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Hi All...
I have just restored 2 of these amplifiers, using a kit from Dillen, and both amplifiers are adjusted regarding idle current, and they both work.
However, one plays at a louder volume than the other ? I can compensate by changing input level to low on one, and high on the other. Then they match, but I don't think this is the correct solution.
They are driven by a BS9000 with BALANCE <> ;)
One BL5 fully connected PL cable from BS9000 to one amp, and another BL5 fully connected PL cable piggybacked to the other.
The one that plays louder, is the one NOT connected to BS9000, so I don't suspect the piggyback board.
The lower playing amp, had 3 breaks in solderings where the line signal meets the op-amp IC2, could the wires I have used to restore the connection, be responsible for lowering the powerlink line signal before the OP-AMP
Any ideas ?
/Weebyx
Use a Sine-Wave generator and Scope ;-)
Disconnect Tr3(drain) on the mainboard. See what happens. This Tr3 responds to the level of heat in it's surrounding. When it becomes to hot inside the Beolab, it weakens the audio-signal.
Beobuddy: Use a Sine-Wave generator and Scope ;-) Disconnect Tr3(drain) on the mainboard. See what happens. This Tr3 responds to the level of heat in it's surrounding. When it becomes to hot inside the Beolab, it weakens the audio-signal.
Thanx, Then I just need a Sine-Wave Gen and a Scope ;)
I have done some more testing though, and it appears that if I set the Input Level to 1 instead of 3(as pr manual for PowerLink) the sound level are the same from both speakers.
During my restoration, they have been given new thermal paste all over, and all old has been removed, also the heat detecting resistor has been cleaned and refitted.
I have also tested the cables and running each speaker from the radio directly instead of piggyback.. So this can only be the beolab200 itself..
The speaker that plays "loudest" is actually running a bit hotter, but maybe it is just because it is in the corner with a sofa around it. It is not much, but juuust a little warmer when you put your hands around the amplifier. Not HOT though, there are no indications that they are getting too hot whatsoever.
Weebyx: new thermal paste all over, and all old has been removed, also the heat detecting resistor has been cleaned and refitted.
new thermal paste all over, and all old has been removed, also the heat detecting resistor has been cleaned and refitted.
Tr3 isn't a resistor, it's a transistor (FET), located on the mainboard between C25 and C27. It hasn't any paste around it.
It shortens the signal a bit. But once and a while they fail and start leaking. Sucking the solderpaste on its drain joint gives you instantly result whether it is or not the culprit.
Beobuddy: Weebyx: new thermal paste all over, and all old has been removed, also the heat detecting resistor has been cleaned and refitted. Tr3 isn't a resistor, it's a transistor (FET), located on the mainboard between C25 and C27. It hasn't any paste around it. It shortens the signal a bit. But once and a while they fail and start leaking. Sucking the solderpaste on its drain joint gives you instantly result whether it is or not the culprit.
Sorry, I didn't mean that the TR3 was the one I have given any paste :) It was just to tell you what I had been doing on the amplifier :)
Since I already have the amplifiers assembled and put on the Penta's, It might be a while before I decide to disassemble them again ;)
Would you still say the problem could be the TR3 since they play fine on input level 1, but not on 3 ?
Tr3 will (probably) be the culprit if you have the same balance difference with both penta's at each inputlevel.
Otherwise the Tr1 and Tr2 on board 7 are responsible for the amount of amplifying.
Beobuddy: Tr3 will (probably) be the culprit if you have the same balance difference with both penta's at each inputlevel. Otherwise the Tr1 and Tr2 on board 7 are responsible for the amount of amplifying.
The difference is not the same on all 3 input levels, at input level 3 the difference is the biggest, and at level 1 it is 98% the same level..
Maybe I should just change all MPF 4392 transistors there is and see what happens :) Just need to find a source where to buy them in Denmark..