
    And now you have shortcut in Q 605...
    and probably in at least one power transistor.
    Check the drivers ande the two powertransistors again.
    Check all emitter-resistors connected to the drivertransistors and the powertransistors.
    Ok, all is back, I have checked all transistors and resistors in the output stage, they are all fine, but still I get sound only in the R channel. When I turn the balance knob to the L position, I have no sound even in headphones. How do I check the pre/tone amp that you mentioned?

  11. #11
    Medlem
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    Sitat Sitat fra Pink_Panther Se Innlegg
    Try to clean the mono/stereo switch.
    Mono switch is clean and switches ok.

  12. #12
    Moderator Kjell_Kranzberg's Avatar
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    Sitat Sitat fra andrei.s Se Innlegg
    Sitat Sitat fra Kjell_Kranzberg Se Innlegg
    And now you have shortcut in Q 605...
    and probably in at least one power transistor.
    Check the drivers ande the two powertransistors again.
    Check all emitter-resistors connected to the drivertransistors and the powertransistors.
    Ok, all is back, I have checked all transistors and resistors in the output stage, they are all fine, but still I get sound only in the R channel. When I turn the balance knob to the L position, I have no sound even in headphones. How do I check the pre/tone amp that you mentioned?
    Navn:      tr 200.jpg
Visninger: 1443
Størrelse: 120.1 Kb

    Red arrows: connection from preamp to power amp; it´s a single shielded wire from the preamp to the power amp. Switch them!
    Green arrows: have you checked these transistors?
    Blue arrow: this capacitor is in the feedback circuit; can cause malfunction if not in working order.
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  13. #13
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    Sitat Sitat fra Kjell_Kranzberg Se Innlegg
    Sitat Sitat fra andrei.s Se Innlegg
    Sitat Sitat fra Kjell_Kranzberg Se Innlegg
    And now you have shortcut in Q 605...
    and probably in at least one power transistor.
    Check the drivers ande the two powertransistors again.
    Check all emitter-resistors connected to the drivertransistors and the powertransistors.
    Ok, all is back, I have checked all transistors and resistors in the output stage, they are all fine, but still I get sound only in the R channel. When I turn the balance knob to the L position, I have no sound even in headphones. How do I check the pre/tone amp that you mentioned?


    Red arrows: connection from preamp to power amp; it´s a single shielded wire from the preamp to the power amp. Switch them!
    Green arrows: have you checked these transistors?
    Blue arrow: this capacitor is in the feedback circuit; can cause malfunction if not in working order.
    Thank you for your time!
    I have swapped the amp cables and still I got sound from R channel only (with L amp cable connected to the R amp).
    I have checked both transistors and it seemed both were dead, Q604 didn't measure on my meter at all, Q602 did, but it was cracked on one leg, so I changed both and still get sound only from R channel. The capacitor C608 is ok. Where do I go next?

  14. #14
    Moderator Kjell_Kranzberg's Avatar
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    Well, hard to say...
    The diodes in the biascircuit?
    The output capacitor?
    Does the fuse still blow? If not, try to follow the signal. Do you have signal on both sides of the input capacitor? If you have; Try to find out where the signal is lost.
    Well, good luck, it's New Years Eve, I wish you a happy new year; I'm going offline for tonight.

  15. #15
    Medlem
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    Sitat Sitat fra Kjell_Kranzberg Se Innlegg
    Well, hard to say...
    The diodes in the biascircuit?
    The output capacitor?
    Does the fuse still blow? If not, try to follow the signal. Do you have signal on both sides of the input capacitor? If you have; Try to find out where the signal is lost.
    Well, good luck, it's New Years Eve, I wish you a happy new year; I'm going offline for tonight.
    The fuse is ok now. I will follow the signal path.
    Thank you for your help! Happy New Year and good luck! I will deal with this TR-200 guy in the new year now

  16. #16
    Moderator Kjell_Kranzberg's Avatar
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    You have probably already checked for bad solderings and cracked components and legs...

    before you go on with following the signal; unsolder the output capacitor on the output side only.

    If you you have'nt checked the output capacitor, it's a good idea to do so. Or even better; replace it.
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  17. #17
    Medlem
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    Sitat Sitat fra Kjell_Kranzberg Se Innlegg
    You have probably already checked for bad solderings and cracked components and legs...

    before you go on with following the signal; unsolder the output capacitor on the output side only.

    If you you have'nt checked the output capacitor, it's a good idea to do so. Or even better; replace it.
    Yes, everything seems ok. There was some bad soldering, but I re-soldered it.
    Do you mean to check C613, C614 caps?

  18. #18
    Moderator Kjell_Kranzberg's Avatar
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    Yes, look at the schematic. They are located in series with the output. The value is 2200 uF or something like that.
    On the circuitboard they are located to the left. There are 4 large capacitors, two of them are the power supply capacitors, but the other two, are the output capacitors. Replace for a new one. Or measure it's value; should be 2200 uF.
    Have you checked the bias-diodes? They are probably ok, but you can never be shure...
    If nothing helps, start from the very beginning and measure all DC-values according to the service manual.
    Siste redigert av Kjell_Kranzberg; 01.01.2017 kl. 18:08.

  19. #19
    Medlem
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    Sitat Sitat fra Kjell_Kranzberg Se Innlegg
    Yes, look at the schematic. They are located in series with the output. The value is 2200 uF or something like that.
    On the circuitboard they are located to the left. There are 4 large capacitors, two of them are the power supply capacitors, but the other two, are the output capacitors. Replace for a new one. Or measure it's value; should be 2200 uF.
    Have you checked the bias-diodes? They are probably ok, but you can never be shure...
    If nothing helps, start from the very beginning and measure all DC-values according to the service manual.
    Yes, these large 4 capacitors are ok. Diodes are ok. Now I will have to measure the DC-values to find where the signal is lost.

  20. #20
    Moderator Kjell_Kranzberg's Avatar
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    Try this:
    Unsolder the output capacitor at the output side only. Check for signal. If signal - the power amp is OK, and the malfunction is to find after the capacitor, for example the loudspeaker switch.

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