Rheostat Audio Interference

In article ,
"RST Engineering" wrote:
Having said all that good stuff, maximum power means maximum heat means
maximum oxidation of the rheostat wire. Either a GOOD cleaning with a
toothbrush and contact cleaner or a little judicious application of very
fine (400-600 grit) wetordry sandpaper followed by a good cleaning to get
the sandpaper and oxide particles out of the rheostat will probably solve
the problem.


Jim,

Thanks for the input. I believe that I have potentiometer/transistor
pairs that perform the dimming function, rather than a true rheostat
(even though Piper still calls it a rheostat in the maintenance manual).
Based on what I've researched, I suspect that I may have a faulty
transistor. I will swap the old one with a new one and see if that
solves the problem.



JKG

NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO.

"Faulty" transistors (whatever the hell THAT means) will not create RFI.
Somewhere something is an arcin' and a sparkin'. Transistors aren't
"faulty"; they either am or they ain't.

Jim



"Jonathan Goodish" wrote in message
...
In article ,
"RST Engineering" wrote:
Having said all that good stuff, maximum power means maximum heat means
maximum oxidation of the rheostat wire. Either a GOOD cleaning with a
toothbrush and contact cleaner or a little judicious application of very
fine (400-600 grit) wetordry sandpaper followed by a good cleaning to get
the sandpaper and oxide particles out of the rheostat will probably solve
the problem.


Jim,

Thanks for the input. I believe that I have potentiometer/transistor
pairs that perform the dimming function, rather than a true rheostat
(even though Piper still calls it a rheostat in the maintenance manual).
Based on what I've researched, I suspect that I may have a faulty
transistor. I will swap the old one with a new one and see if that
solves the problem.



JKG

In article ,
"RST Engineering" wrote:

NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO.

"Faulty" transistors (whatever the hell THAT means) will not create RFI.
Somewhere something is an arcin' and a sparkin'. Transistors aren't
"faulty"; they either am or they ain't.


Well, "faulty" means it isn't working.

The bottom line is that something is wrong, and either way I'm going to
have to endure the pain of pulling the switch assembly out of the panel
and take a look.



JKG

Jonathan Goodish wrote:
In article ,
"RST Engineering" wrote:


NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO.

"Faulty" transistors (whatever the hell THAT means) will not create RFI.
Somewhere something is an arcin' and a sparkin'. Transistors aren't
"faulty"; they either am or they ain't.



Well, "faulty" means it isn't working.

The bottom line is that something is wrong, and either way I'm going to
have to endure the pain of pulling the switch assembly out of the panel
and take a look.

Check all the connections in the circuit. The
noise may be from an arcing connection.

--

Tauno Voipio
tauno voipio (at) iki fi

"Jonathan Goodish" wrote in message
...
In article ,
"RST Engineering" wrote:

NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO.

"Faulty" transistors (whatever the hell THAT means) will not create RFI.
Somewhere something is an arcin' and a sparkin'. Transistors aren't
"faulty"; they either am or they ain't.


Well, "faulty" means it isn't working.

The bottom line is that something is wrong, and either way I'm going to
have to endure the pain of pulling the switch assembly out of the panel
and take a look.

Jonathan,

Remember Occam's Razor? It applies just as much to electricity as it does to
science fiction movies.

Juan

In article ,
"Juan Jimenez" wrote:
Remember Occam's Razor? It applies just as much to electricity as it does to
science fiction movies.


Maybe, and if I'm going to bet on something, it's going to be on a bad
transistor based on the experience of some local mechanics. In any
case, I hope it's a simple fix one way or the other, because I don't
think I could ever work under the panel for a living.


JKG