12V powered propellor SCUBA assistance.
Only 2 on/off sw functions , both reed relay+ external magnets work fine.
Why so much electonics for isolator function sw and motor on and off sw, no
speed control on this one? Assuming it monitors motor overload, what else ?
brown out ?
Uses 2x ST P60NF0?? TO220 size powerfets and ST maybe LM324N 4x TO92 all
unclear under scraped off conformal. A 4mm wide track with central solder
thickening overlay, has fused, in a run of uniform (not deliberately necked)
track, not at a component. Looks as though the trace has heated to point of
melting solder and the underlying copper has split apart by contraction
leaving a neat 1mm gap rather than burning up, copper is still bright
copper. Is this another failing of PbF ? no reported motor stalling from
weed etc , what sort of current would cause this failure?, power devices etc
seem ok as far as no shorts and no other hot spots . Normal in-service
running current and some PbF metalurgical failure ?

On Aug 28, 8:57*am, "N_Cook" wrote:
12V powered propellor SCUBA assistance.
Only 2 on/off sw functions , both reed relay+ external magnets work fine.
Why so much electonics for isolator function sw and motor on and off sw, no
speed control on this one? Assuming it monitors motor overload, what else ?
brown out ?
Uses 2x ST P60NF0?? TO220 size powerfets and ST maybe LM324N 4x TO92 *all
unclear under scraped off conformal. A 4mm wide track with central solder
thickening overlay, has fused, in a run of uniform (not deliberately necked)
track, not at a component. Looks as though the trace has heated to point of
melting solder and the underlying copper has split apart by contraction
leaving a neat 1mm gap rather than burning up, copper is still bright
copper. Is this another failing of PbF ? no reported motor stalling from
weed etc , what sort of current would cause this failure?, power devices etc
seem ok as far as no shorts and no other hot spots . Normal in-service
running current and some PbF metalurgical failure ?

Can you check with the company (maybe online) that designed the
board? Maybe this was an older board rev. and was redesigned.

Bob Villa wrote in message
...
On Aug 28, 8:57 am, "N_Cook" wrote:
12V powered propellor SCUBA assistance.
Only 2 on/off sw functions , both reed relay+ external magnets work fine.
Why so much electonics for isolator function sw and motor on and off sw,
no
speed control on this one? Assuming it monitors motor overload, what else
?
brown out ?
Uses 2x ST P60NF0?? TO220 size powerfets and ST maybe LM324N 4x TO92 all
unclear under scraped off conformal. A 4mm wide track with central solder
thickening overlay, has fused, in a run of uniform (not deliberately
necked)
track, not at a component. Looks as though the trace has heated to point
of
melting solder and the underlying copper has split apart by contraction
leaving a neat 1mm gap rather than burning up, copper is still bright
copper. Is this another failing of PbF ? no reported motor stalling from
weed etc , what sort of current would cause this failure?, power devices
etc
seem ok as far as no shorts and no other hot spots . Normal in-service
running current and some PbF metalurgical failure ?

Can you check with the company (maybe online) that designed the
board? Maybe this was an older board rev. and was redesigned.

vvvvvvvvvvvvvvvv

12v/7.5 Ah Battery
Product Description
Run time of up to 1.5 hours with normal use
so 5 amps in normal use, so 4mm track without solder should do that