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Positive or negative tip: how to tell?

N

nobobo

Jan 1, 1970
0
I have an old Sanyo cassette recorder, model M 1540A. Can find no
information on what polarity of tip it uses. Only know that it's 6.0
Volt. No markings on outside of case to show what it is. Sanyo website
and customer service has no information and websearches come up empty.

I have opened the unit. It takes 4 "C" cell batteries. The circuit
board is old and isn't labeled. I can't tell how the AC adaptor jack
is wired to the board. A label on the outside says to use AC Adaptor
6CV120 or 6CV121.

I have two adaptors I am considering using with it, both positive tip.
One is a class 2 transformer that outputs 6V DC and 300mA. The other
(much bigger)is labeled AC Adaptor and outputs 6V DC and 2000mA.

Any ideas?
 
B

Bob Myers

Jan 1, 1970
0
I have opened the unit. It takes 4 "C" cell batteries. The circuit
board is old and isn't labeled. I can't tell how the AC adaptor jack
is wired to the board. A label on the outside says to use AC Adaptor
6CV120 or 6CV121.

Check to see which end of the battery stack connects
to the PCB "ground" or common (generally, this will
be fairly easy to find on the PCB). The "tip" will
almost certainly be the OTHER end.

Bob M.
 
B

Ban

Jan 1, 1970
0
nobobo said:
I have an old Sanyo cassette recorder, model M 1540A. Can find no
information on what polarity of tip it uses. Only know that it's 6.0
Volt. No markings on outside of case to show what it is. Sanyo website
and customer service has no information and websearches come up empty.

I have opened the unit. It takes 4 "C" cell batteries. The circuit
board is old and isn't labeled. I can't tell how the AC adaptor jack
is wired to the board. A label on the outside says to use AC Adaptor
6CV120 or 6CV121.

I have two adaptors I am considering using with it, both positive tip.
One is a class 2 transformer that outputs 6V DC and 300mA. The other
(much bigger)is labeled AC Adaptor and outputs 6V DC and 2000mA.

Any ideas?

With your ohmmeter put one side to the battery negative connection and check
out which of the adaptors poles has continuity with it (possibly the
outside). Then you can insert the plug without modifications. You can then
try either supply.
 
M

Mike

Jan 1, 1970
0
Don't connect the meter when set to measure ohms to a power source! Make
sure you're measuring volts instead of ohms.

Mike
 
B

Ban

Jan 1, 1970
0
Mike said:
Don't connect the meter when set to measure ohms to a power source!
Make sure you're measuring volts instead of ohms.

Mike

Read again what I wrote and do not confuse the original poster please.
Ban
 
B

Ban

Jan 1, 1970
0
John said:
---
It would probably have confused the original poster less (and possibly
prevented him from damaging his meter or blowing a fuse, or
whatever...) if you'd have advised him to remove the batteries before
doing any continuity testing, don't you think?

How can you reach the terminal with the batteries inside? And I want to see
the guy that has working batteries in a years-old gadget?
 
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