I just got finished a little bit ago replacing the shorted diodes ,
and the PF is working just fine again . Cause of the diode failure is
still a question , may or may not have been an incompatibility between
the welder and the PF unit . I suspect that because the two items were
powered by different breakers there is a possibility that the diodes
were subjected to 220 volts , which could have done this . Point is moot
now though , and now I need to decide whether to re-purpose the old one
or put it back for a spare . I don't plan any undo-able changes , so I
may end up being able to do both !
--
Snag
Race only matters to racists ...

"Snag" wrote in message news:serjga$9t$1@dont-email.me...
I just got finished a little bit ago replacing the shorted diodes ,
and the PF is working just fine again . Cause of the diode failure is
still a question , may or may not have been an incompatibility between
the welder and the PF unit . I suspect that because the two items were
powered by different breakers there is a possibility that the diodes
were subjected to 220 volts , which could have done this . Point is moot
now though , and now I need to decide whether to re-purpose the old one
or put it back for a spare . I don't plan any undo-able changes , so I
may end up being able to do both !
--
Snag
Race only matters to racists ...
---------------------------

I'd be checking the equipment and premises wiring for grounding or neutral
bonding faults. I've had an intermittent neutral fault in my house wiring
that was cured by replacing the meter box and drop from the weatherhead.

On 8/9/2021 11:28 AM, Jim Wilkins wrote:
> "Snag"  wrote in message news:serjga$9t$1@dont-email.me...
>   I just got finished a little bit ago replacing the shorted diodes ,
> and the PF is working just fine again . Cause of the diode failure is
> still a question , may or may not have been an incompatibility between
> the welder and the PF unit . I suspect that because the two items were
> powered by different breakers there is a possibility that the diodes
> were subjected to 220 volts , which could have done this . Point is moot
> now though , and now I need to decide whether to re-purpose the old one
> or put it back for a spare . I don't plan any undo-able changes , so I
> may end up being able to do both !
------------------

I'd be checking the equipment and premises wiring for grounding or
neutral bonding faults. I've had an intermittent neutral fault in my
house wiring that was cured by replacing the meter box and drop from the
weatherhead.

----------------------

The house and shop wiring is new , the neutral is good , the ground is
good , and this sub panel has the neutral and ground bonded per the
recommendation of a local (professional) electrician . This is a Harbor
Fright PF unit so original quality may be an issue . As I said , not a
big deal at this point .
--
Snag
Race only matters to racists ...

"Snag" wrote in message news:ses3j3$bli$1@dont-email.me...

The house and shop wiring is new , the neutral is good , the ground is
good , and this sub panel has the neutral and ground bonded per the
recommendation of a local (professional) electrician . This is a Harbor
Fright PF unit so original quality may be an issue . As I said , not a
big deal at this point .
--
Snag
Race only matters to racists ...
-------------------------------------------------------------

HF electronics quality certainly could be the problem. I put voltage and
current meters on an HF "45 Watt" solar kit controller and soon noticed 12V
on the panel side voltmeter at night. The problem was a pair of Schottky
blocking diodes at the input, one of which was shorted. Neither diode was
rated for the full current; instead of designing the board layout for one
adequately rated diode they had put two smaller ones in parallel. I had to
hang the larger replacement off the side of the board.

I use diodes, silicone wire, etc to pad Amazon orders to qualify for free
shipping. The Schottkys have all been barely at or slightly under their
reverse voltage leakage current spec and some of the wires' resistance
pushed the high limit for the gauge.

On 8/9/2021 4:48 PM, Jim Wilkins wrote:
> "Snag"  wrote in message news:ses3j3$bli$1@dont-email.me...
>
>  The house and shop wiring is new , the neutral is good , the ground is
> good , and this sub panel has the neutral and ground bonded per the
> recommendation of a local (professional) electrician . This is a Harbor
> Fright PF unit so original quality may be an issue . As I said , not a
> big deal at this point .

I did replace the speed control pot a few months ago ... though that
seems to be a design fault for most of the PF's that use this circuit
board . The cool thing - I figgered out - the numbers on the board
identify the component they're next to , like the 33.3k resistor in
series with the power-on neon bulb .
Come to think of it , this would make a great drive for a ball mill
.... an absolute essential if I'm going to make lift powder for the
pyrotechnic dev ices I'd like to make !
--
Snag
Race only matters to racists ...

"Snag" wrote in message news:sesi4r$48v$1@dont-email.me...

I did replace the speed control pot a few months ago ... though that
seems to be a design fault for most of the PF's that use this circuit
board . The cool thing - I figgered out - the numbers on the board
identify the component they're next to , like the 33.3k resistor in
series with the power-on neon bulb .
Come to think of it , this would make a great drive for a ball mill
.... an absolute essential if I'm going to make lift powder for the
pyrotechnic dev ices I'd like to make !
--
Snag
Race only matters to racists ...

-----------------

Maybe you need a 'larger' speed control pot like my Ohmite Model RUS1ROE.
(1 Ohm, 1000 Watts, 31 Amps, a foot in diameter.)
https://www.ohmite.com/catalog/rheostats/RUS1R0E

Then you could leave out all the electronics.

On 8/9/2021 4:35 PM, Snag wrote:
>  The house and shop wiring is new , > ... and this sub panel has the neutral and ground bonded per the
> recommendation of a local (professional) electrician . ...

Are you saying that the sub panel's neutral and ground are tied
together? If so, that is a no-no, per the NEC. Tied _only_ at the
service (main) panel.

"Bob Engelhardt" wrote in message news:sets0l01ajc@news4.newsguy.com...

On 8/9/2021 4:35 PM, Snag wrote:
> The house and shop wiring is new , > ... and this sub panel has the
> neutral and ground bonded per the
> recommendation of a local (professional) electrician . ...

Are you saying that the sub panel's neutral and ground are tied
together? If so, that is a no-no, per the NEC. Tied _only_ at the
service (main) panel.

----------------------------
Prior to the 2008 NEC version that 3-wire feed was permitted for a sub panel
in a detached building, but the sub panel needed its own ground rod. As of
2008 4-wire sub panel feeds with separate ground and neutral wires are
required.

Grounding rules are tricky and evolving, especially for independent power
sources like generators and solar panels. NEC says drive a ground rod, Dig
Safe says NO, wait until we check.

Some solar panel controllers switch the negative side and having panel
negative plus utility grounds (through a UPS) connected shorts the switch.

On 8/10/2021 7:38 AM, Bob Engelhardt wrote:
> On 8/9/2021 4:35 PM, Snag wrote:
>>   The house and shop wiring is new ,  > ... and this sub panel has the
>> neutral and ground bonded per the
>> recommendation of a local (professional) electrician . ...
>
> Are you saying that the sub panel's neutral and ground are tied
> together?  If so, that is a no-no, per the NEC.  Tied _only_ at the
> service (main) panel.
>

I'd have to pull the cover and check , but I'm pretty sure we bonded
the neutral to ground on that panel . As I said , I was advised by a
professional electrician when I wired the shop . Since he is a licensed
electrician I figure he knows what he's talking about .
--
Snag
Race only matters to racists ...

"Jim Wilkins" wrote in message news:seu37n$ncf$1@dont-email.me...

Prior to the 2008 NEC version that 3-wire feed was permitted for a sub panel
in a detached building, but the sub panel needed its own ground rod. As of
2008 4-wire sub panel feeds with separate ground and neutral wires are
required.
------------------

https://structuretech.com/subpanels-when-the-grounds-and-neutrals-should-be-separated/