Tandberg TR-200 problem 1 kanal

andrei.s

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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!
 

andrei.s

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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.
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.
 

atlechri

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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.
 

andrei.s

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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...
 

Kjell_Kranzberg

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Is the pre/tone-amp in working order?
 

andrei.s

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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.
 

Kjell_Kranzberg

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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.
 

andrei.s

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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.
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?
 

Kjell_Kranzberg

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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.
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?
tr 200.jpg


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.
 

andrei.s

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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.
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?
 

Kjell_Kranzberg

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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.
 

andrei.s

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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.
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 :)
 

Kjell_Kranzberg

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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.
 

andrei.s

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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.
Yes, everything seems ok. There was some bad soldering, but I re-soldered it.
Do you mean to check C613, C614 caps?
 

Kjell_Kranzberg

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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.
 
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andrei.s

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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.
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.
 

Kjell_Kranzberg

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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.
 

andrei.s

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I have checked both capacitors on my ESR meter, they both show around 3000mF instead of 2500mF in the manual, ESR is ok.
Could this be a problem?
 

Kjell_Kranzberg

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DC or AC? If DC something is worng in both power amps. There should be no DC at all at the output leg of the output capacitor.
Are you sure you are measuring on the output leg? Is the leg unsoldered from the circuitboard?
Put signal; music; to the Tape input or use the tuner. Connect a cheap loudspeaker to the output leg of the output capacitor.
Do you hear the music? IF you do, the preamp and the capacitor is OK. If not either the poweramp or the capacitor is faulty.
 

andrei.s

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DC or AC? If DC something is worng in both power amps. There should be no DC at all at the output leg of the output capacitor.
Are you sure you are measuring on the output leg? Is the leg unsoldered from the circuitboard?
Put signal; music; to the Tape input or use the tuner. Connect a cheap loudspeaker to the output leg of the output capacitor.
Do you hear the music? IF you do, the preamp and the capacitor is OK. If not either the poweramp or the capacitor is faulty.
AC. Yes, the output leg unsoldered. I will try with the speaker. Thanks.
 

andrei.s

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OK, with the test speaker I could hear music connected to C614 (R ch), and no music, just hum while connecting on C613 (L ch)
 

Kjell_Kranzberg

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I have checked both capacitors on my ESR meter, they both show around 3000mF instead of 2500mF in the manual, ESR is ok.
Could this be a problem?
mF?
Do you mean uF (microfarads)
mF means millifarads.

3000 uF; no problem.

If you have 3000 millifarads; the capacitor is not OK.
 
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Kjell_Kranzberg

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OK, with the test speaker I could hear music connected to C614 (R ch), and no music, just hum while connecting on C613 (L ch)
Try a new capacitor...
If the hum is still there the problem is in the power amp.

Hum often is a sign for problem with the ground/earth.
 

Kjell_Kranzberg

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If the hum is still present - do you have an oscilloscope?
Put a sinewave to Tape input and follow it with the scope.
Indstead of a scope you can use a Signal Tracer/follower. Welleman has a DIY kit.
Good luck!
 

andrei.s

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If the hum is still present - do you have an oscilloscope?
Put a sinewave to Tape input and follow it with the scope.
Indstead of a scope you can use a Signal Tracer/follower. Welleman has a DIY kit.
Good luck!
Yes, I will check it after the 10th January now as I'm off to CES. Thank you so much for your help!
 

andrei.s

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For those maybe interested in TR-200: the problem was with 4 transistors in the output stage of the LEFT channel: Q605 (MPSU06), Q607 (MPSU56), Q609 and Q611 (2N5496), all of them were bad. I have also changed the output capacitors C613, C614 (both 2200uF) and power capacitors C705, C706 (2200uF). The receiver now works fine, the sound is amazing! Thanks to all and have a nice day!
 

Espen64

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For those maybe interested in TR-200: the problem was with 4 transistors in the output stage of the LEFT channel: Q605 (MPSU06), Q607 (MPSU56), Q609 and Q611 (2N5496), all of them were bad. I have also changed the output capacitors C613, C614 (both 2200uF) and power capacitors C705, C706 (2200uF). The receiver now works fine, the sound is amazing! Thanks to all and have a nice day!
Wow, IM impressed. I have a TR-200 that that I am working with. It gives me a lot of strugle. Please have a look on My small YouTube Clip. Any Good sugestion how to fix problem is apreciated.

Espen
 

geirendre

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Du burde kanskje starte en egen tråd for de problemene du har fremfor å henge deg på en gammel tråd med et annet problem beskrevet i.
Men uansett...
Er det forresten samme feil i begge kanaler, høyre og venstre?

1. Det brune stoffet du ser på undersiden av kretskortet er rester av flussmiddel fra da kortet ble loddet i loddebad på fabrikken.
Helt normalt og ufarlig.
2. Skaden på trafo og kondensator på skrå er nok heller ikke årsaken til feilen, men kanskje heller et tegn på at noen har vært inne og tuklet med den...
Kanskje en ide og sjekke at alle interne kablinger står på rett plass etc.
3. Mål at volumpotmetret faktisk virker som det skal, at det ikke er brudd i det.
Du har jo et flott multimeter, mål fra jord og til midtuttaket på potmetert at det øker fra 0ohm til ca 25Kohm når du vrir opp.
og det samme fra topp av potmeter og til midtuttak, at det minker fra 25K ned til 0.
Det er logaritmisk, så det skal gå raskt i begynnelsen og saktere mot slutten.
Måles selvfølgelig uten strøm på radioen. Sammenlign høyre og venstre kanal.
4. Hva om du dytter inn eller drar ut volumknappen, skjer det noen endring i lydstyrken da?
5. Sjekk loddinger.
 
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