Triplett 3423 meter movement help needed

S

Sam Lloyd

Guest
I've been attempting to repair the meter movement in my Triplett 3423
tube tester to correct an open circuit on the coil. The coil wasn't
fried, it just had a bad solder joint from the winding to the
"terminal" on the needle (front)side of the meter.

The meter now operates(!), although not as smoothly as it should. The
spring appears to be binding slightly due to a lack of planar
concentricity (best way I know to describe the problem), causing
sticking and poor repeatability. In other words, if you lay it on a
flat surface some sections of the spring will not lay flat, but will
stick up. I have spent a great deal of time gently poking and coercing
the spring, and while it's better than it was when I started, I just
can't seem to correct for the apparent damage I incurred when I first
ripped it apart.

So, it appears I need to replace the spring. Does anyone know of a
source for clock springs for meter movements? I don't know if there
are standard sizes, but FWIW the meter is a 4.5"x4", 100uA, 250 mV
type.

I may end up replacing the meter movement entirely, but I'd prefer to
just replace the spring as I've developed a decent skill level in
working with this stuff.

Any advice or direction as to a source for clock springs would be
greatly appreciated.

Thanks,
Sam
 
sam_lloyd18@yahoo.com (Sam Lloyd) writes:

I've been attempting to repair the meter movement in my Triplett 3423
tube tester to correct an open circuit on the coil. The coil wasn't
fried, it just had a bad solder joint from the winding to the
"terminal" on the needle (front)side of the meter.

The meter now operates(!), although not as smoothly as it should. The
spring appears to be binding slightly due to a lack of planar
concentricity (best way I know to describe the problem), causing
sticking and poor repeatability. In other words, if you lay it on a
flat surface some sections of the spring will not lay flat, but will
stick up. I have spent a great deal of time gently poking and coercing
the spring, and while it's better than it was when I started, I just
can't seem to correct for the apparent damage I incurred when I first
ripped it apart.

So, it appears I need to replace the spring. Does anyone know of a
source for clock springs for meter movements? I don't know if there
are standard sizes, but FWIW the meter is a 4.5"x4", 100uA, 250 mV
type.

I may end up replacing the meter movement entirely, but I'd prefer to
just replace the spring as I've developed a decent skill level in
working with this stuff.

Any advice or direction as to a source for clock springs would be
greatly appreciated.
Click to expand...
Are you sure it's really the spring? Unless sections of the spring
are touching each other or something else, it is probably not the source
of your sticking. Have you double checked that ferrous particles haven't
made their way between the magnet and yoke?

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.
 
Sam,

I'm not sure I got rid of ALL contamination, but I'm fairly sure the
main interference is spring related. When I disengage (unsolder) the
spring the needle moves freely and doesn't stick. I believe adjacent
spring wraps are rubbing and/or crossing in some cases. Also, I think
the spring is no longer wound as tightly as it should be because I
have to turn the zero adjust full CCW to take the needle to zero.

Got any tips on spring wrapping technique? I'm thinking maybe removing
the spring and laying it on double-faced tape to facilitate holding it
while I adjust the wraps.

Thanks,
Sam





Are you sure it's really the spring? Unless sections of the spring
are touching each other or something else, it is probably not the source
of your sticking. Have you double checked that ferrous particles haven't
made their way between the magnet and yoke?

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.
Click to expand...
 
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