mprobe model RS-3 part identification

[captainvideo462002@yahoo.]

I have an RS-3 that will not read current hen using the clamp mode. It
does work with the test leads though. I posted this a couple of months
back and it was suggested that there might be a couple of diodes
defective. I disasssembled the unit and the only thing that resembles
a diode is a small three terminal device near the bottom of the board
with a red dot on one end. Could this possibly be two diodes in series
with the cathodes connected together? There are no markings on this
device so I'm not sure what it is or if it really is bad. It reads
very low resistance in circuit on all terminals. Can someone please
help me with this? Thanks, Lenny.

 

[Franc Zabkar]

On Sat, 29 Aug 2009 11:46:10 -0700 (PDT),
"captainvideo462002@yahoo.com" <captainvideo462002@yahoo.com> put
finger to keyboard and composed:

I have an RS-3 that will not read current hen using the clamp mode. It
does work with the test leads though. I posted this a couple of months
back and it was suggested that there might be a couple of diodes
defective. I disasssembled the unit and the only thing that resembles
a diode is a small three terminal device near the bottom of the board
with a red dot on one end. Could this possibly be two diodes in series
with the cathodes connected together? There are no markings on this
device so I'm not sure what it is or if it really is bad. It reads
very low resistance in circuit on all terminals. Can someone please
help me with this? Thanks, Lenny.

If the device is a diode pair with the central pin being a common
anode or cathode, then why would the part require a dot? Such a dual
diode would be symmetrical about the centre pin.

If the two diodes were in series, then they could be used for ESD
protection. The centre pin would be connected to the signal input, the
cathode to the positive supply rail, and the anode to the negative
rail.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

On Aug 30, 2:39 am, Franc Zabkar <fzab...@iinternode.on.net> wrote:

On Sat, 29 Aug 2009 11:46:10 -0700 (PDT),
"captainvideo462...@yahoo.com" <captainvideo462...@yahoo.com> put
finger to keyboard and composed:

I have an RS-3 that will not read current hen using the clamp mode. It
does work with the test leads though. I posted this a couple of months
back and it was suggested that there might be a couple of diodes
defective. I disasssembled the unit and the only thing that resembles
a diode is a small three terminal device near the bottom of the board
with a red dot on one end. Could this possibly be two diodes in series
with the cathodes connected together? There are no markings on this
device so I'm not sure what it is or if it really is bad. It reads
very low resistance in circuit on all terminals. Can someone please
help me with this? Thanks, Lenny.

If the device is a diode pair with the central pin being a common
anode or cathode, then why would the part require a dot? Such a dual
diode would be symmetrical about the centre pin.

If the two diodes were in series, then they could be used for ESD
protection. The centre pin would be connected to the signal input, the
cathode to the positive supply rail, and the anode to the negative
rail.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Well I would agree that common cathode, (if thats what this is) would
seem more conventional in the center, however depending on the layout
of the circuit board, I could envision two diodes wired in series,
cathode to cathode and the package configured with the cathodes on one
side. Also there is no supply in the conventional sense. This is the
only component on the board which appears to be an active one. Unless
you use the instrument as a wired voltage meter,(a function that does
work), with the probes supplied this is basically a clamp type
ammeter. Lenny.

http://www.byramlabs.com/product_info.php/products_id/3021/product/AmprobeRS-3%20%20Clamp%20-%20On%20Multimeter%20Analog