Hi all,
I got this class D amplifier with full rail voltage on speaker terminals. and blown R101 resistor.
The problem was in the driver board there was broken trace. after fixing everything i notice one string of transformer melted and was broken. so there might be a short between primary and secondary. i am attaching the picture.
i tried to twist and shake the board while power is applied to see if there is a short but i did not get no current pull.
can i leave the broken string as it is or do i have to connect it and insulate?
I got this class D amplifier with full rail voltage on speaker terminals. and blown R101 resistor.
The problem was in the driver board there was broken trace. after fixing everything i notice one string of transformer melted and was broken. so there might be a short between primary and secondary. i am attaching the picture.
i tried to twist and shake the board while power is applied to see if there is a short but i did not get no current pull.
can i leave the broken string as it is or do i have to connect it and insulate?
Attachments
Do you have voltage on the RCA shields after replacing R101?
Check for voltage while pushing/pulling/twisting on the power transformer.
I have 5.6v on rca shield with black probe connected to power supply ground. This is without pushing and pulling power transformer.
You need to twist/push/pull on the transformer to see if it affects the voltage on the shields (after replacing R101).
Yes it changed from 5.5v to 1.1v when I push the transformer. And it changes when I keep pushing and pulling.
Do these with nothing connected to the amp.
What's the resistance from the RCA shields to the main ground (no power applied)?
What's the resistance from the RCA shields to the B+ terminal? Check this to see if it changes when pushing/pulling/twisting the transformer.
What's the resistance from the RCA shields to the main ground (no power applied)?
What's the resistance from the RCA shields to the B+ terminal? Check this to see if it changes when pushing/pulling/twisting the transformer.
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Do these with nothing connected to the amp.
What's the resistance from the RCA shields to the main ground (no power applied)?
What's the resistance from the RCA shields to the B+ terminal? Check this to see if it changes when pushing/pulling/twisting the transformer.
670kohms from RCA to main ground.
0.670Mohms from RCA to B+ when twisted it gone to 0.8Mohms.
It doesn't appear that there is a short between windings. That may change as the core moves after reinstalled or as it heats up.
Leaving the bad winding isn't the 'right' way to repair it. At the very least, you should tell the owner and give him the option to have you rewind it or replace it at additional cost.
Leaving the bad winding isn't the 'right' way to repair it. At the very least, you should tell the owner and give him the option to have you rewind it or replace it at additional cost.
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