On Tue, Sep 19, 2023, 11:06 PM Dave New, N8SBE <n8sbe@...> wrote:
I had a 10 yr old Elecraft P3 blow up when the AMS1117 shorted the 13.8 VDC supply to the internal 3.3V bus.
Over $400 in repairs later (and a new revision power supply board in the P3), it's working again, but I found out that the 2KW TXMon that was attached to the P3 when the AMS1117 went out is also defective - it has 3.3V-fed surface-mount opamps in it, so I figured it blew out one or both of the opamps, as well.
Beware the AMS1117....
73,
-- Dave, N8SBE
On 2023-04-27 00:38, Shirley Dulcey KE1L wrote:
The first version of the QDX experienced high failure rates of the AMS1117 regulators (same basic design as the LM1117, different supplier). A major problem with the 1117 is that the most common failure mode is a SHORT, letting the full supply voltage through and typically destroying every downstream IC. Later revisions replace the 5V regulator with a 78M05, and run the 3.3V regulator from the output of the 5V regulator rather than directly from the power source.
?
Different radio, but the experience with those regulators is relevant.
On Tue, Apr 18, 2023 at 4:55?PM ajparent1/kb1gmx <kb1gmx@...> wrote:
Farhan,
ITs not the device loading its the posible reverse path due to that parts failure. Fr example if that mosfet develops a gat to dran short then the GPIO pin sees 12V and that's bad. the uln2003 fails or ther eis a board level short to it? the relay select lines can fail at the Pi.
If everything works, its never an issue, only when something is wrong it becomes one.
As a development radio the expectation of >>>oops<<< should be foreseen.
-- Allison ------------------ Please use the forum, offline and private will go to bit bucket.
Sure. You always have to start from the stove (power unit). If it's OK, then you can look for additional errors. Because that's what I learned. This is not obvious to everyone. -- Gyula HA3HZ
HA3HZ