Hi, i have a subwoofer plate amplifier labeled SVS Sledge STA-1000D from a SVS PC-13 Ultra sub.
In fact this plate amp module is really made by Formosa-audio, model FMA 990501.
Did someone ever saw a schematic for these or something that look alike ?
At first the power supply section didn't work.
I've done some cleaning, resoldering and i change an opto isolator.
Now the power supply seem to work, the rails are at 198 vdc - to +.
There is a good - 4.97 / +5.0 vdc on the preamp connector, but the display did not work.
Thanks
In fact this plate amp module is really made by Formosa-audio, model FMA 990501.
Did someone ever saw a schematic for these or something that look alike ?
At first the power supply section didn't work.
I've done some cleaning, resoldering and i change an opto isolator.
Now the power supply seem to work, the rails are at 198 vdc - to +.
There is a good - 4.97 / +5.0 vdc on the preamp connector, but the display did not work.
Thanks
Last edited:
Following up:
The first stage of the PS look ok as feed +161v / -176v on the IGBT rails.
But no IGBT switching (Q101 & Q102), both test good as IGBT.
There are +5vdc and -5vdc on the preamp connector.
But the SD line is at -4.97vdc, TMP at +2.63vdc and CNTL at 0vdc.
The SD signal likely come from the PS/Amp board as it stay at -4.27vdc preamp unpluged.
I don't know exactly what's the TMP and CNTL are doing.
U101 that drive the IGBTs is not powered.
U105 should turn on Q104 wich is feeding U101 Vcc .
In fact Q104 receive no signal via the U105 opto-isolator.
This U105 is driven by Q105 which is reading something via R136, and R146 around the outputs...
It look like the SD line is controling U101 by it's Vcc, even if it has no SD input.
I will remove the outputs IGBT or Mosfet, from the board for testing.
(Q201 ,202, 401, 402)
But the specs of those transistors are not available, AMS6A9...
Can someone ID these transistors please ?
A few other parts on this board have been buffed and renamed with fake/proprietary numbers.
This should be illegal ! 🙁
The first stage of the PS look ok as feed +161v / -176v on the IGBT rails.
But no IGBT switching (Q101 & Q102), both test good as IGBT.
There are +5vdc and -5vdc on the preamp connector.
But the SD line is at -4.97vdc, TMP at +2.63vdc and CNTL at 0vdc.
The SD signal likely come from the PS/Amp board as it stay at -4.27vdc preamp unpluged.
I don't know exactly what's the TMP and CNTL are doing.
U101 that drive the IGBTs is not powered.
U105 should turn on Q104 wich is feeding U101 Vcc .
In fact Q104 receive no signal via the U105 opto-isolator.
This U105 is driven by Q105 which is reading something via R136, and R146 around the outputs...
It look like the SD line is controling U101 by it's Vcc, even if it has no SD input.
I will remove the outputs IGBT or Mosfet, from the board for testing.
(Q201 ,202, 401, 402)
But the specs of those transistors are not available, AMS6A9...
Can someone ID these transistors please ?
A few other parts on this board have been buffed and renamed with fake/proprietary numbers.
This should be illegal ! 🙁