My Sumiko S.9 subwoofer works intermittently.
It will play normally for roughly 30 minutes. Then it stops producing sound. Part of the circuit is still getting power- the led on top stays lit and so does led on the back panel. No sound or noise when it stops. It just drops out. It happens when playing at low or high volumes.
I’m guessing a relay or one of the transistors with the relay might have gone bad? When I manually turn the sub off and on, once it’s dropped out, I can’t hear the relay switch back on. The heat sink is barely warm when it drops out. It’s not overheating.
I’ve taken the amp plate off and had a look. No loose wires, bad connections or anything obvious. Let it sit for sometime or overnight and it goes back to playing normally, until it drops out again.
I can’t find a schematic on line or I would attach it. AB amp not class D.
Figured I’d ask here for thoughts first.
Thanks.
It will play normally for roughly 30 minutes. Then it stops producing sound. Part of the circuit is still getting power- the led on top stays lit and so does led on the back panel. No sound or noise when it stops. It just drops out. It happens when playing at low or high volumes.
I’m guessing a relay or one of the transistors with the relay might have gone bad? When I manually turn the sub off and on, once it’s dropped out, I can’t hear the relay switch back on. The heat sink is barely warm when it drops out. It’s not overheating.
I’ve taken the amp plate off and had a look. No loose wires, bad connections or anything obvious. Let it sit for sometime or overnight and it goes back to playing normally, until it drops out again.
I can’t find a schematic on line or I would attach it. AB amp not class D.
Figured I’d ask here for thoughts first.
Thanks.
If you suspect the relay opens, you could bridge the switched contacts with a resistor of 10-100 ohms. Should the relay open, the volume would go down but there will still be sound.
If so, the next question would be: does something upstream determine that the relay should open or is the relay faulty?
If so, the next question would be: does something upstream determine that the relay should open or is the relay faulty?
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I suspect the relay is closing after the subwoofer plays for 30 minutes or so. When I turn my system on the sub works well, no issues. At some point, it drops out, producing no sound. If I switch it off/on then, it will not go back to playing music and I cannot hear the relay switch on, at that time. All this time, I can see that it still has power, with the LEDs being lit.
I connect to the amplifier with a speakon cable. I’ll have to look into another way to connect to see if the same problem happens.
I have two identical S.9. The other one plays normally.
Yes, I’ll attach some photos.
Attachments
Two relays, one on the big board - speaker relay, and one on
the "green" board - mains relay (is there an automatic switch
on function?). Problem is on the big or on the "green" board.
Use a DVM to check some supply voltages.
the "green" board - mains relay (is there an automatic switch
on function?). Problem is on the big or on the "green" board.
Use a DVM to check some supply voltages.
Yes, there is an automatic switch on function. I’ve tried it both ways, Auto or ON and the problem still happens. Maybe that means it’s the relay on the big board? I’ll check around with my DVM.
Attachments
If the green board relay is "on" you will have the dc operating voltages on the big board.
You can check these if the rectifier leads (rect. block at left side of your pictures) are long enough, or at center of the big transistor pins, expect some 30 .. 60 Vdc, plus and minus.
If these voltages are not present check the green board mains relay is "off". This is an smd board, that leaves you alone, but lytic cap check may be possible.
You can check these if the rectifier leads (rect. block at left side of your pictures) are long enough, or at center of the big transistor pins, expect some 30 .. 60 Vdc, plus and minus.
If these voltages are not present check the green board mains relay is "off". This is an smd board, that leaves you alone, but lytic cap check may be possible.