Dear Hive mind,
I am trying to identify these 2 ceramic disc caps from a pair of Mordaunt Short speakers.
Code 1=
D
-135
05D
is this;
200V, 1.3uF, +-0.5% and
Code 2 =
D
-070
02C
is this;
200V, 7pF, +-0.25pF
Can anyone confirm or point out my error please.
I have attached pictures to help.
I am trying to identify these 2 ceramic disc caps from a pair of Mordaunt Short speakers.
Code 1=
D
-135
05D
is this;
200V, 1.3uF, +-0.5% and
Code 2 =
D
-070
02C
is this;
200V, 7pF, +-0.25pF
Can anyone confirm or point out my error please.
I have attached pictures to help.
Attachments
More likely to be a polyswitch, an auto-resetting protective fuse. Definitely not capacitors.
https://www.mouser.com/datasheet/2/240/Littelfuse_PTC_Rline_Catalog_Datasheet.pdf-1021735.pdf
https://www.mouser.com/datasheet/2/240/Littelfuse_PTC_Rline_Catalog_Datasheet.pdf-1021735.pdf
Measure with ohmmeter; if open circuit, then likely a capacitor. If a low resistance, then a thermistor or a protection device of some sort.
Different manufacturers use different codings.
A switching type PTC resistor is given a resistance rating according to the power handling and impedance of the loudspeaker driver it is required to protect against overload.
There is a calculator on this particular manufacturer's site:
Loudspeaker Protection Components
And there is more information on switching type PTC resistors here:
PTC Thermistor | Resistor Types | Resistor Guide
A switching type PTC resistor is given a resistance rating according to the power handling and impedance of the loudspeaker driver it is required to protect against overload.
There is a calculator on this particular manufacturer's site:
Loudspeaker Protection Components
And there is more information on switching type PTC resistors here:
PTC Thermistor | Resistor Types | Resistor Guide
P.S. Re use of calculator:
For bass drivers, the power to be entered is the system or bass driver power handling (RMS watts).
For tweeters, the power to be entered is suggested in accord with to the dome diameter.
For bass drivers, the power to be entered is the system or bass driver power handling (RMS watts).
For tweeters, the power to be entered is suggested in accord with to the dome diameter.
Those are clearly Littelfuse branded polyswitches
If you really want to read/discover the spec of those particular polyswitches you're gonna have to trawl through the datasheet provided on page one by Rayma, make some physical measurements for one and match them to the datasheet info, but be aware one of them might be long discontinued and not in the datasheet anymore.
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I'd be interested in which model of Mordaunt Short loudspeaker we are dealing with.
I presume it is one of the Series 2 models, a series with which I am familiar.
The best thing to do with those Positecs is to remove them.
If they have been subject to continuous overload, they may not have returned to their low resistance state.
Measure the resistance of your Positecs, taking the resistance of your multimeter leads into account.
You should get around 0.6 ohm and 0.4 ohm for the small and the big one respectively.
I presume it is one of the Series 2 models, a series with which I am familiar.
The best thing to do with those Positecs is to remove them.
If they have been subject to continuous overload, they may not have returned to their low resistance state.
Measure the resistance of your Positecs, taking the resistance of your multimeter leads into account.
You should get around 0.6 ohm and 0.4 ohm for the small and the big one respectively.
Attachments
All the above plus: even if they were capacitors, a "7 pF" one has no place inside a speaker cabinet 😱