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Pioneer st1250

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Gregory Barr

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My pioneer receiver has a problem
No output! Checked quiescent volt, has 3ma so went to relays, main relay can hear it kick in but speaker relay isn't? Checked volt on it has 34.5v on top pins but nothing on lower pins. Also checked voltages around outputs all good!
What should I do ?
 

audioguru

Well-Known Member
Most Helpful Member
Please post its schematic and mark where you measured 3mA as its quiescent voltage (3mA is current, not voltage) and what the top pins and lower pins are for.
 

Gregory Barr

New Member
My pioneer receiver has a problem
No output! Checked quiescent volt, has 3ma so went to relays, main relay can hear it kick in but speaker relay isn't? Checked volt on it has 34.5v on top pins but nothing on lower pins. Also checked voltages around outputs all good!
What should I do ?
Please post its schematic and mark where you measured 3mA as its quiescent voltage (3mA is current, not voltage) and what the top pins and lower pins are for.
My pioneer receiver has a problem
No output! Checked quiescent volt, has 3ma so went to relays, main relay can hear it kick in but speaker relay isn't? Checked volt on it has 34.5v on top pins but nothing on lower pins. Also checked voltages around outputs all good!
What should I do ?
 

motohomer

New Member
Is this a ST1250 or SX. i can find any data on the ST1250 on the internet. Usually you can get a service manual or at least a model picture.

The relay you are referring to i believe is the output protection relays. On some amps like the Technic SU X501 the speaker protection relay is controlled by the amp or processor circuit via a transistor. Some have a permanent supply to the relay and it is given a ground via the transistor. So if the transistor is turned off then the supply on both sides of the relay will be the same as it will not have a ground. Not sure if this will help and getting a service manual will help you a lot.

Picture below is the protection circuit of the Technic amp
 

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