Hi everyone, my first post on this forum so hopefully this is in the right department.
I got a PROEL SMART12MA powered speaker that gives some kind of distortion sound at all volumes.
I opened the speaker and connected the amp to another speaker and same distortion sound appears so I have ruled out that the woofer or tweeter driver is damaged. I also noticed that the original transformer may have been replaced. Looking at the fitting bracket (photo attached) I suspect a toroidal transformer was fitted at factory but somebody have installed 2 smaller linear transformers with the following specs, the first one: 110V-220V 60/50Hz 17-0-17V 2A and the other one 110V-220V 60/50Hz 18-0-18V 2A.
Now I am not sure if this is what causing the distortion sound but if I where to replace it, would a transformer like this one be suitable ? DAC - 24-0-24V X 1, 18-0-18V X 1 - Toroidal Transformer - 434VA
The thing is that there are 2 secondary wiring needed, the circuit board have 2 sides of it where it needs to be connected, one says HI AC IN and the other one LOW AC IN, How much hi and low is supposed to be I am not sure but I have written to manufacturer and hope they will reply.
Any guidance would be appreciated.
Thanks
Rick
I got a PROEL SMART12MA powered speaker that gives some kind of distortion sound at all volumes.
I opened the speaker and connected the amp to another speaker and same distortion sound appears so I have ruled out that the woofer or tweeter driver is damaged. I also noticed that the original transformer may have been replaced. Looking at the fitting bracket (photo attached) I suspect a toroidal transformer was fitted at factory but somebody have installed 2 smaller linear transformers with the following specs, the first one: 110V-220V 60/50Hz 17-0-17V 2A and the other one 110V-220V 60/50Hz 18-0-18V 2A.
Now I am not sure if this is what causing the distortion sound but if I where to replace it, would a transformer like this one be suitable ? DAC - 24-0-24V X 1, 18-0-18V X 1 - Toroidal Transformer - 434VA
The thing is that there are 2 secondary wiring needed, the circuit board have 2 sides of it where it needs to be connected, one says HI AC IN and the other one LOW AC IN, How much hi and low is supposed to be I am not sure but I have written to manufacturer and hope they will reply.
Any guidance would be appreciated.
Thanks
Rick
Attachments
You don´t know the power handling of the original transformer.
And the secondary voltages of the original transformer might also be different.
And the secondary voltages of the original transformer might also be different.
According to this it's a 160W amplifier
PROEL - SMART SMTV12MA - MONITOR AMPLIFICATO - Zecchini - Strumenti Musicali
The high AC could be main power and the low AC could be pre-amp power. Follow the traces and the capacitors after should tell You what voltage the board is expecting.
PROEL - SMART SMTV12MA - MONITOR AMPLIFICATO - Zecchini - Strumenti Musicali
The high AC could be main power and the low AC could be pre-amp power. Follow the traces and the capacitors after should tell You what voltage the board is expecting.
Schematic and parts download here. Just wait that processing stuff..
PROEL SMART 12A AM160 AM161 AM321 AM320 AM320S SM Service Manual download, schematics, eeprom, repair info for electronics experts
PROEL SMART 12A AM160 AM161 AM321 AM320 AM320S SM Service Manual download, schematics, eeprom, repair info for electronics experts
It could be crossover distortion because of inadequate bias current due to the low voltage supply
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