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Audio equipment

Sound system under the volume

HopeI Don't Know
hace 6 años
hace 6 años
I am repairing an LG mcd112 sound system, no matter how much the potentiometer goes up, it does not go up, I think the problem is at the source, I suspect it is a STR that it carries in the primary. I need help, someone who has got that kind of fault
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EzeMelano
EzeMelano
EzeMelano
349
hace 6 años

Hello, the potentiometers of this type of equipment are quite problematic.
Are you sure the pot works well?

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HopeI Don't Know
hace 6 años

The potentiometer indicates on the display that it responds from zero to 42 which is the maximum and only something that is barely heard.

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DJ G
DJ G
DJ G
1.026
hace 6 años
hace 6 años
here is the diagram , check if it has 35v on pins 13 to 15, if there is no voltage check the source all related to IC901 = STR-X6759N, if everything is ok change the str
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DJ G
DJ G
DJ G
1.026
hace 6 años

on page 39 of the service manual is the schematic of the source

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DJ G
DJ G
DJ G
1.026
hace 6 años

Partner please comment on what you did to make it fit for others

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HopeI Don't Know
hace 6 años

I measured the voltage on pins 13 and 15 and there is no voltage, there should theoretically be 35v, but the odd thing about this source is that on the data bus that there should be voltage for the front panel there are 35 volts. It is assumed that the 35v should be for the amplifier stage

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HopeI Don't Know
hace 6 años

I have already bought the STR, I will release it and then tell you if the problem was solved ...

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DJ G
DJ G
DJ G
1.026
hace 6 años

No, that panel voltage is for the illumination of the panel fcl display

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HopeI Don't Know
hace 6 años
hace 6 años
Hi, I changed the STR and the fault still continues. Tell me it can be. the voltages are not being fulfilled as the diagram says, where there should be no voltage ...
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DJ G
DJ G
DJ G
1.026
hace 6 años

Did you check the components associated with the str? Or you just changed the str, check well since it may be bad in opto coupler, tl431, some zener diode in short or leakage.

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DJ G
DJ G
DJ G
1.026
hace 6 años

check zd901- 2.7v, r911- 3.9k, zd905- 9.1v, c910- 100pf, pc901, ic949- ka431 = tl431, r964- 1.8k, r961- 1k, c946- 1uf / 50v, r962- 1k, r948- 24k , r969-2.2k, r963-2k, d941.

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HopeI Don't Know
hace 6 años

Ok i will check

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EzeMelano
EzeMelano
EzeMelano
349
hace 6 años

Could you check it and repair it at the end?

Responder
HopeI Don't Know
hace 6 años

I have already repaired the LG sound system, I changed the STR and the equipment was made to walk ... I thank all those who helped me ... thank you and many blessings

Responder
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