FB7 is the voltage used to power the unit. Are you using 12V?
The voltage across D12 should be somewhere between 0.2V and 0.5V but it looks like you’re measuring over 8V. It’s possible D12 is no good and has burned out forming a resistor. You could try measuring D12’s forward voltage when the unit is powered down.
Since D12 is dropping so much voltage, the CS51414 is not getting a high enough voltage to be powered on correctly. The datasheet says it needs 4.5V but it is getting only 3.6V.
If you determine that D12 is bad, you could remove D12 and short out its two pads as a test to see if the rest of the circuitry is working normally. If it is fine with D12 shorted then replace D12.
Hi Flick, Thanks again for your help.
OK, adjusted power supply to get the following…
FB7 - 9.7v
D12 - Shorted
U12 - 8.22v - 9.6v
D13 - 2.77v - 0.007v
L2 - 2.7v - 2.68v
U13 - 9.7 - 4.95v
After shorting D12 there was no change in operation and i moved onto D13….
With the very low 0.007v on the one side of D13 I thought maybe I should short that also. So I did, L2 then read pretty much 0v each side, I re soldered D13, I didn’t take note of which way it came off (school boy error) but matched it up visually with one further down near the main chip in the centre. Re-powered the unit and U12 popped again
Having lots of fun with this little board.
Hopefully some of my errors may help with you knowing what kind of voltage was hitting L2 from the IC as mentioned in your previous post.
All the best, Dave.