Hi,
I’d like help please troubleshooting some circuitry. I have some knowledge of electronics repair but are eager to learn more!
I have an audio mixer with a faulty switch mode power supply. When switching on the desk the buttons will flash and the screen lights up, but the unit does not boot. Switching the power on/off a few times will eventually get the mixer to boot up but not operate fully. Only half of the boards would light up and respond.
I have since went ahead with the obvious fix and replaced all 21 of the Chinese branded electrolytic capacitors with comparable Panasonic and Nichicon caps purchased from Digi-Key.
No change! Still the same non-working status.
The output voltages under *no load* are close to the specification, but when the 7 control boards are connected the voltages drop like a stone! Connecting up a single PCB on the output has the same affect. I have included the values measured below – in order.
Manufacturers Specification:
+48v
+16v
-16v
+6.6v
+6v
*No load*:
+46.2v
+15.1v
-15.1v
+6.6v
+5.0v
*Load connected (1 PCB)*:
+8.75v
+2.4v
-2.4v
+2.2v
+0.9V
My thoughts now are, could there be something failing in the IC feedback circuitry to increase the voltage when required? This would this cause all the voltages to be affected.
Am I right in thinking? How would I go about checking this?
I have added attachments to help diagnose.
Kind Regards,
Matt
I’d like help please troubleshooting some circuitry. I have some knowledge of electronics repair but are eager to learn more!
I have an audio mixer with a faulty switch mode power supply. When switching on the desk the buttons will flash and the screen lights up, but the unit does not boot. Switching the power on/off a few times will eventually get the mixer to boot up but not operate fully. Only half of the boards would light up and respond.
I have since went ahead with the obvious fix and replaced all 21 of the Chinese branded electrolytic capacitors with comparable Panasonic and Nichicon caps purchased from Digi-Key.
No change! Still the same non-working status.
The output voltages under *no load* are close to the specification, but when the 7 control boards are connected the voltages drop like a stone! Connecting up a single PCB on the output has the same affect. I have included the values measured below – in order.
Manufacturers Specification:
+48v
+16v
-16v
+6.6v
+6v
*No load*:
+46.2v
+15.1v
-15.1v
+6.6v
+5.0v
*Load connected (1 PCB)*:
+8.75v
+2.4v
-2.4v
+2.2v
+0.9V
My thoughts now are, could there be something failing in the IC feedback circuitry to increase the voltage when required? This would this cause all the voltages to be affected.
Am I right in thinking? How would I go about checking this?
I have added attachments to help diagnose.
Kind Regards,
Matt
Attachments
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