Replacing an exploded booster U3.
After swap, on USB power only, all 5v booster supplied things are only a solid 2.51v
VBUS is making it through D62 and Net-(C61-Pad1) sees 5.1v there.
Any tips on what to look for to find why 1/2 voltage where boosted 5v should be?
Not a peep out of the speaker BTW.
There is no boosting going on when you’re only on USB power.
The booster is driven from BATT+, and is only enabled when the saber is ignited or sound is playing.
When the amplifier is playing sounds without getting power from BATT+, I think it’s actually leaching power from the I2S signals.
If the speakers aren’t working at all, it’s possible that the amplifier is blown.
Any metering tests I could do to check, or is no sound pretty much it?
I mean, it could be the speaker that’s broken too.
You could measure the AC output between SP+/SP-.
Yes checked all that. Ok thank you for the wake up call.
Hmmm. swapped the amp too. No dice. That said, it’s off another dead board whose CPU gets hot.
Now there’s no AC on speaker pins out of this one either. I suppose I could try an actual new one.
If not booster or amp, where else to look?
P.S. booster working normal when there’s voltage to batt+.
edit new amp works!
Glad it worked out.
The next step would have been to check the I2S signals. If the I2S signals are not there, then you would need to replace the CPU.